Investigations of the Rear-End Flow Structures on a Sedan Car
Paper in proceedings, 2016

The aerodynamic drag, fuel consumption and hence CO2 emissions, of a road vehicle depend strongly on its flow structures and the pressure drag generated. The rear end flow which is an area of complex three-dimensional flow structures, contributes to the wake development and the overall aerodynamic performance of the vehicle. This paper seeks to provide improved insight into this flow region to better inform future drag reduction strategies. Using experimental and numerical techniques, two vehicle shapes have been studied; a 30% scale model of a Volvo S60 representing a 2003MY vehicle and a full scale 2010MY S60. First the surface topology of the rear end (rear window and trunk deck) of both configurations is analysed, using paint to visualise the skin friction pattern. By means of critical points, the pattern is characterized and changes are identified studying the location and type of the occurring singularities. The flow field away from the surface is then analysed using PIV measurements and CFD for the scale model and CFD simulations for the full scale vehicle. The flow field is investigated regarding its singular points in cross-planes and the correlation between the patterns for the two geometries is analysed. Furthermore, it is discussed how the occurring structures can be described in more generalized terms to be able to compare different vehicle geometries regarding their flow field properties. The results show the extent to which detailed flow structures on similar but distinct vehicles are comparable; as well as providing insight into the complex 3D wake flow.

Author

Charlampos Kounenis

Durham University

Sabine Bonitz

Chalmers, Applied Mechanics, Vehicle Engineering and Autonomous Systems

Emil Ljungskog

Chalmers, Applied Mechanics, Vehicle Engineering and Autonomous Systems

David Sims-Williams

Durham University

Lennart Löfdahl

Chalmers, Applied Mechanics, Vehicle Engineering and Autonomous Systems

Alexander Broniewicz

Volvo Cars

Lars Larsson

Chalmers, Shipping and Marine Technology, Marine Technology

Simone Sebben

Chalmers, Applied Mechanics, Vehicle Engineering and Autonomous Systems

SAE Technical Papers

0148-7191 (ISSN)

Subject Categories

Mechanical Engineering

Vehicle Engineering

Fluid Mechanics and Acoustics

Areas of Advance

Transport

Energy

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

DOI

10.4271/2016-01-1606

More information

Latest update

12/9/2018