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为阐明1+1对转涡轮变工况性能损失的主要来源并提出改进方法,以1+1对转涡轮为例进行了部分载荷工况下的流场模拟、分析和优化。与相同设计参数的同转涡轮进行部分载荷工况流场对比,发现部分转速下同转涡轮在级间导叶吸力面前缘出现分离,而1+1对转涡轮在压力面前缘出现分离。针对此流动损失,为1+1对转涡轮级间导叶提出了一种基于分离角的压力面优化设计方法,提高了近前缘压力面的气流速度,增强了其对负攻角的适应性,基本消除了叶片14%、58%和92%叶高处压力面前缘的流动分离,在正攻角工况下亦保持了良好气动性能。数值验证了该涡轮的效率在全工况范围内明显提高,而设计点效率未受负面影响。其中,在对转涡轮70%和50%设计转速的两个工况点上,低压涡轮效率较优化前分别提升了1.5%和2.0%,涡轮总效率较优化前分别提升了0.5%和0.7%。
In order to clarify the main sources of performance loss of 1 + 1 counter-rotating turbo and propose an improved method, the simulation and analysis of flow field under partial load with 1 + 1 counter-rotating turbo is carried out. Compared with the flow field of the turbine with the same design parameters under partial load, it is found that the turbine at the partial speed is separated at the leading edge of the suction surface of the interstage vane at some speeds, while the 1 + 1 turbine is separated at the front of the pressure surface. Aiming at this loss, a pressure surface optimization design method based on the separation angle is proposed for the guide vane of 1 + 1 counter-rotating turbine stage, which improves the airflow velocity near the pressure surface and enhances its adaptability to the negative angle of attack , Which basically eliminated the flow separation at the pressure front of 14%, 58% and 92% leaves, and maintained the good aerodynamic performance at positive attack angle. The numerical results show that the efficiency of the turbine is obviously improved in the whole working condition, but the design point efficiency is not negatively affected. Among them, the efficiency of low pressure turbines increased by 1.5% and 2.0% respectively before optimizing the efficiency of two turbines at 70% and 50% of design rotational speed. The total efficiency of turbines increased by 0.5% and 0.7% .