Commercial Space Operations Noise and Sonic Boom Measurements (2020) / Chapter Skim
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Commercial Space Operations Noise and Sonic Boom Measurements 19 3 Community Noise Measurement Protocol Introduction The community noise measurement protocol was developed to provide guidelines for conducting community and near-field noise measurements for commercial space operations propulsion noise and sonic booms. Accurate, reliable, and repeatable noise measurements from standardized noise measurement procedures will help ensure confidence in the data used to verify and validate modeling and prediction tools for noise impact assessments.
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Commercial Space Operations Noise and Sonic Boom Measurements 20 Flight Path: Trajectory of the air vehicle. The curve defined by the tangent of the velocity vector of the vehicle as a function of time.
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Commercial Space Operations Noise and Sonic Boom Measurements 21 Sound Exposure Level (SEL) : The sound exposure level is a measure of the total sound energy received during some time interval.
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Commercial Space Operations Noise and Sonic Boom Measurements 22 3.3.2 Microphones and preamplifiers Specifications All microphones shall exceed the requirements of ANSI/ASA S1.15-1997 (R 2011)
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Commercial Space Operations Noise and Sonic Boom Measurements 23 Terrain Ideally, the test site terrain shall permit direct line-of-sight from each microphone location to the source over the duration of the event. In areas where the initial direct line-of-site is not feasible, the microphone locations should be selected so that the duration of the line-of-sight blockage is minimized.
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Commercial Space Operations Noise and Sonic Boom Measurements 24 3.4.2 Microphone layout The following sections provide guidance on the minimum recommended number of measurement arrays and microphones. Additional measurement locations are desirable to increase the spatial resolution and extent of the data available for model validation.
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Commercial Space Operations Noise and Sonic Boom Measurements 25 Far-field community noise of horizontal launch/landing Far-field community noise from horizontal launches should be measured at a minimum of two arrays as shown in Figure 6. Centerline array: One array should be directly under the flight path with a minimum of three microphones.
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Commercial Space Operations Noise and Sonic Boom Measurements 26 Figure 7. Notional microphone layout for sonic boom measurements of vertical launch/horizontal launch/horizontal landing.
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Commercial Space Operations Noise and Sonic Boom Measurements 27 Far-field community noise of static vertical engine firing Far-field community noise measurements of a static vertical engine firing shall be carried out in the same manner as for vertical launches as shown in Figure 9. However, additional microphone arrays should be considered to increase angular resolution, particularly near the hazard zone.
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Commercial Space Operations Noise and Sonic Boom Measurements 28 Figure 10. Notional microphone layout for far-field community noise measurements of static horizontal engine firing.
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Commercial Space Operations Noise and Sonic Boom Measurements 29 Far-field arc array: The far-field arc should consist of microphones located at an angular resolution of at least 10°. When possible, finer resolution should be sought in the 45°-75° from plume centerline region to improve characterization of the principal radiation lobe.
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Commercial Space Operations Noise and Sonic Boom Measurements 30 according to the band-filter skirt shapes in ANSI/ASA S1.11-2014 [8]
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Commercial Space Operations Noise and Sonic Boom Measurements 31 3.6.3 Noise data Individual transducer file data format Each transducer shall have a unique file for each measurement event. The filename shall contain the unique number identifying each transducer (e.g., channel number)
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Commercial Space Operations Noise and Sonic Boom Measurements 32 ;HEADER SIZE..................: 42 ;RUN..........................: RUN0001 ;MISSION NAME.................: CYGNUS CRS OA-8E ;MISSION TYPE.................: ISS Resupply ;MISSION OPERATOR.............: NASA ;MISSION CONTRACTOR...........: ORBITAL ATK ;EVENT DESCRIPTION............: LAUNCH ;EVENT DATE...................: 12 NOVEMBER 2017 ;EVENT TIME...................: 07:19:51 A.M.
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