The Experts below are selected from a list of 3021 Experts worldwide ranked by ideXlab platform
Susan E Cliff - One of the best experts on this subject based on the ideXlab platform.
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usm3d simulations for second Sonic Boom workshop
Journal of Aircraft, 2017Co-Authors: Alaa A Elmiligui, Melissa B Carter, Sudheer N Nayani, Susan E Cliff, Jason M PearlAbstract:The NASA Tetrahedral Unstructured Software System with the USM3D flow solver was used to compute the test cases for the Second AIAA Sonic Boom Prediction Workshop (SBPW2). The intent of this paper ...
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usm3d simulations for second Sonic Boom workshop
Aviation, 2017Co-Authors: Alaa A Elmiligui, Melissa B Carter, Sudheer N Nayani, Susan E Cliff, Jason M PearlAbstract:The NASA Tetrahedral Unstructured Software System with the USM3D flow solver was used to compute test cases for the Second AIAA Sonic Boom Prediction Workshop. The intent of this report is to document the USM3D results for SBPW2 test cases. The test cases included an axisymmetric equivalent area body, a JAXA wing body, a NASA low Boom superSonic configuration modeled with flow through nacelles and engine boundary conditions. All simulations were conducted for a free stream Mach number of 1.6, zero degrees angle of attack, and a Reynolds number of 5.7 million per meter. Simulations were conducted on tetrahedral grids provided by the workshop committee, as well as a family of grids generated by an in-house approach for Sonic Boom analyses known as BoomGrid using current best practices. The near-field pressure signatures were extracted and propagated to the ground with the atmospheric propagation code, sBoom. The USM3D near-field pressure signatures, corresponding sBoom ground signatures, and loudness levels on the ground are compared with mean values from other workshop participants.
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wind tunnel model design for Sonic Boom studies of nozzle jet flows with shock interactions
54th AIAA Aerospace Sciences Meeting, 2016Co-Authors: Susan E Cliff, Marie Denison, Shayan Moiniyekta, Donald E Morr, Donald A DurstonAbstract:NASA and Industry are performing vehicle studies of configurations with low Sonic Boom pressure signatures. The computational analyses of modern configuration designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty in the aft signatures with often greater boundary layer effects and nozzle jet pressures. Wind tunnel testing at significantly lower Reynolds numbers than in flight and without inlet and nozzle jet pressures make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot SuperSonic Wind Tunnel from Mach 1.6 to 2.0 will be used to assess the effects of shocks from components passing through nozzle jet plumes on the Sonic Boom pressure signature and provide datasets for comparison with CFD codes. A large number of high-fidelity numerical simulations of wind tunnel test models with a variety of shock generators that simulate horizontal tails and aft decks have been studied to provide suitable models for Sonic Boom pressure measurements using a minimally intrusive pressure rail in the wind tunnel. The computational results are presented and the evolution of candidate wind tunnel models is summarized and discussed in this paper.
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experimental and computational Sonic Boom assessment of lockheed martin n 2 low Boom models
2015Co-Authors: Susan E Cliff, Alaa A Elmiligui, Donald A Durston, Eric L Walker, Melissa B CarterAbstract:Flight at speeds greater than the speed of sound is not permitted over land, primarily because of the noise and structural damage caused by Sonic Boom pressure waves of superSonic aircraft. Mitigation of Sonic Boom is a key focus area of the High Speed Project under NASA's Fundamental Aeronautics Program. The project is focusing on technologies to enable future civilian aircraft to fly efficiently with reduced Sonic Boom, engine and aircraft noise, and emissions. A major objective of the project is to improve both computational and experimental capabilities for design of low-Boom, high-efficiency aircraft. NASA and industry partners are developing improved wind tunnel testing techniques and new pressure instrumentation to measure the weak Sonic Boom pressure signatures of modern vehicle concepts. In parallel, computational methods are being developed to provide rapid design and analysis of superSonic aircraft with improved meshing techniques that provide efficient, robust, and accurate on- and off-body pressures at several body lengths from vehicles with very low Sonic Boom overpressures. The maturity of these critical parallel efforts is necessary before low-Boom flight can be demonstrated and commercial superSonic flight can be realized.
