`EXPERIMENTAL & NUMERICAL INVESTIGATIONS ON A CENTRIFUGAL SLURRY "

Abstract

The present work is concerned with the evaluation of the performance characteristics of a centrifugal slurry pump. The centrifugal slurry pump considered for present examination has five twisted blades surrounded by a semi circular casing. First of all a pilot plant test loop of 50 mm pipe size has been designed, fabricated and installed using the centrifugal slurry pump to evaluate the performance of the pump with water and with solid liquid mixtures. To achieve the above objectives the performance of the centrifugal slurry pump has been evaluated at three different speeds namely 1150 rpm, 1000 rpm and 800 rpm with the clear water and with solid-liquid mixtures at three solid concentrations (by weight) namely 15.1%, 29.9% and 40.2% with quartz as solid material whose specific gravity is 2.65. At all the speeds, the head developed and efficiency of the pump is found to reduce with increase in solid concentrations. The power input to the pump is also found to increase almost linearly with increase in specific gravity of slurry for the range of experimental investigation. Another part of the work is the numerical analysis of the centrifugal slurry using FLUENT. The geometrical details of pump are collected by physical measurements to develop 3-dimensional computational model for CFD analysis. In computational domain, Multiple Reference Frame (MRF) model is used to simulate the steady flow through the rotating impeller and the stationary casing simultaneously. For turbulence modeling, standard `k —s' model is used. Finite volume method and unstructured grid system are used for solution of discretized governing equations. The numerical estimation of performance characteristics of centrifugal slurry pump is compared with experimentally evaluated characteristics. It is observed that the maximum deviation of numerically predicted head-capacity characteristics of pump compared to experimental result varies in between + 7.8 to -10.7%, which is significant. However, the trend of variation of the pump performance with the speed and solid concentration is similar in both cases.