泵轮偏心条件下高速液力耦合器特性研究

Investigation of the Characteristics of a High Speed Hydraulic Coupler Under the Condition of the Pump Wheel Being Eccentric

为获得液力耦合器泵轮偏心条件下内部流体环流形态及外特性变化规律,对液力耦合器进行建模并抽取三维全流道,基于RNG k-ε模型,采用VOF两相流模型SIMPLEC算法对液力耦合器泵轮在0、0.5和1 mm偏心量下的内流场进行数值模拟,分析内部两相流场的特点以及损失来源。根据三维流场数值解计算无偏心条件下液力耦合器叶轮转矩进而预测其性能,将性能预测结果与实验结果进行比较,误差在5%以内。对比分析不同偏心条件下液力耦合器外特性和相分布规律表明：偏心导致液力耦合器循环圆流量呈现波动状态,使流动非定常激励力增加,涡流、回流、二次流等不规则流动现象增多。流道内湍动能耗散随偏心量增大不断加剧,流动损失增大导致液力耦合器做功能力降低,效率下降。

In order to acquire the law governing changes of the internal fluid ring flow pattern and external characteristics of a hydraulic coupler under the condition of the pump wheel being eccentric, established was a model for a hydraulic coupler and chosen was a three dimensional integral flow passage. A numerical simulation was performed of the internal flow field inside the pump wheel of the hydraulic coupler under the condition of the pump wheel having an eccentricity of 0,0.5 and 1 mm respectively by using the SIMPLEC algorithm in the VOF （ volume of fluid） two-phase flow model based on the RNG k - model. On this basis, the specific features of the internal two-phase flow field and sources of losses were also analyzed and the torque of the pump wheel under discussion was calculated according to the numerical solutions to the three-dimensional flow field under the condition of the pump wheel being not eccen- tric. Furthermore, the performance of the coupler was predicted and compared with the test results, the er- ror being within 5 %. After the external characteristics of the hydraulic coupler and the law governing the phase distribution at various eccentricities had been contrasted and analyzed, it has been found that the eccentricity results in a fluctuation of the circulating flow rate of the hydraulic coupler and makes the unsteady excitation force and such irregular flow phenomena increase as vortex, return flow and secondary flow etc. The dissipation of kinetic energy of the turbulent flows inside the flow passages will ceaselessly deteriorate with an increase of the eccentricity and the flow losses will also increase, leading to a decline of the capacity of the hydraulic coupler to do work and a decrease of the efficiency.