Discharge characteristics of small sonic nozzles in the shape of pyramidal convergent and conical divergent

详细信息	查看全文 | 推荐本文 |

• 作者：Chih-Chung Hu^a ; ^{t10057@cc.kyu.edu.tw} ; Win-Ti Lin^b ; Chun-Min Su^b ; Wen-Jay Liu^a
• 关键词：Small sonic nozzle ; Discharge coefficient ; Critical back pressure ratio
• 刊名：Flow Measurement and Instrumentation
• 出版年：2012
• 期刊代码：65_09555986
• 类别：et
• 出版时间：June, 2012
• 卷：25
• 期：Complete
• 页码：26-31
• 文件大小：946 K

摘要

This study combined KOH anisotropic etching with laser machining to fabricate small sonic nozzles in the shape of a pyramidal convergent inlet followed by a conical diffuser with a divergent angle of 5掳. The diffuser was made into three different lengths. The throat diameters were around 100聽渭m. Experiments were performed to obtain discharge coefficients and critical back pressure ratios in Reynolds numbers ranging from 5.8脳10² to 4.5脳10³. The critical back pressure ratio for one of the nozzle types examined reached 0.486 at . Numerical simulations were also performed to obtain the flow fields at an upstream pressure of 203 kPa. The simulation results revealed that besides flow separation, the first set of oblique shocks appeared in the nozzle jet could also lead to tremendous pressure loss. The weaker the oblique shocks, the higher the critical back pressure ratio obtained.