Rotorcraft Acoustics and Dynamics Group Activities CAV Workshop

Transcription

1 Center for Acoustics and Vibration Rotorcraft Acoustics and Dynamics Group Activities Edward C. Smith, Professor Director, Penn State Vertical Lift Research Center 1 CAV Workshop

2 Presentation Outline Group Highlights VLRCOE Renewal Proposal Review of ongoing group research projects Individual Project Highlights - Coupled Fluidic Vibration Isolators for Multi-Harmonic Loads Reduction

3 Interaction with Other PSU Research Centers ARL Center for Acoustics and Vibration Condition Based Maintenance Dept. Vertical Lift Research Center of Excellence ARL National Center for Advanced Drivetrain Technology Institute for Computational Science Composites Manufacturing Technology Center ARL imast

4 Vertical Lift Center Tech Base Penn State ARL NRTC CRI SBIR Programs apply & transition 5 Faculty 4 Res Assoc 4 + Graduate Students 1 Undergraduate Students (Freshman Sem, AHS Chapter, Senior Class, Design projects) 4 Continuing Education Students (Short course)

5 Vertical Lift Center PSU Directors Ed Smith Ken Brentner Deputy Directors Farhan Gandhi Joe Horn Stephen Conlon (ARL) Administrative Aides Debbie Mottin, Barbara Kepinska Dynamics, aeromechanics Aeroacoustics, VLRCOE Admin Dynamics and smart structures, VLRCOE Education Flight mechanics and control SHM, HUMS, sensors, structural acoustics Affiliated Faculty - Aerodynamics, Aeroacoustics, and Flight Controls Sven Schmitz Applied and computational aero, wind energy Mark Maughmer Airfoil design, aerodynamics Jack Langelaan Guidance, navigation, and controls Rob Kunz (ARL) CFD, multi-phase flow, propulsion and gears Ralph Noack (ARL) CFD, Overset grids, multiphase flows Brian Elbing (ARL) Fluid mechanics Dennis McLaughlin Experimental aerodynamics and aeroacoustics Cengiz Camci Experimental fluid mechanics and heat transfer Barnes McCormick Aerodynamics, stability & control

6 Vertical Lift Center PSU Affiliated Faculty and Research Scientists - Structures and Dynamics George Lesieutre Structural dynamics, materials Bob Bill Propulsion and powertrains Jose Palacios Icing, smart structures, experimental mechanics Zihni Saribay Drive systems and rotordynamics Jianhua Zhang Rotor dynamics and design Chris Rahn (ME) Controls and structural dynamics Chuck Bakis (ESM) Composite structures Joe Rose (ESM) Ultrasound, NDE, guided waves Cliff Lissenden (ESM) SHM, fatigue and fracture, composites Tom Donnellan (ARL) Manufacturing, advanced composites Kevin Koudela (ARL) Composite structures, nano-materials, FEM Steve Hambric (ARL) Structural acoustics Mike Yukish (ARL) Crashworthiness, optimal design Suren Rao (ARL) Drivetrain technologies, manufacturing Doug Wolfe (ARL) Coatings, materials and manufacturing Tim Eden (ARL) Cold spray forming, materials and manufacturing Jim Adair (Mat Sci) Nano-materials Affiliated Faculty and Research Scientists - Condition Based Maintenance Karl Reichard (ARL) HUMS, signal, processing Jeff Banks (ARL) HUMS system integration

7 Group Highlights VLRCOE Renewal Award 1 Separate Tasks 14 Pis Graduate Students 5 years (11-16) $7.5 M Total Partners (cost share) LORD Corp Goodrich Timken Aerospace Penn State Univ Sikorsky Bell Gyrodyne

8 VLRCOE Renewal tasks Aeromechanics: Higher speeds, better fuel efficiency, all weather Unsteady airfoil design methods Rotor hub flow physics for drag reduction Icing physics, modeling, detection Flight Dynamics & control: autonomy, safety, new configs Autonomous multi-lift systems Structures: Lower weight, more reliability Nano-tailored composites for improved toughness and thermal conductivity

9 VLRCOE Renewal tasks Design Concepts: Speed, range, altitude Aeroelastically tailored wing extensions and winglets for Large Civil Tiltrotors Control redundancy on compound rotorcraft for performance, HQ, and survivability Vibration & Noise Control: Active rotors, variable W rotors Physics of active rotors for performance and acoustics

10 VLRCOE Renewal tasks Propulsion and Drive Systems: weight, reliability, noise reduction Comprehensive analysis of gearbox loss of lubrication Affordability: condition-based maintenance, SHM Health monitoring for joints in composite structures Maritime Operations: improving safety / reliability for manned and autonomous operations in the dynamic interface Advanced response types / cueing systems for naval ops Autonomous shipboard take-off and landing

