Optimization of Power Consumed by Scooter Engine Cooling Fan

The effective cooling of a two wheeler scooter engine depends on the efficient performance of the cooling fans. In scooters, centrifugal fan with axial air inflow and radial outflow with either backward curved or forward curved blades are used. The air flow enters the unit axially and then spreads out turning to 90 degrees into radially outward direction before meeting the engine. The work aims at the study of performance characteristics of the forward and backward curved fans when put in to engine cowling and to compare the power consumed and flow delivered by the fans. The objective is to compare and reduce the power consumed by the cooling fans and to increase the air flow velocity across the engine surfaces. A Conjugate Heat Transfer analysis has been done to study the effect of forward and backward cooling fans on flow delivered, power consumed and engine surface temperature. RANS K-Epsilon two equation turbulence model was used to solve the 3-D numerical model. Moving Reference Frame (MRF) model was used to simulate the rotary motion of the fan. The engine cowling geometry was modified to avoid recirculation near the fan region and to have flow expansion near the engine head and block. An experimental validation of the fan with the modified cowling profile is done for flow rate, power consumed, temperatures across the fin surfaces. The power consumption was reduced by 31.27% (80 Watts @ 8000 RPM) by the optimized fan for the same operating point. A complete numerical methodology has been developed for the selection of fan for effective engine cooling.