Evaluation of Critical Pressure Ratios Sonic Nozzle at Low Reynolds Numbers

Title & Authors
Evaluation of Critical Pressure Ratios Sonic Nozzle at Low Reynolds Numbers
Choe, Yong-Mun; Park, Gyeong-Am; Cha, Ji-Seon; Choe, Hae-Man; Yun, Bok-Hyeon;

Abstract
A sonic nozzle is used as a reference flow meter in the area of gas flow rate measurement. The critical pressure ratio of sonic nozzle is an important factor in maintaining its operating condition. ISO9300 suggested the critical pressure ratio of sonic nozzle as a function of area ratio. In this study, 13 sonic nozzles were made by the design of ISC9300 with different half diffuser angles of 2。 to 8。 and throat diameters of 0.28 to 4.48 mm. The test results of half diffuser angles below 8。 ar quite similar to those of ISO9300. On the other hand, the critical pressure ratio for the nozzle of 8。 decreases by 5.5% in comparison with ISO9300. However, ISO9300 does not predict the critical pressure ratio at lower Reynolds numbers than 10(sup)5. Therefore, it is found that it is a better way for the flow of low Reynolds number to express the critical pressure ratio of sonic nozzle as a function of Reynolds number than area ratios. A correlation equation of critical pressure is introduced with uncertainty $\small{\pm}$3.2 % at 95% confidence level.
Keywords
Sonic Nozzle;Critical Pressure Ratio;
Language
Korean
Cited by
1.
소닉노즐의 유량측정 불확도 평가,최해만;박경암;최용문;

대한기계학회논문집B, 2001. vol.25. 12, pp.1898-1904
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