Active Flow Control for Manipulation of Flow Aerodynamics in Jets
Abstract
The ability to modify the angle of thrust generated by an exhaust nozzle on an aircraft (thrust vectoring) has long been of intere,st to the Navy as it is useful for many different applications including hyper-maneuverability and short or vertical take-off/landin,g (S/VTOL) capabilities. In particular, VTOL capabilities would enable the operation of fixed-wing (long endurance) unmanned aerial,vehicles (UAVs) from vessels not equipped with a flight deck. An example application of thrust vectoring to this problem is to use t,hrust vectoring to provide attitude control to a tail-sitter configuration UAV in the hover phase of flight.Thrust vectoring is cu,rrently provided by a highly complex, heavy, faceted nozzle exit geometry. Another method, Coanda-based Thrust Vectoring (CTV), empl,oys the Coanda effect to attach the jet to curved nozzle outlet surfaces termed reaction surfaces but requires a significant amoun,t of bleed air (up to 15% of the primary flow). Localized arc-filament plasma actuators (LAFPAs) exploit natural flow instabilities,in shear flows (e.g. jets) to control the mixing and entrainment characteristics of the flow. This ability could enable them to atta,ch/detach flow from a reaction surface, similar to CTV, laying a foundation for, among other applications, a bleedless, fixed-geomet,ry, very low input power means of thrust vectoring.The proposed application is theoretically grounded and a natural extension from w,ell-documented cases of effective control by plasma actuators. However, the fundamental physics of such a configuration have not yet, been explored. Therefore, it is proposed that a 3-year, basic research project be undertaken to explore the fundamental physics of,employing the LAFPAs in the proposed active flow control concept (AFCC) and assess the effectiveness thereof. The primary objectives, of the proposed work are as follows: 1) to understand the jet response throughout the very broad parameter space of the LAFPAs base,d upon a developed understanding of the key physics involved and 2) to assess the potential of this type of technology for the propo,sed application.LAFPAs will be mounted upstream of two different CTV-inspired reaction surfaces. This coupling of LAFPAs with a reac,tion surface is the primary innovation of this AFCC. Experimental sweeps of excitation frequency and other excitation parameters wil,l be documented using schlieren and pressure measurements to determine the ability of the AFCC to deflect the jet. PIV measurements,will confirm that the deflections observed correspond to induced cross-stream velocity (i.e. vectoring of the thrust). Time-resolved, schlieren measurements will help determine the unsteadiness of the baseline and controlled flow and actuation-locked PIV measuremen,ts of the flow over the reaction surface will provide detailed information about the physics of the LAFPAs control mechanism. Final,ly, a third reaction surface will be designed, building on the project discoveries and in consultation with ONR, and the important p,hysics and improved control authority documented. Overall, this effort will supply crucial information detailing the fundamental phy,sics of the operation of the AFCC, and an assessment of its efficacy for the proposed application.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 16, 2022
- Source ID
- N000142212424
Entities
People
- Nathan J. Webb
Organizations
- Office of Naval Research
- Ohio State University
- United States Navy