5-Belt System - FKFS Simulation of Road Conditions
- Measurement with simulation of road conditions in the full-scale vehicle wind tunnel
Compared to driving on the road, the vehicle rests in a wind tunnel while the air moves relative to it. For this reason, the speed profiles in the ground area deviate from the 'true' speed profile of a ride on the road due to the formation of a friction boundary layer (rectangle or block profile).
Suitable measures must, therefore, be applied to attempt to create a block profile on the test section floor. Besides the boundary layer control, the complete simulation of the road conditions also requires a mapping of the moving road surface and the wheel rotation because they change the flow around the wheels and through the rims. As well as inside the wheel housing.
5-belt systems are installed in both wind tunnels to simulate the road conditions. This technology can be used more universally compared to a moving belt that covers the width of the test section. It also eliminates the rolling resistance of the rotating wheels, although their lift and air drag is considered when determining the aerodynamic coefficients.
Influence of the road conditions simulation based on measured total pressure distributions, in each case in an area behind the wheels and in the caster of the vehicle.
In a 5-belt system, a center belt is located between the wheel tracks. The wheels are powered by four independent wheel rotation units on both sides of the center belt. In the process, the vehicle is fixed by a 4-point mounting restraint system which is connected to the subfloor balance together with the wheel rotation units for measuring the aerodynamic forces. For investigations under cross wind conditions the test section floor, means the turntable, can be yawed together with the 5-belt system.
For an optimal simulation of the road conditions, additional extensive options for influencing the boundary layer are available in addition to the 5-belt system.
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Boundary layer situation on the test section of the full-scale vehicle wind tunnel with and without simulation of road conditions.
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