大型客机涡扇发动机动力特性模拟

机体/发动机干扰问题是现代大型客机设计中必须考虑和解决的核心问题之一。长期以来，商用和in-house计算流体力学（CFD）软件，都是通过在发动机进气口设置质量流量比，排气口和外涵道设置总温比/总压比，建立动力特性模型来等效模拟机体/发动机干扰流场。在现有动力特性模型基础上，借鉴特征边界思想，将外涵道指定为特征边界，建立了一种新的发动机动力特性模型。采用轴对称超高涵道比涡扇发动机模型、轴对称涡轮动力模型以及某型客机带发动机模型对两种动力特性模型进行了系统的验证和确认，结果表明：两种发动机动力特性模型均能很好地模拟涡扇发动机动力效应，且计算结果与试验数据吻合较好，说明了两种动力特性模型的正确性、可靠性以及工程适用性。此外，所建立的新动力特性模型特别适合于大涵道比涡扇发动机的动力效应模拟，且可以在外涵道总温比、总压比等参数未知的情形下，评估发动机的动力特性，在实际工程中应用更广泛。

Propulsion performance simulation of turbofan engine for large civil aircraft

Interaction problem between the airframe and the propulsion system of a modern large civil aircraft is one of the key points that is extremely important and must be carefully dealt with in the process of aerodynamic design. For a long time, commercial and in-house Computational Fluid Dynamics (CFD) solvers construct aerodynamic models to simulate the interference flow field of turbofan engine, by setting up the total pressure ratio and the total temperature ratio at exhaust plane and the mass flow ratio at inlet.Based on the current aerodynamic model and the idea of designating the external duct as the characteristic boundary, we present a new approach of modeling turbofan engine with power. Verification and validation are conducted by simulating the flow field around an axisymmetric ultra-high bypass ratio turbofan simulator, a turbine powered simulator and a typical civil aircraft with turbofan engine.The solutions show that, the traditional and the new model have both simulated the propulsion effects of turbofan engine with power properly, and the surface pressure coefficient distributions coincide well with the experiment data, illustrating the correctness, reliability and engineering applicability of both models. Moreover, our newly presented model is much more suitable for high bypass ratio turbofan engine and the evaluation of dynamic characteristics with unknown total pressure ratio and total temperature ratio at bypass. Hence, the new model has wider engineering application compared to traditional models.