User Guides for Noise Modeling of Commercial Space Operations—RUMBLE and PCBoom (2018) / Chapter Skim
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P a r t I I PCBoom Sonic Boom Model for Space Operations Version 4.99 User Guide Kevin A Bradley Clif Wilmer Vincent San Miguel Wyle Laboratories, Inc.
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C O N T E N T S 113 Chapter 13 Introduction to PCBoom 113 13.1 About PCBoom 113 13.2 Organization of User Guide 114 Chapter 14 Technical Reference 114 14.1 Sonic Boom Background 117 14.2 Sonic Boom Theory 119 14.3 Propagation Using Geometrical Acoustics 122 14.4 Signature Aging 125 Chapter 15 Program Installation and Execution 129 Chapter 16 PCBoom Input Files 129 16.1 Case Description 129 16.2 Ground Pressure and Latitude 131 16.3 Atmosphere Specification 134 16.4 Ray Tracing Altitude Extent Specification 136 16.5 Signature and Vehicle Input Mode 144 16.6 Ray Tracing Azimuthal Control 146 16.7 Flight Trajectory Specification 148 Chapter 17 Sonic Boom Metrics 149 Chapter 18 PCBoom Output Files 150 Chapter 19 Error and Warning Messages 153 Chapter 20 Sample Cases 153 20.1 Sample Case 1: Vertically Launched, Two-Stage-To-Orbit Vehicle 155 20.2 Sample Case 2: Horizontally Launched, Suborbital Vehicle 160 Chapter 21 PCBoom Data Display and Grid Output 160 21.1 WCON Control Features 162 21.2 PCBoom Noise Grid Output for NMPlot 168 21.3 PCBoom Noise Grid Output for AEDT 170 Chapter 22 Generating Sonic Boom Source Signatures 170 22.1 Carlson's Simplified N-Wave Method 173 Chapter 23 Approval Process Guidance for Commercial Space Noise Studies 173 23.1 Procedure for Review of Non-Default Methods and Data 174 23.2 List of Common Methods/Data and AEE Review Requirements 175 23.3 Guidance Regarding a Request to Use Non-Default Methods/Data 177 References 178 Abbreviations
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113 13.1. About PCBoom The sonic boom model is based on PCBoom4 (hereafter referred to as PCBoom)
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114 14.1 Sonic Boom Background A sonic boom occurs when a vehicle operates at supersonic conditions, generating a wave field that can propagate to the ground which is heard as a sonic boom. Figure 52 shows a classical sketch of a sonic boom wave cone generated by an aircraft in steady non-accelerating level flight.
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technical reference 115 Figure 52. Sonic boom wave field.
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116 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom strikes the ground. These isopemps are generated throughout the trajectory, sweeping out an area called the "boom footprint." Note that the aircraft's ground track need not pass through the footprint; it is possible for an aircraft to generate a boom, turn, and never fly over its boom footprint.
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technical reference 117 14.2 Sonic Boom Theory Sonic boom calculations can be divided into three major elements: • Prediction of the pressure disturbance in the vicinity of the vehicle. A near field pressure distribution is required at a reference radius large enough such that the pressure disturbance can be considered a locally axisymmetric acoustic wave, and small compared to atmospheric gradients.
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118 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom at various distances along a ray, between an infinitesimal strength acoustic wave and a unitstrength wave. The nonlinear distortion of each part of the boom signature consists of an advance proportional to its original strength multiplied by the age parameter.
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technical reference 119 focused superbooms to be finite, and validated local solutions are available. Focus solutions must be locally applied to focal zones, using the adjacent geometrical acoustics calculation as a boundary condition.
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120 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom and aerodynamic loads. Acoustic rays, orthogonal to wavefronts, are traced by the method of geometrical acoustics [1]
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technical reference 121 14.3.2 Ellipsoidal Earth Traditionally, sonic boom propagation is computed for a horizontally stratified atmosphere over a flat Earth. This is generally an acceptable approximation for primary downwardpropagating booms, where propagation distances are short relative to Earth's curvature and typical horizontal atmospheric gradients.
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122 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom The 3-D atmospheric extension requires 3-D derivatives of wind and sound speed gradients, as opposed to just the z-gradients required in the stratified model. This was set up as a simple shell atmosphere, with single profile normal to the local surface.
