耦合空化效应的超声滚压系统流场结构优化设计

目的 实现耦合空化效应的超声滚压系统流场结构的优化，提升超声滚压加工质量。方法 首先，利用Fluent流场仿真软件模拟超声滚压加工流场空化情况，获取滚珠周边3个关键位置的气含率。其次，采用最优拉丁超立方方法进行实验设计，并以流场结构参数为优化变量，以3个关键位置气含率为优化目标，基于二阶响应面法建立气含率近似模型。然后，综合运用AHP和熵权法确定各个气含率的权重值，采用遗传算法NSGA-II对近似模型进行优化求解来获取最优流场结构参数。最后，对优化结构与初始结构下获得的气含率进行对比，验证优化结果。结果 基于20组最优拉丁超立方试验结果所构建的二阶响应面近似模型拟合度较好，3个关键位置气含率均在95%置信水平上均通过显著性检验。综合分析后，3个优化目标的权重分别为0.2791、0.2516和0.4692，获得的优化结构的3个关键位置气含率相较于初始结构分别提升了21.6%、156.4%、44.1%，效果明显。结论 优化后的流场结构可以应用在超声滚压加工系统中以提升加工过程中的空化效应。

Structural Optimization Design of Ultrasonic Rolling System with Coupled Cavitation Effect

The introduction of cavitation effect in ultrasonic rolling is expected to further improve the reinforcement quality. In order to maximize the cavitation effect, the optimized design of the flow field structure in ultrasonic rolling was carried out. Firstly, software Fluent was used to simulate the cavitation in ultrasonic rolling, and the vapor volume fraction (VVF) at three key locations around the roller was determined. Secondly, the optimal Latin hypercube method was used for the experimental design. The flow field structure parameters were used as the optimization variables, and the VVF at three key locations around the roller was used as the optimization target. The VVF approximate models were established with the second-order response surface method. Then, the weight values of each VVF were determined by combined AHP and entropy weight method, and the optimal flow field structure parameters were obtained by optimal solution of the approximate models using genetic algorithm NSGA-II. Finally, comparison of the VVF obtained with the optimized structure and the initial structure was performed to verify the optimization results. The results showed that the second-order response surface approximate models constructed for VVF fit well based on the results of 20 optimal Latin hypercube tests, and VVF at all three locations passed the significance test at 95% confidence level. After comprehensive analysis, the weights of the three optimization objectives were determined as 0.2791, 0.2516 and 0.4692. Compared with the initial structure, the VVF at the three key positions of the optimized structure was increased remarkably by 21.6%, 156.4% and 44.1%, respectively. The optimized flow structure can be applied to the ultrasonic rolling system to improve the cavitation effect.