Smith - Flow Interactions and Control - Spring Review 2013
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Smith - Flow Interactions and Control - Spring Review 2013

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Dr. Douglas Smith presents an overview of his program, Flow Interactions and Control, at the AFOSR 2013 Spring Review. At this review, Program Officers from AFOSR Technical Divisions will present ...

Dr. Douglas Smith presents an overview of his program, Flow Interactions and Control, at the AFOSR 2013 Spring Review. At this review, Program Officers from AFOSR Technical Divisions will present briefings that highlight basic research programs beneficial to the Air Force.

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    Smith - Flow Interactions and Control - Spring Review 2013 Smith - Flow Interactions and Control - Spring Review 2013 Presentation Transcript

    • 1DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution14 February 2013 Integrity  Service  Excellence Dr. Douglas Smith Program Officer AFOSR/RTA Air Force Research Laboratory Flow Interactions and Control Date: 04 MAR 2013
    • 2DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution 2013 AFOSR SPRING REVIEW NAME: Douglas Smith BRIEF DESCRIPTION OF PORTFOLIO: Foundational research examining aerodynamic interactions of laminar/transitional/turbulent flows with structures, rigid or flexible, stationary or moving. Fundamental understanding is used to develop integrated control approaches to intelligently modify the flow interaction to some advantage. LIST SUB-AREAS IN PORTFOLIO: Flow Physics for Control Flow Control Effectors Low Reynolds Number Unsteady Aerodynamics Aeromechanics for MAVs
    • 3DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Overview Transition Stability Unsteadiness Interactions Reynolds No. Flexibility Bio-inspiration Separation Vortices Turbulence Flow Control Kinematics Energy Time/length scales Boundary layer Shear layer Jets Wakes Modeling Flight stabilization Energy pathways Experiments Simulations
    • Portfolio map Flow Physics for Control Flow Control Flow Control Bio-Aero Studies Unsteady Low Rey Aero Fluid- Structure Interaction Flow Control Wygnanski Fasel Glezer Graham Gregory Spedding Mahesh Little Karagozian YIP MorrisSondergaard Leishman MURILRIR Hubner Lang Ifju OL Eldredge Edwards Gopalarathnam Ringuette Buchholz Jones Rockwell Gursul Gordnier Visbal Koochesfahani YIP YIP YIP LRIR LRIR LRIR Rival Williamson Breuer Golubev Flow control collaboration Flow physics & Control Applied flow control Low Reynolds number unsteady aerodynamics Flight physics for MAVs Key to Lines PI Co-PI 2013 New Start Bio-inspiration Bons Bernal Mittal Cattafesta Ukeiley Alvi Cybyk Rowley Williams Colonius Thurow Mittal Thomson Deng Beran Sytsma Dong Swartz Rempfer Wark Shkarayev LRIR Dudley Glezer McKeon Amitay - Theofilis Gordeyev BRI LRIR
    • 5DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Study of Physics-based Control of Jets in Crossflow K. Mahesh, Minnesota & A. Karagozian, UCLA ExperimentSimulation Spectra inside nozzle shows similar behavior to spectra along upstream shear layer Controlled transverse jet mixing requires understanding fundamental instabilities and their response to jet excitation • Is it possible to simulate/predict the instability behaviors for different jet velocities? • What is the fundamental mechanism for the transition between behaviors?
