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Author(s): Kaliappan S, S. Mohana Murugan, Nagarajan P.K.
Keywords: CFD, Sinusoidal, Trapezoidal, Hydro-thermo dynamic and Mechanical characteristics
This paper is aimed at a comparative investigation on two different velocity profiles for piston movement namely sinusoidal and trapezoidal profiles for an I.C engine. In sinusoidal velocity profile for piston motion in IC engines, has many disadvantages such as high mean velocity that leads to high inertial force, frictional losses, wear and high rate of heat leakages. Nearly 20% of the total power produced by the engine is dissipated into heat because of friction. Of this 20%, about 75% is due to friction of piston rings on the cylinder walls. This is an irreversible loss and can be seen as a consequence of high mean piston velocities associated with the existing sinusoidal piston velocity profile. In addition, varying velocity profile can cause rapid acceleration and finally jerks. This forms of considerable mechanical vibration and noise. As a result the mechanical strength of engine material should be high to withstand the inertial force, friction and wear. To overcome these difficulties an extensive attempt is made to optimize the piston movement by restructuring the piston velocity profile with reduced mean velocity that is constant for most of the crank angle. A comprehensive experimental examination is conducted for the sinusoidal velocity profile. These results are utilized in arriving at an optimal computational procedure for applying CFD and to validate the numerical results & used to analyze and understand the engine with modified trapezoidal velocity profile. There is almost 20% reduction of mean piston velocity that considerably improves hydro-thermo dynamic and mechanical characteristics