电推进涵道风扇气动快速求解方法及性能分析研究

Fast aerodynamic prediction method and performance of electrically driven duct fan

随着绿色航空发展,为了能在设计阶段快速获得涵道风扇气动性能参数和非定常流场特征,有必要开发一种高效的数值求解方法。基于小型电推进风扇内流弱可压和尾迹耗散特性,本文将转子和涵道的面元与尾迹涡粒子耦合,使用面元法求解固壁流场,使用涡量输运方程求解远场尾迹传播特征,克服了有限体积法尾迹耗散快的问题。研究表明,本文发展的面元-涡粒子耦合方法对涵道风扇叶表压力与有限体积法趋势一致,整体推力误差为7.83%,能满足工程快速预测需求。本文发展的高效非定常计算方法的尾迹计算数值耗散低,能揭示更为复杂的非定常流动现象,仿真结果显示风扇涵道对尾迹发展有明显约束,而当尾迹传播至外部时,涡量呈现出明显的收缩和对称分布特征。在计算效率方面,本文发展的耦合方法非定常计算效率高,计算相同非定常时间步耗时仅为有限体积法的1/6,具有潜在的涵道动力非定常设计应用价值。

With the development of green aviation,it is necessary to develop an efficient numerical solution method for the purpose of obtaining the performance parameters and unsteady aerodynamic flow field characteris-tics of duct fan quickly in the design stage.Based on the weak compressibility of low speed inner flow and wake dissipation property of small electric propulsion fan,panel elements from rotor and duct are combined with the wake particles in this research.The panel method is used to solve the flow field near the blade solid wall,and the vorticity transport equation is used to solve the far-field wake propagation characteristics,which overcomes the fast wake dissipation problem of the finite volume method.The results show that the relative error of thrust by pan-el-vortex particle method is 7.83%,and the static pressure from panel-vortex particle method developed in this paper is consistent with finite volume method,which proves this method meets the engineering fast prediction re-quirements.The method developed has low numerical dissipation in the wake calculation,which can reveal more complex unsteady flow phenomenon of duct fan,indicating that the duct has obvious constraints on the develop-ing of wake.After the wake propagates outside,the vorticity shows contraction and symmetrical distribution char-acteristics.In terms of calculation efficiency,the panel-vortex particle method is efficient,and the time con-sumed is nearly 1/6 of that by finite volume method for simulating same unsteady time steps,and this proves pan-el-vortex particle method is suitable for unsteady aerodynamic design of duct fan.