光滑流道涡轮一维优化设计方法研究

One-Dimensional Turbine Optimum Design Method with Smooth Flow Path

关键词:  轴流涡轮  一维设计  光滑流道  优化设计  等熵效率

Key words:  Axial turbine  1D design  Smooth flow path  Optimum design  Isentropic efficiency

摘要:

为保证涡轮流道型线设计结果的光滑性，发展了一种先反设计初始流道，再进行光滑流道优化的轴流涡轮一维优化设计方法。设计方法针对涡轮中径处气动参数计算，求解一维流动控制方程，采用能量损失和速度损失系数模型，考虑冷气掺混和变比热影响；并结合了遗传算法，以提升等熵效率为目标，对流道几何、级功率分配和速度三角形参数进行优化。利用设计方法对两台文献涡轮进行了验证设计，对一台四级涡轮进行了优化设计。通过分析结果可知，设计方法可以有效设计光滑涡轮流道并提升等熵效率；流量、膨胀比和等熵效率计算较为准确，级载荷系数和流量系数分布计算较为可靠；叶排出口气流角误差绝对值的平均值在3.2°以内，马赫数误差绝对值的平均值在0.054以内；叶排损失随级数变化趋势基本准确。

Abstract:

To ensure the smoothness of turbine flow path profile， a 1D axial flow turbine optimum design method has been developed. The design method can inversely design initial flow path at first， and then optimize smooth flow path. The method focuses on the calculation of aerodynamic parameters at turbine mean radius by solving 1D flow formulae， and utilizes energy and velocity loss coefficient models. The influence of cooling air mixing and variable specific heat can be included in the method. And genetic algorithm is also implemented to obtain optimum flow path geometry， stage work distribution， and velocity diagram parameters， aiming to improve isentropic efficiency. The design method has been used to commence validating computation on two reference turbines and optimum design on a four stage turbine. Finally， through result analysis， it can be shown that the design method can effectively design smooth flow path and improve isentropic efficiency. Mass flow rate， expansion ratio and isentropic efficiency calculation results are basically accurate. Stage loading and flow coefficient distribution are relatively reliable. Meanwhile， average absolute value of blade row exit flow angle error is within 3.2°， with average absolute value of Mach number error less than 0.054. Besides， variation trend of blade row loss with stage is generally accurate.