Numerical Simulation And PIV Measurements On The Flow Field Of Axial Flow Pump

Axial flow pump, a kind of turbomachine, is widely used in different aspects, and axial flow pump with high performance is needed for the development of civil economy and national defence. However, the flow field of axial flow pump is complex and various three-dimensional flows have a large impact on working performance and stability of axial flow pump. Therefore, the research and cognition on the flow field's principle of axial flow pump will benefit for understanding hydro-dynamic of axial flow pump, accumulating key experimental data, offering theory and improving design and performance of axial flow pump and pump system.Experimental measurement and numerical simulation are both basic ways for research on the flow field of turbomachine. With the development of science and technology, Laser velocimeters, such as particle image velocimeter, provide the powerful tools to measure the flow fields; and also the CFD codes provide the useful methods to simulate the flow field of turbomachine. In this thesis, the flow field of axial flow pump is investigated by both experimental measurement and numerical simulation.Main contents of this thesis are described as the following:1 Performance test is conducted according the national standard SL140-97, and the performance curves are obtained. The experimental data are coincident with expectant design.2 PIV system is used for the flow field of rotational impeller in axial flow pump, and some practical problems in laser measurement are solved, such as demarcation in measurement, locating the measurement circumference position relative to the rotor, selecting the seeding particles and transmitting as well as receiving the laser light, et al.. Two dimensional flow field in the inlet, outlet and different blade span are obtained, and the separate flow near trailing edge of blade and the flow structure of backflow and vortex are investigated. And optical errors in PIV experiment are analyzed.3 Based on the Navier-Stokes equation set, the standard k-εturbulence model and with the use of SIMPLEC method, the numerical simulation of the flow field in axial flow pump is conducted. The pump performance curves resulted from numerical simulation is verified with the experimental results; and furthermore, the computational distribution of relative velocity and streamline in inlet, the discharge region and different blade span is compared with the results measured by PIV in the same positions, and they are in a good agreement, which indicated the validity and correctness of the numerical simulation.4 The distribution of pressure and velocity in the flow field of axial flow pump is analyzed. The work of blade increases along radial direction according to the distribution of pressure coefficient. The generation and development of passage vortex are predicted, and the difference between pressure surface and suction surface is the main cause to passage secondary flow. The structure of blade tip flow in 50% chord is analyzed. The distribution of water vapour volume fraction in different flow rate is investigated.