小长径比直孔内的流场实验研究

Flow field measurements in normal hole with low length-to-diameter ratio

关键词:  流动分布  流量系数  薄膜冷却  速度测量  五孔探针+

Key words:  Flow distribution  Flow coefficient  Film cooling  Velocity measurement  Five hole probe~+

摘要:

用五孔探针对小长径比、进出口倒角后的直孔内的流场情况进行了详细的测量,着重研究不同速比和雷诺数对孔内流动规律的影响。实验结果表明:速比的变化会显著改变孔内的流场结构,从而影响孔的流量系数;而同一速比下,雷诺数变化的影响则相对较小。在孔壁附近存在着气流的反卷现象,该结果有助于深入了解气膜冷却的内在机理。

Abstract:

Experimental results were presented to describe the flow behavior in the normal hole with a sharp square-edged inlet/outlet, and a low length-to-diameter ratio value. Measurements were performed using a straight five-hole probe. Important aspects of the study include: (1) flow characteristic of the hole and its discharge coefficient are varied strongly with the velocity ratio. (2) renold number does not play the primarily role while comparing to the velocity ratio. (3) reversed flow occurs near the wall, which is helpful to the detailed analysis of film cooling physical mechanisms.