| Natural fliers have shown the capability to utilize unsteady fluid phenomena to increase their flight performance. As engineered vehicles operating in equivalent flight regimes are developed, a method to predict the development and aerodynamic response to these unsteady fluid phenomena is desired. This dissertation utilizes various aerodynamic parameters such as the instantaneous angle of attack, angle of attack rate, and pitch rate to classify the leading-edge vortex (LEV) and tip vortex (TV) development over a low-aspect-ratio, flat plate driven through various pitch-plunge kinematic motions. Particle Image Velocimetry (PIV) measurements are utilized assess the vortex structures along the leading edge and wing tip. The aerodynamic response to the vortex structures are measured and computed utilizing a sting balance and control volume technique respectively. The LEV development is dominated by the angle of attack, whereas the angle of attack rate alters the development of the LEV at constant angles of attack. The pitch rate response was minimal at angles of attack greater than 10.0°. Similarly, the TV development is shown to be a function of angle of attack and angle of attack rate. The LEV structure formed an inward spiraling structure at angles of attack below 10.0°. With the increase in angle of attack or decrease in angle of attack rate, the LEV transitioned to an outward spiral. The aerodynamic lift associate with the outward spiraling LEV is more responsive to changes in the angle of attack rate due to additional momentum driven into the TV structure, thereby increasing the three dimensional flow on the aft of the wing. Furthermore, a control volume lift estimation technique suggests the unsteady vortex structures dynamically alter the bound circulation over the wing. The spanwise distribution of this circulation will have to be accounted for to increase the accuracy of current lifting-line, unsteady models. |
