Helicopter Noise and Vibration (EU Project "HELINOVI") Hans-Jürgen Langer, DLR Aeronautics Days 19th/21st June 2006, Vienna
Overview Motivation Acoustic Problem Vibration Problem Partners Tools - Configurations Results and Findings Outlook Aeronautics Days 19th/21st June 2006, Vienna 2
The Motivation Main-Rotor Flow Interaction with - Empennage -Fuselage - Tail Rotor Noise and Vibration Generating Flow Around Helicopter Blades and Fuselage vibration noise Tail-Rotor FlowInteraction with - Empennage -Fuselage -Main Rotor vibration noise Aeronautics Days 19th/21st June 2006, Vienna 3
The Acoustic Problem Tail Rotor Contribution to Noise Emission Level Flight at 115kts Aeronautics Days 19th/21st June 2006, Vienna 4
The Vibration Problem Vibration Excitation Structural Response Aeronautics Days 19th/21st June 2006, Vienna 5
Typical Helicopter Vibration Characteristics Vibration g 12,3 m/s 50,6 m/s 70,0 m/s Flight Speed, kts Aeronautics Days 19th/21st June 2006, Vienna 6
The Consortium NTUA Aeronautics Days 19th/21st June 2006, Vienna 7
Test Plan for Comprehensive Wind Tunnel Measurements in DNW (120h Tunnel Occupation) Configurations Two sets of Tail Rotor Blades Variable Tail Rotor Sense of Rotation Variable Tail Rotor Position Reduction of Distance Main Rotor to Fuselage Shell PIV and SPR applied to low, medium, and high speed Combined PIV set-up for Noise and Vibration Different Test Set-Up for SPR and PIV Blade and Fuselage Dynamic Pressure w/ Kulites PIV - Particle Image Velocimetry SPR- Stereo Pattern Recognition Aeronautics Days 19th/21st June 2006, Vienna 8
The Tools Accelerations Flap Strains Lag Strains 24x Fus. Pressure 51x Surface Pressures Blade Strains 36x Surface Pressure (S102 ; NACA 0012) 4x Strains (2x for safety) Modified Fuselage Shape Mast Strains Accelerations Actuator Forces RPM, Torque Model Pitch & Roll Fuselage Balance Rotor Balance Rotor Azimuth Accelerations Pivot for TR position RPM, Torque Pitch, Flap Azimuth Accelerations Aeronautics Days 19th/21st June 2006, Vienna 9
Acoustics Set-Up Aeronautics Days 19th/21st June 2006, Vienna 10
PIV Set-Up Aeronautics Days 19th/21st June 2006, Vienna 11
SPR Setup Stereo Pattern Recognition Determination of object locations by detecting blade and body markers thru Stereo Imaging and 3D-reconstruction On each side 2 Cameras mounted on the ground and triggered to the rotor azimuth 30 strong stroboscopic lights Measurement accuracy 0.4 mm Stroboscopic lights SPR Cameras Aeronautics Days 19th/21st June 2006, Vienna 12
Aeronautics Days 19th/21st June 2006, Vienna Results and Findings
Blade Motions measured by SPR 22 kts 95 kts 135 kts Aeronautics Days 19th/21st June 2006, Vienna 14
Main Rotor Vortex Trajectories for Climb and Level Flight measured by PIV Aeronautics Days 19th/21st June 2006, Vienna 15
Analysis of Dynamic Pressure Data Sensor Positions Warped Data Aeronautics Days 19th/21st June 2006, Vienna 16
88 TR noise Reduction Benefits 800 Hz 800 Hz 1. TR Reversed sense of rotation 2. Change TR rotor position 3. Reducing rotor tip speed 12 climb at 60kts Y(m) 4 3 2 1 0-1 -2-3 89 90 93 94 12 Climb at 33m/s MR+TR TR ASD 95 96 92 97 94 84 85 91 98 88 Max 96 89 90 96 95 99 95 TR 97 93 93 92 94 94 85-2 0 2 X(m) Mic Array Results dba 93 88 91 83 84 95 Y(m) 4 3 2 1 0-1 -2-3 85 12 Climb at 33m/s MR+TR TR ASU 88 89 88 Max 90 88 85 89 TR 84 84 85-2 0 2 X(m) Inflow Microphone Results dba 85 88 84 85 89 88 100 99 98 97 96 95 94 93 92 91 90 89 88 85 84 83 82 Aeronautics Days 19th/21st June 2006, Vienna 17
Benefits of TR Noise Reduction DNW Test Sense of Rotation (ASD -> ASU) at 110kts, Level flight Sense of Rotation (ASD -> ASU) at 65kts, 12 climb flight New TR Position 110kts, Level flight Reduced Tip Speed 110kts, Level flight 6.1 dba 5.8 dba 1.0 dba 2.3 dba Noise reduction benefits were observed for both test and simulation Aeronautics Days 19th/21st June 2006, Vienna 18
Hub Load Increments by Fuselage Contour Modification Comparison of experimental and numerical results 3/rev Magnitude - Nm 40 30 20 10 0 3/rev Flap Bending Moment (r/r=3%) Baseline airframe Baseline 0 10 20 30 40 50 60 70 80 Wind Speed - m/s Modified Low clearance Experimental results Increase of vibratory loads by 50% Difference of Amplitudes - Nm 20 15 10 5 3/rev Flap Bending: Absolute Difference Wind Tunnel Test 0 0 10 20 30 40 50 60 70 80 Wind speed - m/s Analysis Vibratory load increase Comparison Test Versus Theory Aeronautics Days 19th/21st June 2006, Vienna 19
What comes next? Continuous use of acoustic and vibration data base for code improvement Expansion of testing tools 3 papers for the European Rotorcraft Forum Sept. 2006 (4 papers in 2005) For more Information visit www.fluid.mech.ntua.gr/~helinovi/ Aeronautics Days 19th/21st June 2006, Vienna 20