Pressure Distribution Along The Casing Of A Centrifugal Pump And Its Effect On Support Bearing Temperature Distribution

In a centrifugal pump, impeller transfer energy to liquids and a part of the transferred kinetic energy converts into the pressure energy in the surrounding casing. Any asymmetric pressure distribution around the impeller gives rise to radial force, which increases temperature at support bearings of the pump. An effort has been made in the present work to relate rise in the bearing temperature with the pressure distribution around the impeller with and without minor change in its position (by 0.5 - 1.0 mm) relative to the casing. The maximum bearing temperature is found at full open delivery valve (low delivery pressure). It has been observed that the reduction in asymmetric pressure distribution reduces the bearing temperature rise to the order of 10°C. It is seen that a small eccentricity of 1.0 mm in the position of impeller with respect to the volute casing gives less asymmetric pressure distribution at the low delivery pressure where as at high delivery pressures, it results in higher asymmetric pressure distribution compare to the concentric mounting of the impeller. Copyright © 2004 by ASME

Numerical study of the Winter-Kennedy method for relative transient flow rate measurement

The Winter-Kennedy (WK) method is used to estimate relative flow rate using the differential pressure between two taps located at a radial section of a spiral casing (SC). It is widely used in index testing, for double regulated turbines optimization and sometimes for continuous discharge measurement in low head plants. This paper explores the possibility of using the WK method for relative transient flow rate measurements. A numerical model of a Kaplan model turbine from the penstock to the distributor has been developed. Unsteady RANS simulations with k-ω SST turbulence model are performed. Previously conducted experiments on the model turbine are used to validate the numerical results. In the simulations, the guide vanes (GVs) are closed from 26.5°, the best efficient point (BEP), to about 5° opening angle. Two azimuthal locations of the SC and four different WK configurations at each location are considered. The variation of the WK coefficients with time are investigated and compared to the ones at several stationary GV angles. The results showed a difference between the WK coefficients obtained at transient and stationary operations. However, there may be a possibility of using the WK method during transients by locating the pressure taps in appropriate locations for an acceptable variation of the WK coefficient from its BEP value. The research has been funded by Swedish Hydropower Centre (SVC).Konferensartikel i tidskrift</p

Entropy generation optimization of EMHD mixed convective flow with higher order chemical reaction: Sensitivity analysis

This investigation deals with the sensitivity analysis of the unsteady, incompressible fluid flow past a vertical elongating surface using the Response Surface Methodology. The impact of Joule heating, viscous dissipation, non-uniform heat source, and higher-order chemical reaction are encountered under the influence of external electric and magnetic fields. The governing equations are modeled by the boundary layer assumptions with slip conditions, which are changed to dimensionless form by incorporation of the transformation variables. The dimensionless equations are higher-order ordinary differential equations. These ordinary differential equations are numerically simulated by the application of iterative shooting technique with Runga Kutta 4th-order numerical method. Outcomes corresponding to the fluid velocity, temperature, and concentration profile are presented in the graphs, surface plots, and contours for different influential parameters like Eckert number, electric field parameter, Prandtl number, and chemical reaction parameter. It is observed that the Nusselt number escalates with an increment in the electric field parameter and Hartmann number. The entropy formation rate is greater along the higher Hartmann number values and lesser along the higher electric field parameter values. Findings of this attempt are helpful in heat storage systems, pharmaceuticals, biological engineering, medication delivery, safer cooling surgery, cooling reactors, biosensors, magnetic cell isolation, and military fields