关键词: 空洞, 边界层, 流场规律

Abstract: Flow field visualization test is one of important contents in wind tunnel experiment. Limited by similar conditions, the flow field measurement of modles about dunes or sand preventing engineerings may not be conducted under sand holding condition. So, there is most significance to proclaim flow field law under empty tunnel for programme's design and result's calibration. The experiment is conducted in the famous indoor wind tunnel of Lanzhou Desert Research Institute. The total length of the tunnel is 3778 m, in which that of working section is 1623 m. Its cross section has 10 m width and 06 m height. Wind velocity can be regulated from 2 m/s to 40 m/s, and turbulency is less than 0.4% in the tunnel. There are five groups of wind velocity including 60,80,100,120 and 140 m/s are tested. Between the section of 33-141 m, there are eight cross sections at 35,55,75,90,10.5,120,135 and 145 respectively. All sixty three measurement points distribute within the right part of cross sections and 0-03 m over the bottom floor. The studing results prove that the isogram of wind velocity in whole cross sections looks like butterfly; the wind velocity distribution in boundary layer of bottom floor obeys exponent law, and the coefficient (d) of wind velocity increasing along the axis can be expressed as d=0062x 0.431; the development of boundary layer over bottom floor follows a formula of δ=3046x 0.676. According to the study, it is suggested that experiment model should be located between 10 and 140 m in working section, and 01 m away from lateral wall of the tunnel; the testing wind velocity should be controlled within 20 m/s.

Key words: Empty tunnle, Boundary layer, Flow field law