Flow Coupling of Aerodynamic Surfaces with Distributions of Integrated Swirling Jets
Abstract
As US Navy-Marine Corps forces tactically seek to become increasingly distributed andinterconnected across coming decades, aviation,plays a critical role in supporting this operationalparadigm. In order for future unmanned aircraft to best perform ISR, enemy engag,ement,deceptive swarm tactics, and other support roles, it is important these vehicles feature a highspeedcapability above those of,traditional rotorcraft, while having operational constraintscompatible with many sea- or land-based resources, including small ship,decks. The use ofdistrib,ding capabilities for space-constrained VTOL operations, alongsidesignificantly higher top airspeed capabilities than open-rotor cou,nterparts. However, the detailedflow physics imposed by integrating these distributed jet systems into aerodynamic bodies is notwell, understood. Recent studies on aero-propulsive bodies like those described here havesuggested that proper integration can introduce,several performance and operational benefits forsuch configurations, though the strongly-coupled viscous interactions between aerody,namicsurfaces and propulsive devices are still not well understood. Furthermore, the operation of thesesystems near unsteady ground,planes introduces several challenges that are well recognized, yetnot well characterized.This research program seeks to address seve,ral of these open areas of investigation, byconducting a detailed experimental study of viscous flow interactions produced by distri,butedducted fan systems when integrated with an aerodynamic body. Advanced flow diagnostictechniques will be utilized inside a subso,nic wind tunnel to measure the flow entrainmentcharacteristics induced by ducted fan systems, which will be linked to associated ent,rainmentinducedsuction zones across aerodynamic surfaces. The impact of thrust vectoring onboundary-layer attachment will also be as,sessed, emulating low-speed, high-lift transition phasesof VTOL operations, with the end result being a mapping between boundary-lay,er or separatedshear-layer states and associated performance parameters. The influence that the swirling jetefflux produced by the i,ntegrated ducted fan system has on the evolution of a three-dimensionalaerodynamic geometry vortical wake will also be determined, a,s this feature has a distinct impacton the flow characteristics observed in the near-field of the aerodynamic body. The overallevolu,tion of the wake topology will be identified and subsequently coupled to a theoretical farfieldanalysis framework to gain valuable i,nsights into future vehicle configuration studies.Additional experimental study will be conducted to understand the physical interac,tionsproduced by impingement of a ducted fan swirling jet efflux across an unsteady ground planesurface. The fundamental differences, between a uniform axisymmetric jet, a swirling ducted fanjet efflux, and an open-rotor slipstream will be assessed through measurem,ent of the propulsivewakes produced for each system, both in and out of the effect of a steady ground plane. Thisapproach effectivel,y allows the influences of swirl and vortex wake dynamics on wall-jet growthrates and fountain flow to be independently determined.,Following this initial characterization,the effect of unsteady motion of the ground plane on the associated physics of the flowimpin,gement process will be determined for the ducted fan swirling jet efflux.This fundamental research program is envisioned to serve as, a springboard towards futuretechnology development and configuration studies related to small, agile VTOL UAV systems.Approved for,Public Release
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 05, 2022
- Source ID
- N000142212191
Entities
People
- Phillip J. Ansell
Organizations
- Office of Naval Research
- United States Navy
- University of Illinois Urbana–Champaign