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technical reference 123 14.4.1 The Age Parameter The age parameter [6] is a quantity based on the local speed of sound, scale factors, and the Blokhintsev invariant that defines how much the signature has steepened.
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124 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom program, and by NASA [10] in planning boom measurements from Saturn launches.
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125 PCBoom is a full-ray tracing model capable of calculating sonic boom overpressure footprints and ground signatures from supersonic vehicles performing arbitrary maneuvers. It comprises a suite of modules consisting of the following programs, run sequentially: • FOBOOM: the primary sonic boom computational solver.
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126 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom Filename Description Foboom499.exe PCBoom primary sonic boom solver, version 4.9 pcbfoot.exe PCBoom footprint and signature post-processor wcon.exe PCBoom contouring and visualization ShapeFactorDatabase.exe Launch vehicle shape factor database generator ShapeDatabase.ks Launch vehicle shape factor database Geometries.csv Launch vehicle geometry interface pcboom_guide.doc This document – the PCBoom user manual and technical reference example.dat PCBoom example case example.trj PCBoom example trajectory example.att Example atmospheric file Table 10. PCBoom distribution files.
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program Installation and execution 127 To run FOBOOM from the command prompt: foboom499 casename[.dat] [ioutputs]
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128 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom To run WCON from the command prompt: wcon casename.qwk This will start WCON, an interactive GUI for viewing boom footprints and signatures. Users can plot overpressure and sound level contours, identify regions of focusing, and export results to both image and user-readable text files.
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129 The primary FOBOOM propagation input file is referred to as the PCBoom case input file (*
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130 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom Section Input File Section 16.1 Case Description 16.2 Ground Pressure and Latitude 16.3 Atmosphere Specification 16.4 Ray Tracing Altitude Extent Specification 16.5 Signature and Vehicle Input Mode 16.6 Ray Tracing Azimuthal Control 16.7 Flight Trajectory Specification Table 13. Fundamental FOBoom input file sections.
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pCBoom Input Files 131 The ground altitude corresponds to the altitude of the first point in the atmosphere definition. Note that the physical ground for signature output (defined in Section 16.4)
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132 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom y-velocity, and pressure do not need to match each other, i.e., there can be any number of altitude pairs for each atmospheric variable. Altitudes are defined as kilofeet above mean sea level (MSL)
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pCBoom Input Files 133 account for the centrifugal force of Earth's rotation. The uniform atmosphere mode must be specified with a constant temperature.
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134 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom A range of dates must be specified, and the generated web page saved as an ASCII text file. The file name is specified in Line Type 11, Table 17.
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pCBoom Input Files 135 72403 IAD Sterling Observations at 00Z 01 Jan 2007 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- PRES HGHT TEMP DWPT RELH MIXR DRCT SKNT THTA THTE THTV hPa m C C % g/kg deg knot K K K -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1015.0 88 7.8 -0.2 57 3.73 150 10 279.8 290.3 280.4 1000.0 212 6.8 -0.2 61 3.79 145 13 279.9 290.7 280.6 988.7 305 6.0 -0.3 64 3.79 150 12 280.1 290.8 280.7 983.0 353 5.6 -0.4 65 3.80 152 13 280.1 290.9 280.8 952.4 610 3.5 1.1 84 4.37 160 17 280.5 292.8 281.2 946.0 665 3.0 1.4 89 4.50 166 19 280.6 293.2 281.3 … snip … 13.2 28956 -54.3 -87.1 1 0.02 55 13 752.8 753.0 752.8 12.7 29227 -53.9 -86.9 1 0.02 37 17 763.3 763.5 763.3 12.6 29261 -53.9 -86.9 1 0.02 35 17 764.4 764.6 764.4 10.4 30480 -55.0 -87.1 1 0.02 100 13 803.3 803.5 803.3 10.2 30630 -55.1 -87.1 1 0.02 808.2 808.5 808.2 Station information and sounding indices Station identifier: IAD Station number: 72403 Observation time: 070101/0000 Station latitude: 38.97 Station longitude: -77.47 Station elevation: 88.0 Showalter index: 6.31 Lifted index: 22.88 LIFT computed using virtual temperature: 23.21 SWEAT index: 257.17 K index: 22.20 Cross totals index: 19.40 Vertical totals index: 20.30 Totals totals index: 39.70 Convective Available Potential Energy: 0.00 CAPE using virtual temperature: 0.00 Convective Inhibition: 0.00 CINS using virtual temperature: 0.00 Bulk Richardson Number: 0.00 Bulk Richardson Number using CAPV: 0.00 Temp [K] of the Lifted Condensation Level: 271.93 Pres [hPa]
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136 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom a value of 5,000 ft AGL will suffice. Table 19 shows the altitude extent and ray tracing control parameters.
