Development of a test rig for investigating the flow field around guide vanes of Francis turbines

Abstract

This paper summarizes the development of a test rig containing three guide vanes of a Francis turbine, whose flow field is set up to match with that of the actual turbine. The rig is made suitable for Particle Image Velocimetry (PIV), such that the flow field around guide vanes can be measured. It has been studied that using three consecutive guide vanes in the rig give optimum results in terms of the lab capacity and having minimum influence of the wall surrounding the guide vanes. This rig also facilitates the measurements at off-designed conditions by changing the guide vane's opening angles. The flow conduits at inlet and outlet of the vanes have been optimized using CFD, to match the velocities corresponding to the turbine's design. The rig is also made suitable for testing the guide vanes with different clearance gaps. On comparing the results obtained from the experiment with CFD on the basis of velocity and pressure measurements, it is seen that the two results are comparable.