无导叶对转涡轮三维流场数值分析

Three-dimensional numerical investigation of vaneless counter-rotating turbine

关键词:  对转涡轮+  激波  叶型  流场数值模拟

Key words:  Counter-rotating turbine~+  Shock wave  Blade airfoil  Flow field numerical simulation

摘要:

为了揭示1+1/2(无低压导叶)对转涡轮流场的流动规律,运用全三维粘性流场计算程序对某对转涡轮模型级的流场进行了数值模拟。结果表明,对转涡轮各方面性能基本达到了设计目标,说明高压动叶采用收扩型叶栅通道且整个涡轮子午流道也采用收扩结构的设计可以获得满意性能;三排叶片(尤其是高压动叶)仍有改进余地,即涡轮效率还有进一步提升的潜力;高压动叶出口沿整个叶高均为超声速,出口马赫数节距平均值在1.4~1.6之间;高压动叶尾缘斜激波强度以中展为中心向两侧递减;涡轮性能随出口背压的增加而下降;涡轮出口背压的变化对高压转子性能基本没有影响,但对低压转子性能的影响较大。

Abstract:

In order to reveal the flow characteristics in a VCRT,a three-dimentional,viscous,steady CFD analysis was performed for investigating the turbine performance.Results show that the performance of this VCRT basically reaches the original objective,which indicates that a convergent-divergent blade passage in the high pressure rotor and a convergent-divergent meridian plane of the VCRT are suitable for the VCRT.All of these blade rows of the VCRT,especially high pressure rotor,need much more optimization.The efficiency of the VCRT can be improved through some optimized methods,such as blade curving,throat location adjusting,and so on.The results of the numerical simulations also show that the pitch-averaged Mach number of the outflow of the high pressure rotor is about from 1.4 at the hub to 1.6 at the shroud.The strength of oblique shock waves is strongest on the midspan in the trailing edge of the high pressure rotor.However,it is weaker on the hub and the shroud.Meantime,the results also indicate that the performance of the VCRT will decrease with the increase of the outlet pressure.The performance of the high pressure rotor is retained with the change of outlet pressure.However,performance of the low pressure rotor is greatly influenced with the change of outlet pressure.