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NASA Contractor Report 352174

Investigation of Impingement Region andWall Jets Formed by the Interaction of HighAspect Ratio Lift Jets and a Ground Plane

(N ASA -CR- 152174) INVESTIGATION OF N81-19017IMPINGEMENT REGION AND WALL JETS FORMED BYTHE INTERACTION OF HIGH ASPECT RATIO LIFT 14c*A01 /mFO A01JETS AND A GROUND PLANE Final Report, 19 UnclasSep. 1977 - 19 Sep. 1978 (McDonnell Aircraft GJ/02 1178,31

D.R. Kotansky and L.W. Glaze

McDonnell Aircraft CompanyMcDonnell Douglas CorporationSt. Louis, Missouri

Prepared forAmes Research Centerunder Contract NAS2-9646

NILV%National Aeronautics andSpace Administration

I

0

T

apert o, G overnment Accession o, , Recipient's Catalog o,NASA CR-152 .:.74

T itle and Subtitle + 5. Report DateInvestigation of Impingement Region and Wall .Jets 19 September 1978Formed by the Interaction of High Aspect Ratio Lift 6, Performing Organization CodeJets and a Ground Plane

7. Author(s) 8, er orm ng Organization Report No,

Donald R. Kotansky10. Work Unit No.L10 d W. Glaze

9, Performing O rganization Name and Address

McDonnell Aircraft Company11. Contract or Grant No.P.O. Box 516

St. Louis, Missouri 63166 NAS2-964613. _Type of eport and Periodovere

Final Technical.1 ponsor^ gAgency l as me anAddress,National Aeronautics and Space Administration 9/19/77 - 9/19/78

14. Sponsoring Agency CodeAMES Research CenterMoffett Field, California 94035

}TS.--Supplementary Wotes

AbstractAn experimental investigation was conducted of the flow field character-

istics of impinging turbulent jets emanating from rectangular exit area con-verging nozzles of exit area aspect ratio four, six and eight. The primaryemphasis was placed on the determination of the azimuthal distribution of theradial momentum flux of the wall jet about the impingement region of singleJets. The measured azimuthal distributions of wall jet radial momentum fluxin the ground plane we.ee found to be strongly directional and sensitive torectangular nozzle exit area aspect ratio, jet impingement angle and heightabove ground, H/D. In addition to the basic investigation of impinging rect-angular j ets, the effects of jet exit velocity profile non-uniformities wereinvestigated, and a limited number of dual nozzle (two ,jet) ,jet impingementflow field investigations were conducted.

The data obtained from the single nozzle rectangular jet impingement in-vestigations were incorporated into an existing VTOL aircraft ground ;flow fieldcomputer program. This provides an extended jet impingement data base for thecomputation of ground flow fields which was pl.eviousl.y based solely on theimpingement characteristics of round jets. This computer program togetherwith the Douglas Neumann program modified for V/STOL applications may be usedfor the analysis and prediction of flow fields and resulting forces and momentson multi -jet V/STOL aircraft hovering in ground effect.

17. Key Words (Suggested by Authors)) 18, Distribution StatementV/STOLGround effectsJet impingementNon-axis ;y►tmnetric jets

Security Classif ( of this report 20. Security Classif (of this page) 21. No. of Pages 22. Price

1 :JUnclassifiedI

Unclassified 85

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FOR k,'. W'o RD

This report was prepared, by the Aerodynamics Department of40V the McDonnell Aircraft Company (MCAIR), St. Louis, Missouri, for

the Ames Research Center of the National Aeronautics and SpaceAdministration. The objectives of the study were to investigateexperimentally certain characteristics of impinging turbulentjets emanating from rectangular exit area nozzles of high aspectratio and to incorporate the experimental results into a VTOLground flowfield computer program developed originally for theNaval Air Development Center. Specifically, the primary datarequired were the azimuthal distributions of turbulent wall jetradial momentura flux about the impingement region of the rec-tangular jets. The in^.lusion of these data into the ground flow-field computer program provides an extended jet impingement database for the computation of ground flow fields which was pre-viously based solely on the impingement characteristics of roundjets. This computer program together with the Douglas Neumannprogram modified for V/STOL applications may be used for theanalysis and prediction of flow fields and resulting forces and

Ifmoments on multi-jet V/STOL aircraft hoverincl in ground effect.

The principal investigator of this study was Dr. Donald A.Kotansky of the McDonnell Aircraft Company Aerodynamics Depart-Tent. The NASA Ames technical monitor was David G. Koenig ofthe Large Scale Aerodynamics Branch of the Plight Systems ResearchDivision.

iii

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TABLE GF CONTENTS

t

SECTION PAGE

SUMMARY . 1

INTRODUCTION . . . . 2

EXPERIMENTAL TEST PROGRAM . . . . . 4

TEST FACILITIES, HARDWARE AND INSTRUMENTATION 6

Test Facilities . . . . . . . . . . . . . . . 6Nozzles . . . . . . . . . 7Ground Board « . . . . „ . . . . . . . . 7Hot Film Anemometer . . . . . . . . . . . . . . 8

DATA ACQUISITION AND REDUCTION . . . , . . . . . . . . 9

Data Acquisition . . . . . . . . 9Data Reduction . . . . . . . . . . . . . . 10

EXPERIMENTAL 'RESULTS . . . . . . . . . . . . . 11

Free aet Characteristics . . . . . . . . . . . . 11Reynolds Number Effects . . . , . . . . . . . . . . 1'?Vertical Impingement . . . . . . . . . . . . . . 12Oblique Impingement . . . . . . . . . . . . 13Velocity Profile Effects . . . . . . . . 19Nozzle Spacing Effects . . . . . . . . . . . . . . i5

MODIFICATION OF GROUND FLOWFIELD PROGRAM . . . . . 16

CONCLUSIONS . . . . . . . . . . . . . . . . 16

APPENDIX . . . . . . . . . . . . . . . . . . 18

REFERENCES . . . . . . . . . . . . . . . . 85

iv

-T-77

LIST OF TABLES

Table No.

1 Basic Test Program . . . . . . . . . . . . . . 19

2 Flowfield Surveys . . . . . . . . . . . . . . 19

3 Normalized Wall Jet Momentum Flux DistributionCoefficients, Vertical Impingement 20

4 Normalized Wall Jet Momentum Flux DistributionCoefficients, Oblique Impingement - Pitch

. . 21

5 Normalized Wall Jet Momentum Flux DistributionCoefficients $ Oblique Impingement - Roll . . . 22

LIST OF ILLUSTRATIONS

Figure No. Ra2_0

1 Test Nomenclature . . . . . . . . . . . . . . 23

2 Single Nozzle Configurations . . . . . . . . . 24

3 Aspect Ratio Four Rectangular Exit ConvergingNozzle . . . . . . . . . . . . . . . . . . . . 25

4 Flow Spoiler installation . . . . . . . . . . 26

5 Aspect Ratio Six and Eight Rectangular ExitConverging Nozzles . . . . . . . . . . . . . . 27

6 Ground Board and Support Hardware . . . . . . 28

7 Hot Film Anemometer Mean Flow Calibration . . 28

8 Hot Film Anemometer Yaw calibration . . . . . 29

9 Wind Tunnel Test Data Acquisition Elements . . 30

10 Wind Tunnel Test Data Reduction Program . . . 31

11 Free-Jet Velocity Profile, L/D = 4 . . . . . . 32

12 Free-Jet Velocity Profile, L/D = 8 o . . . . . 33

13-24 Wall Jet Velocity Profile . . . . . . . . . . 34-45

25-33 Azimuthal Distribution of Wall Jet RadialMomentum Flux, Vertical Impingement . . . . . 46-54

34-42 Azimuthal Distribution of Wall Jet RadialMomentum Flux, Oblique Impingement-Pitch . . . 55-63

v

LIST OF ILLUSTRATXONS (Continued)

Figure No.- Me-43-51 Azimuthal Distribution of Wall Jet Radial

Momentum Flux,Oblique Impingement-Roll . . . . . 64-72

52-54 Azimuthal Distribution of Wall Jet RadialMomentum Flux, Vertical Impingement-Dual Jut . 73-75

55-57 Dual Jet Yaw Angularity . 0 0 0 * 0 0 0 * 0 76-78

58-60 Azimuthal Distribution of Wall Jet RadialMomentum Flux,Vertical Xmpingement-Dual Jet . 79-81