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summary of the 2008 nasa fundamental aeronautics program Sonic Boom prediction workshop
Journal of Aircraft, 2014Co-Authors: Michael A Park, Melissa B Carter, Susan E Cliff, Michael J Aftosmis, Richard L Campbell, Linda S BangertAbstract:The SuperSonics Project of the NASA Fundamental Aeronautics Program organized an internal Sonic Boom workshop to evaluate near-field Sonic-Boom prediction capability at the Fundamental Aeronautics Annual Meeting in Atlanta, Georgia, on 8 October 2008. Workshop participants computed Sonic-Boom signatures for three nonlifting bodies and two lifting configurations. Cone–cylinder, parabolic, and quartic bodies of revolution comprised the nonlifting cases. The lifting configurations were a simple 69 deg delta-wing–body and a complete low-Boom transport configuration designed during the High Speed Research Project in the 1990s with wing, body, tail, nacelle, and boundary-layer diverter components. The AIRPLANE, Cart3D, FUN3D, and USM3D flow solvers were employed with the ANET signature propagation tool, output-based adaptation, and a priori adaptation based on freestream Mach number and angle of attack. Results were presented orally at the workshop. This article documents the workshop and results and provides c...
Michael A Park - One of the best experts on this subject based on the ideXlab platform.
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nearfield summary and analysis of the third aiaa Sonic Boom prediction workshop c608 low Boom demonstrator
AIAA Scitech 2021 Forum, 2021Co-Authors: Michael A Park, Melissa B CarterAbstract:A summary and statistical analysis of the nearfield Computational Fluid Dynamics (CFD) submissions for the Third AIAA Sonic Boom Prediction Workshop is provided with a focus on the C608 Low Boom Flight Test Demonstrator. The C608 is more complex in terms of geometry and propulsion boundary conditions than previous workshops cases and is more representative of vehicles with lower ground loudness and the potential for lower annoyance. The nearfield signatures submitted by the participants are propagated to the ground to compute statistics of loudness measures over the vehicle Sonic Boom carpet. Principle component analysis is used to extract the primary variation modes. Context from previous Sonic Boom workshops indicates that this workshop has the lowest variation even though the case is more challenging because it is quieter and more complex. The international state-of-the-art results documented in this summary indicates that nearfield CFD variation is low enough for meaningful low-Boom design and can contribute toward the discussion of replacing the prohibition of overland superSonic flight with a certification standard.
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nearfield summary and statistical analysis of the second aiaa Sonic Boom prediction workshop
Journal of Aircraft, 2017Co-Authors: Michael A Park, Marian NemecAbstract:A summary is provided for the Second AIAA Sonic Boom Workshop held on January 8–9, 2017, in conjunction with AIAA SciTech 2017. The workshop used four models of increasing complexity: an axisymmetr...
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summary of the 2008 nasa fundamental aeronautics program Sonic Boom prediction workshop
Journal of Aircraft, 2014Co-Authors: Michael A Park, Melissa B Carter, Susan E Cliff, Michael J Aftosmis, Richard L Campbell, Linda S BangertAbstract:The SuperSonics Project of the NASA Fundamental Aeronautics Program organized an internal Sonic Boom workshop to evaluate near-field Sonic-Boom prediction capability at the Fundamental Aeronautics Annual Meeting in Atlanta, Georgia, on 8 October 2008. Workshop participants computed Sonic-Boom signatures for three nonlifting bodies and two lifting configurations. Cone–cylinder, parabolic, and quartic bodies of revolution comprised the nonlifting cases. The lifting configurations were a simple 69 deg delta-wing–body and a complete low-Boom transport configuration designed during the High Speed Research Project in the 1990s with wing, body, tail, nacelle, and boundary-layer diverter components. The AIRPLANE, Cart3D, FUN3D, and USM3D flow solvers were employed with the ANET signature propagation tool, output-based adaptation, and a priori adaptation based on freestream Mach number and angle of attack. Results were presented orally at the workshop. This article documents the workshop and results and provides c...
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specialized cfd grid generation methods for near field Sonic Boom prediction
AIAA Aerospace Sciences Meeting, 2014Co-Authors: Michael A Park, Alaa A Elmiligui, Susan E Cliff, Richard L Campbell, Sudheer N NayaniAbstract:Ongoing interest in analysis and design of low Sonic Boom superSonic transports re- quires accurate and ecient Computational Fluid Dynamics (CFD) tools. Specialized grid generation techniques are employed to predict near- eld acoustic signatures of these con- gurations. A fundamental examination of grid properties is performed including grid alignment with ow characteristics and element type. The issues a ecting the robustness of cylindrical surface extrusion are illustrated. This study will compare three methods in the extrusion family of grid generation methods that produce grids aligned with the freestream Mach angle. These methods are applied to con gurations from the First AIAA Sonic Boom Prediction Workshop.
