This study presents a numerical study concerning flow control by suction and injection. The case studied is the flow field over a subsonic airfoil with four suction and injection slots on the suction side of the airfoil. Five different angles of attack, 0, 5, 10, 13.3 and 20 with the Mach number of 0.15 are studied. Three cases are studied in each angle of attack. The three cases are airfoil with surface suction, surface injection and the base airfoil. A commercial CFD code, the FLUENT, is used in this study. The effect of suction and injection on aerodynamic coefficients is investigated. The results show that the surface suction can significantly increase the lift coefficient. The injection decreases the skin friction.

For some manufacturing processes, the heat transfer between the components, the tools and the environment has an effect on tool-life and the accuracy of the formed component. Consequently, the measurement of Thermal Contact Resistance (TCR) is of increasing interest to researchers and industrial engineers participating in the manufacture of high-precision components. A new transient method and measurement apparatus are used in which the measurements are conducted on specimens, which are retained under pressure. An apparent advantage of this method is the ability to estimate the TCR under specifically controlled conditions. The other advantage is that no prior information is needed on the variation of the TCR, since the solution automatically determines the functional form over the domain specified. Therefore, in this research, a new method of determining TCR has been successfully used to measure the dependence of TCR on the pressure and the specimen texture.

No abstract

A large-scale, high-resolution finite element methodology for thermomechanical analysis of complex engine components has been developed. This paper describes the process and presents an example evaluation of an engine cylinder head. Because of its non-symmetric configuration, the cylinder head was entirely modelled. The geometric nature of the cylinder head requires very precise three-dimensional analysis techniques. The geometry modelling was carried out using a computer-aided engineering tool. Full multidimensional mechanical and thermal stress analysis in the cylinder head is made by using a finite element analysis commercial code. Validation of the simulation is achieved by comparison between simulation and experimental test results. The results of this analysis show high stresses at the valve bridge. These stresses result from a constrained thermal expansion of the cylinder head, and are generally compressive and radial in nature. Finite element analysis (FEA) and computational fluid dynamics (CFD) used in conjunction with experimental verification were found to be very powerful analysis tools for engine component development and design.

An interesting application of system identification method is to investigate the heat transfer from the exhaust valve, especially the valve burning at high temperatures. This study consists of experimental and analytical works. For the experiment, two co-axial rods were used to transfer heat constantly at their contact surfaces. Using the measured temperatures at different locations of the rods and the analytical method, the temperatures distribution of the rods were calculated; consequently the heat transfer coefficient at contact surface was calculated. By applying the system identification method and having the temperatures at both sides of the contact surface, the temperature transfer function was calculated. The transfer function is changed as the operating conditions are varied. Using the calculated transfer function and the system identification method, a computational model was created. By knowing the temperature of one rod, the temperature of the other rod was estimated with high accuracy.

Flow separation and reattachment around the vehicle A-pillar region dictates strong pressure fluctuations on the side window surfaces and can also lead to generate aerodynamic noise. The objective of this work is to investigate qualitative flow visualization of airflow behaviour around vehicle A-pillar and its potential to generate windnoise in this region. By means of Computational Fluid Dynamic (CFD) under laboratory operating conditions, a series of three-dimensional Navier-Stokes simulations for the vortical flow around two simplified basic car models with different A-pillar/windshield geometry were carried out at different cruising speed. Both models were made with 60° flat inclination angles but with deferent A-pillar/windshield curvature, a small semi-ellipsoidal shape, a slanted sharp-edged shape. Investigations were carried out at velocities 60,100 and 140 for 0 and 15 degrees yaw angles. Results of mean pressure coefficient obtaining using CFD modeling were also compared against available experimental data. Furthermore; using Boundary Layer Noise Source Model, an approximate measure of the local contribution to total acoustic power per unit surface area were carried out in a given turbulence field. The studies provided reasonable agreement against available experimental data. The studies show that the surface mean pressure coefficients magnitudes are independent of Reynolds numbers and dependent largely to A-pillar and windshield effective corner radii. In addition, surface acoustic power level analyses show that A-pillar and windshield local corner radii effects significantly to potential of noise generation around A-pillar region

The system identification method is one of the most important topics in engineering. An interesting application of this method is to investigate the heat transfer from the exhaust valve, especially the valve burning at high temperatures. This study consists of experimental and analytical work. During experimentation, two co-axial rods were used to transfer heat at their contact surfaces. Using the measured temperatures at different locations on the rods and the analytical method, the temperature distribution of the rods and the heat transfer coefficient of the contact surface were calculated. Using the above calculated temperatures at both sides of the contact surface and applying the system identification method, the temperature transfer function was estimated. Using the transfer function, a computational model was created. The results were compared to previous research work. An experimental apparatus, including an analog to digital board, was designed and set up for the experiment.