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The Torque from an engine is a very critical parameter which controls the drivability of the vehicle, better torque availability at Partially Open Throttle (POT) condition improves drivability at city driving condition and better torque at Wide Open Throttle (WOT) condition improves cruising at highway driving condition, conventionally engine produces better torque at one particular operating condition leaving poor drivability at others. The Torque characteristics of an engine depends upon the volumetric efficiency of the engine. The volumetric efficiency of a naturally aspirated engine can be improved by tuning the intake manifold. With an overall improvement in volumetric efficiency throughout the engine operating conditions better torque curve can be achieved, which facilitates improved drivability.

In scooters, the Continuously Variable Transmission (CVT) is used to transmit the power from the engine to the wheels. The CVT transmission consists of a two pulleys connected to each other through a belt. The change in the transmission ratio is achieved due to the change in the pulley diameters. A centrifugal clutch is attached to the rear pulley to transmit the power to wheels once the engaging engine speed is reached. The heat is generated due to the belt slippage and the engagement of the centrifugal clutch. Excessive heating may damage the belt, clutch and deteriorate its performance. The cooling of the belt, pulleys and the clutch is thus important for its safe operation. The cooling is achieved by the centrifugal cooling fan which forces the air over the belt, pulley and clutch. A clear understanding of the cooling system is important in designing the air flow path for clutch cooling of CVT housing.

The basic requirement of a vehicle cooling system is to ensure that the components of the engine are adequately cooled under vehicle operating conditions. Engine life and effectiveness can be improved with effective cooling. In designing process, simulation plays a vital role. A clear understanding of the coolant flow and pressure developed within the cooling system is important in designing the coolant circuit. The efficiency of the cooling system depends on the flow delivered by the impeller. The work aims at the study of performance characteristics of a backward curved impeller in a two wheeler cooling system. The objective is to compare the operating points such as pressure drop, flow delivered and power consumed from mapped Computational Fluid Dynamics (CFD) simulation and closed loop CFD simulation. Moving Reference Frame (MRF) model was used to simulate the rotary motion of the impeller.