61 Momentum Flux Distribution Curve-VittVarticalimpingement . . . . . . . & 0 . a 0 P 0 # . 0 . 82

62 Momentum Flux Distribution Curve-Fit,ObliqueImpingement-Pitch . . . . . . . . . . . . . . . 83

63 Momentum Flux Distribution Curve-Fit, ObliqueImpingement-Roll . . . . . o . . . . . . . . . . 84

vi

NOMENCLATURE

D Rectangular nozzle exit width

E Voltage

AE Voltage difference (E2 - E l ) between HrA channels I and 2

f 0) Momentum distribut,-Lon about jet impingement region

H Nozzle exit height above ground

HFA Hot film anemometer

L Rectangular nozzle exit length

L/D Rectangular nozzle exit area aspect ratio

Momentum flux

mass flow

N Normal distance above ground plane

NPR Nozzle pressure ratio

P Pressure

R Radius measured from real or apparent jet impingementpoint

Re D Reynolds number based on rectangular nozzle exit width,V. D p

Re peD P

S Nozzle exit centerline spacing between long axes

T Temperature

U Wall jet velocity

V Jet velocity

VWFreestream velocity

X ' Y ' Z Cartesian coordinates

Z Jet centerline coordinate

a jet impingement angle measured in pitch (rotation aboutshort nozzle exit axis, see figures 1 and 34)

AM-, 8 j

Jet impingement angle measured in roll (rotation aboutlong nozzle exit axis, see figures 1 and 43)

1

vii

NOMENCLATURE (Continued)

p Density

$ Azimuthal angle measured around periphery of jet impinge-ment region. For aj 9 90 0 or 8j # 90 0 , = 0 0 in direc-tion of horizontal component of jet mean flow (see figures1 0 34 and 43)

+Y Wall jet flow angularity with respect to a radial lanethrough the jet impingement point

Subscripts

l,2 Anemometer channels

amb Ambient conditions

e Jet exit station

j Jet

max Maximum value

N Nozzle

p Probe

. T Total properties

1/2 Half-velocity point

r

viii.

I

INVESTIGATION OE IMPINGEMENT REGION At"!DWALL JETS FORMED BY THE INTERACTION OF HIGH

A

ASPECT RATIO LIFT ,JETS AND A GROUND PLANE

DONALD R. KOTANSKY AND LLOYD W. GLAZE

SUMMARY

An experimental investigation was conducted of the flow

field characteristics of impinging turbulent jests emanating from

rectangular exit area converging nozzles of exit area aspect

ratio four, six and eight, The primary emphasis was placed on

the determination of the azimuthal distribution of the radialmomentum flux of the wall jet about the impingement region.

Both vertical and oblique impingement were investigated for vari-

ous values of the ratio of height above ground to nozzle exitwidth, H/D. The oblique impingement conditions included simu-

lated nozzle rotations about the short axis of the nozzle exit

opening (pitch) and also,, about the long axis of the nozzle exit

opening (roll). However, simultaneous combinations of pitch

` and roll were not investigated. The measured azimuthal distri-

butions of wall jet radial momentum flux in the ground plane were

found to be strongly directional. They were found to be sensi-

tive to rectangular nozzle exit area aspect ratio, jet impinge-

ment angle and height above ground, H/D.

Reynolds number effects were investigated by determining

the non-dimensional shape of the wall jet velocity profiles for

fixed test conditions while varying only the Reynolds number

(nozzle pressure ratio) over a range of low nozzle pressure

ratios to avoid compressibility effects. The jet exit Reynolds

number range investigated was from 146,000 to 275,000 based on

the rectangular nozzle exit width. Reynolds number effects

were found to be insignificant over this range. The effects of

a flow spoiler inserted in the exit plane of the aspect ratio

four nozzle were investigated over a limited range of jet im-

pingement test conditions to identify the possible influence of

jet exit velocity non-uniformities on the azimuthal distributions

If of wall jet radial momentum flux. These effects, also, were

found to be insignificant..Additional measurements of azimuthal distributions of wall

jet radial momentum flux were conducted for rectangular nozzlepairs of exit area aspect ratio eight which produced dual jetsimpinging vertically for two values of the height above groundto nozzle width ratio, H/D. This was accomplished for threevalues of nozzle exit centerline spacing (between the long axesof the nozzle exit openings) rat:ioed to nozzle exit openingwidth. The selected combinations of jet exit spacing, SID, andheight above ground, H/D, that were investigated resulted in nosignificant merging of the jets prior to ground impingement.A significant flux of wall jet radial momentum in zhe groundplane was identified along the ideal stagnation line formed bythe interac,ion of the two jet flows for these cases.

INTRODUCTION

Recent studies have revealed the complexity of the viscousflowfield produced by the .multiple lift jet systems of v/STOLaircraft in ground effect. Test data have shown the sensitivity

of the net ,forces and moments acting on the vehicle to thegeometry of the airframe and the propulsive lift jet system incombination with the ground surface. A number of recent studieshave been directed specifically at the development of engineer-

ing methodologies for the prediction of induced forces and

moments on arbitrary multi -jet V/STOL aircraft both in and outof ground effect. Pertinent recent work in these areas is

summarized in a "V/STOL Aerodynamic Technology Assessment"

published by the Naval Air Development Center (NADC), reference

1.

Most of the experimental, and analytical work to date hasbeen concerned with multi -jet flows emanating from ax symmettric(round) nozzles,since these types of nozzles have been associ-ated with CTOL and V/STOL aircraft historically. Only recently

has serious effort been expended on the design and development

of non=axisymmetric nozzles. This is largely a result of inves-

tigations of potential benefits associated with the substitution

2

of non-axisymmetric nozzles for round nozzles in CTOL and lift-plus-lift-cruime V/STOL aircraft prDpulsion systems and thedirect requirement for rectangular nozzles in certain STOL andVTOL systems such as upper surface blowing and thrust augmentingejector systems. The work described herein expands a neededempirical data base on turbulent jet imp."Oigement characteristicsfrom that currently available for round jets to rectangul^i •,' exitarea jets of aspect ratio four, six and eight.

The computation and prediction of the viscous (turbulent)flowfield between a multi-jet V/STOL aircraft and the groundis strongly dependent on the mean stru qtv-o,e (geometry) of theflows in the turbulent jets. The significant jet mean flowgeometry and overall flowfield geometry includes:

o The two dimensional mean velocity distribution at thenozzle exit, V je (XN , YN , ZN = 0) (this specification

includes nozzle exit shape);o Lift jet system arrangement including the number of

Jets i jet exit s-n-ci ixis and jet exit- orientation withrespect to thr aircraft axes (including vector andsplay angles); and

o Aircraft orientation and height above ground.Most of the above geometric variables were taken into

account in the development of a ground flowfield prediction com-puter program by the McDonnell Aircraft Company for NADC, whichis described in detail in reference 2. Howover t this work wasbased on the fundamental free jet flow development and Impinge-ment characteristics of round jets which, for the most part,were available in the published literature. Specifically,the free jet entrainment data of Xleis and Foss (reference 3)and the geometric and kinematic properties of free and imping-ing round jets established by Donaldson and Snedeker (reference4) were utilized extensively. The data of Donaldson and Snedekerwere also utilized to determine required analytical expressionsfor wall jet entrainment.

I .

3

LoVq

A key element in the modelling of the ground surface flow-field below a hovering V/STOL aircraft is the local distribu-tion of momentum flux about the individual jet impingementpoints on the ground plane. The data of Donaldson and Snedekershow that this distribution for a round turbulent jet issensitive to the i o^t impingement angle and relatively insensi-tive to tho ratio of height above ground to nozzle exit dia-mete-r (H/D). These distributions of momentum flux togetherwith the magnitudes of the total momentum fluxes emanatingfrom the nozzle exits establish the location and (momentum)strength of the fountains in the flowfield below the aircraft.

The primary purpose of this study was to determine experi-mentally the azimuthal distributions of wall jet radial momentumflux about the impingement points of high aspect ratio rectan-gular jets as a function of nozzle exit area aspect ratio, jetimpingement angle and nozzle exit height above ground. Addi-tionally, Reynolds number effects, non-uniformities in rectangularjot exit velocity profiles and dual nozzle impingement including

jet exit spacing effects were investigated.This data base for high aspect ratio rectangular nozzles

was then incorporated into the ground flowfield qomputerprogram originally developed for round jets for NADC and deliveredto NASA Ames. This computer pro4ram, together with the DouglasNeumann potential flow program modified fov V/STOL applications(reference 5) may then be used in the analysis and predictL^nof induced forces and moments on multi-jot V/STOL aircrafthovering in ground effect as described in reference 2.