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pCBoom Input Files 137 Line Type Position Variable Type IMODE Description 9 1 Integer - Signature input mode (IMODE)
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138 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom 16.5.2 IMODE 2 – Simple F-function Mode Mode 2 is the simple F-function input mode and is useful if Δp/p∞ is known only at the 0° (downward, undertrack) azimuthal angle and booms are expected to be N-waves.
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pCBoom Input Files 139 16.5.3 IMODE 3 – Carlson's F-function Mode Mode 3 is used to generate an N-wave F-function based on Carlson's simplified model [13]
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140 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom 16.5.3.2 Mode 3B – Launch Vehicle Mode Launch vehicle mode is used when a vehicle is expected to emit an underexpanded plume, which will generate its own pressure waves and must be accounted for in the sonic boom propagation analysis. The signature is again calculated from Carlson's simplified N-wave method, and is based on a shape factor corresponding to Tiegerman's hypersonic boom theory [15]
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pCBoom Input Files 141 16.5.3.3 Mode 3C – Axisymmetric Shape Factor Mode The axisymmetric shape factor mode is used when the vehicle's geometry can be sufficiently described using an axisymmetric shape factor. To trigger this mode, set the shape factor curve ID in Line Type 11E to "17" (Table 30)
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142 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom Line Type Position Variable Type Line Type 10F 1 Float Vehicle length (ft) 2 Float Vehicle weight (klbs)
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pCBoom Input Files 143 Line Type Position Variable Type Line Type 10G 1 Float Vehicle length (ft)
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144 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom Figure 70. Radial distributions of selected launch vehicles (default configurations, all in meters)
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pCBoom Input Files 145 Figure 71. Launch vehicle database file (ShapeDatabase.ks)
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146 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom Line Type Column Variable Name Line Type 20 2 – 8 KEYWORD Keywords, defined in Table 40. Note that the first column is left blank.
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pCBoom Input Files 147 Figure 72. Trajectory file example.
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148 PCBoom computes full sonic boom waveforms. The footprint post-processor PCBFOOT and the signature post-processor WCON compute the sound metrics Pmax, Lpk, Lflt, CSEL, ASEL, and PL, as described below.
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149 PCBoom generates a number of intermediate and output files used throughout the PCBoom workflow. Optional detailed output files can also be generated for further user post-processing.
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150 C h a p t e r 1 9 The error and warning messages which FOBOOM may generate are itemized here along with an explanation of what is causing the message. If appropriate, recommended changes to the input file are provided.
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error and Warning Messages 151 On occasion, when PCBoom is tracing rays and determining the geometry of a focus, certain unexpected exceptions to the geometric handling procedure occur. These are flagged with a negative integer focus abort code, written to the .out file, and an output message is generated to the .un6 file.
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152 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom Code Description –1 Caustic intersected the lowest altitude –2 Focal points were straddling a cusp –3 An auxiliary ray cut off before focusing –4 Focus above ZMAX –5 The ray, in a carpet boom case, cut off –6 An auxiliary trajectory point is subsonic –7 N/A – Legacy versions only –8 Focus occurred less than 4 ray steps from the vehicle –9 Overran dimensions in tube (condition detected and NP1 set to –1 as a flag in tube)
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153 This section provides instructions on how to promptly start using PCBoom Version 4.99 to compute sonic boom from spacecraft operations. To illustrate the process of running PCBoom, two sample cases are provided that model vertically and horizontally launched spacecraft.
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154 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom Figure 73. Open a command prompt to run PCBoom.
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Sample Cases 155 mouse to create a zoom box around the boom contours, the contours will appear as they do in Figure 78.
