涡轮动叶表面换热特性的试验研究

Experimental Research on Heat Transfer Characteristics of Turbine Blade Surface

关键词:  航空发动机  气膜冷却  涡轮  叶片  冷却效率  对流换热

Key words:  Aeroengine  Film cooling  Turbine  Blade  Cooling efficiency  Convective heat transfer

摘要:

航空发动机性能的提高对涡轮叶片耐热极限提出了更高的要求，为了更准确地分析涡轮叶片的传热特性，选取某型气冷涡轮动叶10%，50%和90%叶高的特征型面采用低导热光敏树脂材料经过3D打印而成，通过叶片表面粘贴厚度为0.02mm康铜加热膜接通恒定电流加热，使用红外热像系统精确测量叶片壁面温度，在平面叶栅中研究了吹风比M和雷诺数Re对气膜绝热冷却效率和努塞尔数Nu的影响（试验中基于弦长的进口雷诺数Re为8.0×10⁴~16.7×10⁴，吹风比M为1~3。试验结果表明：M=1时气膜能够较好附着在叶片表面，叶片表面得到较好冷却；随着主流雷诺数的增加，绝热壁面温度逐渐升高，绝热效率逐渐降低；吹风比对涡轮叶片的传热特性的影响与气膜孔出流角度有关，随着吹风比的增大，压力面绝热冷却效率逐渐增大，由于吸力面的气膜孔出流角较大，吹风比增大使得吸力面的绝热冷却效率逐渐减小；随着吹风比的增加，对流换热系数增大。

Abstract:

The improvement of aero-engine performance puts higher requirements on the heat resistance limit of turbine blades. In order to analyze the heat transfer characteristics of turbine blades more accurately， a certain type of air-cooled turbine blades with 10%， 50%， and 90% blade heights are selected to be 3D printed with low thermal conductivity photosensitive resin materials. The constant current heating is pasted on the surface of the blade with a constant film with a thickness of 0.02mm. The infrared thermal imaging system is used to accurately measure the temperature of the blade wall. The effects of blowing ratio （M） and Reynolds number （Re） on the efficiency of film adiabatic cooling and Nusselt number （Nu） are studied （in the test， the mainstream Reynolds number based on chord length is 8×10⁴~16.7×10⁴， and the blowing ratio M is 1～3）. The test results show that： When M=1， the air film can better adhere to the surface of the blade， and the surface of the blade is better cooled. As the mainstream Reynolds number increases， the temperature of the adiabatic wall gradually rises， and the adiabatic efficiency gradually decreases. The effects of the blowing ratio on the heat transfer characteristics of the turbine blades are related to the outlet angle of the air film holes. With the increase of the blowing ratio， the adiabatic cooling efficiency of the pressure surface gradually increases. While the outlet angle of the film holes on the suction surface is larger than the outlet angle of the film holes on the pressure surface， the increase in blowing ratio makes the adiabatic cooling efficiency of the suction surface gradually decrease. As the blowing ratio increases， the convective heat transfer coefficient increases.