The Effect of Stagnation Pressure on the Critical Back- Pressure Ratio of Sonic Nozzle by Positive Pressure Method

Feng Gao, LiFen Wan, Tao Wang, QiMing Li, Yong Wang, Qian Cheng

Abstract

A test system for the critical back pressure ratio (CBPR) of sonic nozzle was built in Hubei Institute and Measurement and Testing Technology, which was based on the high pressure sonic nozzle gas flow standard facility. The system used a gas volume flowmeter to judge the CBPR. A pressure reducing valve was installed upstream of the gas volumetric flowmeter and the back pressure ratio was adjusted by the valve downstream of the sonic nozzle. The experimental study on the CBPR at different Reynolds numbers was carried out. The results showed that for a nozzle with the positive pressure condition, the CBPR at different flowrates was different. It increased with the increase of the stagnation pressure. During the operation of the standard facility, special attention should be paid to the effect of this difference on the state parameters to ensure the quality and accuracy of gas flowmeter calibration at high pressure.

Keywords

Sonic nozzle; CBPR; Positive pressure method

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IMEKO-TC9-2019-089.pdf

DOI

10.21014/tc9-2022.089

IMEKO TC

TC9 - Flow Measurement

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