CFD BASED PERFORMANCE ANALYSIS OF MODIFIED PUMP USED AS TURBINE

Abstract

Energy plays an important role in almost all areas of human and commercial activities. Electricity generation through the non-renewable sources is quite common to meet the demand of the growing population and developing world. But the non-renewable energy sources are not expedient from ecological point of view and also responsible for producing major greenhouse gas (GHG) and promote global warming. These impediments forces to look for other clean and cheap sources for energy generation. The current concern on the global environment has imposed restraints on the production of electricity. The emphasis is put on the development of environmental friendly methods to promote the sustainable social development. It is in these circumstances, that micro hydro power is drawing more attention. The conventional turbine technologies like Pelton and cross flow turbines that have been implemented in micro hydropower sites having different head and discharge, have to be custom-made and are therefore more expensive also need expert design and precise manufacturing skills for a good performance. This often becomes a bottleneck especially for low capacity projects. An alternative of using well-known approach of `Pump as Turbine' can be contemplated and popularized. A large number of theoretical and experimental studies have been reported to predict the performance of centrifugal pumps in turbine mode. However, there is a need to study further this concept in order to get the advantages for sustainable development. Recently attempts to predict performance of PAT have been made using computational fluid dynamics. Some modifications in pump to improve PAT efficiency have also been attempted. Experimental study has also been carried out in order to improve the part load efficiency of pump in the turbine. Under the present investigation, performance analysis of a commercial centrifugal pump provided with movable guide vanes to improve part load efficiency in turbine mode has been carried out using Computational Fluid Dynamic. Complete model for simulation was prepared using Pro-E 2.0 and mesh was generated using ANSYS `MESH'. Simulation was carried out for different guide vanes positions using ANSYS `FLUENT'. Operating characteristics for modified PAT was drawn and compared with available experimental results. A good agreement has been found between the numerical and experimental results.