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Evaluation of Critical Pressure Ratios Sonic Nozzle at Low Reynolds Numbers
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 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;
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 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 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 crossref(new window)
 References
1.
ISO 9300, 1990, Measurement of Gas Flow by means of Critical Flow Venturi Nozzles

2.
박경암, 1994, '임계음속노즐의 입구형상이 유출 계수에 미치는 영향,' 대한기계학회, 제18권 제3호 pp. 701-706

3.
유성연, 이상윤, 박경암, 1996, '소닉노즐의 유출 계수에 영향을 미치는 인자에 관한 연구,' 대한기계학회, 제20권 제12호 pp. 4027-4035

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Brain, T. and Reid, J., 1974, 'Operating Characteristics of Circular Arc Critical Flow Venturies,' Nation Engineering Laboratory Report 564

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Hillbrath, H. E., 1981, 'The Critical Flow Ventury an Update, Flow: Its Measurement and Control in Science and Industry,' Edited by W.W Durgin, Instrument Society of America, Vol. 2, pp. 407 -420

6.
Nakao, S., Yokoi, Y., and Takamoto, M., 1996, 'Development of a Calibration for Small mass flow rates of Gas and Uncertainty of a sonic Venturi Transfer Standard,' Flow Measurement and Instrumentation, Vol. 7, pp. 77-83 crossref(new window)