Large-Eddy Simulations are conducted on a centrifugal pump at design and reduced flow-rates for three diffuser geometries, to investigate the effect of changing the diffuser inlet angle on the overall performance and the pressure fields. In particular, pressure fluctuations are investigated, which affect the unsteady loads acting on the pump, as well as vibrations, noise and cavitation phenomena. The considered modification of the diffuser geometry is targeted at decreasing the incidence angle at the off-design flow-rate by rotating the stationary blades of the pump around their leading edge. Results are compared against those of an earlier study, where the same modification of the diffuser inlet angle was achieved by increasing also the radial gap between impeller and diffuser, whose blades were rotated relative to their mid camber location. The comparisons across cases demonstrate that the radial gap between the trailing edge of the impeller blades and the leading edge of the diffuser blades has a more profound influence on pressure fluctuations, compared to the angle of incidence on the diffuser blades of the flow coming from the impeller.

在离心泵的设计上进行了大涡模拟，并针对三种扩压器几何形状降低了流速，以研究改变扩压器进口角对整体性能和压力场的影响。尤其要研究压力波动，该波动会影响作用在泵上的不稳定负载以及振动，噪声和气蚀现象。考虑到的扩散器几何形状的修改旨在通过使泵的固定叶片绕其前缘旋转来减小偏离设计流量时的入射角。将结果与早期研究的结果进行了比较，在早期研究中，通过增加叶轮和扩压器之间的径向间隙也实现了对扩压器进口角的相同修改，而叶轮和扩压器的叶片相对于其中曲面位置旋转。