基于通流CFD方法的涡轮可控涡设计研究

Controlled-vortex Design of Turbine Based on Through-flow CFD Method

为进一步实现高性能涡轮精准气动设计、提升涡轮效率,基于Euler方程通流计算流体力学(computational fluid dynamics,CFD)技术发展了控制叶排出口环量的涡轮可控涡设计方法。设计方法通过时间推进法求解二维流动方程,采用具有TVD性质的三阶精度Godunov格式,时间方向按显式-隐式交替求解。损失系数通过模型计算后在径向重新分布,在给定叶排出口环量分布后涡轮气动设计开始进行。利用设计方法对某型航空发动机单级涡轮进行了自由涡和可控涡设计,并利用三维CFD方法验证气动性能。通过对比分析,可以发现设计方法可以有效实现可控涡设计。相比三维模拟结果,通流结果流量误差在0.2%左右,膨胀比误差在-0.02左右,效率误差不超过0.77%;可控涡设计比自由涡设计效率更高,转子叶根反力度更高,叶排根部二次流和流动分离更弱、损失更低。

In order to achieve precise aerodynamic design of high performance turbine and improve efficiency,a controlled-vortex turbine design method based on Euler through-flow CFD technology has been developed,which can control blade row exit circulation.The design method solves 2D flow equations by time-marching approach,and utilizes third order Godunov scheme,which has TVD property with alternatively explicit-implicit approach in time direction.Loss coefficient will be redistributed radially after calculated by loss model,and turbine aerodynamic design will be commenced once blade row exit circulation distribution is given.A single stage turbine of aeroengine is designed in free-vortex and controlled-vortex style separately by the design method.And 3D CFD is implemented to verify turbine aerodynamic performance.After comparison and analysis,it can be found that the design method can effectively achieve controlledvortex design.Compared with 3D simulation results,the mass flow error of through-flow results is around 0.2%,the expansion ratio error is around-0.02,and the efficiency error is no more than 0.77%.Meanwhile,controlled-vortex design can provide higher efficiency and higher rotor hub reaction than free-vortex design,with weaker secondary flow and flow separation,and less loss at blade hub.