Propulsor Hydrodynamics andHydroacoustics

Presented

To

Committee on Naval Engineering in the 21st Century

Dr. Ki-Han Kim

ONR 331Kihan.kim@navy.mil

30 September 2009

Distribution Statement A: Distribution Unlimited

Research Sub-Area Breakdown

Advanced Sea PlatformHydromechanics

Propulsor Hydrodynamics and Hydroacoustics

Cavitation & Highly Unsteady Flow

Flow Noise &Propulsor Noise

Evolution of Naval Propeller Concepts

Conventional Propeller Highly-Skewed Prop

(1970’s)Ducted Prop: USS

Glover (1965)

Azimuthing Podded Prop(late 1980’s)

Advanced Blade Section:DDG-51 (1980’s)

Advanced Waterjet(2000’s)

Future?Podded Prop(2000’s)

Strategic Long-Term Vision

•

Develop knowledgebase of the governing physics (6.1)

•

Develop accurate, reliable and robust predictive/simulation tools and methods for design and behavior of propulsors (6.1, 6.2)

•

Explore and demonstrate at lab-scale novel propulsor concepts (6.2)

Provide the ship and submarine communities with quiet, efficient and affordable propulsor concepts

(options) and capabilities (knowledgebase and computational tools and methods) that would meet

the emerging mission requirements.

Research Sub-Area Breakdown

Advanced Sea PlatformHydromechanics

Propulsor Hydrodynamics and Hydroacoustics

Cavitation & Highly Unsteady Flow

PIs:

S. Ceccio

(U. Michigan) J. Katz (Johns Hopkins)K. Mahesh (U. Minnesota)S. Apte

(Oregon State U.)G. Chahine

(Dynaflow, Inc.)S. Kinnas

(UT, Austin)E. Paterson (ARL/PSU)J. Kerwin

(Alion/MIT)S. Jessup (NSWCCD)S. Kim (NSWCCD)P. Chang (NSWCCD)J-P Franc (Grenoble)

Flow Noise &Propulsor Noise

Cavitation of Naval Interest

Sheet Cavitation

Cloud Cavitation

Tip Vortex CavitationTip Leakage Vortex Cavitation

Significant source of noise for ships and submarines

Erosion damage on materials

Source of performance degradation

Hull vibration

Efficiency loss – thrust breakdown

Motivation for Cavitation Research

Pump Impeller

DDG51 Rudder

CVN 76 Propeller

Critical Technical Issues

Cavitation Inception

Inception is critical to submarine propeller

Physics of inception poorly understood

Thrust Breakdown

Important to surface ship propellers, particularly waterjets

Material Erosion due to Cavitation

Important to surface ship propellers, particularly waterjets

& composite propellers

Scaling

Scaling of inception not well understood

Scaling of erosion poorly understood

Modeling of Cavitation

Multiphase physics modeling–

Discrete Bubble Model (cavitation

inception)•

Bubble dynamics –

Lagrangian

particle tracking approach using Rayleigh-Plasset

equation•

Carrier flow -

highly turbulent flows (experiments or computations using RANS/LES

–

Continuum Mixture Model •

For different types of “developed”

cavitation

(sheet, vortex, and cloud cavitation)

•

Mass transfer model based bubble dynamics

Turbulence modeling for multi-phase flows–

Modern RANS turbulence model for steady & quasi-steady state flows

–

Large Eddy Simulation (LES) and URANS/LES hybrid approach for higher spatio-temporal resolution

Bubble-Tip Vortex Interaction

•

Developed computational model to predict multiple bubbles interacting with propeller vortical flow

•

Bubble dynamics modeled by Rayleigh- Plasset equation, surrounding vortical flow by experiments or computations (RANS, LES)

•

Current capabilities includeSingle bubble: spherical, non-spherical (2D),

and 3-D shapesMultiple bubbles with size distribution

interacting with surrounding flow (tracking up to 200,000 individual bubbles so far)Bubble deformation: elongation, splitting

and cavitation inception criteriaBubble trajectory in the vortical flowAcoustic pressure resulting from bubble-

vortical flow interaction•

Future PlansDevelop bubble coalescence model

Nuclei Distribution

2 2 ( )s ig n a l a cq u is itio n tim e

l U r tt

NACA-0015 Hydrofoil

= 8°, Re = 3 x105

Courtesy: Prof. Roger ArndtSt. Anthony Falls Laboratory

U. of Minnesota

URANS ComputationS.E. Kim (2008 )

27th Symp. On Naval Hydrodynamics

(

= 1.08) (

= 1.2)

Sheet-to-Cloud Cavitation

Summary of Cavitation and Erosion Predictive Capability

Inception Extent Scaling Control

Sheet Cavitation

Tip Leakage Vortex Cavitation

Tip Vortex Cavitation

Thrust Breakdown N/A

Cloud Cavitation

Cavitation Erosion

: Reasonably well understood. Some well-documented validation case available.