11 Other CAV Group/VLRCOE Projects LORD Corp Conceptualization, Modeling, and Characterization of a CF Driven Multi- State Lead-Lag Bypass Damper Vibration Control via Coupled Fluidic Pitch Links NASA Acoustically Tailored Panels for Low Cabin Noise (Hambric & Koudela) NASA High Fidelity CFD Analysis and Validation of Rotorcraft Gear Box Aerodynamics (Kunz) GE Global Research Wind Turbine Ice Protection Coating Performance Evaluation (Palacios) Ice Accretion Shapes to Wind Turbine Airfoils (Palacios) Ice Accretion to Cascade Flow Configurations of Engine Compressors (Palacios)

12 Other CAV Group/VLRCOE Projects Vertical Lift Consortium (Army, Navy + Industry) Durability Evaluation of Single Crystal Energy Harvesters (Conlon, Reichard, Smith) Evaluation of Pericyclic Transmission Concepts (Rao, Saribay, Bill, Smith) Static and Dynamic Characterization of Composite Materials for Future Driveshaft Systems (Bakis and Smith) Centrifugally Driven Pneumatic Actuators for Active Rotors (Palacios, Smith) Modeling of Rotor Blade Ultrasonic Deicing and Experimental Comparison with Electrothermal Ice Protection Systems (Palacios, Smith) FBS Inc/NAVAIR SBIR A Multi-Functional Ultrasonic Sensor System for Composite Rotor Blade Ice Protection, Ice Sensing, and Structural Health Monitoring Bell Helicopter TEXTRON Civil Certification Noise Prediction Tools (Brentner) Analysis of Rotor Startup/Shutdown in Complex Winds (Smith, Kunz) Alternate Control Laws for Fly-by-Wire Helicopters (Horn)

13 Penn State VLRCOE - New Facilities Water Tunnel for Hub Drag flow visualization Upgrades to Flight Simulation Facility New rotary-wing UAV for autonomous flight research 11 DURIP Awards Laser Vibrometer (ONR): Profs. Capone and Conlon Rotor Rig Upgrades (ARO): Lesieutre and Smith Adaptive Flight Inc., Hornet Mini

14 Presentation Outline Group Highlights VLRCOE Renewal Proposal Individual Project Highlights - Coupled Fluidic Vibration Isolators for Multi-Harmonic Loads Reduction

15 Coupled Fluidic Vibration Isolators for Multi-Harmonic Loads Reduction Lloyd Scarborough, Nicolas Kurczewski, and Dr. Christopher Rahn Department of Mechanical and Nuclear Engineering Dr. Edward Smith Department of Aerospace Engineering Dr. Kevin Koudela Applied Research Laboratory May 14, 1 CAV Workshop: Rotorcraft Acoustics and Dynamics Group

16 Fluidic Vibration Isolator Accumulator Objective: minimize f out (t) for a given input force, f in (t) = sin(ωt). Fluid track f in (t) induces fluid flow in the fluid track. The fluid s inertance and accumulator s capacitance dictate the isolation frequency. f out (t) Pump Mass f in (t) 16

17 Fluidic Vibration Isolator Spring-only isolator Fluidic isolator The fluidic isolator achieves the same reduction at 16 Hz, but with 7 times the static stiffness of the spring-only isolator. Can isolate only one frequency! f out (t) f in (t) 17

18 Vibration Isolator Examples Dynamic Antiresonant Vibration Isolator (DAVI) [Flannelly 1967] Liquid Inertia Vibration Eliminator (LIVE ), LORD Corporation s Fluidlastic devices [Halwes 198, McGuire 3] Images from McGuire, D. P., High Stiffness ( Rigid ) Helicopter Pylon Vibration Isolation Systems, AHS 59 th Annual Forum, Phoenix, Az., 3. 18

19 Motivation: Pitch Link Loads Reduction The pitch link connects the swashplate to the blade root to provide cyclic blade pitch given by the pilot s control input. Blade root Pitch link From Burkhard Domke Aerodynamic blade loads cause fatigue damage. Excitation frequencies are harmonics of the constant main-rotor speed: Cyclic blade pitch control: 1/rev Aerodynamic blade excitations:, 3, 4, 5, /rev Swashplate 19

20 Project Objectives Explore new pitch link devices for multiharmonic loads reduction. Develop a series of analytical models suitable for design. Validate concepts and models via bench-top experiments.

21 Motivation for Coupling Isolators Each blade sees the same loading, just offset in time. f in (t) = A sin (ω t φ), where φ = π / N b N b is the number of blades. Replace rigid pitch links with fluidic isolators. Utilize odd-harmonic loading to pump fluid back and forth between two pitch links on opposite sides of the swashplate. 1

22 Coupled Fluidic Vibration Isolators f in1 (t) f in (t) Mass Elastomer Piston f out1 (t) Fluid track f out (t)

23 Odd and Even Harmonic Forcing Out-of-phase forcing (Odd Harmonic) In-phase forcing (Even Harmonic) f in (t) f in (t) f in (t) f in (t) Fluid flow One isolation frequency No fluid flow No isolation (direct load transmission) 3

24 Experimental Setup Fluid track Stinger Rubber diaphragm Isolators Masses Shakers 4 Load cell (output load) Load cell (input load)

