2020 Volume 7 Issue 1 Pages 07006-1-07006-7
It is well known that the mainstream turbulence intensity in wind tunnel experiments affects flow transition and separation. To reduce this intensity, wind tunnel straightening conditions have been examined in the past. However, these conditions did not reduce the turbulence intensity of the blowdown wind tunnel in our laboratory, because the turbulence from the dustproofing device at the air inlet of the fan is not straightened, even if it passes through the straightening section of the wind tunnel. In this research, the relationship between the mainstream turbulence intensity and the dustproofing device is investigated. In the experiment, two types of mesh and four types of dustproof felt with different resistance values are installed on the air inlet of the fan. The mainstream velocity and turbulence intensity values are calculated from the fluctuation velocity measured by the hot-wire anemometer at the center of the wind tunnel exit. The mainstream velocity is adjusted by changing the faninverter frequency from 0 to 60 Hz. Although it depends on the air-inlet condition of the fan, the mainstream velocity is approximately 0 to 25 m/s. The mainstream velocity is found to be related to the resistance coefficient of the wire meshes and felts. However, no difference in turbulence intensity due to the resistance coefficient can be observed, and esistance coefficients above a certain level are considered to affect the turbulence intensity. The important point of the wind tunnel inlet conditions is considered to ensure the required inflow rate for the fan, even with the filter attached.
