1+1/2对转涡轮可调高压导叶流场及损失的数值研究

Numerical Investigation of Flow and Loss in a Variable High-Pressure Guide Vane of 1+1/2 Counter-Rotating Turbine

关键词:  1+1/2对转涡轮  高压导叶可调  总压损失系数  泄漏涡  数值仿真

Key words:  1+1/2 counter-rotating turbine  Variable high-pressure guide vane  Total pressure loss coefficient  Leakage vortex  Numerical simulation

摘要:

调节高压导叶开度可以有效控制1+1/2对转涡轮流量,同时导叶的调节也伴随着一些附加损失的产生,为了使采用可调导叶获得的效益不被涡轮效率的下降抵消过多,有必要对可调导叶的流场及间隙流动进行详细的分析。通过数值研究表明,当采用可调导叶端部加入间隙后,在上下两端壁附近会出现高损失区。间隙泄漏流除了进口端壁的来流之外,还有一部分来自于叶片压力面的附面层,使得压力面出现明显的展向二次流。泄漏流的流量越大越容易形成泄漏涡,压力面和吸力面之间的压差是泄漏涡形成的主要动力。

Abstract:

Variable high-pressure guide vane could effectively control the massflow of 1+1/2 counter-rotating turbine, meanwhile it brings some additional loss. In order to ensure that the benefit produced from the variable high-pressure guide vane is not offset too more by the reduced turbine efficiency, it is necessary to study the flow of the variable high-pressure guide vane and the end wall clearances. The numerical results show that the high loss regions grow around the tip end wall and the low end wall when the end wall clearances are added. Besides the inlet endwalls flow, the pressure surface boundary layer flow is another part of the leakage flow, which makes the spanwise secondary flow appear on the guide vane pressure surface. The higher the massflow of leakage flow is, the easier the leakage vortex appears. The pressure difference between the pressure surface and the suction surface is the major factor of the formation of leakage vortex.