涡轮叶片端壁表面温度相似性研究

Study of the Similarity of the Temperatures on the Surfaces of End Walls of Turbine Blades

以燃气透平端壁气膜冷却特性为研究对象,在满足流-固耦合换热温度场相似性条件的基础上,首次提出了一种新的气膜冷却端壁表面温度分布预测方法。提出端壁表面温度场相似性成立条件:(1)主流雷诺数和吹风比相同,维持主流温度恒定,改变冷气进口温度;(2)维持冷气进口温度恒定,改变主流温度。首次用定量的方法,描述流-固耦合换热温度分布图的相似性现象,发现当冷气进口温度恒定为750 K时,主流和冷气温差大于150 K才有较好的相似性;当主流温度恒定为1 700 K时,主流和冷气温差大于250K才有较好的相似性。预测方法要求具有两组已知温度场。当被预测工况与已知工况之间的温差在[-400 K,200 K]区间之内时,预测偏差小于5.5%。

With the air film cooling characteristics of the end walls of blades in a gas turbine serving as the object of study,on the basis of meeting the similarity conditions of the fluid-solid coupled heat exchange temperature field,the authors put forward for the first time a new method for predicting the temperature distribution on the surface of the end walls cooled by the air film. Furthermore,they also believed that the conditions for the similarity of the above-mentioned end wall surface temperature field are as follows: to change the temperature of the cooling air at the inlet under the condition of maintaining a same Reynolds number and blowing air ratio in the main stream and keeping the temperature in the main stream constant or to change the temperature of the main stream under the condition of keeping the temperature of the cooling air at the inlet constant. For the first time,they adopted a quantitative method for depicting the phenomena of similarity on the fluid-solid coupled heat exchange temperature distribution chart and discovered that when the temperature of the cooling air at the inlet is kept constant at 750 K,a relatively good similarity can be obtained only when the temperature difference between the main stream and the cooling air is greater than150 K. When the main stream temperature is kept constant at 1 700 K,a relatively good similarity can be obtained only when the temperature difference between the main stream and cooling air is greater than 250 K. The prediction method necessitates two groups of known temperature field. When the temperature difference above-mentioned between the operating condition predicted and known is in a range between- 400 K and 200 K,the prediction deviation will be less than 5. 5%. The use of the prediction method proposed by the authors can extremely reduce the work load and cost spent in the experimental study and numerical simulation of a complex air film cooling member.