# Active flow control on a 1:4 car model

Active flow control on a 1:4 car model Lift and drag of a passenger car are strongly influenced by the flow field around its rear end. The bluff body geometry produces a detached, transient flow which induces fluctuating forces on the body, affecting the rear axle, which may distress dynamic stability and comfort significantly. The investigations presented here deal with a 1:4 scale model of a simplified test car geometry that produces fluctuating lift and drag due to its strongly rounded rear geometry. To examine the influence of active flow control on this behavior, steady air jets were realized to exhaust from thin slots across the rear in three different configurations. Investigations were performed at $$Re = 2.1 \times 10^{6}$$ R e = 2.1 × 10 6 and included the capturing of effective integral lift and drag, velocity measurements in the surrounding flow field with Laser Doppler Anemometry, surface pressure measurements and surface oil flow visualization on the rear. The flow field was found to be dominated by two longitudinal vortices, developing from the detachment of the flow at the upper C-pillar positions, and a recirculating, transverse vortex above the rear window. With an air jet emerging from a slot across the surface right below the rear window section, tangentially directed upstream toward the roof section, total lift could be reduced by more than 7 %, with rear axle lift reduction of about 5 % and negligible drag affection ( $$<$$ < 1 %). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Experiments in Fluids Springer Journals

# Active flow control on a 1:4 car model

, Volume 55 (5) – May 10, 2014
11 pages

/lp/springer_journal/active-flow-control-on-a-1-4-car-model-ms2zbmvMl0
Publisher
Springer Journals
Subject
Engineering; Engineering Fluid Dynamics; Fluid- and Aerodynamics; Engineering Thermodynamics, Heat and Mass Transfer
ISSN
0723-4864
eISSN
1432-1114
D.O.I.
10.1007/s00348-014-1738-0
Publisher site
See Article on Publisher Site

### Abstract

Lift and drag of a passenger car are strongly influenced by the flow field around its rear end. The bluff body geometry produces a detached, transient flow which induces fluctuating forces on the body, affecting the rear axle, which may distress dynamic stability and comfort significantly. The investigations presented here deal with a 1:4 scale model of a simplified test car geometry that produces fluctuating lift and drag due to its strongly rounded rear geometry. To examine the influence of active flow control on this behavior, steady air jets were realized to exhaust from thin slots across the rear in three different configurations. Investigations were performed at $$Re = 2.1 \times 10^{6}$$ R e = 2.1 × 10 6 and included the capturing of effective integral lift and drag, velocity measurements in the surrounding flow field with Laser Doppler Anemometry, surface pressure measurements and surface oil flow visualization on the rear. The flow field was found to be dominated by two longitudinal vortices, developing from the detachment of the flow at the upper C-pillar positions, and a recirculating, transverse vortex above the rear window. With an air jet emerging from a slot across the surface right below the rear window section, tangentially directed upstream toward the roof section, total lift could be reduced by more than 7 %, with rear axle lift reduction of about 5 % and negligible drag affection ( $$<$$ < 1 %).

### Journal

Experiments in FluidsSpringer Journals

Published: May 10, 2014

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