: Poorly understood. No documented validation case available. Significant investment required.

: Currently invested with some promising results. : Currently invested. No significant results yet.

Highly Unsteady Flow: Crashback

Crashback generates side forces

that could produce highly undesirable maneuvering

forces and moments.

High amplitude pressure fluctuations on blades may cause high stress and bending moments

–

potential cause of blade failure.

Large eddy simulations (LES) may be the optimal method for computing the highly separated and turbulent flows that occur during crashback.

Approach

Develop predictive capability: Energy conserving, unstructured LES code (U. of Minnesota)

Validation experiments (NSWCCD)

Water Tunnel

Test

LCC Test

(With Fully Appended Model Hull)

Towing Tank Test

Large Eddy Simulatioin

(LES)

LES Computational Grid

Instantaneous Velocity Vectors and Pressure

Dynamic Blade Loading during High Amplitude Event in Crashback: J=-0.5

Crachback Code Validation

LES predictions show good agreement with experimental results of Jessup et al., (2004).

10−2

10−1

100

101

10−8

10−7

10−6

10−5

10−4

10−3

10−2

10−1

frequency [rev−1]

KT p

ower

spe

ctra

l den

sity

[1/r

ev−

1 ]

LES

Exp (Jessup)

THRUST(J=-0.5)

0.0160.0110.057Experimental Data36in WT

0.0140.0100.056LES Predicted

KFMAGKQKT

0.0160.0110.057Experimental Data36in WT

0.0140.0100.056LES Predicted

KFMAGKQKTStandard Deviation

J

KT

-1.2 -1 -0.8 -0.6 -0.4 -0.2 0-1

-0.8

-0.6

-0.4

-0.2

0

Open WaterVPWTMpcugles

J

10K

Q

-1.2 -1 -0.8 -0.6 -0.4 -0.2 0-1.4

-1.2

-1

-0.8

-0.6

-0.4

Open WaterVPWTMpcugles

Mean KT

& KQ

Fluid-Structure Interaction for Crashback: Coupling with FEM: J=-0.5

Ducted Propulsor Crashback

Grid Instantaneous Axial Velocity and Pressure

Model in the Water Tunnel

Iso

Contour p = -0.29

Research Sub-Area Breakdown

Advanced Sea PlatformHydromechanics

Propulsor Hydrodynamics and Hydroacoustics

Cavitation & Highly Unsteady Flow

PIs:

M. Wang (U. Notre Dame) W. Devenport

(VPI)R. Simpson (VPI)S. Glegg

(FAU)S. Morris (U. Notre Dame)W. Blake (NTI)R. Martinez (Alion)D. Noll (NSWCCD)J. Anderson (NSWCCD)I. Zawadski

(NSWCCD)

Flow Noise &Propulsor Noise

Flow Noise Sources

Hull TBL (smooth surface)

Sail/Control Surface

Cavity Flow

Roughness: current focus of Hydroacoustics

program

Step Flow

Gap FlowSurface

Discontinuities

Roughness Noise Mechanisms

IncidentTurbulence

(Likely more significantfor larger roughness size)

Rayleigh-LikeTurbulence Scattering

(Likely more significantfor smaller roughness size)

Shed Vorticity(Likely more significant

for larger roughness size)

Surface roughness drastically enhances TBL noise–

Diffraction of hydrodynamic pressure–

Distortion of incoming turbulence–

Turbulence generation (vortex shedding, horseshoe vortices …)

Source mechanisms are difficult to separate–

Strong nonlinear interactions

EXPERIMENTAL

Predictive Model Development

x*

rs

φs

ars

x*

rs

φs

ars

Frequency

SP

L (d

B) Other

Sources

Roughness

Overall

COMPUTATIONAL

ANALYTICAL

Radiated SoundPrediction Tool

INTEGRATED EXPERIMENTAL

AND COMPUTATIONAL EFFORTS IN CONCERT WITH THEORETICAL ANALYSES SUPPORT

COMPREHENSIVE, ROBUST MODEL DEVELOPMENT

VPI Wind Tunnel NSWCCD AFFDevenport, Simpson (VPI) Anderson, Blake (NSWCCD)

Wang (U. Notre Dame)

Martinez (Alion) Glegg

(Florida Atlantic U.)

