基于熵产理论的叶栅型线优化设计

Optimization design on cascade profile based on entropy generation theory

将熵产理论引入二维叶栅的优化设计中,提出了一种能够准确量化在任何位置的流场不可逆损失的分析方法.基于热力学第二定律,理论推导了湍流下的流场熵产计算公式,采用涡黏性模型对叶栅流场熵产进行计算,详细讨论了安装角、叶栅稠度、叶型厚度对叶栅性能及流动损失的影响规律.通过B样条曲线完成叶栅参数化建模,并将改进的带精英策略的非支配排序的遗传算法(NSGA2)与计算流体力学(CFD)相耦合,建立一种以最大总压升和最小熵产率为目标的叶栅自动优化方法,进而得到优化叶栅的Pareto解.与初始种群相比,优化叶栅具有更优的气动性能,在总压提高的条件下,流场熵产率减少.

An analysis method based on entropy generation theory was introduced into the optimization design of the twodimensional cascade.This method could accurately quantify the local irreversible loss of the flow field at any position.Based on the second law of thermodynamics,an expression of entropy generation rate for arbitrary control volume,including the turbulence effects,was derived theoretically.The eddy viscosity model was used to calculate the entropy generation rate.The influence of installation angle,cascade consistency and blade thickness on the performance and flow loss of cascade was discussed in detail.The cascade automatic optimization design was realized by coupling the B-spline parametric method with improved non-dominated sorting genetic algorithm II(NSGA2)multi-objective optimization algorithm and computational fluid dynamics(CFD).This method was applied to the aerodynamic optimization design,defining the total pressure and entropy generation rate as the objective functions.Compared with the initial population,the optimized cascade has better aerodynamic performance.Under the condition of increased total pressure,the entropy generation rate of the flow field was reduced.