    • 6DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Newtonian Re=3600 • Red: constant vortex strength Q. • Green: constant vx. Viscoelastic Wi = 80, b=0.97, Ex=103 57% DR Exploiting the nonlinear dynamics of near-wall turbulence for skin-friction reduction M. Graham, Wisconsin 0 10 20 30 0 1000 2000 3000 4000 Wi TimeScales 0 0.1 0.2 0.3 FH TA TH FH average duration of active turbulence fraction of time taken by hibernation Onset of DR average duration of hibernation Laminar flow Turbulent flowUpper branch ECS Low-drag excursions- hibernation Turbulent bursts Basin boundary: • lower-branch ECS • edge state Initial condition that becomes turbulent Initial condition that becomes laminar High-drag active turbulent dynamics Proposed schematic of the state space dynamics of turbulent wall-bounded flow. drag
    • 7DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution (BRI) Wall Turbulence With Designer Properties: Manipulation of Energy Pathways McKeon & Tropp, Caltech & Goldstein, UT-Austin & Sheplak, Florida PROGRADE HAIRPINS RETROGRADE HAIRPINS Wu & Moin, J. Fluid Mech. 2008 Adrian, Meinhart & Tomkins, J. Fluid Mech. 2000 Decreasing complexity Decreasing complexity Navier-Stokes Eqns
    • Portfolio map Flow Physics for Control Flow Control Flow Control Bio-Aero Studies Unsteady Low Rey Aero Fluid- Structure Interaction Flow Control Wygnanski Fasel Glezer Graham Gregory Spedding Mahesh Little Karagozian YIP MorrisSondergaard Leishman MURILRIR Hubner Lang Ifju OL Eldredge Edwards Gopalarathnam Ringuette Buchholz Jones Rockwell Gursul Gordnier Visbal Koochesfahani YIP YIP YIP LRIR LRIR LRIR Rival Williamson Breuer Golubev Flow control collaboration Flow physics & Control Applied flow control Low Reynolds number unsteady aerodynamics Flight physics for MAVs Key to Lines PI Co-PI 2013 New Start Bio-inspiration Bons Bernal Mittal Cattafesta Ukeiley Alvi Cybyk Rowley Williams Colonius Thurow Mittal Thomson Deng Beran Sytsma Dong Swartz Rempfer Wark Shkarayev LRIR Dudley Glezer McKeon Amitay - Theofilis Gordeyev BRI LRIR
    • 9DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Biological Inspiration
    • 10DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Biological Inspiration From Nature – Attenborough’s Life Stories – Life on Camera Courtesy of WETA
    • 11DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Micro Air Vehicle Unsteady Aerodynamics M. OL, AFRL/RQ At Re = 10000, lift an drag histories are mutually similar, and net aero force is wall- normal. At Re = 60, viscous effects tilt the net aero force aft, far more so for translation than for rotation. This might explain benefits of insect-type flapping at very low Re Case-study: rotation vs. translation impulsive-start Rotating AR=2 plate vs. Translating AR=4 plate Acceleration is linear ramp over 1 chord t' CL CD 0 0.5 1 1.5 2 0 1 2 3 0 1 2 3 AFRL 1c Re=62 AFRL Re=62 rot AFRL 1c Re=62 AFRL Re=62 rot Re = 60, translation, lift Re = 60, rotation, lift Re = 60, translation, drag Re = 60, rotation, drag t' CL CD 0 0.5 1 1.5 2 0 1 2 3 0 1 2 3 surge 1c =45 AR4 rotate 1c =45 surge 1c =45 AR4 rotate 1c =45 Re = 10000, translation, lift Re = 10000, rotation, lift Re = 10000, translation, drag Re = 10000, rotation, drag Case-study: Re effects on hovering plate Hovering plate at 45° incidence , rectilinear motion: LEV and TEV production at semi-stroke extremum, but no vortex stability. Vortices at Re = 10,000 almost indistinguishable from Re = 300 Re 10,000 Re 300(Courtesy M. Ringuette) Role of Leading Edge Vortex
    • 12DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Flapping-Wing Vortex Formation and Scaling M. Ringuette (YIP 2010), Buffalo For both ARs, stable LEV over inboard ~50-60% span AR-effects: outboard LEV detaches for AR = 4 AR = 2 stays close to plate 60% span 50% span AR = 2 Top view s/c = chords traveled by tip, ϕ = rotation angle AR = 4Stable LEV Detached LEV LEV breakdown CL rise after initial peak due to continual evolution of overall vortex flow. AR=4 breakdown affects CL growth.
