International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 02 | Feb 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1392 NUMERICAL ANALYSIS OF DIESEL ENGINE COMPONENT UNDER THERMAL LOADING Anthony Kpegele Le-ol 1 , Charles B. Kpina 2 1 Department of Mechanical Engineering, Rivers State University, Port Harcourt, Nigeria. 2 Department of Mechanical Engineering, Nigeria Maritime University Okerenkoro Delta State. ----------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - This research is intended to numerically analyze the thermal stress on marine diesel engine piston crown. It analyzes the basic stress form and distribution on the piston crown. Engine pistons are one of the most complex components amongst all internal combustion engine components and the piston crown which is subjected to pressure fluctuation and thermal stress during normal engine operation. Damage mechanisms have different origins and are mainly wear, thermal and fatigue related. Among the fatigue damaged, thermal stress and mechanical stress either at room temperature, play a prominent role. In this research, analytical model and solid works were integrated to modeled and simulate the piston crown, analyzing the basic stress form and distribution on the piston crown. Two materials were used to demonstrate the model of the piston, such as the Aluminium Alloy and Malleable Cast Iron. Applying a pressure of 5MPa, the result of Malleable Cast Iron gives best performance than the result of Aluminium Alloy. Key Words: Marine Engine, Thermal stress, loading, Piston 1. INTRODUCTION Thermal stresses on marine engine components in the combustion chamber of marine diesel engine are the main factors limiting the performance and durability of Marine engines. One of the most loaded elements is the piston head/crown, exceeding the permit set temperature of the piston causes various types of material losses and leads to an excessive increase in diameter of the piston, resulting in its galling. In turn temperature fluctuations may cause formation of crakes, leading to development of leakages and even preventing further work of the engine [1]. The effect of the heat during the engine operation causes reversible and irreversible dimensional changes in the piston which determines the valve of the clearance of the piston-cylinder assembly, the clearance of the tightness of the combustion chamber and thus on the side of the change losses. This is particularly important for marine engines, where the loss of charge during compression reduces the real excess air ratio in the engine combustion chamber. An improper class of the piston cylinder assembly has a negative impact on oil consumption, the capability to start the engine and the noise. The piston temperature is significantly affected by the proper position of engine rings. From 60 to 80% of the heat acquired by the piston from the working medium is required through the rings into the cylinder. Requirements for the location of the rings are incompatible. In order to reduce the thermal load of the rings they should be located as far away from the piston head as possible and in order to reduce the thermal load of the piston they must be placed possibly higher [1]. For all engine speed and loads, a distinct reduction in the piston temperature is achieved in all of its points by reducing the distance between the ring and the piston head. Changing the number and heights of rings also causes a change in the piston temperature due to changes in this surface via which the heat exchange occurs. Apart from the design conditions of marine engines, also the service conditions also affect the thermal loads of piston, the conditions of the engine operation include a change in the effective pressure, assuming that mechanical efficiency is constant, and increase in the average effective pressure is equivalent to a higher heat emission, which leads to an increase in the piston temperature. Thermal stresses are difficult to simulate because there are in piston two types of stress  Thermal stress due to the vertical distribution of the homogenous and regular gradient of temperature at the top and lower temperature at the bottom. There is a homogenous and regular gradient of temperature on the radial direction along the head of the component. It is observed that the bowl rim area is the areas where temperatures are higher thermal deformations under the operating bowl rim temperature are contained by the surrounding material. After creep relaxation of the high compression stresses and when the piston gets cold creep effect gives rise to tensile residual stress on the bowl rim. This cycle origins cracks distributed all around the rim area.  Thermal stress due to the different temperature at the head of the piston due to the flow of the hot gasses or to fuel impingement (related to high- pressure infections). This distribution causes localize warmer areas [2].