reqirements of nozzle shape iso9300 versus reality

Dr. B. Mickan, 20th Sep. 2013 - 1 -

Reqirements of Nozzle ShapeISO9300 versus reality

Dr.-Ing. B. Mickan; PTBSonic Nozzle Workshop; 2013-09-20; Poitiers


- requirements in ISO 9300 for toroidial nozzles (conventional)

- indirect measures for nozzle geometry for small nozzles

- procedure of dimensional measurements at PTB (d > 2 mm)

- Examples for larger nozzles

- relation to cd-values

- Conclusions/discussions/proposals

Content


Requirements out of ISO9300

- divergent section:

steps, discontinuities, deviation from circularity shall be < 1% dlocal

but Ra shall be < 10-4d (7.1.4)

- Inlet section: Ra shall be < 1.510-5d (7.1.3 [7.2.2.4])

- Inlet section: curvature of toroid shall be 1.8 < Rc < 2.2

deviation from ideal toroid form always < 10-4d (7.2.2.4)


Indirect measures of geometry for small nozzles

5.0Re

bacD

RC = G-1(b) [Geropp];a = H(RC) (Kliegel/Levine, Hall, Oswatitsch)RC … close to curvature at throat but not identical

Dm cdQ 2

4

=> You can determine b as well as d out of Flow rate measurements at different pressures.

Prior information about d:422 nozzles design value or manufacturer spec.80 nozzles values for d determined at PTB


0,1 1 100

1

2

3

4

5

6

7

8

9

10b

throat diameter dth

b ideal value

mm


It is not very likely that the curvature can be fullfilled for small nozzles near to the throat.



0,1 1 10

-4

-2

0

2

4

d/d

throat diameter dth

%

mm

d -0.4

Red – manufacturer infoBlue – PTB measurement



-3 -2 -1 0 1 2 30,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

acc

. fre

q

d/d0.6

0,1 1 10-3

-2

-1

0

1

2

3

d/d

0.6

throat diameter dth

mm

Red – manufacturer infoBlue – PTB measurement

In average we have agreement between dimensional measurementand flow measurement !!


Measurement procedure of inner shape (PTB)

X

Y

Z0

h

Y

zA zEzH

-8 lines- 200 points each line- one circle with 360 points at throat



-0,8 -0,6 -0,4 -0,2 0,0 0,2 0,40,48

0,50

0,52

0,54

0,56

0,58

0,60

0,62

0,64

-0,10 -0,08 -0,06 -0,04 -0,02 0,00 0,02 0,04 0,06 0,08 0,100,4995

0,5000

0,5005

0,5010

0,5015

0,5020

0,5025

0,5030r/

d

z/d

Approximation with B-Splines

Dr. B. Mickan, 20th Sep. 2013 - 10 -


-0,8 -0,6 -0,4 -0,2 0,0 0,2 0,4-0,0003

-0,0002

-0,0001

0,0000

0,0001

0,0002

0,0003

resi

du

als

/d

z/d

res

For cD = 0.995 => displacement thickness is 0.00125d=> What is a relevant roughness?

Dr. B. Mickan, 20th Sep. 2013 - 11 -

Nozzle shapes from real live

Nozzle 71996-2013-08dthroat = 26,0395 mm

Dr. B. Mickan, 20th Sep. 2013 - 12 -



Dr. B. Mickan, 20th Sep. 2013 - 13 -



Dr. B. Mickan, 20th Sep. 2013 - 14 -

Other Nozzle shapes and cD-Value

Nozzle dThroat [mm]

#1 0,9915

#2 1,3436

#3 2,295

#4 3,903

#5 6,646

#6 11,261

0,000 0,002 0,004 0,006 0,008 0,010

0,965

0,970

0,975

0,980

0,985

0,990

0,995

1,000nozzle #1 #2 #3 #4 #5 #6

ISO9300 (1) with ±0.3% confidence band ISO9300 (2) with ±0.2% confidence band

c D

1/Re0.5

-1,8 -1,5 -1,2 -0,9 -0,6 -0,3 0,0 0,3

-0,3

0,0

0,3

0,6

0,9

1,2

1,5

1,8

nozzle #1 #2 #3 #4 #5 #6

ISO9300 with confidence band (clause 7.2.2.4)

curv

atu

re r

atio

normalised position z/d

throat

Dr. B. Mickan, 20th Sep. 2013 - 15 -

Conclusions/discussion/proposals

- Shape requirements are not very practical

- Roughness criteria to sharp for laminar region?

- Deviation from toroid form is not so important far away from throat

- Curvature at throat is critical in production as well as for cd-behavior

- But not as ciritcal as is seems first

- Curvature evaluation depends much on

measurement and evaluation procedure

Dr. B. Mickan, 20th Sep. 2013 - 16 -

Conclusions/discussion/proposals

• Is it helpful to define the measurement procedure

of dimensional measurement as well as evaluation of it?

• Determination of an average RC (physically weighted [Geropp])?

• cD as a function of such a RC (0.8 [?] < RC < 5[?])

(e.g. addionally supported by theoretical/numerical knowledge)?

reqirements of nozzle shape iso9300 versus reality

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