Influence Of Volute On Non-Overload Performance In The Centrifugal Pump

The prime movers of low specific speed centrifugal pump are tending to overload or burned out when the pump working at large flow area cause the power curve sharply rise with the flow rate; whereas non-overload pump never overload with a suitable prime mover cause the pump has a maximum power value. Domestic and foreign experts have had most research on impeller of non-overload pump, less research on the influence of volute on non-overload. Based on the area ratio principle, the performance of pump, especially non-overload performance have studied by changing tongue setting angle, sectional area and section shape of volute. The main research content are as follows:(1) Based on the basic theory of the centrifugal pump and the description of the theory of saturated shaft power of the non-overload centrifugal pump and influence of area ratio principle on pump performance, the theoretical conditions of saturated shaft power are derived. The relationship of pump performance and area ratio principle are analyzed.(2) The theory of CFD simulation technique of pump and the basic procedure of CFD simulation was introduced systematically, including pre-processing such as computational domain modeling, mesh generation and boundary conditions setting; basic theory and option of simulation such as governing equation, discretization scheme, solving method, turbulence model; post-processing such as prediction of pump performance.(3) The influence of tongue setting angle on pump power and performance have been studied by change tongue setting angle. The result of decreasing tongue setting angle show that the power, head and efficiency increased and the power curve become steep, whereas H-Q curve become flat, the maximum efficiency move toward large flow; and the pump can avoid overload by obtain performance of saturated shaft power.(4) The influence of sectional area of volute on pump power and performance have been studied by change sectional area. The result show that when sectional area increase, the power increase and power curve become flat, the pump trend to overload; and the H-Q curve become flat; the efficiency have a promote at large flow area, whereas efficiency of pump has a large drop at small flow area.(5) The influence of section shape of volute on pump power and performance have been studied by change sectional shape as rectangular, trapezoid, round shape. The result show that the section shape has unobvious influence on pump performance. The pump power increase from round shape, trapezoid shape to rectangular shape; the maximum efficiency move to large flow area when volute section shape is round; and the maximum efficiency move to small flow area when volute section shape is rectangular,.(6) In order to check the reliability of CFD simulation, a group of pump performance tests about model pump and the retrofit pump with tongue setting angle is16°were carried out. The comparison shows that test results were very close to the simulation results, the prediction error is within5%when pump works at normal condition.