Discharge Characteristics of Small Sonic Nozzles in the Shape of Pyramidal Convergent and Conical Divergent |
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| Chih-Chung Hu, Win-Ti Lin, Chun-Min Su, Wen-Jay Liu |
- Abstract:
- This study cooperated the KOH anisotropic etching with the 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°. Three different diffuser lengths were made for the nozzles. The throat diameters were around 100 µm. Experiments were performed to obtain discharge coefficients and critical back pressure ratios in Reynolds numbers ranging from 5.8 × 10² to 4.5 × 10³. The critical back pressure ratio for one of the nozzle type examined reached 0.486 at Re = 4.4 × 10³. Numerical simulations were also implemented to discover 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 lead to tremendous pressure loss. The weaker of the oblique shocks, the higher the critical back pressure ratio would be obtained.
- Keywords:
- Small Sonic Nozzle, Discharge Coefficient, Critical Back Pressure Ratio
- Download:
- IMEKO-TC9-2010-052.pdf
- DOI:
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