Tuesday, November 5, 2019

Aerodynamic Development Of Land Speed Record Car Engineering Essay

Aerodynamic Development Of Land Speed Record Car Engineering Essay This project is focused on the baseline aerodynamic analyses and optimisation of a Land Speed Record vehicle in terms of performance of drag and aerodynamic stability, and thereby, speed the vehicle can attain. The vehicle `Stay Gold’ shown below belongs to the David Tremayne, a Formula One journalist. It is his plan to break the current British Land Speed Record by achieving a speed of about 350 m/s. A photograph of the vehicle in its current form can be seen below. C:UsersCecilDesktopDSC07489.JPG Figure 1, (20)- Photograph of the Land Speed Record vehicle in its current form. In aerodynamic analyses, the prohibitive costs of conventional wind testing along with the advent of computing power, characterised by its decreasing cost has brought the applications of Computational Fluid Dynamics (CFD) to the fore front of research and industrial applications, (2). The complications of actual wind tunnel testing ranging from differences in boundary conditions to the scale and mounti ng of the object is covered well in existing literature, (1). CFD is a method for analysing complex fluid flow problems using numerical methods to solve the Navier-Stokes governing equations. This report begins with the study of high speed vehicle aerodynamics to understand the important physical phenomena taking place, i.e. Air flows linked with different parts of the vehicle. CFD has been established as a proven tool used to perform baseline simulations with different turbulence models, boundary conditions and grids. Consequently, the influence of compressibility by running cases with progressively faster operating speeds up to Mach 0.5 and the effects of varying the geometry of nose and body of the vehicle using low-drag fairings are studied. Literature Review: High Speed Vehicle Aerodynamics: Aerodynamics is the study of various forces when a body is in motion. As we know, any vehicle moving through a fluid experiences forces induced by the fluid on it. When a vehicle moves forw ard it displaces the static air in front of it and hence disrupts the air flow around the body. These induced fluid forces can be characterised into three main forces which can be represented on a Cartesian coordinate system as shown in the figure below, (19). Figure 2, (19)- Forces acting on a vehicle represented on Cartesian coordinate system The vertical force along the Z axis is called lift. In this context, the vertical force is usually pushing the car towards the ground. Lift force then would be negative. Instead, the term downforce will be used, which is the positive vertical force towards the ground. The horizontal force moving in the opposite direction as the vehicle along the X axis is called drag force. Drag force is created by the vehicle’s resistance to motion moving through the air. . Drag will always be negative with this axis system, although in the results it will be displayed as positive, (19). The horizontal lateral force along the Y axis is called side for ce which occurs due to strong cross winds or by vehicles being in proximity to each other. The magnitude of these forces depends on various factors like the geometry & speed of the vehicle, mass of the fluid, viscosity & compressibility. These three forces are the basic aerodynamic forces that act on a moving solid body. We concentrate on the reducing the drag force alone to achieve higher speeds.

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