Browsing by Author "Subodh Kumar Sharma"

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Computational modeling of temperature field and heat transfer analysis for the piston of diesel engine with and without air cavity
(Hashemite University, 2015) Subodh Kumar Sharma; Parveen Kumar Saini; Narendra Kumar Samria
The present paper presents a theoretical study carried out to investigate the temperature field and heat transfer rate from the pistons of diesel engines with and without air cavity. The material was removed inside the piston, creating an air cavity. This cavity acts as an insulating medium which prevents the heat flow; thus, the need for providing insulation coating on piston crown is minimized. The main motive of this is to reduce the weight of the engine and the cost associated with thermal barrier coating. A detailed analysis was given for estimating the heat transfer rates to the cooling media and temperature field (isothermal distribution) in the piston body of water-cooled engines at different loads with and without air cavity. This analysis was done with numerical simulation models using FORTRAN programming. Results indicate that after creating an optimized air cavity in the piston, temperature, at all nodal point, decreases, which was presented in the form of contour bands and 4% of reduction in heat loss through piston, which leads to a better thermal efficiency. The FEA result provides effective theoretical evidence for further improving the pistons' performance. Additional benefits include protection of metal combustion chamber components from thermal stresses and reduced cooling requirements. © 2015 Jordan Journal of Mechanical and Industrial Engineering.
Experimental Thermal Analysis of Diesel Engine Piston and Cylinder Wall
(Hindawi Limited, 2015) Subodh Kumar Sharma; P.K. Saini; N.K. Samria
Knowledge of piston and cylinder wall temperature is necessary to estimate the thermal stresses at different points; this gives an idea to the designer to take care of weaker cross section area. Along with that, this temperature also allows the calculation of heat losses through piston and cylinder wall. The proposed methodology has been successfully applied to a water-cooled four-stroke direct-injection diesel engine and it allows the estimation of the piston and cylinder wall temperature. The methodology described here combines numerical simulations based on FEM models and experimental procedures based on the use of thermocouples. Purposes of this investigation are to measure the distortion in the piston, temperature, and radial thermal stresses after thermal loading. To check the validity of the heat transfer model, measure the temperature through direct measurement using thermocouple wire at several points on the piston and cylinder wall. In order to prevent thermocouple wire entanglement, a suitable pathway was designed. Appropriate averaged thermal boundary conditions such as heat transfer coefficients were set on different surfaces for FE model. The study includes the effects of the thermal conductivity of the material of piston, piston rings, and combustion chamber wall. Results show variation of temperature, stresses, and deformation at various points on the piston. © 2015 Subodh Kumar Sharma et al.