Effect of blade tip cutting angle on energy conversion mechanism of side channel pumps

Typical industrial blade side channel pumps with tip cuts have been used for many years because the blade profile has significant effect on the performance of the pump. To investigate the effect of the tip cutting angle on the energy conversion mechanism of the pump, the original and the industrial blades with different tip cutting angles were studied in detail. A comprehensive analysis revealed that the cutting tip enhances the hydraulic performance of the side channel pump, especially when the angle is equal to 20 degrees. The act of cutting the tip reduces the intersection of exchanged inflow and outflow between the impeller and side channel, especially at the outer radius, and eliminates the secondary flow at the corner. Furthermore, the application of the new Omega vortex identification method characterizes the dynamic vortex structures in three directions: axial, longitudinal, and radial. Based on the Galilean invariance of the vorticity, this paper operates coordinate transformation and uses the dimension reduction method to simplify the complex 3D (3 dimensional) vortex into 2D (2 dimensional) vortex intensity on specific research surfaces. By comparing each type of vortex, it can be established that the total vortex in the tip cutting scheme is more than the original scheme. This is because the cutting tip will produce extra space for vortex formation. Thus, the cutting tip schemes lead to a higher longitudinal vortex and lower axial vortex, thereby increasing the dynamic vortex and decreasing of the unfavorable vortex is the main reason for better performance. While the radial vortex seems equivalent, the tip cutting will increase this kind of vortex in the outlet region but decrease it in the inlet region as above. This work helps to understand the mechanism of energy conversion of side channel pumps and serves as a guide for further research in fluid engineering with strong swirling flows. Published under an exclusive license by AIP Publishing.