Abstract
Daily and Nece distinguished four flow regimes in an enclosed rotor-stator cavity, which are dependent on the circumferential Reynolds number and dimensionless axial gap width. A diagram of the different flow regimes including the respective mean profiles for both tangential and radial velocity was developed. The coefficients for the different flow regimes have also been correlated. In centrifugal pumps and turbines, the centripetal through-flow is quite common from the outer radius of the impeller to the impeller eye, which has a strong influence on the radial pressure distribution, axial thrust and frictional torque. The influence of the centripetal through-flow on the cavity flow with different circumferential Reynolds numbers and dimensionless axial gap width is not sufficiently investigated. It is also quite important to convert the 2D Daily and Nece diagram into 3D by introducing the through-flow coefficient. In order to investigate the impact of the centripetal through-flow, a test rig is designed and built up at the University of Duisburg-Essen. The design of the test rig is described. The impact of the above mentioned parameters on the velocity profile, pressure distribution, axial thrust and frictional torque are presented and analyzed in this paper. The 3D Daily and Nece diagram introducing the through-flow coefficient is also organized in this paper.
Highlights
In radial pumps and turbines, the leakage flow is quite common from the outer radius of the impeller to the impeller eye, which has a major impact on the pressure distribution, axial thrust (Fa ) and frictional torque
The results indicate that the distinguishing lines
An example is provided on the applications of the results in this paper
Summary
In radial pumps and turbines, the leakage flow (centripetal through-flow) is quite common from the outer radius of the impeller to the impeller eye, which has a major impact on the pressure distribution, axial thrust (Fa ) and frictional torque. Nece [3] examined the flow of an enclosed rotating disk both analytically and experimentally. They distinguished the four flow regimes, shown, by correlating different empirical equations of the moment coefficients. Kurokawa et al [4,5,6] studied the cavity flow with both centrifugal and centripetal through-flow. Schlichting and Gersten [7] organized an implicit relation based on the results of Goldstein [8] for the moment coefficient under turbulent flow conditions. Poncet et al [9]
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