Optimization design and effect analysis of multi-operation conditions of axial-flow pump device

Abstract: The flow units of pump device will produce a bad flow regime when the axial-flow pump runs under off-design condition. The paper uses the numerical simulation and numerical optimization techniques, changes the geometric design parameters of axial-flow impeller, and carries out the optimization design of multi-operation conditions of axial-flow pump device. The optimization design based on pump device experiment analysis aims to improve the efficiency of operation under off-design conditions, broaden the scope of the efficiency of pump device, and reduce the operating cost of pump station. Firstly, this paper performs the parametric modeling of axial-flow impeller, and uses fewer design parameters to control the shape of pump blades by FORTRAN. According to the design condition to design an axial-flow impeller with high efficiency, and design the guide vane based on the design condition and the impeller. Use the impeller, the guide vane, and the standard inlet and outlet pipe to calculate the hydraulic performance of axial-flow pump device. Then do the experiment of the pump device to verify the accuracy and reliability of the numerical simulation of the pump device. Lastly, this paper carries out the optimization design of multi-operation conditions of axial-flow pump device. The design flow is 360 L/s, the small flow is 300 L/s and the large flow is 420 L/s, and the 3 flow conditions is chosen as the multi-operation conditions. Change the design parameters of axial-flow impeller, select the weighted average efficiency of pump device as the optimization object and the head of each condition as the constraint, and carry out the optimization design of multi-operation conditions of axial-flow pump device. For each design parameter, every change corresponds to a complete numerical simulation of pump device. Last but not least, this article does the internal flow field analysis of pump before and after optimization. The analysis mainly includes the streamline comparison of the different flow conditions for the outlet pipe, and the pressure comparison of the different flow conditions in the outlet of the impeller; besides, the NPSH(net positive suction head) is compared before and after optimization. The optimization results show that the optimized high efficiency range of axial-flow pump device is widened obviously compared to the initial pump device. The efficiency of small flow condition is increased by about 2.6%, the efficiency of design flow condition is increased by about 0.5%, and the efficiency of large flow condition is increased by about 7.4%, which is the most. As to the head of the axial-flow pump device, it is little changed, and can also meet the operation requirement. The optimized pump device can greatly reduce the operation cost of pump station, and the optimization design method of multi-operation conditions of axial-flow pump device can greatly shorten the design cycle. From the comparison of streamline and pressure before and after optimization, it can be seen that the optimized streamline is smoother and the pressure distribution is more reasonable. And the NPSH is similar, and does not become worse. This paper adopts the computational fluid dynamics (CFD) simulation as the subject analysis method, which is combined with experimental study and replaces artificial way of optimization design based on experience, and proves the reliability and efficiency of the optimization design of multi-operation conditions of axial-flow pump device.