급 확대부 내 수축 노즐 출구 유동장 분석

초록

A numerical investigation of the flow-field at the convergent nozzle exit in suddenly expanded channels wasperformed based on pressure and geometry ratios. The numerical test model consisted of a convergent nozzleand suddenly expanded channel. The inlet and outlet diameters of the convergent nozzle were 30 and 10 mm,respectively. The dimensions of the suddenly expanded channel were selected for diameters of 16, 25, and 35mm and lengths of 50, 100, and 150 mm. The pressure ratio represents the total pressure at the nozzle inletrelative to the static pressure at the nozzle exit, and the considered pressure ratios were 2 to 10 with a stepsize of 1. The geometry ratios were composed of diameter and length ratios. The diameter ratio and lengthratio mean the channel diameter and length to the nozzle outlet diameter, respectively. The selected diameterratios were 1.6, 2.5, and 3.5, and the selected length ratios were 5, 10, and 15. An asymmetrical supersonicflow was observed in a suddenly expanded channel at a low pressure ratio, and each geometry ratio had adifferent critical ratio that stabilized the flow field.

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