EXPERIMENTAL TEST PROGRAM

The experimental test program was designed to provide data

on the rectangular nozzle free jet characteristics and jet im-

pingement characteristics ov6r a meaningful vange of pertinent

parameters associated with the operation of a V/STOL aircraft in

the hover mode in ground effect. The baseline nozzle configur-

ation and test parameter variations are sui-v.arized in table 1.

The purpose of the free jet surveys was primarily to establish

4

the quality of the flow emanating from the high aspect ratiorectangular nozzles in terms of velocity profile shape and flowsymmetry achieved. Reynolds number effects were investigated bydetermining wall jet velocity profiles for a fixed set of florageometry while varying only nozzle pressure ratio at low pressureratio levels to avoid the effects of compressibility.

The desired wall jet momentum flux distributions about therectangular jet impingement points wore established by surveyingthe turbulent wall jet velocity profiles about the peripheryof the jet impingement region for vertical and oblique jet im-pingement. In the oblique impingement experiments, pure pitch(about the nozzle exit short axis) and pure roll (about the noz-zle exit long axis) were investiga.tern, but combinations of pitchand roll were not investigated. In the case of vertical impinge-ment, one quarter of the periphery was surveyed since two planesof flow symmetry existed, and in the case of oblique let impinge-ment, one half of the periphery was surveyed since in this caseonly one plane of

symmetry ax- Jis -IL-ed . The

wall jets wve ruo Survoye d.

at 15 0 increments in azimuth (^) uvor the region of interestabout the jet impingement point. Figure I defines the geometryand the coordinate systems for the jet impingement tests. Itshould be noted that the rectangular exit area nozzle width, D,was a fixed physical dimension of 2.0 cm. for all nozzles through-out the test program.

Nozzle exit flow velocity profile non-uniformities and theireffect on the azimuthal distribution of wall jet radial momentumflux about the rectangular jet impingement point were investi-gated with the aspect ratio four nozzle at the lowest height aboveground (H/D = 23, for both vertical and oblique jet impingement.The flow non-uniformity was produced by placing a circular rod(0.47 cm. diameter) along the long axis of the aspect ratio fournozzle at the center of the nozzle exit plane. Free jet profileswere determined with the flow disturbance in place to quantifythe extent of the velocity profile non-uniformity produced.Wall jet surveys were then conducted to identify the effectsof the flow disturbance on the wall jet momentum distributions.

5

The final segment of the test program consisted of surveys

of wall jet momentum flux distributions about the impingement

region of pairs of aspect ratio eight rectangular jets. This

was accomplished for three values of nozzle exit spacing be-

tween the nozzle exit long axes (SID =4, 6 1 8) with vertical im-

pingement of both jets for two values of height above ground

(H/1D = 2, 8). The flowfield surveys obiained during the test

program are summarized in table 2.

TEST FACILITIES, HARDWARE AND INSTRUMENTATION

Test Facilities

Test operations were conducted utilizing the multiple jet

interaction test apparatus of the Inlet Simulator (IS) test cell,

which is a Part of the McDonnell Aircraft Company (MCAIR)

Propulsion Subsystem Test Facility (PSTP). The PSTF was de-

signed and developed specifically to allow a wide range of ex-ploratory static testing to b(: accomplished rapidly and economi-

cally. The facility utilizes high pressure (4137 kP,) air,

sharing the air storage system of the MCAIR Polysonic Wind Tunneland vacuum sources of low pressure facilities.

The jet interaction test apparatus utilizes the pressure

control system of an adjacent PSTF test cell to set, and auto-

matically hold, nozzle pressure ratio. Two 48.3 cm. ID settling

chambers are supplied with high pressuri air to provide uniform

flow to the nozzle plenums. The settling chambers have conical

and normal screens. The nozzle plenums are I 'D" shaped with theflat side toward the test model. The plenums are provided with

two internal screens and removable nozzle mounting plates that

are compatible with various nozzle configurations. A special

nozzle mounting plate was fabricated for this test to accommo-

date the three, high aspect ratio rectangular nozzles. in addi-tion, this nozzle mounting plate provided the capability of set-

ting three nozzle centerline spacings (SID = 4.6,8) for the dualnozzle -configurations through the use of zppropriate spacer plates,

6

Nozzles

Five, high aspect ratio, rectangular nozzles were fabrica-ted for this test. The nozzles Caere constructed of fiberglasswhich was permissible because of the low nozzle pressure ratiosselected for the test program. Three of these nozzles, shownschematically in figure 2 (L/D = 4,6 f 8), were used for thesingle jet configurations and had internal flow area contractionratios of 10.00, 8.33 and 7.50 respectively. The two nozzles(L/D = 8) used for the dual jet configurations in which theeffects of jet spacing were investigatei had internal flow areacontraction ratios of 3.96. Photograp),,,s of the nozzles areshown in figures 3 and S. The aspect ratio four nozzle shown infigure 3 is shown with the nozzle exit flow spoiler in place.Details of the flow spoiler installation are shown schematicallyin figure 4. The aspect ratio eight and E,i.x single nozzles andthe aspect ratio eight dual nozzle pair are shown in figure 5.The individual nozzles in the nozzle pair used for the jetspacing investigation were structurally reinforced with a fiber-glass ring around the periphery of the converging section nearthe nozzle exit as can be seen in :^igure 5.

Ground Board

A 150 cm. diameter, circular ground board, fabricated fromaluminum, was used to simulate the ground plane. The groundboard was mounted on a motor driven, rotational bearing whichallowed for 360 1 azimuthal (^) rotation. in additionr thebearing was mounted on a gimballed frame affixed to a movablecart with which variations in ground board height, H/D, couldbe established. The gimballed frame made po6sible jet impinge-ment pitch angles, a j , of 60 0 , 75 0 or 90 0 (see figure 6). Witha 90 1 rotation of the base of the gimballed frame on the cart,ground board roll angle, O i , settings of 60 0 , 75 0 or 90 0 wereobtainable. Use of the gimbal system permitted changes inground board pitch and roll angle while maintaining the centerof the ground board coincident with the jet centerline asprojected from the fixed nozzle exit location which was

7

N^W L

established by the plenum and support system. Height above

ground was defined as the distance from the center of the nozzle

exit to the ground plane measured perpendicularly to the ground

plane.

In making a wall jet velocity profile survey, a two component

hot film anemometer probe was traversed through a .508 cm. hole

in the ground board, in a direction normal to its surface,

using a remotely controlled, one degree-of-freedom, probe tra-

verse device. This probe drive device was mounted on the back

of the ground board adjacent to the five radial hole positions

(R/D = 6.5, 14.0 1 21.5, 29.0, 36.5). The five holes were loca -ted at five different azimuthal positions on the ground board

with a 72 0 azimuthal spacing between radial positions as shown

in figure 6. This was done to prevent any flow disturbance

from an upstream hole on a downstream measurement station.

Hot Film Anemometer

The free jet and wall jet velocity profile surveys were

accomplished with two component, directionally sensitive hot filar

anemometer probes. The selected probe configuration was the

Thermo- ,Systems Model 129.0-20 "Cross -Flow" probe used in conjunc-

tion with a two--channel Thermo-System model. 1.050-2C anemometerunit. The plane of the sensor cross was parallel to the ground

board resulting in the measurement of velocity and flow direction

in the R, ^ plane. Angularity was sensed with respect to the

local, = constant reference at the five ground board hole posi-

tions. The Local angularity zeroing technique for the probe

sensors is discussed in the Data Acquisition section. A total

of four dual sensor "Cross-Flow" probes were consumed during the

experimental test program, two probes were lost to identifiable

electrical malfunctions and two were lost due to identifiable

mechanical. damage.

All probes were calibrated for mean flow velocity and flow

angularity in a modified Thermo-Systems Model 1125 Calibrator.

Angularity data were obtained with the calibrator supported on a

manually adjusted turntable which allowed the calibrator to be

rotated about the probe support axis. The zero angularity refer-

ence position for each probe was established by nulling out the

8

difference between the two sensor outputs at a selected mean

velocity level. Calibrations were performed at an anemometer

overheat ratio of 1.5 for mean velocities in the range of 0 to

approximately 90 mjsec and for yaw a ngularity, *, of +25 0 at

four selected mean flow velocity magnitudes. A set of actual,

mean flow and yaw angularity calibration curves are shown in

figures 7 and 8 for probe no. H576. These calibration curves

were fit with polynomial expressions for inclusion in the data

reduction program.

