机匣温度边界条件对跨声转子性能的影响

Effects of Casing Temperature Boundary Conditionon Performance of a Transonic Rotor

关键词:  机匣  温度边界条件  效率  熵  跨声转子

Key words:  Casing  Temperature boundary condition  Efficiency  Entropy  Transonic rotor

摘要:

为探究机匣壁面温度对跨声转子性能的影响，利用数值模拟对等温机匣壁面和绝热机匣壁面两种情况的跨声转子Rotor 37进行研究，对比分析了其对特性线、总温等参数的展向分布和叶顶流场结构的影响及其机理。结果表明，等温壁面相比于绝热壁面更接近实验的真实情况，采用等温壁面边界条件预测的出口总温径向分布在90%叶高以上更符合实验数据。等温壁面边界条件使Rotor 37转子的效率在数值上提升了约2%，更接近实验数据，但对三维流场的进一步分析表明，其对转子真实性能的影响很小。通过对熵的对比分析发现，由于采用等温壁面，机匣和外界的热交换可达轮缘功的1.4%，导致传统的绝热效率计算公式失效，而在使用增加了热交换项的修正效率公式后，两种温度边界条件的Rotor 37重新计算的效率几乎相等。

Abstract:

In order to investigate the influence of casing temperature on the performace of transonic rotors， numerical simulation of Rotor 37 was performed with two different temperature boundary conditions at casing， adiabatic end wall and isothermal end wall. A comprehensive comparison was studied in characteristic lines， spanwise distributions of properties like total temperature at the outlet and flow structures near the casing. It indicates that compared with the adiabatic casing， the isothermal casing is more according with the experimental condition， and the spanwise distribution of total temperature at the outlet is closer to experiment data above 90% span. Although the efficiency of the cases with isothermal end wall are 2% higher than those with adiabatic end wall， it shows the temperature has little influence on the performance of Rotor 37 through the flow-field analysis. According to the contrast of entropy， it is found the conventional adiabatic efficiency formula has failed in the isothermal end wall condition because the heat transfer between the surrounding and the casing is up to 1.4%， which is non-negligible. And the efficiency of the two casing are found to be almost equal using a corrected formula which added the heat transfer effect.