涡轮转速对无导叶对转涡轮流动特性的影响

INFLUENCE OF ROTOR SPEEDS ON FLOW CHARACTERISTICS IN A VANELESS COUNTER-ROTATING TURBINE

为了探究无导叶对转涡轮在不同涡轮转速下的流动特性,运用CFD方法对某无导叶对转涡轮模型级的流场进行了三维定常多叶片排的数值模拟。结果表明,涡轮转速的变化对无导叶对转涡轮的喉部位置基本没有影响;随涡轮转速的升高,高压动叶内的激波损失增大,低压动叶内的激波损失减小,源生于低压动叶吸力面上的激波沿吸力面向尾缘移动;对于远离设计点的非设计工况,流动分离损失及低压动叶中的激波损失构成了对转涡轮损失中的主体;涡轮转速的变化对高低压动叶出口气流角及高压动叶出口马赫数的影响作用较大;高低压涡轮出功比、对转涡轮的总功率及等熵效率均随涡轮转速的增大而增大。

In order to reveal the flow characteristics under design and off-design rotor speeds, three- dimensional multiblade row steady Navier-Stokes simulations have been performed in a Vaneless Counter-Rotating Turbine （VCRT）. Results show that the throat location of the VCRT is not directly dependent on the rotor speeds. The shockwave loss increases in the high pressure turbine. （HPT） rotor and decreases in the low pressure turbine （LPT） rotor as the rotor speeds increase. And when the rotor speeds increase, the shock wave rooted on the suction surface of the LPT rotor will migrate towards the downstream. The results also indicate that the most of loss in the VCRT is consisted of the shockwave loss in the LPT rotor and the flow separation loss under off-design rotor speeds. The effects of the rotor speeds on the flow angle and the Mach number at the outlets of the HPT and the LPT are very strong. The ratio of the specific work of the HPT to that of the LPT, the power, and the isentropic efficiency are all increased when the rotor speeds increase.