    • 13DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Flow Structure and Loading on Revolving-Pitching Wings D. Rockwell, Lehigh Leading-Edge Vortex Downwash v αeff = 60° DOWNWASH IN RELATION TO LEADING EDGE VORTEX Iso - Q Root VortexTip Vortex Leading-Edge Vortex Trailing-Edge Vortex αeff = 60° VORTEX SYSTEM ON ROTATING WING
    • 14DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution UMD/Daedalus (ARL/MAST) High-Resolution Computational Studies and Low-Order Modeling of Agile Micro Air Vehicle Aerodynamics J. Eldredge, UCLA AeroVironment ‘Nano Hummingbird’ Linear Quasi-Steady Wingbeat-ave’d Flight Ctrl Reduced Maneuverability Develop low-order models that can capture the critical phenomena for agile maneuvering with flapping wings. Improvement via model optimization Experimental flow viz (Granlund et al., AFRL) High-fidelity results Low-order model streamlines
    • 15DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Control of Low Reynolds Number Flows with Fluid- Structure Interactions I Gursul, Bath  Conventional flow control techniques are not practical for MAVs (weight limitation, insufficient space for actuators)  Attempt to exploit aeroelastic vibrations of flexible wings  Excite the fluid instabilities with structure Wing deformation measurements Time-averaged lift measurements =15 post-stall Sr=1.5 resonance frequency CLflexible/CLrigid  2
    • 16DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Understanding the Flow Physics of Energy Extraction from Gusting Flows to Enhance MAV Performance D. Williams, IIT & T. Colonius, Caltech U(t) is at the same peak value for both images, but lift is different LEV structure controls L’ Deeper insight obtained from numerical simulations shown in next slide k = 1.0 Min Lift k = 0.5 Max Lift Lift fluctuations for different Reynolds numbers Instantaneous flow structure (vorticity) on flat-plate airfoil @ Re=500 at maximum of U (max quasi-static lift) at minimum U  (min quasi-static lift) Max LEV at minimum U∞ suppresses quasi-static fluctuations Max LEV at maximum U∞ enhances quasi-static fluctuations AOA=15 o e = 0.05 Simulation Re=100 Re=200 Re=300 Re=400 Re=500 Experiment Re=57000  Max fluct. Min fluct.
    • 17DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution 3D physics-based morphology analysis of flexible flapping wings Wing gaits analysis using SVD (Singular Value Decomposition) Physics-based morphology analysis and adjoint optimization of flexible flapping wings H. Dong, UVa & M. Wei, NMSU Mode1(Flapping) Mode3(Twisting)Mode2(Vibrating) T nnnmmmnm VSUA   3333 Snapshots of wing location Mode 1 Mode 2 Mode 3 Quantifying wing morphology in chord-wise and span-wise HoverCruise Initial Optimum Initial (rigid) Optimum
    • 18DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Time-Dependent Fluid-Structure Interaction & Passive Flow Control of Low Reynolds Number Membrane Wings P. Hubner, A. Lang, Alabama & L. Ukeiley, P. Ifju, Florida -1 -0.5 0 0.5 1 0 0.2 0.4 0.6 0.8 1 z/c x/c -1 -0.5 0 0.5 1 0 0.2 0.4 0.6 0.8 1 z/c x/c 10 1 10 2 10 -8 10 -6 10 -4 10 -2 10 0 PSD[mm2/Hzor(m/s)2/Hz] Frequency (Hz) PSD from DIC and PIV - 16 aoa Left Membrane Middle Membrane Right Membrane Flow-Field @ x/c=0.8 Membrane vs. Rigid membrane rigid Mean displacement RMS displacement Wing tip vortices suppress oscillations
    • 19DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Aerodynamics and Mechanics of Robust Flight in Bats S. Swartz & K. Breuer, Brown • Social animals are known to fly (birds & bats) or swim (fish) in large groups with diverse geometric arrangements • May be fluid dynamic and energetic advantages depending on the circumstances • For bats, little is known of the group flight dynamics Flying bats generate wakes that may be sensed by other individuals to control spacing, reduce flight cost, and increase aerodynamic force production. leading bat trailing bat Cynopterus brachyotis, the lesser dog-faced fruit bat, and the robotic flapping wing based on its anatomy and flight behavior. Flight power with and without wing folding, with respect to main flapping axis[(a), left] and front-back axis [(b), right]. Plots are mean and 95% CI for 160 wingbeats at 8 Hz and 60° stroke plane; grey shading is downstroke.
    • 20DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Biological Inspiration Courtesy of Breuer & Swartz, Brown
    • 21DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution An Integrated Study of Flight Stabilization with Flapping Wings in Canonical Urban Flows R. Mittal, JHU & Hedrick, UNC Active stabilization of Hawkmoth in vortex perturbation Open-loop flight instability in hovering Hawkmoth • Stabilization of flapping wing vehicles in complex flows is critical for effective operation of these vehicles. • Study of flight stabilization in insects could lead to new insights for designing small, agile flying vehicles
    • 2214 February 2013 DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution