Numerical Simulation And Theoretical Analysis Of High-speed Centrifugal Pump With Inducer

Cavitation devastation is one of the main reasons to arise the malfunction of centrifugal pump. How to improve the suction performance of centrifugal pump is an important research aspect in the field of fluid mechanism. And the main energy transform is completed in impeller of impeller mechanism. So to know the flow principium in impeller is very significant to design high-efficiency impeller and to save the energy and cost. The researches were carried out on the above questions.The main contributions of this thesis are as follows:In chapter 1, the method of improving the suction performance of centrifugal pump and current research progress of the inducer were reviewed. The research progress of flow in centrifugal pump and the development and application of commercial CFD software were mainly described. The main research subjects were presented.In chapter 2, the numerical methods adopted in this paper were introduced. The N-S controlling formulation for relative velocity in rotating frame of reference and the S-A turbulent model were given. The spatial and time discretizations of the N-S controlling formulation were introduced. And four-stage Runge-Kutta iterative method of time discretization was introduced. Then, the accelerating computational methods including implicit residual smoothing and full multigrid strategy were presented. The convergence criterion was given.In chapter 3, the suction performance of inducer was analyzed and the design methods of single and two-phase inducers were given. Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three-dimensional turbulent flow in single and two-phase ones designed was simulated numerically. The relative velocity and static pressure in them were analyzed. And the experiments of the centrifugal pump with inducers were carried out.In chapter 4, using the jetting device to improve the suction performance of centrifugal pump was presented. The theories of jetting were analyzed and the jetting device was designed. Experimental studies on two centrifugal pumps with jetting device were carried out. And the cavitation tests were carried out at different feed-back capacity.In chapter 5, the design method of complex impeller was given and the flow mechanism of centrifugal impeller was analyzed. The simulative and experimental researches were carried out on four low-specific complex impeller with different number of mid and short splitter blades. The relative velocity and pressure distribution in them was analyzed. The influence mechanism of the number of splitter blades on the flow in impellers was disclosed. And the flow field in the semi-open four-long-blade impeller and four-long four-mid-blade impeller with different clearance was simulated numerically. The influence of clearance on the flow was analyzed.