DATA ACQUISITION AND REDUCTION

Data Acquisition

Riot film anemometer probe sensor outputs and the probe sen-

sor position potentiometer output were recorded on magnetic tape

by the PSTF data acquisition system as the probe was traversed

through the free jets and the wall jets for each test condition.

The data acquisition system (DAS) is shown schematically in

figure 9. The DAS scanned all data channels continuously at ascan rate of ter, scans per second. The anemometer output signals

were filtered with a low pass filter to 2 Hz. Probe data were

recorded continuously for two second intervals at the rate of

twelve data intervals per minute during all traverses. The

traverse rate was preset on the remote control unit of the

traverse drive motor and varied from approximately 3 to 8 cm..

per minute depending on the wall jet thickness. For the wall

jet surveys, the traverses were begun slightly below the ground

plane level and continued through the wall jet until the anemo-

meter output reached a preselected minimum level. In addition

to recording the hot film anemometer output and probe position

on the PSTF DAS, an on-line X-Y-Y plotter was wired into the

test instrumentation system to provide graphical displays of

both channels of anemometer output as a function of probe posi-

tion. Both types of data recording were used for all velocity

profile surveys in the test program. The X-Y-Y plotter output

allowed on-line monitoring of the duality and repeatability of

the data.

a

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Prior to each azimuthal (fl sweep series of velocity profilesurveys, the anemometer bridge was balanced to insure compati-

bility with the overheat ratio of the hot film probe calibrationperformed prior to the test. Since changes in flow temperature

affect the probe output, it was periodically monitored throughouteach series of runs, and the anemometer bridge was rebalanced if

a significant temperature change was indicated. To further checkthe quality of the data recorded, the first survey of an azimuthal

sweep series was repeated at the end of the series (and, in some

cases, a whole series of runs was repeated) to insure the repeat-

ability of the hot film data.

in order to properly align the anemometer probe with the

flow,the probe calibration chamber was mounted to the circular

ground board such that the chamber centerline coincided with a

radial line connecting the ground board renter with the probe

center. With the anemometer probe extended through the ground

board and aligned with the calibration chamber nozzle flow,

conditions corresponding to a point on the mean velocity cali-

bration curve were reproduced, and the probe was rotated until

no voltage difference was indicated between the two channels of

the anemometer, indicating zero flow angularity. This procedure

was followed each time the probe was moved to a new radial sta-tion.

Data Reduction

The wind tunnel test data reduction program is shown in

block diagram form in figure 10. The data reduction program,

executed on the CDC Cyber 175 computer, summed and averaged each

two second interval of data scans to produce single point hot

film anemometer and probe position data. The averaged hot film

data were then input to the calibration curves with the result-

ing output being mean velocity and yaw angularity. The program

also integrated the velocity and velocity squared profiles using

the trapezoid rule with the upper limit of integration (N 1 ) pre-

determined as a common value for each run in an azimuthal sweep

series. These integrated values were then used in the calcula-

tion of wall jet mass flow, ;, and wall jet momentum flux, 1,1,

as follows:

d^ = P U WINfN=O

N

d= P U 2RdN f

N=O

Additional data output by the data reduction program includednozzle configuration, nozzle height above the ground board (II/D),

jet impingement angle ( ot j or e j )p nozzle pressure ratio (NPR),probe radial position (R/D), ground board azimuthal angleand ambient temperature (T amb ) and pressure (P amb)"

EXPERIMENTAL RESULTSThe objectives of the experimental test program were dis-

cussed in the section entitled Experimental Test Program. Thetest was conducted in six phases corresponding to the six majoritems in table 1. The resull-.6-:1 of the experimental investigationwill be presented in that same order largely through the presen-tation of plots of the experimental test measurements.

Free Jet CharacteristicsFree jet surveys were performed to investigate the shape of

the velocity profile produced at the nozzle exit and to examinethe symmetry of the jet flows. Velocity profile surveys wereobtained for the test conditions given in table 1 under Free JetCharacteristics. In all cases, the velocity profile data indi-cated acceptable nozzle exit flow conditions. Figures 11 and 12present the jet exit velocity profiles for the aspect ratio fourand eight rectangular nozzles. Data are presented at four posi-tions (XN/L) across the nozzle exit plane from the nozzle mid-plane (XN/L=O) 'to the edge of the nozzle (XN/L=0.50). A slightnon-uniformity in velocity level is noted in the aspect ratioeight nozzle (internal contraction ratio of 7.50) at the XN/L0.17 survey position. The effects of the turbulent shear stresson the edge of the velocity profile (at the XN/L=0.50 surveyposition) can be clearly seen in both figures 11 and 12.

11

Reynolds Number Effects

Reynolds number effects were :investigated by determining

the characteristic shape of the wall jet non--dimensional velocity

profiles for a constant set of parametric test conditions while

only the Reynolds number (nozzle pressure ratio) was varied.

Three Reynolds numbers were investigated; 146,000; 205,000 and

275,000 corresponding to nozzle pressure ratios, NPR, of 1.07

1.15 and 1.28. figures 13, 14 and 15 present non-dimensionalwall jell. velocity profiles for the aspect ratio six nozzle at

H/D 8.0. These data were measured at R/D = 14.0 and 0 = 00

which corresponded to a radial position in the ground plane that

was perpendicular to one of the short sides of the rectangular

exit area nozzle. Figures 16, 17 and 1.8 show similar data for

the $ = 90 0 position (in a radial direction in the ground plane

perpendicular to one of the long sides of the nozzle exit).

Figures 19 through 24 show a similar set of data for the same

nozzle and test conditions with the velocity profiles obtained

at the R/D = 29.0 radial. position. From these data and corres-

ponding data on the aspect ratio four and eight nozzles, it was

concluded that no significant Reynolds number effects Caere pre-

sent. This result is consistent with the observations of R.cou

and Spalding, reference 6, who noted that for free jet exit

Reynolds numbers in excess of approximately 30,000,flow charac-

teristics were insensitive to Reynolds number.

Vertical Impingement

The basic characteristics, including azimuthal distribu-

tions of wall jet radial momentum flux, for vertically impinging

jets emanating from rectangular exit area nozzles of aspect

ratio four, six and eight were obtained for the test: conditions

given in tabled . Figures 25 through 33 present the azimuthal

distributions of wall jet radial momentum flux measured in this

phase of the test program. On each curve, the independent vari-

able is the azimuthal angle, ^, over a range of one quarter of

the jet impingement region periphery from a perpendicular to a.

short nozzle side at ^ 0 0 to a perpendicular to a long nozzle

side at ^ 901 in the ground plane. The measurements at radial

stations R/D = 14.0 and R/D 29.0 are presented.

12

The data in figures 25 through 33 clearly indicate that the

preferential, direction of momentum :flux is perpendicular to the

long side of the rectangular nozzle exits, and that this direc-

tional bias is a function of H/D decreasing with increasing H/D.

However, even at H/D = 16, this preferential, direction is still

present indicating that the impinging free jets were strongly

non-axisymmetric even for the lowest aspect ratio. Most of the

data show a decrease in the magnitude of the radial momentum flux

with increasing R/D from R/D 14.0 to R/D 29.0.

Oblique Impingement

The azimuthal distributions of wall jet radial momentum

flux for oblique impingement are shown in figures 34 through 42

for oblique impingement caused by rotation about the short axis

of the nozzle exit (pitch) and in figures 43 through 51 for

oblique impingement caused by rotation about the long axis of

the nozzle exit (roll). In these figures, the independent vari-

able is the azimuthal angle, ^, over a range of one half of the

jet impingement region periphery. For the pitch data (figures

34-42) the angles ^ = 0 1 and ^ 180* correspond to directions

perpendicular to the short sides of the nozzle exit, with ^ = 00

corresponding to the direction of the horizontal component of

the free jet mean flow (see insert in figure 34). For the roll

data (figures 43-51) the angles ^ = V and ^ = 180* correspond

to directions perpendicular to the long sides of the nozzle exit,

with 0 = 00 corresponding to the direction of the horizontal com-

ponent of the free jet mean flow (see insert in figure 43).

The parametric variable on each figure is the pitch or roll im-

pingement angle in each case except for figures 42 and 51.

Figures 42 and 51 present the effects of parametric variations

of nozzle aspect ratio on the momentum flux distributions for

cc j = 60 0 (pitch) and e ' = 60°, (roll) respectively.

