Investigation of the effect of gaps between the blades of open flume Pico hydro turbine runners

Abstract

This study will analyze the impact of gap size in two different runners called runner A (five blades) and B (six blades) to provides recommendations in design and manufacture of open flume turbine runners so that maximize the conversion of kinetic and potential energy. There are three methods was used to investigate its: analytical method is used to design the turbine; experimental to determine the actual turbine performance; computational fluid dynamics (CFD) to study the physical phenomena and re-check the velocity triangle on the runner to validate the design and manufacturing process. Using the results obtained, gaps between the blades can alter the velocity vector on the outlet and unbalance the rotation of runner; this imbalance could cause cavitation. Then, the decreasing torque is assumed because water pressure in the draft tube is similar to atmospheric pressure. Two conditions must be satisfied to maximize the performance of the turbine: swirling flow is required after the water flows past the runner in order to minimize the radial velocity on the outlet so that the draft tube can function properly; the dimensions of the blade must be carefully selected to avoid the formation of gaps between the blades.

Application of the Grid Convergency Index Method and Courant Number Analysis for Propeller Turbine Simulation

“…Studies examining propeller turbines using computational methods have been carried out. Adanta et al, [13] studied the effect of gaps between blades on the energy conversion process. Simulation from computational methods describes the flow field in the propeller turbine in detail and precision [13].…”

“…Adanta et al, [13] studied the effect of gaps between blades on the energy conversion process. Simulation from computational methods describes the flow field in the propeller turbine in detail and precision [13]. The computational results visualise changes in fluid velocity vector due to wide gaps between blades [13].…”

“…Simulation from computational methods describes the flow field in the propeller turbine in detail and precision [13]. The computational results visualise changes in fluid velocity vector due to wide gaps between blades [13]. Warjito et al, [14] investigated the transfer of energy on flat and aerofoil blades in propeller turbines.…”

Study of Turbulence Model for Performance and Flow Field Prediction of Pico Hydro Types Propeller Turbine

“…One type of pico hydro turbine that can be used in remote areas is propeller turbine. The propeller turbine is categorized as reaction turbines which have performance relatively high and stable in low head conditions because a wide range of specific speed (Ns) [7][8][9]. The propeller turbine is a turbine that has a high modularity and compact so that it is able to be easily distributed to remote areas [7].…”

“…Based on numerical analysis, the runner designed based power function had better performance [15]. Adanta et al, [9] explained that the distance between blades could change the flow velocity at the outlet where this made torque decrease causing the reduction of efficiency.…”