Search Results

Being a continuous subject of research, the authors present in this paper new aspects and results concerning the relevance of diffusers in vehicle aerodynamics. In the first stage of investigation, a generic car model with wheels was considered, starting from the Ahmed body, and the effect of adding wheels to the body was studied. Latter, the influence of diffuser length and angle, within ranges relevant to hatchback passenger cars, on drag and lift was studied for the Ahmed body with wheels. The results show that the addition of wheels and wheelhouses results in increasing of drag and lift due to the vortices which originate from the wheels. Concerning the underbody diffuser, the results show that both drag and lift of the bluff bodies with wheels are reduced with increasing diffuser length for moderate values of angle, up to six degrees for the cases studied.

In the present work a three-dimensional analysis is used to study cooling performances of copper- ethylene glycol nanofluid through the flat tubes of an automobile radiator to evaluate their superiority over the base fluid. A numerical simulation is carried out by solving the governing continuity, momentum and energy equations for laminar flow. The investigation covers Reynolds number, inlet temperature and nanoparticle concentration level in the ranges of 10-125, 348-368K and 0-2% respectively. The effects of using the nanofluid on the heat transfer inside the flat tube are investigated. Numerical results have been validated by comparison of simulations with those available in literature.

In this paper, using the facilities offered by the ANSYS CFX, CFD code, the authors investigate numerically the flow around the Ahmed body for the rear slanted upper surface of 35°, fitted with a simple underbody diffuser, without endplates, in order to find the influence of the later one on the main aerodynamic characteristics, drag and lift. Relative motion between body and ground is simulated. The study is performed for different geometrical configurations, length and the angle of the diffuser being the parameters which are varied in ranges which are relevant for hatchback passenger cars. Later, based on a theoretical approach, a coefficient of the equivalent hydraulic resistance of the diffuser is computed, which helps to evaluate the drag due to underbody diffuser.

In this paper a numerical model is used for analysis of parameters which affects heat pipe operation. The steady state incompressible flows are solved in Cartesian coordinates in both vapour region and wick structure, using professional CFD (Computational Fluid Dynamics) software. The objectives of this work were to study of the parameters variation on the operation of heat pipes. The heat pipes are made from copper tube with the outer diameter 8.9 [mm ] and the length 200 [mm ]. The water is used as a base working fluid while the nanoparticles used in the present study are the iron oxide nanoparticles. Two cases, with volume concentration 0% and 2% for iron oxide nanoparticles are considered.

The aerodynamic characteristics of a vehicle have a significant role on its dynamics performances, fuel consumption, level of produced noise etc. In this sense the automotive engineers design vehicle having some much elaborated exterior shape, the main goal being the reduction of drag. But, in many cases, the geometry of the underbody was neglected from this point of view, especially in the cases of the off-road vehicles, which have recently become more versatile, as seen in Sport Utility Vehicles (SUV). In this paper, using a SUV as example, the contribution of the underbody geometry on total drag is studied using the facilities offered by a professional CFD code. The results show that solutions for the optimization of the body of vehicles from an aerodynamic point of view can be obtained even in a very early design stage, accelerating the design process.

Because the aerodynamic loads, which are acting on the high-speed vehicles, play a significant part concerning the dynamic behaviour of the latter, the aerodynamics is one of the most important design considerations for cars such as Indy or Formula 1. The goal of this study is to investigate the contributions of the main structural components of a racing car on total drag using the facilities offered by a professional CFD code. The results show solutions for the optimization of the body of vehicles from an aerodynamic point of view, even in a very early design stage, the design process being accelerated.

Using a prototype of terrain car as example, a process of flow simulation around a vehicle with rotating wheels is described by using a professional CFD (Computational Fluid Dynamics) software. The influence of the wheels motion on main aerodynamic characteristic of the car, drag, is studied in two ways, commonly used in wind tunnels [10], respectively with the moving wall approach and with the aid of the rollers for the wheels rotation. The conclusions are demonstrated by the results using the relative drag increment and by the computergraphics visualizations. There are also presented some considerations concerning the importance of the rotating wheels in aerodynamics of the road vehicle and the opportunity to simulate it in a virtual environment. The present contribution is a companion paper by Huminic & Chiru (2004).