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summary of the 2008 nasa fundamental aeronautics program Sonic Boom prediction workshop
51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2013Co-Authors: Michael A Park, Melissa B Carter, Michael J Aftosmis, Richard L Campbell, Susan Cliff, Linda S NangertAbstract:The SuperSonics Project of the NASA Fundamental Aeronautics Program organized an internal Sonic Boom workshop to evaluate near- and mid-field Sonic Boom prediction capability at the Fundamental Aeronautics Annual Meeting in Atlanta, Georgia on October 8, 2008. Workshop participants computed Sonic Boom signatures for three non-lifting bodies and two lifting configurations. A cone-cylinder, parabolic, and quartic bodies of revolution comprised the non-lifting cases. The lifting configurations were a simple 69-degree delta wing body and a complete low-Boom transport configuration designed during the High Speed Research Project in the 1990s with wing, body, tail, nacelle, and boundary layer diverter components. The AIRPLANE, Cart3D, FUN3D, and USM3D ow solvers were employed with the ANET signature propagation tool, output-based adaptation, and a priori adaptation based on freestream Mach number and angle of attack. Results were presented orally at the workshop. This article documents the workshop, results, and provides context on previously available and recently developed methods.
Melissa B Carter - One of the best experts on this subject based on the ideXlab platform.
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nearfield summary and analysis of the third aiaa Sonic Boom prediction workshop c608 low Boom demonstrator
AIAA Scitech 2021 Forum, 2021Co-Authors: Michael A Park, Melissa B CarterAbstract:A summary and statistical analysis of the nearfield Computational Fluid Dynamics (CFD) submissions for the Third AIAA Sonic Boom Prediction Workshop is provided with a focus on the C608 Low Boom Flight Test Demonstrator. The C608 is more complex in terms of geometry and propulsion boundary conditions than previous workshops cases and is more representative of vehicles with lower ground loudness and the potential for lower annoyance. The nearfield signatures submitted by the participants are propagated to the ground to compute statistics of loudness measures over the vehicle Sonic Boom carpet. Principle component analysis is used to extract the primary variation modes. Context from previous Sonic Boom workshops indicates that this workshop has the lowest variation even though the case is more challenging because it is quieter and more complex. The international state-of-the-art results documented in this summary indicates that nearfield CFD variation is low enough for meaningful low-Boom design and can contribute toward the discussion of replacing the prohibition of overland superSonic flight with a certification standard.
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usm3d simulations for second Sonic Boom workshop
Journal of Aircraft, 2017Co-Authors: Alaa A Elmiligui, Melissa B Carter, Sudheer N Nayani, Susan E Cliff, Jason M PearlAbstract:The NASA Tetrahedral Unstructured Software System with the USM3D flow solver was used to compute the test cases for the Second AIAA Sonic Boom Prediction Workshop (SBPW2). The intent of this paper ...
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usm3d simulations for second Sonic Boom workshop
Aviation, 2017Co-Authors: Alaa A Elmiligui, Melissa B Carter, Sudheer N Nayani, Susan E Cliff, Jason M PearlAbstract:The NASA Tetrahedral Unstructured Software System with the USM3D flow solver was used to compute test cases for the Second AIAA Sonic Boom Prediction Workshop. The intent of this report is to document the USM3D results for SBPW2 test cases. The test cases included an axisymmetric equivalent area body, a JAXA wing body, a NASA low Boom superSonic configuration modeled with flow through nacelles and engine boundary conditions. All simulations were conducted for a free stream Mach number of 1.6, zero degrees angle of attack, and a Reynolds number of 5.7 million per meter. Simulations were conducted on tetrahedral grids provided by the workshop committee, as well as a family of grids generated by an in-house approach for Sonic Boom analyses known as BoomGrid using current best practices. The near-field pressure signatures were extracted and propagated to the ground with the atmospheric propagation code, sBoom. The USM3D near-field pressure signatures, corresponding sBoom ground signatures, and loudness levels on the ground are compared with mean values from other workshop participants.
