Aerodynamic Drag Reduction of a Notchback Car Geometry by Delaying Flow Separation using Vortex Generators

Abstract

For any high performance vehicle the aerodynamic properties are significant when attempting to optimize performance. One of the main source of aerodynamic drag is the flow separation which occur near the vehicle's rear end. In aerodynamics, flow separation can often result in increased drag particularly pressure drag which is caused by the pressure differential between the front and rear end as it travels through the fluid. For this reason much effort and research has gone into the design of aerodynamic and hydrodynamic surface which delays flow separation and keep the local flow attached to the surface for a long possible time. To delay the flow separation, vortex generator are tested for application to the roof end of the vehicle just before the point of separation of flow. But the vortex generator themselves also create the drag. But the drag created by vortex generator is very small as compared to the drag reduced by it. Example; Fur on tennis ball, Dimples on a golf ball, Leading edge extensions, Vortex generators, Turbulator on a glider.

Quantitative Analysis of Drag Reduction Methods for Blunt Shaped Automobiles

“…VGs at the front end were considerably effective in point of wake size reduction (10.7%-12.19% compared to 2.8%−5.8%); C D was not calculated in that work. Shivam et al [89] concluded that the VG optimal height is the boundary layer height. The VG was placed to delay the flow separation, and for that reason, it was moved to the trailing edge.…”

The Evaluation of Mesh Characteristics of the Car Modeling and Simulation Using CFD Analysis

“…Another aerodynamic device that is traditionally seen on aircraft, vortex generator, could also be implemented in cars. A study found that a notchback type car model with vortex generator results in lower drag coefficient than the same car model but without vortex generator because vortex generator causes the flow separation to happen downstream [11]. Flow separation that happens downstream prevents the early formation of wake region.…”

Experimental Approach and CFD Simulation of Battery Electric Vehicle Body

“…Singla, et al [20], investigated the aerodynamic consideration in designing body for a solar car which is to participate in world solar challenge, the world's top solar car race. Shivam, et al [21], investigated vortex generators was done to install immediately upstream of the flow separation point in order to control the separation of air flow above the car's window and improve the aerodynamic characteristics. Damissie, et al [22], this computational analysis showed that there is possibility of improving the aerodynamic performance of bus by modifications in exterior design of bus body.…”