基于动网格6DOF模型的框架式流速仪水力特性数值模拟与明渠测流速率常数预测

Numerical Simulation of Hydraulic Characteristics of Frame-type Current Meter Based on Dynamic Grid 6DOF Model and Prediction of Flow Measurement Rate Constant in Open Channel

摘要:

为分析明渠内框架式流速仪流场特性与运动姿态，同时对流速仪倍常数K和摩阻系数C进行率定，根据不可压缩流体流动的Navier-Stokes方程和SST k-ω湍流模型，结合VOF多相流模型，建立动态网格下的6自由度(6DOF)刚体动力学耦合数值仿真模型，对水冲击流速仪旋桨使之被动旋转过程进行了仿真，分析了流速仪在不同位置对流速仪倍常数K和摩阻系数C的影响规律。结果表明：采用动网格6DOF模型可以较好地模拟框架式流速仪在明渠的流动状态，仿真结果可靠性较高；通过对不同时刻转速与流速拟合曲线分析可知，流速仪位置不同会影响流速仪摩阻系数C，对流速仪倍常数K影响不大。研究结果可为进一步研究框架式流速仪优化和不同含沙水流条件下对流速仪的磨损提供参考。

关键词:明渠测流;水力特性;框架式流速仪法;动网格6DOF仿真模型;速率常数预测

Abstract:

A six degrees of freedom rigid body dynamics coupled numerical simulation model under dynamic grid was established, and the passive rotation process of the propeller caused by water impacting the frame-type current meter was simulated. It was based on the Navier-Stokes equation for incompressible fluid flow and the SST k-ω turbulence model, combined with the VOF multiphase flow model. This was done to analyze the flow field characteristics and motion posture of the frame-type current meter in the open channel, while calibrating the multiplier constant K and friction coefficient C. In this way, this can analyze the influence of different positions of the current meter on the multiplier constant K and friction coefficient C. The results showed that the use of the dynamic grid 6DOF model can effectively simulate the flow state of the frame-type current meter in open channels, and the simulation results were highly reliable. By analyzing the fitting curves of rotational speed and flow velocity at different times, it can be concluded that the different positions of the current meter would affect the magnitude of the friction coefficient C of the current meter, and it had little effect on the multiplication constant K of the current meter. This achievement can provide theoretical basis and technical support for the construction of digital twin irrigation areas and the measurement of open channel water in irrigation areas. The research results can provide necessary references for further research on the optimization of frame-type current meter and the wear of current meters under different sediment flow conditions.

Key words:open channel flow measurement;hydraulic characteristics;frame-type current meter method;dynamic grid 6DOF simulation model;numerical simulation;rate constant prediction