In order to solve the trim problem of computational fluid dynamics (CFD) simulation for rigid coaxial rotor, a hybrid trim model coupling CFD method and high-efficiency model (blade element theory) is established. In the trim process, the Jacobian matrix is solved by the high-efficiency model, while the CFD solver is only called for rotor performances modifying after each trimming step. The influences of pseudo time step, number of CFD revolution, and inflow model are investigated. Validation cases of AH-1G and Harrington-1 rotors are carried out, and good agreements are obtained. Results show that the trim efficiency can be significantly improved by saving the calculation of CFD for the Jacobian matrix. The trim accuracy is guaranteed by the correction operation with the CFD solver at each step. Moreover, as only time-averaged rotor performances are useful for trim, the efficiency can be further improved by adopting appropriately small pseudo time step and CFD revolution. The hybrid trim model has high robustness. The accuracy of inflow model for the coaxial rotor affects the convergence speed, but the final convergence can be achieved generally.

中文翻译：

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刚性同轴转子CFD仿真的高效混合修整方法

为解决刚性同轴转子计算流体动力学（CFD）模拟的修整问题，建立了一种耦合CFD方法和高效模型（叶片元理论）的混合修整模型。在修整过程中，雅可比矩阵通过高效模型求解，而 CFD 求解器仅在每个修整步骤后对转子性能进行修改。研究了伪时间步长、CFD转数和流入模型的影响。进行了AH-1G和Harrington-1旋翼的验证案例，取得了良好的一致性。结果表明，通过节省雅可比矩阵的CFD计算，可以显着提高修剪效率。通过在每一步使用 CFD 求解器进行校正操作来保证微调精度。而且，由于只有时间平均的转子性能对配平有用，因此可以通过采用适当小的伪时间步长和 CFD 转数来进一步提高效率。混合修剪模型具有很高的鲁棒性。同轴转子入流模型的精度影响收敛速度，但最终收敛一般都能达到。