Study Of Numerical Simulation And Experimental Investigation On Clearance Flow In Axial Flow Pump

The influence factor of clearance flow through the tip clearance needs considering in three-dimensional aerodynamic design, due to clearance flow's influence on the structure of flow fields, distribution of flow loss, and efficiency of machine, according to study of axial flow compressor. Clearance flow causes large efficiency loss. Clearance flow also changes the condition of exit flow. Therefore, it is important for designers to predict the clearance flow phenomena accurately, for further improving efficiency of axial flow compressor.Pump is a kind of general machinery, in which axial flow pump is used extensively. Hydro efficiency of domestic axial flow pump is lower than foreign advanced level. Present study of real flow phenomenon in pump cannot meet the design of high performance axial flow. Similar study of axial flow pump has not been reported. Therefore, the study of numerical simulation and experimental investigation on clearance flow in axial flow pump is carried out in order to investigate the influence of tip clearance on flow fields and performance.Flow measurements are made before, inside, and behind an axial flow rotor by LDV. Based on the application interface of LDV, coding system is developed, periodic multi-sampling and continuous measurement are realized, and the difficult problem of circumferential locating and phase locking is solved. The experimental data processing procedure can automatically process data, provide relevant chart, curve and graphics, thus flow phenomena, flow condition, and flow behavior can be investigated through the senses.A parametric modeling method of axial flow pump is put forward based on COM. A polynomial fitting approach is presented, and thus the key question of fitting smooth blade surface from limited airfoil section is solved. Automatic modeling of axial flow pump is realized through basic parameter in airfoil database and the modeling software that adopts COM technology and OLE DB interface. Parametric modeling method, which ensures the precision of model, avoids the complex process of interactive modeling, is an effective geometry setup methodwhich adapts numerical simulation of three-dimensional flow in axial flow pump.Three-dimensional flow in axial-flow pump is simulated based on Reynolds-averaged N-S equations, standard k-e turbulence model, SIMPLEC algorithm, and unstructured mesh. The numerical simulation is done with various work conditions and tip clearance by FLUENT. The calculative method is reliable and effective through the validation by experimental data. At the same time, velocity distribution at the exit of rotor, velocity vectors at the axial plane through rotating center, pressure contour on the suction surface of the blade and flow behavior are analyzed in detail. The predict model of hydro-performance of axial flow pump is established on the basis of numerical simulation. The model can reflect the performance character of rotor, predict performance of axial flow pump, optimize geometry parameter of rotor, and provide basis for hydro design of axial flow pump.To setup geometry model of wetted parts through parametric modeling method, simulate flows using FLUENT, compare numerical result with LDV experiment, and establish predict model of hydro performance formed a system approach which studies complicated flow phenomena in axial flow pump.