CFD Analysis of Car Using NACA 4412 Spoiler

Abstract

Presently stabilizing the vehicles at high speed with fuel optimization has become a field of concern. These two crucial factors are due to two significant forces drag and lift respectively. CFD is becoming a useful technique in current fluid dynamics research, because to the rapid advancement of digital computers. It brings together fluid mechanics, mathematics, and computer science. This work targets to simulate the drag and lift force on simple SEDAN car modeled in commercial CAD tool using commercial SIMULATION platform. This work focused on variation of dominant forces using an add-on device rear spoiler which was designed using NACA 4412 cross section at different angle of attacks. Then the work focused on evaluating optimal angle of attack at which the spoiler is most economic. The work then focused on variation in flow properties and co-efficient with various Reynolds number. Standard k-epsilon model with standard wall functions and second order upwind equations was used to investigate aerodynamic properties and to acquire the flow structure surrounding the car with rear spoiler. The variation with Reynolds number shows the increase in turbulence and other flow separation phenomenon with increasing Reynolds number. The effect of spoiler with increasing Reynolds number showed that after certain value the lift co efficient becomes almost constant but drag co-efficient increases with increased Reynolds number. With spoiler, it was found that the spoiler was most economic at 80 angle of attack by increasing the negative lift twice the previous value without spoiler and drag increment of 10.34% for spoiler with a value of CD= 0.322 and CL = -0.27, where without spoiler it stood for CD= 0.29 and CL = -0.1325.