LES Computations

Enabled by collaboration among computational and experimental performers

y/δ

x/δ

Instantaneous Streamwise Velocity (U)

PI: M. Wang (U. of Notre Dame)

Rough-Wall TBL: Large-eddy simulation (LES)

Far field: Lighthill’s theory with appropriate Green’s function

LES

Lighthill’stheory

U

= 27.5 m/shg

= 1.4 mm (0.036)h+

= 95

= 39.3 mm

= 3.82 mmRn

() = 7500X=1.35D downstream

2 Hemispheres: Acoustic Spectra

Spectral levels are amplified at all frequenciesBroad peak in streamwise

dipole sound from 2nd hemisphere

(x, y, z) / = (50, 50, 0) (x, y, z) / = (0, 50, 50)

1st hemisphere

2nd hemisphere

both hemispheres

1st hemisphere

2nd hemisphere

both hemispheres

pa

M 2 U2 2 U

f U f U

Streamwise

Velocity Vorticity

Distributed Roughness Elements

Simulation set-up based on experiment at NSWC/CD (Goody et al.)

Roughness parameters: h = 0.127 delta, L=5.88h, (Re)h=3898

In wall units: (h)+ = 162

4L in wall normal direction y

L

0.34L

3L

9L 4L

4L

4L

4L

TurbulentInflow

Instantaneous Vorticity

(Coarse Mesh: Preliminary Results)

Propulsor Hydroacoustics

Trailing-Edge Noise

–

Direct radiation (focus of previous initiatives)

Tonal and BB

noise from propulsor/inflow interaction

–

Superposition time mean and homogeneous turbulence

Ingestion of locally quasi-

deterministic but globally turbulent structures into propulsor

and their role in the generation of tonal and BB

noise

Global viscous response of blade to large-scales

Current Design Practice(Knowledge Gaps Exist)

New direction in space-time large- scale nonhomogeneous turbulence

International Collaborations

Global Optimization using Variable Fidelity / Variable Physics Approach–

Italian Ship Model Basin (INSEAN), Italy

–

National Maritime Research Institute (NMRI), Japan–

Iowa Institute of Hydraulic Research (IIHR), U.S.

Modeling of Cavitation Erosion–

Grenoble Institute of Technology, France

–

Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland

–

Dynaflow, Inc., U.S.

•

Presidential Early Career Award for Scientists & Engineers (PECASE): J. Dabiri

(Caltech)•

Popular Science Magazine “Brilliant 10” Scientists: J. Dabiri

(Caltech)•

Clair-elect, American Assoc. of Engineering Society & AIAA Past President: R. Simpson (VPI)•

Associate Vice President for Research: S. Ceccil

(U. Michigan)•

Technical Editor (1), J. of Fluids Eng., ASME: J. Katz (Johns Hopkins)•

Associate Editor (2), J. of Fluids Eng., ASME: S. Ceccio

(U. Michigan), M. Wang (U. Notre Dame)•

Editorial Board, J. of Sound and Vibration, AIAA: S. Glegg

(FAU)•

Editorial Board, J. of Aeroacoustics, AIAA: S. Glegg

(FAU)•

Deputy Editor, J. of Marine Science & Technology: Y. Tahara

(NMRI, Japan)•

Editorial Board, J. of Marine Science & Technology (2): F. Stern (U. Iowa), E. Campana

(INSEAN) •

Editorial Board, J. of Boundary Element Method (S. Kinnas, U. Texas, Austin)•

Editorial Board, Theoretical and Computational Fluid Dynamics: J. Dabiri

(Caltech)•

Editorial Committee (2), J. of Ship Research: S. Kinnas

(UT, Austin), F. Stern (U. Iowa)•

Corresponding Editor: Computational Modeling in Engineering & Science: S. Lee (U. MD)•

Associate Fellow (2), AIAA: W. Devenport

(VPI), S. Glegg

(FAU)•

Chair, Award Committee, AIAA Aeroacoustics: S. Glegg

(FAU)•

Plenary Speaker, APS 2009: S. Ceccio

(U. Michigan)•

Executive Organizing Committee for G2010 Workshop, SIMMAN2 Workshop: F. Stern (U. Iowa)

Accomplishments (FY2009)

27

Refereed

Journals

published47

Conference papers

presented18

Graduate students supported

Honors & Awards

4

Post-docs supported4

PhDs graduated3

Masters graduated