低レイノルズ数域におけるタービン静翼の三次元流れ : 損失と流れの構造に与える主流乱れ度の影響

概要

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Aerodynamic measurements were conducted to evaluate the performance of an axial-flow turbine nozzle, with a focus on the influence of freestream turbulence intensity at low Reynolds numbers. The turbulence intensity was varied between 0.5% and 8.9% by modifying turbulence generation sheet settings. The nozzle flow was measured using a five-hole pressure probe and a hot-wire anemometer. The Reynolds number was a determinative parameter, while the turbulence intensity was found to have had negligible effect on overall total pressure loss. However, increased separation on the suction surface and decreased secondary vortices near the endwalls were observed at higher turbulence intensity. Instantaneous velocity signals proved the transformation of the flow mechanisms in separation zone. Since the increase in profile loss (separation) and the decrease in net secondary loss (secondary vortices) offset each other, the net overall loss remained almost constant.
2002-11-20