THE UPSTREAM INSTALLATION EFFECT ON THE CBPR OF SONIC NOZZLE

Lifen Wan, Chunhui Li, Yan Li, Lishui Cui

Abstract

The test for the critical back pressure ratio (CBPR) of a sonic nozzle by using an orifice plate is established, and six types of upstream conditions are set up. Preliminary experimental results show that the upstream conditions have almost no effect on the CBPR at throat Reynolds number larger than 1.1 × 10⁵, but better upstream conditions or the longer lengths of upstream straight pipe can improve flow stability; when throat Reynolds number smaller than 1.1 × 10⁵, the upstream installation condition would have a significant impact on the CBPR, because of the occurrence of the premature unchoking phenomenon. Therefore, it is necessary to measure the CBPR in use for small throat diameter nozzle.

Keywords

gas flow, sonic nozzle, CBPR, orifice plate

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IMEKO-TC9-2013-073.pdf

DOI

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IMEKO TC

TC9 - Flow Measurement

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