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Figure 78. WCON display of maximum overpressure contours and trajectory for Sample Case 1.
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Sample Cases 157 After WCON starts up, the sonic boom contours (and isopemps) are displayed for Sample Case 2 as shown in Figure 81.
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Figure 81. WCON display of maximum overpressure contours and isopemps for Sample Case 2.
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Figure 83. WCON display of A-weighted SEL contours for Sample Case 2.
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160 21.1 WCON Control Features PCBoom displays sonic boom footprints and signature output using the program wcon. When wcon is started, the footprint display shows the following on an X-Y plot: • Contours of equal overpressure, psf • The trajectory • The isopemps • A legend of contour levels • A size scale • A user-editable legend The contour values and the scale of the plot can be adjusted.
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pCBoom Data Display and Grid Output 161 • Home: zoom original Zoom to the original (default) size and position • Click L: zm window Select a zoom box.
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162 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom the coordinate dialog, the ground signature will be shown. In complex regions (generally the case near a focus)
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pCBoom Data Display and Grid Output 163 Figure 85. NMPlot grid summary screen.
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164 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom Figure 87. NMPlot screen to manually specify contour levels.
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pCBoom Data Display and Grid Output 165 Figure 89. NMPlot contour plot screen showing PCBoom grid control points.
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166 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom Figure 90. GIS map of sonic boom contours for Sample Case 1: vertically launched TSTO vehicle.
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pCBoom Data Display and Grid Output 167 Figure 91. GIS map of sonic boom contours for Sample Case 2: horizontally launched suborbital vehicle.
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168 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom Complex data sets, such as the A-weighted SEL grid generated for Sample Case 2, may place a heavy burden on NMPlot depending on the user's system performance; grid files may take more than 5 minutes to load and operations within NMPlot may initially be slow. Performance degradation in NMPlot when loading some complex data sets generated by WCON appears to be due to two factors.
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pCBoom Data Display and Grid Output 169 Figure 92. AEDT metric results screen showing PCBoom grid control points and A-weighted SEL values.
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170 C h a p t e r 2 2 Generating Sonic Boom Source Signatures 22.1 Carlson's Simplified N-Wave Method A method for generating F-functions based on linearized supersonic theory is described in Carlson's simplified method [13]
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Generating Sonic Boom Source Signatures 171 Note that this does not take into account flight path curvature or vehicle acceleration, and therefore does not apply to maneuvering flights. The term 1 0S b d x ∫ ( )
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172 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom 0 0.1 0.2 0.3 0.4 0.5 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.6 0.7 0.8 0.9 1 Figure 94. Carlson's shape factor parameter curve.
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173 The FAA Office of Environment and Energy (AEE) has approved models for detailed noise analysis.
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174 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom to an EA, EIS, or study report as part of the NEPA documentation. The format of the review package is described in Section 23.3.
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approval process Guidance for Commercial Space Noise Studies 175 23.2.2 Analysis Methods/Data that Do Require AEE Review and Approval The following analysis methods or data are recommended to require AEE review and approval. • Sensitivity – Any supplemental noise analysis that involves impacts that are likely to be highly controversial on environmental grounds.
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176 User Guides for Noise Modeling of Commercial Space Operations -- rUMBLe and pCBoom – Carlson's F-function (Mode 3B and Mode 3E are most likely to be used by practitioners)
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178 AEDT Aviation Environmental Design Tool AEE Office of Environment and Energy AGL Above Ground Level ANSI American National Standards Institute ARAP ARAP Sonic Boom Program ASCII American Standard Code for Information Exchange ASEL A-weighted Sound Exposure Level AST Office of Commercial Space Transportation CFD Computational Fluid Dynamics CSEL C-weighted Sound Exposure Level D4M Delta IV Medium dB Decibel deg Degree DNL Day-Night Average Sound Level EA Environmental Assessment EFG Earth-fixed Geocentric (coordinate system) EIS Environmental Impact Statement ESEL Unweighted Sound Exposure Level FAA United States Federal Aviation Administration ft Feet (length)
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Abbreviations 179 Pmax Peak overpressure (unit of pressure, pounds per square foot) psf Pound-force per Square Foot s, sec Second (time duration)
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