The strong ;influence of oblique impingement in both pitch

and roll cases is clearly evident from these figures. In pitch,

the largest fraction of momentum flux appears in a ^ direction

approximately coincident with the magnitude of the impingement

angle, and all significant flux of momentum occurs within the

1.3

grange of 00 to 1200 of the impingement <egion periphery.

t:The exact location of the momentum flux peak in the pitch inves-tigations, especially at H/D = 2 and 4 1 is somewhat uncertain,since the wall jet profiles were obtained at fixed intervals of15 0 in azimuth. The roll data indicate strong distributions ofmomentum flux in the sectors of azimuth adjacent to perpendi-culars to the long sides of the nozzle exit (0 = 0 0 and 0 = 1800),with the strongest momentum flux occurring at the 0 = 0 0 posi-

tion as would be expected based on the simplest flow deflection

model.velocity Profile Effects

Exit velocity profile non-uniformities were created by

affixing a flow spoiler to the nozzle exit plane of the aspectratio ,four nozzle, as shown in figures 3 and 4. Two flow spoilers

were considered. a 0.51 cm (0.20 in.) metal bar and a 0.47 cm(3/16 in.) metal. rod. The rod was chosen because it created a

more symmetrical velocity depression. Wall jet surveys wereobtained for this configuration at one nozzle hei ght above ground

(H/D = 2.0), two radial stations (R/D = 6.5, 14.0) and for both

vertical (a j = e j = 90 0 ) and oblique impingement (a j = 600,

75 0 0j = 60°, 75°) at ten azimuthal stations in the vicinity

of the velocity depression. Surveys of the magnitude of the

velocity profile non-uniformity created in the free jet werealso conducted. At an axial station of one nozzle width

downstream of the aspect ratio four nozzle exit (Z N/D = 1.0) a

velocity depression of 89 m/sec out of a maximum of 149 m/secwas measured. This depression mixed out of the jet very rapidly,

and at ZN/D = 4.0, a central flat profile had formed with a velo-

city magnitude of approximately 126 m/sec. Because of this

rapid mixing within the jet, the detrimental effects of the flowspoiler appear largely to reduce nozzle thrust performance, but

to have little, if any, effact on the wall jet radial momentumflux distributions. In fact, this was the case, since no signi-

ficant indication of a local velocity depression could be iden-tified for any of the test conditions investigated even at theminimum radial: position of R/D 6.5.

14

Nozzle Spacing Effects

Azimuthal, distributions of wall jet radial momentum flux

were obtained for pairs of aspect ratio eight rectangular exit

area nozzles for nozzle (long axis) centerline spacings of

S/D = 4, 6, 8 for the case of vertical impingement at HID = 2and 0. Wall jet velocity profiles were surveyed at two radial

positions, R/D - 14.0 and 29.0 over a range of one quarter

(minimum) of the impingement region periphery, since in this

case, two planes of flow symmetry exist in the ideal case. In

this dual nozzle arrangement, the direction ^ 90 0 corresponds

to a direction perpendicular to the long sides of the nozzle

exits, and the direction ^ = 0 1 corresponds to a direction coin-

cident with ;,.? ideal stagnation line which would be formed on

the ground plane by the interaction of the two nozzle flows.

Free jet surveys of the dual nozzle flows were conducted

at distances downstream of the dual rectangular nozzle exits

of Z/D = 2 and 8 corresponding to HID = 2 and 8. Only in one

case, for the closest nozzle spacing ( SID = 4) at an axial, sta-

tion corresponding to H/D = 8 did the dual jets begin to merge

at the inner jet boundaries. Figures 52, 53 and 54 present th eazimuthal distributions of wall jet momentum flux for the inner

radial station R/D = 14.0, and figures 55, 56 and 57 present the

local flow angularity at a distance of approximately 1 cm. above

the ground board for the same conditions. The independent vari-

able on figures 52, 53 and 54 is again the azimuthal. angle ¢,

and the parametric variable is H/D. The momentum flux peaks at

$ = 90 0 correspond to the basic single nozzle momentum flux

characteristics presented in figures 31 and 32 for the aspect

ratio eight nozzle. The second, lower peaks, at ^ = 0 0 represent

the accumulation of wall jet momentum flux in the base of the

fountain formed between the two impinging jet flows. The

angularity data in figures 55, 56 and 57 indicate that these

flows are diverging from the direction ^ = 0 0 near the ground.

plane. Figures 58, 59 and 60 present wall jet momentum flux

distribution data for the outer radial station R/D = 29.0. The

decay of the magnitude of the momentum flux in the fountain base

15

region (0 = 0 0 ) is clearly indicated by these data; the consis-

tent increase of wall jet momentum flux in the 900 regionespecially for the H/D - 2.0 configuration is not well understood

and needs further verification and investigation,

MODIFICATION OF GROUND FLOWFIELD PROGRAM

The azimuthal distributions of wall jet radial momentum

flux presented in figures 25 through 33 for vertically impinging

rectangular jets and those presented in figures 34 through 41 and

43 through 50 for oblique impingement have been curve fit for incor-

poration into the ground flow field computer program originally

developed for axi-symmetric jets for NADC, reference 2. The meth-

od of curve fitting and the necessary functional.l expressions andconstants are presented in the appendix. The constants present-ed in the appendix have been derived by imposing the requirement

that the integral of the momentum flux distribution function be

equal to 27r around the complete circumference of the jet impinge-ment region. This manipulation is necessary to permit scaling

of the momentum flux distribution with the total momentum faux

of the individual lift jets in a multi-jet lift system. Wall

jet radial momentum flux characteristics for geometry and flow

conditions other than those investigated here, but within therange of those investigated, are obtained by appropriate inter-

polation schemes within the ground flowfi.eld computer program.

CONCLUSIONS

The following conclusions were reached based on inspection

of the experimental data obtained in the experimental test

program:

I. Reynolds number effects on the impinging turbulent jet flow

fields were found to be insignificant over the range from146,000 to 275,000 based`oi the rectangular nozzle exit

width, D,

16

2. The azimuthal distribution of ground wall jet radial momen-

t t'um flux was found to be strongly directional for impinging

rectangular jets of nozzle exit area aspect ratio four

through eight at heights above ground as high as sixteen

nozzle exit widths, H/D - 16,

3. The directionality of the wall jet radial momentum flux

distribution is a strong function of H/D for low values of

H/D typical of VTOL aircraft hovering in ground effect. The

relative magnitudes of the momentum flux peaks and the

average distribution lovel diverge as H/D decreases. Sig-

nificant differences in azimuthal momentum flux distribution

exist at H/D a 16 even for the lowest aspect ratio nozzle

tested (L/p4.0)4. Measurements of wall jet radial momentum flux representative

of a fixed sector of azimuth at different radial stationsindicate a significant decay of wall jet radial, momentum

flux between H/D = 14 and R/D - 29,

5. No significant effect on the azimuthal distribution of wall,

jet radial momentum flux was measured as a result of a

spoiler placed in the center o`t,i;he aspect ratio four nozzle

exit at an impingement height above ground of H/D = 2.0 for

either vertical or oblique impingement, and

6. Measurements of azimuthal distributions of wall jet momentumflux about the impingement region of pairs of aspect ratioeight rectangular jets impinging vertically on a groundplane at heights above ground of H/D = 2 and 8 indicate a

significant flux of wall jet momentum along the stagnationline formed by the interaction of the two jet flows.

4

1

17

APPBNDIX

The wall jet radial momentum flux distributions, ill"a trat-

cad in figures 25-41 and 43.50 for the cases of vertical impinge-

ment, oblique Impingement in pitch, and oblique impingement in

roll,, were curve-fit in a piecewise manner as shown in figures

61-63 and than normalized for inclusion in the ground flowfiel.dcomputer program. The vertical impingement distributions were

fit using polynomial and trigonometric functions of azimuthal

angle, ^, and nozzle exit aspect ratio, L/o. Similar functions

of 0 alone were determined for the oblique impingement distribu-

tions. The distributions were normalized by adjusting the

coefficients in a manner such that the integral of the vertical

impingement momentum flux distribution curves, over the range of

0 - 0 to 0 _ ffj2, was equal to n/2; and such that the integral

of the oblique impingement momentum flux distribution curves,

over the range of ^ = 0 to 0 - n, was equal to ?rThe functional forms of the momentum flux distribution

curves, as well as the corresponding normalized constants and

coefficients, are shown in tables 3, 4 and 5 for the cases of

vertical impingement, oblique impingement in pitch, and oblique

impingement in rolls, respectively.

