Asymmetric Vortex Control on Slender Bodies at High Angles of Incidence
Abstract
The proposed research aims to identify the physical mechanism(s) responsible for observed vortex asymmetry on slender cones and cone cylinders at high angles-of-attack. The current working hypothesis is that micro-imperfections in the surface of the nose cause disturbances that are amplified by the flow. The character of the imperfections and the mechanisms responsible for amplifications are still unknown, and the proposed research seeks to identify, characterize, and ultimately control the growth of these perturbations. If successful, this research may allow for mitigation and/or control of "phantom yaw" which is the side force on a slender body created by the vortex asymmetry. The proposed research effort will utilize theory, computation and experiment in order to achieve its objectives. Controlled micro-imperfections will be introduced near the nose apex (the region hypothesized to be most sensitive to such imperfections) and the resulting perturbations will be tracked with digital particle image velocimetry (DPIV), plenoptic PIV, and unsteady surface pressure measurements. Linear stability analysis methods will be used to understand the initiation, evolution and interaction with other flow structures and to guide the design of control and/or mitigation strategies. One such notion is to use fluid dynamic blunting, in which a small jet of air is ejected from the tip of the cone to divert the incoming flow stream away from the most disruptive micro-imperfections and avoid the initiation of the events leading to the eventual symmetry breakdown. Also to be explored are the effects of freestream turbulence and Reynolds number on the transition characteristics and instability growth behavior. High fidelity numerical simulations will explore the details of some of the parameter space where the flow is most sensitive to perturbation.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2017
- Source ID
- W911NF1510583
Entities
People
- Kumar Rajan
Organizations
- Army Contracting Command
- Florida A&M University
- United States Army