梯形薄壁堰流量规律数值模拟研究

Numerical simulation of discharge law for a trapezoid thin-walled weir

旨在用数值模拟方法推求计算梯型薄壁堰堰流的简化公式。通过推求梯型薄壁堰堰流的基本理论公式,并求解气液两相流时均方程,辅以RNG k-ε湍流模型模拟了5种不同堰顶水头下梯形薄壁堰的过流能力。用SIMPLE算法对模拟体系中的压力与速度的耦合进行求解,同时用VOF法对自由水面的流动变化信息进行捕捉;进而通过最小二乘法的拟合得到模拟的流量值随堰顶水头变化的简化计算式,采用此公式计算了梯形薄壁堰在不同堰顶水头时的过流流量,与所推基本理论公式的计算值相比结果基本一致,可为实际工程中流量的控制和测量提供参考。

The purpose of this paper is to derive a simplified formula by the method of numerical simulation calculation of ladder type thin-wall weir flow. A theoretical formula for calculating the discharge rate of a trapezoid thin-walled weir is derived, numerically solving the gas-liquid two-phase time-averaged equations along with RNG k-ε turbulence model, and flow capacity under five different water heads over the crest is simulated. The coupling velocity and pressure equations are solved with SIMPLE(Semi-Implicit Method for Pressure-Linked Equations) algorithm. The VOF(Volume of Fluid) method is applied to track the flow surface. By using the least square method, the relationship between the discharge rate and the corresponding water head over crest is obtained, so the simple formula of trapezoid thin-walled weir is obtained. It is found that flow variation of the head over crest is similar with the theoretical formula, which provides a reference for controlling and measuring the flow rate in actual project.