18

TABLE 1BASIC TEST PROGRAM

5

Free Jet CharacteristicsL/D n 4,8Z/L r 0, 1/2, 1, 2, 4PT/Pamb . 1.16

Reynolds Number Effect1./D = 4, 6, 8H/D . 8oil-900PT/Pamb w 1.07, 1.15, 1.28R; D = 14.0, 28,00 . 00, 900

Vertical ImpingementL/D =4,6,8H/D , 2, 8,16ai , 900PT/Pamb " 1.15R/D n 14,0, 29.00 - 00, 150, 300, 450, 600, 750, 900

Oblique impingementL/D n 4,6,8H/D ,* 2, 4, 8aJ : 750, 60o01-760,600PT/Pamb 's 1.15RD w 21.5

00,150, 300, 460, 600, 750, 900,1050, 1200, 1350, 1500, 1650, 1800

(H/D w 2 condition not taster; for allcombinations of L/D and impingementangle)

Exit Velocity Profile EffectL/D 4HID 2al >M 930 , 750 , 60001-760,600P'T/Pamb' 1.158/0 * 6.5, 14.00 -10 angles in vicinity of PT depression

Nozzle Spacing Effect (Two Nozzles)L/D a 8H/D*7.,8

09 - 90° (both Jets)PT/Pamb'° 1.15R/D - 14,0, 29.0

00, 150, 300, 450, 600, 750, 900S/D-4,6,8

TABLE 2Fl ^WFIELD SURVEYS

Surveys

1. Free Jot Characteristics ..................... 51

2. Reynolds Number Effect ......... . .... . . .. . . 47

3. Vertical Impingement ..................... 126

4. Oblique Impingement ..................... 436

S. Exit Velocity Profile Effect .................. 153OP78•07d01

6. Nozzle Spacing Effect, .....................115

Total ....... 928

19

(See Figure 50)

• F o= fo+C10+ 0202 +C3^3(0<0<02)

• F 0 w f2 + (C4 + C5 L/D) sin 6 (0 - 02) (02 < 0 < 2)• f-F&F 2^

1r/2

f f do= rr2

L/D H/D 02 fo f2 C1 C2 C3 C4 C5

4 2 5ir/12 0,310 1,920 1,113 -3,977 3,107 1,177 0.3106 2 5rc/12 0,291 1,803 1.044 -3,733 2,917 1.105 0.2918 2 5n/12 0.274 1,697 0,983 -3,515 2.746 1,040 0,274

4 8 5>r/12 0.325 2,065 0.927 -2.340 2,022 -1.376 0,4596 8 5x/12 0,296 1,881 0,844 -2.132 1,842 -1,254 0,4188 8 5rr/12 0.272 1.728 0,776 -1.958 1.692 -1,152 0,384

4 16 1113 0.563 1.310 -0.219 1.279 -0,370 -0,218 0.1096 16 >r/3 0.551 1.282 -0,215 1,251 -0,362 -0,214 0,1078 16 rr/3 0.539 1,253 1-0.210 1,223 -0,354 -0,209 0.104

GP78-0770,71TABLE 3

NORMALIZED WALL JET MOMENTUM FLUXDISTRIBUTION COEFFICIENTS

Vertical 'Impingement

20

J

r.

Z.'0,

V

XD

vO

\1 v^M

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w ll. LL LL LL v-N • • • • • •

MNWNNWMM tO h f`, Nc ` ° rn o v Cl ri 01 IQ 0 00.. clw Q

In w at In at .- M M W In Ln h M M M

r O t(i ^^ tOl^ tN n VM (i^^Dyy r- QhQ ^^ tO0In 0Q r, ^ t^ 00

O00 O a r N O C1 00

V ^t In r N p m 0'

w 4 M w V' w NNi

N N N N I (N

1 NN

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wr wr Mr

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ct h N M MIn 00 M M N In a' In Mva fD M tD V' CA to d' M M to ct M to -tO O v O O O G O O O O O^ C?

sêQCtôci tôp000ci

N M r O M O r o In M h N In OJ tS r- .- r00 to M 00 to

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v Ln M v M N M 147 M M ct Ar N Nto r 0 p M O p m 0 0 9 00 at to m

r- N In M to h co co M co co 00 6t) h [t toV- h I tD C) M In Co P OS M M M . a! r Mr r e- r r r N r. r r '-. r ^ N r

00 to M In 00 M to M O M O f4 w p h

.Q 0 0 n M M M CO M M CO W in •- n toIn Ott In M N t,: to [t M O f-I t"; .- p60000 0 0 0 0-0 O r r r

N NM M V V M MN N M M h h N N

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GroundBoars!

FIGURE 1TEST NOMENCLATURE

Horizontal

GP70.0770.20

23

O O co O O

iI

2,00 cm

Ii

O — O O O

GP78.0770.54

FIGURE 2SINGLE NOZZLE CONFIGURATIONS

24

WJNNOZ

0Z

0crwZOUHXw

M crW Qc J

^_ C71L ZQF-Uwcc

a^

gN3

_OLL.

t

3

crDO

O

F—Q

HUWCLNQ

A4Q4 41 r^IS►

r

25

All dimensions in centimeters.

1 I

1 ^

10.00 r

f t o,00 ------^

GP?O 0440 43

1t

-0,47 DIA

r 16.00 I

FIGURE 4FLOW SPOILER INSTALLATION

26

a

WWJNNOZ

C7_Z

ccW

ZOUHXW

QJD

ZQUWccF-

C7

W

ZQ

X

NO

F-QccHUWCLNQ

QUALITY

b

HFA Probe Drive

0 750 ai - goo Gimballed Ground60 Board Frame

^^ t^►

^^^,00

0lo

MotorDrivenBearing

Movable

HFA Probe Ground

Cart --^

Position Board

8

All dimensions In cm

FIGURE 6

GP Ta,0770.20

GROUND BOARD AND SUPPORT HARDWAREPitch Configuration

6

40

W4

0•^{}— Circuit 1

•^ — Circuit 2Overheat Ratio o 1.5

2

00 10 20 30 40 50 60 70 80 90 100

Freestream Velocity, V. - m/secGP79.0770,53

FIGURE 7

HOT FILM ANEMOMETER MEAN FLOW CALIBRATIONVoltage vs Freestream Velocity Probe No. B576

28

1.0

0.5

A 0

—0.5

—i -n

r.

1.0

0.5

0

aE

—0.5

p-110

1 G

44^Q1 .

V00 * 15,7 m/sec V,„ p 76.2 in/sec

—30 ®20 —10 0 10 20 30 30 —20 —10 0 10 20 30^

dog

0 -degGP78.0770,55

FIGURE 8HOT FILM ANEMOMETER YAW CALIBRATION

Voltage Difference vs Probe Yaw AngleProbe No. 8576AE E2 r E1

29

Sensed Velocity Hot Film Volts

Signals Anomometer

Rectangular Wind TunnelNozzle Data Acquisition

Test Hardware System

Probe Position Road-OutAnd Other Counts

Sensed Date (ROCS)

Basic AerodynamicDato

• Pressures

Data Reduction• Tempereture

VelocitiesProgram • Plow Angularity

• Probe Position• Integrated Velocity

Profiles

FIGURE 9GP7e•0770•16

WIND TUNNEL TESTData Acquisition. Elements

A

'II

RevisedData in the

Event of ProbeReplacement

Calibration Data

Calculate Velocities,Plow Angularity

integrate Velocity,velocity Squared

Profiles

Write Scan Outpr,t

Test for End of Rune

Yes

Write IntegratedValues

FIGURE 10 OP78.0770•52

WIND TUNNEL TEST

Data Reduction Program

x

Ii

Read Pioneer

Initialize Scan summatioihs

ReadSingle Poin t Data

Sum Scan Velocities,Pressures, Temperature

^ (ROC.)

