Abstract
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.
Highlights
For proper functioning of the internal combustion diesel engine, accurate piston temperature distribution is required because piston temperature has an important influence on ignition process of engine, ignition time delay, rate of burning, thermal efficiency, and production of pollutants
In engine piston experiences high forces due to combustion chamber pressure and thermal load, which come from combustion process and from the huge temperature gradient between intake and exhaust gas flows [3,4,5,6] so, it is important to guarantee the durability of engine components like piston, piston rings, valves, and cylinder wall, to avoid engine body distortions and to improve engine design related to weight and auxiliary energy consumption
The analysis presented in this paper is divided into two sections, the temperature field distribution and the thermal stresses
Summary
For proper functioning of the internal combustion diesel engine, accurate piston temperature distribution is required because piston temperature has an important influence on ignition process of engine, ignition time delay, rate of burning, thermal efficiency, and production of pollutants. A common procedure used by some authors is to approximate the mean temperature of the distribution with one or more (very few) local measurements obtained by thermocouples [1, 7] These approaches implicitly assume errors that can be acceptable for heat balances but can lead to uncertainties in simulation cycles or temperature distribution analyses. In this paper a methodology is proposed for the estimation of the temperatures in piston and cylinder wall, piston body distortions, and radial stresses of a water-cooled fourstroke single cylinder direct injection diesel engine These temperatures were obtained by simulation and experimental setup with the help of thermocouples and other sensors and other calculations that are particularized to that engine
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