Three-dimensional Vortex Dynamics in Unsteady, Separated Flows
Abstract
The objective of the proposed research is to understand the mechanisms of vorticity transport governing the growth and evolution of vortices in unsteady, separated flows on aerodynamic bodies, and to implement targeted control strategies to perturb these mechanisms and thus alter aerodynamic loads. Many aerodynamic problems involve the interaction between a separated vortex and the body. As a simplified canonical case, we consider the leading-edge vortex formed by a rolling and pitching wing within a uniform flow. A parameter governing rotational effects is proposed, and its effect on vortex evolution and the mechanisms of vorticity transport will be examined throughout a broad parameter space in which roll and pitch rates are varied. In addition, targeted, open-loop flow control through blowing and suction will be implemented to modify the nature of the interaction between the leading-edge vortex and the opposite-sign secondary vorticity. It has been shown that, undisturbed, this interaction yields a significant sink of leading-edge-vortex circulation, and it is therefore anticipated that the proposed perturbations will result in significant modifications to vortex strength, evolution, and increases or decreases in aerodynamic loads, based on the forcing strategy. These effects, and the basic mechanisms of vorticity transport within the vortex will be investigated through volumetric reconstruction of planar PIV data, and acquisition of plenoptic 3D PIV data, which will enable a much larger survey of the parameter space. Wing surface vorticity fluxes will be estimated using surface pressure distributions, and aerodynamic loads will be measured with and without the application of flow control. Due to the ubiquity of secondary vorticity when vortices interact with solid boundaries, it is anticipated that the framework developed here for interrogating and altering flow physics and aerodynamic loads will provide insight into the control of flows in a broad range of aerodynamic applications.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 24, 2016
- Source ID
- FA95501610107
Entities
People
- James Buchholz
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Iowa