保证调压室水位波动三维CFD模拟准确性的方法

Approaches to guarantee accuracy of 3D CFD simulations of surge tank wave

用三维CFD方法模拟调压室水位波动的尝试越来越多,但全三维模拟结果与实验或实测数据的吻合程度较差.研究了水体惯性、系统阻力、水库边界设定三方面对三维CFD模拟调压室水位波动准确性的影响,指出常规CFD方法可以准确模拟水体惯性和局部水头损失,但模拟沿程水头损失的准确度不高,故在隧洞较长时,不宜采用全系统三维模拟,而应采用一维管道与三维调压室耦合的方法.用一维三维耦合方法对某水电站调压室的涌浪进行了实例计算,获得与实验数据一致的结果,验证了所推荐方法的准确性,同时还展示了一维方法所无法研究的调压室内部流态的演变规律.

Many of attempts have been made in 3D CFD simulations of surge tank wave. However, recent research results show that the 3D results are not in good agreement with the experimental data, and the reasons are urgent to be studied. This paper studies the influences of water inertia, system resistance and boundary conditions on the surge wave. After sensitivity analysis of the influencing factors, it has been found that the conventional CFD method can accurately simulate the water inertia and the local head los ses; but the simulating accuracy of the frictional head losses is inadequate. Thus, this paper proposes to use coupling scheme of the 1D water conveyance system and 3D surge tank, when the water conveyance system is very long. Moreover, simulation of a real surge tank wave by using the 1D-3D coupling approach is performed. The results agree with the experimental data well. In this way, the accuracy of simulation is guaranteed. Meanwhile, the transient flow patterns in the surge tank are analyzed.