平面运动机构试验CFD仿真影响因素分析

Influencing Factor Analysis of Planar Motion Mechanism Test CFD Simulation

为提高基于重叠网格法的平面运动机构试验的仿真精度,以SUBOFF标模为计算对象,对计算域大小、时间步长、运动频率和湍流模式等参数进行计算对比。结果表明:内部运动区域的大小对计算结果的影响可忽略;综合效率和精度,时间步长取1个周期300步较好;采用Realizable k-ε湍流模式与采用SST k-ω湍流模式得到的结果相差较小,前者与试验结果更为符合;当振幅取0.04 m或0.04 rad时,运动频率取0.1 Hz^0.5 Hz均可,对结果的影响相对较小;单个频率下的结果具有较大的随机误差,需根据多个频率进行线性仿真。采用研究所得方法进行仿真分析,并将仿真结果与试验结果相对比,发现加速度导数、位置导数和旋转导数的误差分别在35%、23%和33%以内,显现出模拟结果具有较高的精度,满足工程初步分析中的精度要求。

In order to improve accuracy of the Planar Motion Mechanism CFD simulation based on overlap grid method, comparative simulations are carried on SUBOFF, focused on calculation area, time step, motion frequency and turbulence model. The result shows that the inner motion area size has almost no effect on simulation, the time step would better set 300 steps per cycle. While vibration amplitude is set 0.04 m or 0.04 rad, the motion frequency within 0.1 Hz^0.5 Hz has little effect on the result. A single frequency case simulation would lead to remarkable random error. It is better to take several frequency cases to linear fitting. The Realizable k-ε and SST k-ω turbulence model cause little difference and the former is more accurate. Using the method, comparing with the simulation and experiment data, it is found that acceleration derivatives, location derivatives and rotating derivatives error is within 35%, 23% and 33% respectively. The result shows that the simulation is satisfied and meets the accuracy requirements in preliminary engineering analysis.