The Measurement Of Flow Fields At The Exit Of An Axial Flow Pump Impeller By 3D-PIV

The flow fields at the exit of an axial flow pump impeller are the rotary ones which have intense three dimensional character and they reflect not only the flow condition behind the impeller, but also the flow in front of the guide vanes. This dissertation adopted the technique of the 3D-PIV to measure the flow fields accurately for the first time at home which was important to reveal the regularity of the flowing at the exit of an axial flow pump impeller, to verify the mathematical model of the CFD computation and boundary conditions and optimize the hydraulic design of the impeller.ZM60, a 150mm- diameter water power model impeller with four screwy blades was selected . To meet the request of measurement , the rear guide vanes were moved away and a complete transparent impeller chamber was packed a quadrate water tank to minish the error effectively arose by the curve refraction.The performance of the pump was measured at the operating speed of 1450rpm to get the performance curve and five operation points such as the small flow rate, designable and large ones etc. An orbicular region which was formed by six axial planes in the plane of the horizon and three ones in the vertical plane at the exit of the impeller . The testing data was analyzed with the theory of cross-correlation to get the distribution figs of the radial velocity, the axial velocity and the circumferential velocity in every section. And by post processing , we obtained the spacial streamlines in the testing region and the distribution figs of the three kinds of velocity in planes which were perpendicular to the axis ,then the character ,the flow fields at the exit of the impeller were the intense three-dimensional spiral turbulent flow , was acquired . At last, errors of the experiment were discussed .From the analysis of results of the experiment ,the technique of the 3D-PIV is completely adaptive to the measurement of the flow fields at the exit of an axial flow pump impeller, and the actual condition of the three-dimensionalflow was obtained correctly .which provides the important reference for the design of axial flow pumps and is helpful for the proof of the result of the numerical calculation-CFD.