Research Summaries

Back A Study of Boundary Layer Physics to Successfully Influence Synthetic Jet Actuator Flow Control

Fiscal Year 2017
Division Graduate School of Engineering & Applied Science
Department Mechanical & Aerospace Engineering
Investigator(s) Chandrasekhara, Muguru S.
Sponsor Army Aero-Flight Dynamics Directorate (Army)
Summary The Pl developed this proposal as part of a competed ILIR effort through (and for) the AFDD, which the Army selected for further pursuit. Subsequently, the AFDD received the necessary funding. This proposal is being submitted to AFDD to request funding for the Pl so that he can now contribute to the research effort through NPS. The Pl will provide his expertise to advance the project while also directing and assisting AFDD scientists in the process. This proposal aims to conduct a basic study of the behavior of a turbulent boundary layer under adverse pressure gradient conditions when flow separation occurs and the issues involved when that separation is controlled by synthetic jets. Many flow characteristics are highly sensitive to the variables of the control process. Hence, structural changes will occur in the non-equilibrium turbulent boundary layer that develops under the adverse pressure gradient both with and without synthetic jet blowing flow control. These will be investigated for a range of parameters with the hope that such changes serve as markers which can then be used to identify and devise proper (successful) implementation of the technique for a range of applications. A simple, tilting wall flat plate turbulent boundary layer experiment will be set up in a new boundary layer wind tunnel being designed currently. Its detailed structure will be measured using appropriate tools. Synthetic jets will be activated to observe changes introduced due to the interactions of the jet structure with that of the boundary layer. For the latter, ensemble averaged flow details; phase locked to the jet cycle will be recorded. Comparisons of various boundary layer parameters ranging from the simple momentum thickness, studies of the turbulent kinetic energy spectra including the low wave number large eddy activity, the turbulent kinetic energy balance, the induced anisotropy of the stress tensor, will be made for conditions without flow control and when flow control effort has been deemed successful. Also, the results will be used to identify the non-dimensional mass and momentum fluxes, the blowing frequency, and jet angle that are most likely to produce the necessary changes to the structure for effective control. Additionally, the return of the boundary' layer to its precontrolled state will be evaluated in an effort to establish if repeated flow perturbations will be needed to sustain control.
Publications Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal
Data Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal