Test Research of Unsteady Characteristic of Flow Inside Test Section of Automotive Wind Tunnel

Abstract:

Three dimensional hot wire was used to test the unsteady characteristic of the flow inside the test section of an 1:15 scaled wind tunnel under different situations. By analyzing the power spectrum density (PSD) data of the test points, conclusions were drawn that when nozzle speed was lower than 37 m·s-1 the turbulent density concentrates at the frequency of about 20 Hz. At the speed of 25 m·s-1 the PSD value was max. When nozzle speed was higher than 37 m·s-1 the turbulent density was concentrate at the frequency of about 43Hz. At the speed of 41 m·s-1 the PSD value was max. Under both low speed and high speed situations the peak of the velocity fluctuations were all enlarged along with the flow from nozzle to collectors. And the amplification was larger under the situation of high speed. From test we also found that when the angle of the collectors was 0 degree the velocity fluctuations were much lower than that of 15 degree collectors.