低雷诺数下横流-射流中剪切涡的试验研究

为深入分析横流-射流(JICF)的流动特性及其中的复杂涡系结构,从流动机理上研究燃机叶片气膜冷却,揭示高温燃气流与冷却流的掺混机理,本文对横向流中单孔射流所形成的剪切涡开展了试验研究。主要研究了速度比、雷诺数及射流角对JICF所形成剪切涡的影响。结果表明:速度比、雷诺数以及射流角会改变主流与射流之间的掺混程度,从而改变射流轨迹的曲率、高度及垂向渗透能力,最终改变剪切涡的特性;迎风涡与背风涡分别是由射流边界层涡与主流边界层涡形成的,当主流边界层涡强度大于射流边界层涡时,背风涡是流场的主导结构,反之,迎风涡将成为流场的主要涡系结构。

Experimental investigation on shear vortex of jet in cross-flow at low Reynolds number

The flow characteristic and vortical structures associated with the jet in cross-flow (JICF) is studied to reveal the mixing mechanism between coolant jet and hot cross-flow in film cooling of turbine blades.Experimental investigations on shear vortex of single-jet in cross-flow are carried out in this paper.The effects of velocity ratio,Reynolds number and inclined angle on the characteristics of shear vortex are studied mainly.Results show that the velocity ratio,Reynolds number and inclined angle have a great influence on the mixing between jet and cross-flow,and therefore affect the jet trajectory and jet penetration into cross-flow which results in various characteristics of shear vortex.We also find that the leading-edge shear vortex and trailing-edge shear vortex are formed by boundary layer vortex of jet flow and cross-flow,respectively.The trailing-edge shear vortex becomes the main flow structure when the cross-flow boundary layer vortex is stronger than jet boundary layer vortex.On the contrary,the leading-edge vortex becomes dominant.