Design and Analyses of Car Model by CFD Software

Abstract

Performance, Handling, Safety, and Comfort of a passenger car aresignificantly affected by its aerodynamic properties. Getting high power under the normal conditions is not enough to judge the performance of the car. Aerodynamic properties must be considered for the purpose of studying the drag and stability performance of a car. In order to improve car aerodynamic drag and its stability, an aerodynamic device is needed such as Spoiler. Spoiler is an aerodynamic device that functions to slow down and collect air, causing it to stagnate. This device creates an area of high pressure to replace the usual low pressure over the trunk resulting increasing stability. The objective of this study is to investigate the effects of aftermarket spoiler to car aerodynamics drag and stability. Several spoilers design is attached at rear and roof parts of base line model. Both Base line model, rear and roof spoiler models are built in CAD software. The CAD mode then, either with or without rear and roof spoiler are analyzed in CFD software to estimate the drag and liftforce which is acting on the car. Taking CFD software as the platform and the car as the research object, the air's resistance coefficients and speed are solved by using k-ε equations and dynamic mesh method and taking boundary conditions such as 100 kmph. The finite volume method is used to discrete the governing equations, Then CAD data , either with or without rear and roof spoiler are analyze in CFD software to estimate the drag and lift force which is acting on the car. Force, drag and lift coefficient values will be determined in order to study their effect to drag and stability. Some limitations occurred due to the complexity of the design. From the result, compared to with or without rear and roof spoiler roof is best in increasing stability of car at high speed.

Keywords: Aerodynamic Drag, Coefficient of Drag, Coefficient of Lift, Tail Plate, Wind tunnel simulation, PTC Creo, ANSYS FLUENT, Generic passenger car, CFD.