CFD BASED DESIGN MODIFICATIONS IN CROSS FLOW TURBINE

Abstract

In hilly region micro hydro up to 100 kW have momentous role in utilization of mechanical power and electricity generation. The capacity of micro hydro power plant up to 5.0 kW is considered under development of water mill program by Ministry of New and Renewable Energy (MNRE), Govt. of India. The popularity of the turbines under micro hydro lies in the fact that they are less costly and can be fabricated locally. There are various types of turbines that can be used in micro hydro. Cross-Flow turbine has been considered techno-economically viable for such sites. Cross flow type runner can be fabricated locally, which results in the poor efficiency. The vanes can be made even from the pipes cut along the length. Also this kind of runner is suitable for low discharge and high head conditions, which is a common case in the hills. A cross flow type runner has a drum shape consisting of two parallel discs connected together by a series of curved vanes or blades. The water from the nozzles strikes the vanes and convert 2/3rd part of the potential into the mechanical power. The water that comes out from this blade strikes the diametrically opposite vane and the remaining conversion of 1/3`d part takes place. The problem with the fabrication of cross flow turbine runner at the local level is that its efficiency decreases due to lack of proper design and fabrication. The low efficiency is the basic inspiration to improve the existing design of cross flow runner. This study presents the design modifications in cross flow turbine using Computational Fluid Dynamics (CFD). The runner was modeled on the GAMBIT software Pro-Engineer and was meshed. The meshed model was imported to the CFD software FLUENT. The flow analysis was carried out on FLUENT. It is observed that the efficiency of cross flow turbine can be increased by introducing guide tube to guide the crossing flow towards the second stage of the runner. This study intends to study the flow pattern obtained using different types of guide tube. The results of this analysis can be used to study the performance of a cross flow runner for suggesting improvements. 111