Ground Simulation With Moving Belt and Tangential Blowing for Full-Scale Automotive Testing in a Wind Tunnel

Full-scale vehicle tests were made on a standard-type passenger car in a wind tunnel and on the road in order to evaluate different moving-ground simulation techniques for wind tunnels. The test was first executed over a moving belt, supporting the car with a rear sting and measuring the aerodynamic forces with an internal balance. The test was then repeated with the same support arrangement over a fixed test-section floor, and moving-ground simulation was attained with boundary layer control by tangential blowing. Besides force measurements, the surface pressure distribution underneath the vehicle and at the base were also measured. Furthermore, the velocity distribution between vehicle and ground floor was assessed by measuring the total-pressure distribution. In order to compare the results with road tests the interference effects of the sting support and the wheel gap were investigated with the car sitting on the tunnel floor and forces measured on the external balance of the tunnel. Initially, the sting support was present but disconnected from the internal balance; finally, it was removed from the test section altogether.