1.1 Fluid Dynamics: A Passive Bio-inspired Micro-adaptive Separation Control Mechanism Derived from Shark Skin
Abstract
This proposal aims to identify whether the bristling of individual scales in certain species of sharks is responsible for a passive flow separation control mechanism. It is hypothesized that the flexibility of shark scales is biased in such a way as to be sensitive to the action of reversed flow, which causes the scales to bristle and prevent further flow separation from occurring. The actuated scales may have the potential to both impede local flow reversal as well as to induce mixing to bring higher momentum fluid near the wall, thus re-energizing the boundary layer and preventing separation/promoting reattachment. An experimental approach will be used to conduct this study. The study will begin by conducting baseline measurements of unsteady separation from a flat plate boundary layer at Reynolds numbers of 2(10^5). An adverse pressure gradient will be imposed by a rotating cylinder with time-varying rate of rotation, allowing the formation of both laminar and turbulent boundary layers, dependent on the configuration of the setup. Planar time-resolved DPIV and volumetric DPIV studies will be conducted in order to gain quantitative visualization of the turbulent boundary layer dynamics. Once the baseline experiments are complete, samples of shortfin mako skin will be tested to quantify the control of flow reversal in the unsteady laminar and turbulent separation scenarios. Measurements will be obtained with normal skin and then with skin painted so as to render the bristling mechanism ineffective. 3D printed bristles will also be developed and tested (in both laminar and turbulent unsteady separated flows) to investigate the viability of an "engineered" skin.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 14, 2016
- Source ID
- W911NF1510556
Entities
People
- Amy Lang
Organizations
- Army Contracting Command
- United States Army
- University of Alabama