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非结构网格下的大涡模拟方法是解决叶轮机械内部复杂几何流道中强剪切湍流问题的有效途径,而降低算法的数值耗散是提高模拟精度和可靠性的关键之一。该文基于动能守恒特性推导了非结构网格下的低耗散数值方法,使其在维持格式稳定的前提下达到数值耗散最小,并在此基础上发展了与其相适应的无反射边界条件。进一步选取了5个具有代表性的基础算例进行模拟,结果表明:该文方法较传统迎风格式具有低耗散的特性且计算量减少了近75%。
Large eddy simulation method under unstructured grid is an effective way to solve the problem of strong shear turbulence in the complicated geometrical runner of the impeller. Reducing the numerical dissipation of the algorithm is one of the keys to improve simulation accuracy and reliability. Based on the conservation of kinetic energy, this paper deduces the numerical method of low dissipation under unstructured grids, and achieves the minimum numerical dissipation under the condition of maintaining the stable format. On the basis of this, the nonreflective boundary conditions are developed. Five representative basic examples are further selected for simulation. The results show that the proposed method has the characteristics of low dissipation compared with the traditional upwind scheme and the computational cost is reduced by nearly 75%.