主流逆压力梯度下气膜孔流量系数的实验

Experiments of discharge coefficient of film cooling holes under adverse pressure gradient

关键词:  航空发动机  燃气涡轮  二次流  流量系数  试验

Key words:  Aircraft engine  Gas turbine  Secondary flow  Discharge coefficient  Experiment

摘要:

为研究主流逆压力梯度下气膜孔的几何结构和气动参数对流量系数的影响规律,采用放大模型在低速回流式风洞中进行了实验。在对比研究圆柱孔和双向扩张孔流量系数基础上,重点研究了双向扩张孔的流量系数。结果表明,双向扩张孔的流量系数比圆柱孔的流量系数高。前倾角越大,流量系数越高;径向角越大,流量系数越高。流量系数随动量比的增加而增高,在动量比小于4时增幅尤其明显。主流湍流度增大使流量系数增大,动量比越小,增幅越大。除了在孔轴线与平板的夹角较大情况外,密度比对流量系数的影响较小。

Abstract:

To study the influence of geometries and aerodynamic parameters on discharge coefficient in the presence of the mainstream adverse pressure gradient,experiments were carried out in a scaled up low speed wind tunnel.The discharge coefficient of the expanded holes is compared with that of the cylindrical holes firstly and then the investigation is focused on the discharge coefficient of the expanded holes.The results show that the discharge coefficient of the expanded holes is larger than those of the cylindrical holes.Both the large plane angles and the small radial angles provide the greater discharge coefficient.Discharge coefficient increases when the momentum flux ratios increase,especially at the momentum flux ratios lower than 4.The high turbulence intensity produces the large discharge coefficient,especially at the low momentum flux ratios.Density ratios have weak influence on the discharge coefficient,except at the large inclination angles of the film cooling holes.