Wind speed characterization of active turbulence generators installed upstream and downstream of the wind tunnel test section

Abstract

The current study designed and fabricated multi-fin active turbulence generators (ATGs) and evaluated their wind speed characteristics with the long term aim of reproducing atmospheric flow in a lab environment. Two ATGs designed for the study are: (1) upwind ATG which consists of 24 square and triangular fins and is installed upwind from the test section and (2) downwind ATG which consists of 3 rectangular fins and is installed downwind from the test section. Experiments are conducted for several combinations of rotational speed and rotational angle and the amplitude of wind speed variation (uA) which is the difference between minimum and maximum wind speeds for each cycle is used to describe the characteristic of the ATGs. For the upwind ATG, values of uA decrease significantly with downstream distance. uA is large for larger rotational angle, but the effect of rotational speed is not very significant. For the ATG downwind, magnitude of uA is smaller compared to upwind ATG. However, uA does not vary significantly with streamwise location and maintains strong correlation with the cyclic motion of the ATG fins.