基于热色液晶的异型气膜孔气膜分布特征的可视化实验

通过在气膜孔下游不同位置设置涂有热色液晶的黑色尼龙网,根据尼龙网上的彩色无量纲温度轮廓,对圆柱孔、水滴孔和簸箕孔在吹风比为0.5,1,2下的气膜分布状况进行可视化实验研究.结果表明:气膜孔沿主流流向的扩张会降低出流平均动量,较小程度地减弱了肾形对涡强度,使气膜的覆盖范围和气膜厚度都有所增大;展向扩张使出流平均动量降低的同时使其具有展向速度分量,明显降低了肾形对涡强度,显著增大气膜覆盖范围、降低气膜厚度,增强气膜的贴壁性;吹风比增大使气膜脱离壁面的趋势增强,降低气膜覆盖范围;排孔的相邻孔的出流会相互影响,有利于将气膜压向壁面,相比单孔来讲排孔的冷却效果和气膜覆盖效果更好.

Visualization experiment on film distribution characteristics of shaped film holes based on thermochromic liquid crystal

Black nylon net coated with thermochromic liquid crystal was set at different locations downstream the film holes. The film distribution of cylindrical hole, water-drop hole and fan-shaped hole were visualized according to the colorful dimensionless temperature images on the nylon net under three blowing ratios of 0.5, 1 and 2. Results show that the stream-wise expansion of film hole weakens the exit mean momentum and intensity of kidney eddies slightly, so the coverage area and thickness of film are increased. The lateral expansion greatly improves the film coverage area and attachment performance by decreasing the intensity of the kidney eddies, exit mean momentum and film thickness and increasing the velocity in the spanwise direction. High blowing ratios make the film lift off the wall and decrease the film coverage aera. In addition, the interaction of jets issued from adjacent holes of film holes row has the effects of pressing the film towards the surface, making the cooling and coverage performance of film holes row better than that of an individual film hole.