Computational Method on Sonic Conductance of Air Flow through Pneumatic Orifice

doi:10.3901/JME.2018.16.195

Abstract

Abstract: By introducing the one-dimension force defect model, an analysis model of orifice's sonic conductance is proposed. The model compressively considers the local and friction loss, and the influences of different parameters are analyzed systematically. Flow-rate characteristics of different orifices are measured by the upstream constant pressure method according to ISO6358, and then a simple formula is derived by amending the analysis model based on the experiment data. By comparing with former literatures, the formula is verified to be with best accuracy and suitability, and the mean error is less than 5%. The study shows that the sonic conductance decreases with the decreasing of diameter-ratio or the increasing of length-to-diameter, and the diameter-ratio is the most influential variable, followed by length-to-diameter ratio and critical pressure ratio. When the length-to-diameter is less than 10, the change rate of sonic conductance is less than 5%. Last, the critical pressure ratio can be set as 0.5 but has little effect on the results.

Key words: critical pressure ratio, diameter ratio, length-to-diameter ratio, orifice, sonic conductance

CLC Number:

TH412

YANG Fan, LI Gangyan, KAGAWA Toshiharu. Computational Method on Sonic Conductance of Air Flow through Pneumatic Orifice[J]. Journal of Mechanical Engineering, 2018, 54(16): 195-203.

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