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Dr. B. Mickan, 20 th Sep. 2013 - 1 - Reqirements of Nozzle Shape ISO9300 versus reality Dr.-Ing. B. Mickan; PTB Sonic Nozzle Workshop; 2013-09-20; Poitiers

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Dr. B. Mickan, 20 th 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

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Dr. B. Mickan, 20 th Sep. 2013 - 3 - Requirements out of ISO9300 - divergent section: steps, discontinuities, deviation from circularity shall be < 1% d local but Ra shall be < 10 -4 d (7.1.4) - Inlet section: Ra shall be < 1.5 10 -5 d (7.1.3 [7.2.2.4]) - Inlet section: curvature of toroid shall be 1.8 < R c < 2.2 deviation from ideal toroid form always < 10 -4 d (7.2.2.4)

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Dr. B. Mickan, 20 th Sep. 2013 - 4 - Indirect measures of geometry for small nozzles R C = G -1 (b) [Geropp]; a = H(R C ) (Kliegel/Levine, Hall, Oswatitsch) R C … close to curvature at throat but not identical => 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

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

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Dr. B. Mickan, 20 th Sep. 2013 - 6 - Indirect measures of geometry for small nozzles d -0.4 Red – manufacturer info Blue – PTB measurement

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Dr. B. Mickan, 20 th Sep. 2013 - 7 - Indirect measures of geometry for small nozzles Red – manufacturer info Blue – PTB measurement In average we have agreement between dimensional measurement and flow measurement !!

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Dr. B. Mickan, 20 th Sep. 2013 - 8 - Measurement procedure of inner shape (PTB) X Y Z 0 hh Y zAzA zEzE zHzH -8 lines - 200 points each line - one circle with 360 points at throat

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Dr. B. Mickan, 20 th Sep. 2013 - 9 - Measurement procedure of inner shape (PTB) Approximation with B-Splines

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Dr. B. Mickan, 20 th Sep. 2013 - 10 - Measurement procedure of inner shape (PTB) For c D = 0.995 => displacement thickness is 0.00125d => What is a relevant roughness?

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Dr. B. Mickan, 20 th Sep. 2013 - 11 - Nozzle shapes from real live Nozzle 71996-2013-08 d throat = 26,0395 mm

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Dr. B. Mickan, 20 th Sep. 2013 - 12 - Nozzle shapes from real live Nozzle 71988-2013-08 d throat = 6,5147 mm

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Dr. B. Mickan, 20 th Sep. 2013 - 13 - Nozzle shapes from real live Nozzle 71986-2013-08 d throat = 3,2566 mm

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Dr. B. Mickan, 20 th Sep. 2013 - 14 - Other Nozzle shapes and cD-Value Nozzled Throat [mm] #10,9915 #21,3436 #32,295 #43,903 #56,646 #611,261

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Dr. B. Mickan, 20 th 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

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Dr. B. Mickan, 20 th 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 R C (physically weighted [Geropp])? c D as a function of such a R C (0.8 [?] < R C < 5[?]) (e.g. addionally supported by theoretical/numerical knowledge)?

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