Experimental and CFD Simulation-Based Analytical Optimization of Air-Cooling System for a Small 4-Stroke Scooter Engine

Progressive demand being placed on more efficient and quite engines require engine subsystem to be optimized without compromising their performance. Cooling system is one of the important engine sub system to be optimized to achieve better performance with reduced noise levels and with minimum power consumption. In the present paper an effort is made to optimize a fan-driven air-cooling system for a small 4-stroke scooter engine. Complete three-dimensional analysis has been done with commercially available computational fluid dynamics (CFD) codes. Analytical results are validated with the experimental results. A good correlation has been observed between analytical and experimental results. The work is done in two phases. In the first phase, complete flow and heat transfer analysis of the present system has been done. Flow analysis revealed flow blockage, significance of leakage through various parts of the cowling, and separation of the flow inside the vane passages of the fan. In the second phase, the system is modified to minimize the leakages and streamlining the flow inside the cowling. Vane layout of the fan is changed to decrease the fan power consumption and fan loses. Improvement in the efficiency of the cooling system without compromising on engine performance has been achieved. Quantitatively, a decrease of 43% fan power consumption and 3 dB of the noise level have been achieved.