ملخص البحث :

Internal combustion engine is considered as a highly stressed structure due to high entire temperature and presser. For the engine structures and their entire components like cylinder head; it’s no arguing that this structure can consider a highly loaded, because it’s subjected to high fluctuations in temperature, pressure and clamping loads. The main objectives for this research work are to evaluate the materials response distortion, stress distribution and their effects on the engine performance. For these considerations, finite elements analysis methods by using (ABAQUS / CAE) software have been adopted for modelling and analysis purpose. The model with two layers (elastoplastic –viscoelastic) is considered as a best model which suitable to modelling the materials response of aluminum cylinder head with plasticity as well as considerable time-dependent at room and elevated temperatures. The results shown that the distortion in the cylinder head, valve ports and nearby regions is caused by the thermal stresses concentration and Von Mises stress distribution. The normal assessing of product performance is depending on fatigue and failure prediction in the overall structure. Also the direct cyclic analysis procedure is normally depending on the design considerations and this normally used for calculations of fatigue life.

ملخص البحث :

A hydrothermal performance of helical annular turbulent flow in a shell and tube heat exchanger has been investigated numerically. The numerical investigation involves a three dimension numerical solution of four models by a commercial package ANSYS FLUENT 16.0. The boundary conditions of all models that solved by the numerical solution was taken as a constant temperature and constant heat flux for inner tube wall, while the outer wall of shell side was insolation. The first model has a straight annular with air flow in annular regime, while the second model has a straight annular with water flow in annular regime. The third model has a twist annular with air flow in annular regime, while the fourth model has a twist annular with water flow in annular regime. Different Reynolds number for the air and water flow inside the annular regime of heat exchanger namely (500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, and 6000) were used for each model. The results indicated that the annular shape has significant effects on the hydrothermal performance; it found enchainment in all results of twist annular compared with the results of the straight annular, which included increasing in temperature difference of 9.1% and 24.2%, outlet temperature of 3.2% and 5.8%, while the increasing in heat flux, Nuselts number, and heat transfer coefficient of 11.2% and 31.3%, finally the increasing in pressure drop of 29% and 29.2% for air and water flow respectively. The results obtained from numerical solution presented the static temperature contours and showed that the temperature distribution of twist annular is better than straight annular. The present numerical results have been compared with the available previous studied and give a good agreement