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

Dr. B. Mickan, 20th Sep. 2013 - 2 -

- 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

Dr. B. Mickan, 20th Sep. 2013 - 3 -

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)

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

Dr. B. Mickan, 20th Sep. 2013 - 5 -

0,1 1 100

1

2

3

4

5

6

7

8

9

10b

throat diameter dth

b ideal value

mm

Indirect measures of geometry for small nozzles

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

Dr. B. Mickan, 20th Sep. 2013 - 6 -

Indirect measures of geometry for small nozzles

0,1 1 10

-4

-2

0

2

4

d/d

throat diameter dth

%

mm

d -0.4

Red – manufacturer infoBlue – PTB measurement

Dr. B. Mickan, 20th Sep. 2013 - 7 -

Indirect measures of geometry for small nozzles

-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 !!

Dr. B. Mickan, 20th Sep. 2013 - 8 -

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

Dr. B. Mickan, 20th Sep. 2013 - 9 -

Measurement procedure of inner shape (PTB)

-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 -

Measurement procedure of inner shape (PTB)

-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 -

Nozzle shapes from real live

Nozzle 71988-2013-08dthroat = 6,5147 mm

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

Nozzle shapes from real live

Nozzle 71986-2013-08dthroat = 3,2566 mm

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)?