Masters Theses

Date of Award

12-2005

Degree Type

Thesis

Degree Name

Master of Science

Major

Aerospace Engineering

Major Professor

Robert Bond

Committee Members

Majid Keyhani, M. W. Milligan

Abstract

The principle idea upon which the use of vortex generators (VGs) is based has been to control flow separation. The characteristic of VGs has been used to improve lift and alter the stall characteristics of aircraft and has been a relatively common practice for many years. Due to the seemingly limitless range of VG geometries and arrangements, which are largely dependant upon the desired aerodynamic performance, there has been a broad investigation into VG application.

The purpose of this experimental investigation has been to collect data to be used to establish the effects of various delta shaped vortex generators (delta-VGs) geometries and locations for comparison with a baseline model The data for this research were collected using the University of Tennessee subsonic wind tunnel and were used to produce aerodynamic information including coefficients for lift, drag and pitching moment.

In this research program it was found that delta-VGs mounted along the flap-hinge line produced little effect on lift. It was believed that flow separation was either induced by the delta-VGs or that separation simply occurred before the delta-VGs could aide in the flow characteristics on the model. Testing with the delta-VGs near the leading edge of the model produced significant aerodynamic benefit regardless of the delta-VG arrangement. Continued experiments on some of the more beneficial arrangements identified that the length and the spacing between the delta-VGs produced results that could improve the maximum lift coefficient, the angle of attack at which it occurred and improved the lift to drag ratio. In the case of a 3/4" length delta-VG with a 2” spacing and a 60° sweep angle, improvements by as much as 57% from the baseline were observed in CLmax.The separation region for this configuration was also delayed by 4°.These experiments also revealed that decreasing the spacing between delta-VGs increased the magnitude of the lift to drag ratio and in some cases extended the angle at which the maximum lift to drag ratio occurred.

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