Test forNo End of Scan

Yes L

Average Scan Velocities No

Pressures, Temperatureand Convert from

ROCS to Metric Units

a

31

I

L/D w 4 Z N/L R 0,6 NPR u 1.15

XN/L w 0,00 XNtLw U.17200

200

160

s 120E

Z~

080

X NIL - 0,33 X NIL a 0,60

160

120E

80

40

0

40

0 4—2 0 2 4 —4 —2 0 2 4

YN•cmFIGURE 11

YN-cm

FREE-JET VELOCITY PROFILE GP78-0770.22

32I

AN/1, v' 0 -- XNIL m 0.60200

160

120

80

40

L/D,18 2 N /L*0.5 NPR*1.16

200 XN/L Q 0.00 XNIL m 0.17

160

,N 120

so

40

0

-4

—2 0 2 4 —4 —2 0 2 4

YN -cmFIGURE 12

YN - cm

FREE-AT VELOCITY PROFILE GP78-0770.21

33

L/D = 6

HID =8

RID = 14.0

Owl = Ma2.4

07

0002 . 0

I .6

Z 1.2

Z

0.8

0.4

f

0.0 7

0.0 0.2 0.y 0 6 0.8 1.0

L1/u MRxGP78.0770.68

FIGURE 13

WALL JET VELOCITY PROFILE

L/D = 6

H/D = 8

R/D = 14.0

nui -. ma

.1S

► i 000

2.4

2.0

N

z 1.2

Z

0.8

0,4

0.0

0.0 0.2 0.4 0,6 0.8 1.0

Ulu MHX

FIGURE 14 OP70 0770;67


35

i' w

i

's

I,

Mw Mlf"

0.0

0.0 0.2 0.4 0.6 0 8 1.0

u/u MHXGP70.0770.04

2.4

2.0

1.6

N

Z 1.2

Z

0.8

0.4

L/D = 6

HE'D=8

R/D = 14.0

PW I = m

28

000


366

FIGURE 15

L/D = IS

H/D = 8

RtD = lH.M

PHI = So a

NPR = 1.07

RE., = I HE., 000

c 0 -1

2.0

I's

ru

z 1.2

Z

0.8

0,u

0.0 0,2 0.4 0.13 0.8 1.0

li/U MRXGP78,0770.69

FIGURE 16WALL JET VELOCITY PROFILE

37

LID = 6

HID = 8

RID = 1 4. 0

Pw I = qm a

is

/ 000

41-1

2.0

N

z 1.2%NZ

0 . B

0.4

0.0

0.0 0.2 0.4 0 ' 6 0.8

^ U/U MRX

GP78-0770.68


38

FIGURE 17

L/D = E

H/D = 8

R/D = 1 11. 0

Pw I = C301 a

.28

:/ 000

2.y

2.0

Ns.Z

0.8

0.H

0.0

0.0 0.2 0.H 0.6 0.8

I U/[i MHX


1.0

GP78,0770-63

39

F.

L/D = 6

H/D = 8

R/D 29.0

PHI = 0°

NPR = 1.07

RE D = 146 000

1.6ti

0.4

0,00.0

2.0

2.4

n

nn

nn

n

nn

n

0.2 0.4 0.6 0.8 1.0

U f U MRXGP78.0770•66

Z 1.2Z

0.8


40

2.4

2.0

1.6

z 1.2

Z

0.8

0.4

If

L/D = 6

H/D =- 8

R/D = 29.0

Owl = Ma

.IS

:"0011

1.0

GP78,0770•61

0.0

0.0 0.2 0.y 0.6 0.8

L / U MRx


41

L/O = 6

H/D • 8

R/D = 29.0

awl = A°

z8

000

tY'

f

a

v

2.4

2.0

1.6

N

Z L.2

Z

0.8

0.4

0.0

0.0 0.2 0.4 0.6 0.8 1.0

u / U MRxGP70-0770-62


2.4

2.0

1.6

N1

Z I.2

Z0.8

0.4

L/D = 6

H/D = 8

R/D = 29.0

pw I Rm

07

X000

0.0 -}---------i----- -r------^

0.0 0.2 0.4 0.6 0.8 1.0

U / L) MRxWM0770.59


43

LID = 6

HID = 8

R/D = 29.0

puI -- qm

IS

i 000

Err

W' w

2.4

2.0

1.6N

Z 1.2

Z

0.8

0.y

0.0

0.0 0.2 0 4 0.6 0.8

U/U MRX


1.0

GP78.0770.60

t !

44

2.4

2,0

1.6

N

1. 2

Z

0,8

0.4

0.0

L/D = 6

H/D = 8

R/D = 29.0

Owl = aa°

.28

► ^ 000

0.0 0.2 0.y 0,6 0,0

U / U MRxFIGURE 24


1.0

OP78-0770.60

45

LID a ^ , 000 RID - 14,0 pHID 7,0 01 . 900RID w 29.0 0

NPR 1.16

70

00

50

N8

,- 40

EE

Z'G

sV

30

tG

20

I---

0 30 a0 90 120 150 180

• degGP79.0770.36

FIGURE 25AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUX


f

46

V--,"

LID 4 ^ a 90° RID . MA 0Htp * 8.0 0, * floe RID . 28.0 ANPR 1,16

70

60

60

40Q^.

ZM

cN> 30

a

20

10

0 30 60 90 120 164 180

deg GP78-0770.36


Vertical I mpinrement

47

t ' I

L/D 4 aj 90° R/D = 14.0 OH/D • 16.0 0i g0° R ID n 29.0

. NPR « 1.161

70

6,

00I

I60

A

1

t

Nua^ 40

i

E' zI ^

30{

o:

20

Ci

10

f

10030 60 90 120 150 180

a0 • deg GP78.0770.37

iFIGURE 27

AZIMUTHAL DISTRIBUTION OF (MALL JET RADIAL MOMENTUM FLUXVertirai Impingement

i

48

g.

L/D a 6 ttj SO° R/D x 14.0 O IH/D = 2 Oj 90° R/D » 29.0NPR 1.16

70

I

60 ;

i

i

Nua

v 40EiZv

a

20

^tJ

0 30 60 90 120 150 180

5 . degGP78.0770.38

FIGURE 28

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUXVertical l mpingement

49

70

w

LID a 6 41 . 000 AID * 14.0 O

HID - 8.0 01 r 900 n/D « 20.0 0

NPR - I W

60

N

4V

E1

4N

tia

20

10

0 30 60 90 120 150 180

4) - dogOP70-0770-19


Vertical I mpingement

LID - G a1 a 900RID a 14.0 OH/D . 16,0 01 M 900RID - MO A,NPR = 1.15

70

80

50

Nt74 40

vE

Zv

>1

20 I

i

10 I

0,0 30 ;1090 120 150 180 i

0 R deg GP78.0770.40

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUXVertical Impingement

FIGURE 30

LID - 8 Ci - g0° RID - 14,0 0HID - 2.0 Oi n g0° R/D - 29.0 0NPR - 1.15

70

60

50

NU.^ 40

VE

ZN

30

20

10

Oa0

w-uua



52y{

T

ldD - 8 aJH/D - 8,0 01NPR r 1,15

[s

^f

70

60

50

NUJt 40

E

zN>, 30

ac

20

10

00 30 60 90 120 150 180

- deg GP78.0770-2



53

L/D B a n 9& R/D = 14.0 QH/D 16.0 01 . 900R/D » 29.0

NPR y 1.16

70

60

50

r

40vE

zVN?^ 30

20

10

0,^-

0 30 60 90 120 150 180

0-deg GP78.0770-3

FIGURE 33

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUX


54

Y,

h

^y !

L/D 4 R/D - 21,6 60° OH/D w 2 .0 Of * 909 75° ANPR s 1,16

y^

70

s0

50

N40

E

Z

N> 30a

20

10

1D - Nozzle Width

LT-,H

0 0of

0-1800

0Akk

0 30 60 90 120 150 180

0 - deg GP78-0770-4


Oblique Impingement - Pitch

55

70

L/D . 4 R/D - 21,6 C^ . 600 OH/D a 4.0 41 - 900 a, - 760

NPR w 1,16

60

50

NU1 40VE

z'ON

30

e`

20

10

016

0

0 • deg cP78-0770•e



56

rt

UD 4 R/D 21,6 °i . 600 OH/D - 8,0 0! 410° i 750 ANPR 1,16

70 —^

60

50

N40

E

ZN

30

o^

^o

10

00 30 60 90 120 150 180

0-dog GP78.077"


Oblique Impingement- Pitch

57

u

70

LID w 6 RID 21,6

HID • 2.0 01 AQ°NPR - 1.15

Al759

w

w

N

EZ 40

NtiD:

30

20

10

T ^ I l ^^^0 30 90 90 120 150 180

0 • deg GP7e ,077041



a

58

WD 6 SID o 21,6 of - 60° pHID 4.0 D1 . 000 0^ 700 0

NPR 1.16

70

lf0

so

N

1 40v^

Z•o

30x

20

10

00 30 60 w 13-0 1

0 - deg GP78-0770,43FIGURE 38



59

6

2

5N

E4

N

c3

r

LID 0 a RID 21,6 600 Q

HID o 8.0 01 5100 ^"t ^ 760 e

NPR o 1.16

0-deg GP78.07 44



60

0

LID n 8

HID - 4.0

NPR - 1.10

70

n/o a 21.6 ec? 0

oj- goo

76' A

60

50

1,19< 40-E

> 30

20

10

01.

