https://ntrs.nasa.gov/search.jsp?R=20120001762 2019-07-06T19:40:15+00:00Z National Aeronautics and Space Administration Doug Counter NASA MSFC ER42 Janice Houston Jacobs ESTS Group Ares I Scale Model Acoustic Test Liftoff Acoustic Results and Comparisons Noise and Physical Acoustics: Launch Vehicle Noise II www.nasa.gov Session 4pNS November 3, 2011 Introduction: Liftoff Acoustics Liftoff acoustics (LOA) noise is caused by the supersonic steady jet flow interaction with surrounding atmosphere and launch complex, persisting for 0-20 seconds as the vehicle lifts off. Challenges for determining Ares I Rocket Liftoff Environments New Solid Motor Motor Sound Sources New Mobile Launcher Launch Pad Deflector Effects New Tower Plume Sound Reflections off of Launch Pad Ares I LOA Environments Documented in Ares I Acoustics Databook Validate LOA environments Ares I-X flight Verify LOA environments Ares I at Kennedy Space Center Launch Complex Ares I Scale Model Acoustic Test 2 Ares I LOA Validation and Verification Comparisons Oct 28, 2009 Nov 2010 –July 2011 Ares I - Databook Ares I-X Flight Vehicle at Kennedy ASMAT Model at Marshall Space Space Center Launch Complex-39B Flight Center Test Stand 116 3 METHODOLOGY 4 ASMAT Acoustic Analysis The goal is to find maximum sound response and the corresponding steady state time window This max sound corresponds to when the solid motor’s chamber pressure reaches steady state Data Processing: Typical Time History of ASMAT Solid Motor Data File Sample Rate: 256,000 sps Data post-processing using PCSignal 1/3 Octave Band Frequency analysis 1/3 Octave Band Range (Center Frequency): 250 to 63,000 Hz Analysis Window: 1 to 1.9 seconds Window Type: Rectangular Reference Pressure: 0.00002 N/m2 N Average: 7 Analysis Window Overlaid on Chamber Pressure Measurement 5 ASMAT Data Corrections ASMAT data shown in the following slides not corrected for Mass Flow Differences 2 I 13,500 8,200 2 0.05 2 0.818 I1 39.3 8,400 SPL1 SPL1 10 I2 10 SPL2 10log 10 10log 10 0.818 SPL1 0.87 dB I1 Grid response, Frequency response, Atmospheric Absorption Impacts 500 hertz and above for full scale frequencies Frequency spectra are scaled using Strouhal number V d f 2 1 f f 0.0488f f 0.05f 2 V d 1 2 1 2 1 1 2 6 ASMAT Results Scaled to Ares I-X Full Scale ARES I-X Flight Data vs ASMAT Zone 6 155 Ares I-X Flight (IAD095P) 150 ASMAT @ 5 feet (Model Scale Frequency) ASMAT @ 5 feet (Full Scale Frequency) 145 140 135 130 Sound Pressure(dB) Level Sound 125 120 115 10 100 1000 10000 100000 1/3 Octave Band Center Frequency (Hz) *Scaling process primarily driven by frequency scaling 7 DATA RESULTS 8 Validation: ASMAT vs. Ares I-X (Zones 1 and 4) ARES I-X Flight Data vs ASMAT 155 150 145 140 135 130 Ares I-X AAD158P (0 degrees, Aft Skirt) 125 ASMAT (Zone 1) Ares I-X (AAD155P) Sound Pressure Level (dB) Level SoundPressure 120 Ares I-X (AAD157P) ASMAT (Vert#5) 115 ASMAT (Vert#7) ASMAT (Vert#11) 110 10 100 1000 1/3 Octave Band Center Frequency (Hz) 9 Validation: ASMAT vs. Ares I-X (Zones 6) ARES I-X Flight Data vs ASMAT 155 150 145 140 135 130 125 IAD098P (0 degrees) IAD097P (45) 120 IAD095P (80) Vert #5 (5 feet) Sound Pressure Level (dB) Level SoundPressure 115 Vert #7 (5 feet) Vert#11 (5 feet, No LM) 110 10 100 1000 1/3 Octave Band Center Frequency 10 Validation: ASMAT vs. Ares I-X (Zone 10) Ares I-X Flight Data vs. ASMAT 155 OAD838P (5) 150 OAD839P (45) IAD915P (0 degrees) IAD619P (45) 145 Vert #5 (5 feet) Vert #7 (5 feet) 140 Vert #11 (5 feet, No LM) 135 130 125 Sound Pressure Level (dB) Level SoundPressure 120 115 110 10 100 1000 1/3 Octave Band Center Frequency (Hz) 11 Verification and Validation of Overall Sound Pressure Levels ASMAT vs. Ares I-X 160 ASMAT Vehicle Model Ares I-X ASMAT (Vert#5) ASMAT (Vert#7) 155 ASMAT (Vert#11) 150 Frustum 145 Overall Sound Pressure Level Level (dB)PressureSound Overall 140 0 20 40 60 80 100 120 140 160 180 200 Model Scale Distance from Nozzle Exit Plane (inches) Results Summary: ASMAT OASPL compares well to Ares I-X OASPL Scaling methodology works Frustum has higher OASPL than zones below and above 12 Verification of Frustum Sound Pressure Levels ASMAT vs. Databook 155 ASMAT Vehicle Model 150 145 140 135 130 ASMAT P95/50 with Flight Sample Deviation 125 Frustum (dB) Level Pressure Sound Ares I Data Book Environment (Zone 5) 120 ASMAT Xbar 115 10 100 1000 10000 1/3 Octave Band Center Frequency (Hz) Results Summary: The ASMAT P95/50 environment is significantly higher than Ares I Acoustics Databook LOA environment for the Frustum Recommend increasing the Databook environment for Zone 5 13 Conclusions and Recommendations Conclusions Ares I-X flight data validated the ASMAT LOA results Ares I Liftoff acoustic environments were verified with scale model test results Results showed that databook environments were under-conservative for Frustum (Zone 5) Recommendations Databook environments can be updated with scale model test and flight data Subscale acoustic model testing useful for future vehicle environment assessments 14 .