Date of Award

Spring 1-1-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Aerospace Engineering Sciences

First Advisor

John Farnsworth

Second Advisor

John Evans

Third Advisor

Kenneth Jansen

Abstract

A longitudinal gust generator was designed, constructed, installed and tested in the low-speed research wind tunnel within the Experimental Aerodynamics Laboratory at University of Colorado Boulder. The system consists of a dynamic shutter (louver) system composed ten airfoil vanes geared together in five counter-rotation pairs which was installed at the wind tunnel inlet. By dynamically adjusting the angle of the airfoil vanes, the inlet area was rapidly varied from 0 to 85% blocked area. After installation, a quasi-static evaluation of the system was performed to determine the relationship between inlet area blocked by the airfoil vanes and reduction of test section velocity. It was found that the test section speed could be reduced to around 50% of the fully open test section speed. Once the static qualification was completed, the vanes were dynamically opened and closed to create time-varying gusts in the test section (longitudinal) velocity. The velocity response of the tunnel was quantified using a combination of three hotwire anemometers distributed throughout the test section. Several types of gust proles were created including: (1) continuous sinusoidal oscillations of the free stream velocity magnitude, (2) discrete impulses, and (3) linear ramps. Using hotwires at different points in the test section, the speed at which disturbances traveled through the tunnel was measured. The wind tunnel was found to have two distinct time responses, a faster time

response for decelerating the flow, and a slower time response for accelerating the flow. The speeds at which the disturbances propagated through the test section was at least an order of magnitude higher than the freestream velocity for all speeds and types of pulses tested. This suggests that the disturbances behave globally with a closed test section.

Share

COinS