叶片内冷通道中采用汽雾换热或蒸汽换热的实验研究

Heat Transfer Experimental Investigation of Mist/Steam or Steam Within Gas Turbine Blade Internal Cooling Passage

气(汽)雾冷却叶片是新一代高效叶片冷却技术的一个重要发展方向,具有广阔的应用前景和发展潜力。在构建的高温涡轮叶片内冷通道气(汽)雾两相流对流冷却实验平台上,研究雷诺数、壁面热流密度以及水雾质量流量对汽雾冷却通道壁面温度分布和换热系数的影响,并与相同工况下蒸汽的换热性能进行对比。主要结果显示,向主流蒸汽中喷入少量细小雾滴形成汽雾两相流冷却介质,其平均努赛尔数最高可达纯蒸汽的3.46倍;当冷却工况因子小于23时,汽雾冷却通道中部区域将出现明显的大液滴沉降和蒸发,冷却效果显著提高。

Convective mist/air （steam） cooling is one of potential promising technology for advanced gas turbine blade cooling. It can greatly improve the cooling effectiveness of turbine blade using two-phase flow. Based on the experimental platform which was built to investigate the convection cooling of mist/steam two-phase flow within high temperature turbine blade cooling channels, the effect of Reynolds number,wall heat flux and mist mass flow rate on the temperature distribution and heat transfer coefficient of mist/steam cooled passage wall was studied. The thermal performance of steam and mist/steam was compared under the same conditions. The results show that the average Nusselt number of mist/steam, which is two-phase flow cooling fluid formed by injecting a small amount of fine water droplets into the main steam, is up to 3.46 times the pure steam;When the cooling condition factor is less than 23, significant settlement and large droplets evaporate will be occurred in the central region of mist/steam cooled passage. Then the cooling effect of gas turbine blade internal cooling passage is significantly improved.