基于CFD的空间导叶出口边线性控制及内流分析

为提高多级潜水电泵的水力性能,采用试验验证和数值模拟相结合的方法,对Q80-20型多级潜水电泵的空间导叶展向各流面包角的变化规律用线性方程量化,探究方程斜率变化对导叶内部角区分离流的影响以及与导叶性能的映射响应关系.采用CFX17.1对2级模型进行全流场数值模拟,结果表明,线性方程斜率为负时,导叶的水力性能优于正斜率时.在负斜率基础上采取2种方案优化,结果表明,调整轮缘包角并增大包角差时,轮毂中部横向二次流被削弱,轮毂到轮缘的展向二次流增强,抑制了角区低能流体堆积,导叶性能随斜率的减小而单向升高.调整轮毂包角并增大包角差时,同样可增强中部轮毂到轮缘的展向二次流,但进口加剧的展向冲刷增大了能量损失,导致导叶的水力性能先增大后减小,存在最佳斜率.研究成果为后续研究空间导叶出口边型线对多级潜水电泵水力性能的影响提供研究基础和科学支撑.

Linear control design and internal flow analysis of diffuser trailing edge based on CFD

In order to improve the hydraulic performance of multistage submersible pump, the method of combining test verification and numerical simulation was adopted for Q80-20 multistage submersible pump. The linear equation was used to express the variation of the wrap angle of the diffu-ser and explore the influence of the change of equation slope on the separation flow in the corner of diffuser. CFX17.1 was used to simulate the whole flow field of the two-stage model, and the results show that the hydraulic performance of diffuser is better when the slope of linear equation is negative than positive. On the basis of negative slope, two schemes are adopted for optimization. When the linear equation intercept is kept constant and the slope is gradually reduced, the results show that the transverse secondary flow in the center of the hub is weakened, the spanwise secondary flow from the hub to the shroud is enhanced, the accumulation of low-energy fluid in the corner region is inhibited. The performance of diffuser increases unidirectionally with the decrease of slope. Shroud wrap angle remains unchanged, and the gradually decreasing slope also enhances the spreading secondary flow from the central hub to the shroud. However, the energy loss increases due to the intensified transverse scour at the inlet, which results in first increase and then decrease of the hydraulic performance of the diffuser, and there is an optimal slope. The results provide the research foundation and scientific support for the subsequent research on the influence of diffuser stacking on the hydraulic performance of multistage submersible pumps.