消力池内水流噪声数值模拟分析

摘要

为解决水噪声试验中因改变边界条件耗时费力的问题,采用了基于VOF和k-ε 黏度模型的CFD分析方法,通过改变上游来流量、消力池长度及尾坎高度,对宽顶堰消力池内的各水力要素及水噪声场进行了数值模拟,并且与物理模型试验所得结果进行比较.结果表明:模拟水面线变化趋势与实测水面线误差在30％之内;模拟流速与实测流速误差在30％之内;模拟水噪声在4500～8000Hz之间与实测结果声压级误差在6.5db之间,数值模拟结果与物理模型试验结果较为吻合,说明采用该数学模型模拟低水头情况下宽顶堰消力池内水流的流态与水噪声是可行的.得到了各水力要素及水噪声随流量、消力池长度及尾坎高度变化的规律.相同尾坎高度和消力池长度情况下,上游来流量为12.5,10.3,6.9L?s-1都有水跃产生,同时距上游越近,水面位置处的流速越大;相同上游来流量和消力池长度情况下,尾坎高度对水跃影响明显,同时越靠近宽顶堰位置,水面处的流速越大;相同上游来流量和尾坎高度情况下,消力池长度对水跃影响也比较明显.同时发现水流噪声最大声压值都出现在消力池尾坎附近.%In order to overcome the problem of time consuming as a result of changing boundary conditions in water noise test, the CFD analysis method based on VOF and k-ε viscosity models were used, and numerical simulation of various hydraulic elements and water noise fields in the power tank of a wide roof weir was carried out by changing upstream flow, the length of pool and the height of tail, and the results were compared with numerical simulation to experimental data. The results showed that the error between variation trend of simulated surface line and the measured surface line was less than 30％. The error of simulated velocity and measured velocity was less than 30％. Simulated water noise was between 4500-8000Hz, whose error with the measured result sound pressure level was around 6.5db, and the results of numerical simulation were consistent with the experimental results of the physical model, showing that it is feasible to use the mathematical model for simulating the flow state and water noise of water flow in lower water head. The various hydraulic factors and the law of water noise variation with the variation of flow, the length of absorption pool and the height of tail sill were obtained. Under the same height of tail sill and the same length of stilling pool, hydraulic jump emerged with the upper reaches flow rate of 12.5, 10.3 and 6.9 L?s -1. The nearer the upstream was, the greater the velocity was in the water surface. With the same upstream flow rate and the length of stilling pool, the height of tail sill obviously affected the height of the water jump, and the closer to the position of the wide top weir, the greater the flow velocity at the surface of the water. The influence of the length of stilling pool on water jump was also obvious under the same flow rate and the same height of tail sill. It was found that the maximum sound pressure of flow noise was in the vicinity of the tail of stilling pool.