25 Odd Harmonic Results from Experiment Isolation frequency decreases with increasing fluid track length. Isolation Experimental results match the theory well. Theory Experiment Baseline Fluid track 3 Fluid track 5 Fluid track 5

26 Even Harmonic Results from Experiment Direct load transmission Theory Experiment Baseline Fluid track 3 Fluid track 5 Fluid track 6

27 Design Requirements and Possible Fluidic Circuit Configurations Design requirements Symmetric circuit All pitch links should behave identically. Statically stiff Pitch links must transmit the 1/rev control loads. Fluidic circuit configurations Air accumulator Inertance and resistance Soft-tubing accumulator 7

28 Add Vertical Fluid Track with Accumulator (One degree-of-freedom evident for both odd and even forcing) f in1 (t) f in (t) C a - capacitance m C a, p a m R - flow resistance I - inertance Q flow D p 1 (t) k I a, R a Q a (t) Q 1 (t) p m (t) Q (t) k D p (t) p internal pressure f out1 (t) I, R f out (t) 8

29 S PENN Transfer Functions Odd forcing ( f in1 = - f in ): One complex pole, one complex zero Even forcing ( f in1 = f in ): One complex pole, one complex zero 9 k R A s s A I m k R A s s A I F F in out 1 1 ) ( a a a a a a in out C A k A s R R s I I A m C A k A s R R s I I A F F / ) ( )] ( [ / ) ( ) ( D π A

30 Example Plots Force Transfer Function F t1 /F 1 (db) F out1 / F in1 (db) F out1 / F in1 (db) phase angle (deg) 4 - Odd Forcing Even Forcing frequency (Hz) frequency (Hz) Same as before (no flow into accumulator) Zero for even frequency (Hz) forcing D =.197 ft m = 83.7 lbs k = 35,1 lb/ft I = 894 lb s /ft 5 I a = 1,3 lb s /ft 5 C a = 3.69e-7 ft 5 /lb Fluid density: 1.55 slugs/ft 3 Fluid track diameter:.4 ft Flow resistance: 1, lb s/ft 5 /ft 3

31 Two Vertical Fluid Tracks (Two degrees-of-freedom evident for even forcing, one for odd forcing) f in1 (t) f in (t) C a1, p a1 C a, p a I a1, R a1 I a, R a Q a1 (t) Q a (t) f out1 (t) f out (t) 31

32 Example Plots Force Transfer Function Odd Forcing F out1 / F in1 (db) F out1 / F in1 (db) 4 4 F t1 /F 1 (db) Even Forcing Same as before (no flow into accumulator) I a1 = 4,11 lb s /ft 5 C a1 = 7.38e-9 ft 5 /lb I a =,6 lb s /ft 5 C a = 7.4e-7 ft 5 /lb phase angle (deg) Two zeros (All other values are the same as in the previous example.) frequency (Hz) 3 4 frequency (Hz) frequency (Hz) 3

33 Two In-line Accumulators PENN (Two degrees-of-freedom evident for odd forcing, one for even forcing) f in1 (t) f in (t) S In-line accumulators C a, p a (flexible tubing) Q 1 (t) I 3, R 3 Q (t) Q 3 (t) I, R f out1 (t) f out (t) 33

34 Example Plots Force Transfer Function F out1 / F in1 (db) F out1 / F in1 (db) 4 Odd Forcing 4 F t1 /F 1 (db) - - I 3 = 13 lb s /ft 5 phase angle (deg) Even Forcing frequency (Hz) 3 4 frequency (Hz) Two zeros frequency (Hz) C a = 1.11e-7 ft 5 /lb (All other values are the same as in the previous examples.) 34

35 Odd Forcing F out1 /F in1 (db) Even Forcing F t1 /F 1 (db) - F t1 /F 1 (db) F /F phase (db) angle (deg) t F /F phase (db) angle (deg) t frequency (Hz) frequency (Hz) frequency (Hz) frequency (Hz) F /F phase (db) angle (deg) t F /F phase (db) angle (deg) t frequency (Hz) frequency (Hz) frequency (Hz) frequency (Hz) Multi-harmonic isolation demonstrated! e angle (deg) angle (deg) 35

36 Conclusions Converting rigid pitch links to pumpers and coupling them via a fluidic circuit provides isolation at multiple harmonics. The inertances and capacitances of the fluidic circuit dictate the number and the locations of the isolation frequencies. Experimental results validate the analytical predictions for the simplest fluidic circuit. 36

37 On-Going Research Experimental validation of proposed fluidic circuit configurations Pitch link loads reduction Explore potential for coupled fluidic pitch links for higher-harmonic blade pitch control Tailor dynamic response to natural airloads Noise and vibration reduction 37

38 Acknowledgement The authors would like to express their appreciation for the financial support provided by LORD Corporation, the Applied Research Laboratory (ARL) at The Pennsylvania State University, and Dr. Patricia Gruber, director of the ARL Exploratory and Foundational Graduate Assistant Program. 38