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 (u_A) 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 u_A decrease significantly with downstream distance. u_A is large for larger rotational angle, but the effect of rotational speed is not very significant. For the ATG downwind, magnitude of u_A is smaller compared to upwind ATG. However, u_A does not vary significantly with streamwise location and maintains strong correlation with the cyclic motion of the ATG fins.