00 • dog OP78,0770-7


Oblique impingement- Pitch

61

{t

LID n 8 RID . 21,6 «j 600 0HID . 8,0 OJ - 90° a n 760NPR - 1,16

70

60I

I 50I

crv1 40EV

> 30

20

r

10

00 30 60 90 120 150 180

0 - deg GP78-0770.8



LE,

62

O L/o - 4 HID - 8.0 Cy'j - 60"

A LID - 6 NPR » 1,16 dj - g0°q L/D - 8 RID M 21,6

70

60

60

Nu

40

E

ZvN

30

20

10

0`0

0 , dog GP78,0770.14

FIGURE 42

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUXObiigUe I mpingement - Piton

^k

63

s

L/D - 4 R/D r 21,6 01 600 OH/D - 2,0 . 90076°NPR * 1,16

70

L - Nozzle Length

60p

H

50 0 0j 0-1800

^RNU

40E

zN

1n 30cr-

20

10

00 30 60 90 120 150 180

0 dog GP78.0770-9

FIGURE 43

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUXOblique Impingement- Rol l

L/D 4H/D - 4,0NPR 1.15

R/D R 21.5a)£10°

©ja 6&001 4 7&A

70

60

50

NU40

"'*E

z

30

20

10

0L0

0 - deg cP78•0770-1 0


Oblique Impingement- Roll

65

LID 4 RID 21,5 01 - 50° 0HID 8,0 A'i Y 9& 01 * 75°NPR 1,15

70 —

60

50

v40

aEi^v

> 30cc

20

10

00 30 60 90 120 150 180

0 . deg GP78.0770-11



66

L/0 a6 8/0 - 21.5H/D . 2.0 dj - 90pNP13 * 1,15 t71 750

?0

60

so

vE 40

2N}

a

20

10

00 30 60 90 120 150 Is(

. deg GP78-0770-42



I.—If

67

s

LID - 0 RID 21.6 0, 600 OHID - 4,0 of 90° 01 750 A

NPR a 1,16

k

QQ^^

` OV

h

70

60

r50

I

NUNi

EZ

a N

^>

y

h 30 s

i

20

10

00 30 60 90 1 0 150 180

4^-de9GP78-0770.46



iI

68

70

60

so

-!a 4C

E

X

A

I(

LfD = 6 RID - 21.6 V, - bou 0WD u 8.0 ai - go, n"NPR , 1.16

OR

0 120 15,0 1,80

0 . deg GPID 0770 46

FIGURE 48

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUXOblique Impingement- Roll

WD 8 R/D 21,6 0j *+ b0° 0H/D 4,0 00° 01 760 ANPR ►« 1.16

120

110

100

90

80

N 70

E

z 60N

Cx50

40

30

20

10

00 30 60 90 120 160 180

0 • dogGP7B•0770-12

FIGURE 49

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUXOblique Impingement- Rohl

70

4

L/D w 8 R/D - 21,6 01 - 0000

H/D n 8,0 r 960 01 - 750 ANPA . 1,15

1

70

50

50

40

30

20

0

n

a

etEZ'o

0 30 60 90 120 150 1800 - deg GP78.077a13



Q UD A 4 H/D 8.0 01 w 900L/D - 6 NPR 1.16 01 - 600

D UD 8 RID 21.6

00

70

60

50Ny

`,'d'

40"O

N

30 ,1

2Q

10

0Q 30 60 30 120 15Q 180

dog GP79,0770 1,6

FIGURE 51AZIMUTHAL DISTRIBUTION OF WAIL JET RADIAL MOMENTUM FLUX


72I

71

et

LID 8 (1 - goo HID 2 0SID 4 di - goo HID aNPR 1,16 RID o 14A

4 4

cv>

20

' tn—30 0 30 60 90 120 150

0 - deg GP M0770,34

FIGURE 52

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUXVertical Impingement- Dual Jet

73

LID 8goo

HID 20

SID 6 tt goo HIE)

NPA 1,15 BID a 14,0

I F71

64

61

k^

3

2

1

—30

io

deg

GP78-0770.33

FIGURE 53

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUXVertical I mpingement - Dual Jet

74

7

LID 6 (r, - goo H/D - 2 0SID 8 0, goo HID - 8 ANPR 1.16 RID 14.0

r,

-9 4IE

or3

2

D

I I

30 0 30 60 90 120 150

0-deg OPM0770,48


Vertical Impingement- Dual Jet

75

Ygoo

LID m H

S!D .4

H!D . 2.0X F /D w 14.0

_ o0

FIGURE 55 GP78-0770-23

DUAL JET YAW ANGULARITY

O

goo

LID 4 8SID - 6

X HID - 2,0

0, 00

FIGURE 56

GP78 07M26

DUAL JET YAW ANGULARITY

77

Ygoo

L/D - 8

S/O - 8

H/D - 2.0X nin - lAf%

0 = 00 GP78-0770-25

FIGURE 57DUAL JET YAW ANGULARITY

78

L/D = 8 at - fl00 HID 2 OSID % 4 01 . go, HID 8 A

NPR - 1.16 R/D 29.0

70

I

60

60

NV

40

"'E

vN

ti

20

I

i{

10

II

1

i 00 90 90 120 150 180

deg GP78•0770.31

FIGURE 58

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUXVertical Impingement- Dual Jet

irr

i

79

J, I

br

LID - 8^ , 900 HID 2 0

SID - 6 0, - goo H/D B ANPR 1.15 RID 29.0

70

60

so

NV

40

E

C14

ti>

30

20

j

10

00 90 120 150 180

0, d g GP78-07M32

FIGURE 59


Vertical i mpingement . Dual Jet

so

LID = 8 a( g0° HID o 2 OSID a 8 01 goo HID - 8 A&

NRR ¢ 1.15 RID 28.080

70

60

50

vEZ 40V

N

D;

20

10

0 0 60 90 120 150 180

0 - deg Gp78.07M30

FIGURE 60

AZIMUTHAL DISTRIBUTION OF WALL JET RADIAL MOMENTUM FLUXVertical Impingement • Dual Jet

81

fm

f

f f0

f min

0-

0

'min

01

¢z g0°

GF79.0770.10FIGURE fit

MOMENTUM FLUX DISTRIBUTION CURVE -FITVertical Impingement

F

F(-I) F^

f2

ff I - f:

fool

f4 -

o L0

4p f5

I

1800

GP70-0770.17

0 1 02 03 04

0

FIGURE 62

MOMENTUM FLUX DISTRIBUTION CURVE-FIT


83

01 020

03

FIGURE 63MOMENTUM FLUX DISTRIBUTION CURVE-FIT


04 1800

GP78 . 0770-1 B

I f0

f4

f2

f3

f

f1f5

84

id^

REFERENCES

1. Walters, M., and Henderson , C., "V/STOL Aerodynamics Techno-

logy Assessment," Report No. NADC-77272. 60, Naval Air

Development Center, 15 May 1978.

2. Kotanskyr D. R., Durando, N. A., Bristow, D. R., and

Saunders, P. W., "Multi-Jet Induced Forces and Moments on

VTOL Aircraft Hovering In and Out of Ground Effect,"

Report. No. NADC-77-229-30, Naval Air Development Center,

19 June 1977.

3. Kleis t S. J., and Foss, J. F., "The Effect of Exit Cond itionson the Development of an Axisymmetric Turbulent Free Jet,"

Third Year Technical Report, NASA Grant NGR 23-004-068,

Michigan State University, 15 May 1974.

4. Donaldson, C. du P., and Snedeker, R. W., "A Study of Free

Jet Impingement, Part I _ Mean Properties of .Free and

impinging Jets," Journal of Fluid Mechanics, Vol.. 45, Part 21

pp 281 . 3 .1_9r 1971-

5. Saunders, P. W, and Bristow, D. R., "Douglas Neumann

Computations for Potential. Flow About Arbitrary Three-Dimensional Bodies with Modifications for V/STOL Applica-

tions," McDonnell. Douglas Corporation Report MDC A4707,

1 March 1977.

6. R cou, F. P., and Spalding, D. B., "Measurements of Entrain-

ment by Axi-symmetric Turbulent ,pets," Journal of Fluid

Mechanics, Vol.. Ii, Part 1 1 p 21, 1961.

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