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experimental and computational Sonic Boom assessment of lockheed martin n 2 low Boom models
2015Co-Authors: Susan E Cliff, Alaa A Elmiligui, Donald A Durston, Eric L Walker, Melissa B CarterAbstract:Flight at speeds greater than the speed of sound is not permitted over land, primarily because of the noise and structural damage caused by Sonic Boom pressure waves of superSonic aircraft. Mitigation of Sonic Boom is a key focus area of the High Speed Project under NASA's Fundamental Aeronautics Program. The project is focusing on technologies to enable future civilian aircraft to fly efficiently with reduced Sonic Boom, engine and aircraft noise, and emissions. A major objective of the project is to improve both computational and experimental capabilities for design of low-Boom, high-efficiency aircraft. NASA and industry partners are developing improved wind tunnel testing techniques and new pressure instrumentation to measure the weak Sonic Boom pressure signatures of modern vehicle concepts. In parallel, computational methods are being developed to provide rapid design and analysis of superSonic aircraft with improved meshing techniques that provide efficient, robust, and accurate on- and off-body pressures at several body lengths from vehicles with very low Sonic Boom overpressures. The maturity of these critical parallel efforts is necessary before low-Boom flight can be demonstrated and commercial superSonic flight can be realized.
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summary of the 2008 nasa fundamental aeronautics program Sonic Boom prediction workshop
Journal of Aircraft, 2014Co-Authors: Michael A Park, Melissa B Carter, Susan E Cliff, Michael J Aftosmis, Richard L Campbell, Linda S BangertAbstract:The SuperSonics Project of the NASA Fundamental Aeronautics Program organized an internal Sonic Boom workshop to evaluate near-field Sonic-Boom prediction capability at the Fundamental Aeronautics Annual Meeting in Atlanta, Georgia, on 8 October 2008. Workshop participants computed Sonic-Boom signatures for three nonlifting bodies and two lifting configurations. Cone–cylinder, parabolic, and quartic bodies of revolution comprised the nonlifting cases. The lifting configurations were a simple 69 deg delta-wing–body and a complete low-Boom transport configuration designed during the High Speed Research Project in the 1990s with wing, body, tail, nacelle, and boundary-layer diverter components. The AIRPLANE, Cart3D, FUN3D, and USM3D flow solvers were employed with the ANET signature propagation tool, output-based adaptation, and a priori adaptation based on freestream Mach number and angle of attack. Results were presented orally at the workshop. This article documents the workshop and results and provides c...
Sriram K. Rallabhandi - One of the best experts on this subject based on the ideXlab platform.
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summary of propagation cases of the second aiaa Sonic Boom prediction workshop
Journal of Aircraft, 2019Co-Authors: Sriram K. Rallabhandi, Alexandra LoubeauAbstract:A summary is provided for the propagation portion of the second AIAA Sonic Boom Prediction Workshop, held 8 January 2017 in conjunction with the AIAA SciTech 2017 Conference. Near-field pressure wa...
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mean flow atmospheric effects and their impact on Sonic Boom propagation
Journal of the Acoustical Society of America, 2018Co-Authors: Sriram K. RallabhandiAbstract:One dimensional augmented Burgers equation has been generally used for nonlinear lossy Sonic Boom propagation. This equation models the effects of nonlinearities, loss mechanisms such as absorption and dispersion due to molecular relaxation and thermoviscous dissipation, and geometric spreading through ray tube areas including Blokhintzev scaling as well as atmospheric stratification. However, in the presence of atmospheric winds, original terms in the augmented Burgers formulation do not account for the Doppler effects, where the observer is moving with the local flow rather than being fixed in space. Instead, wind is accounted for by updating the ray paths and effective speed of sound. Inclusion of mean flow wind effects in all terms of the augmented Burgers equation allows for an enhanced prediction capability that is closer to the underlying physics. This work will update sBoom, an augmented Burgers' solver, to reflect the mean flow wind enhancements. The Sonic Boom ground signatures and other relevant data are compared against those obtained without using mean flow wind effects. The shock rise times, Sonic Boom duration and peak pressures are some variables that are expected to be different, resulting in differences in noise metrics. Such differences will be discussed and documented for cases which may include shaped low-Boom as well as strong shock signatures.
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Sonic Boom mitigation through aircraft design and adjoint methodology
Journal of Aircraft, 2014Co-Authors: Sriram K. Rallabhandi, Eric J Nielsen, Boris DiskinAbstract:This paper presents a novel approach to design of the superSonic aircraft outer mold line (OML) by optimizing the A-weighted loudness of Sonic Boom signature predicted on the ground. The optimization process uses the sensitivity information obtained by coupling the discrete adjoint formulations for the augmented Burgers Equation and Computational Fluid Dynamics (CFD) equations. This coupled formulation links the loudness of the ground Boom signature to the aircraft geometry thus allowing efficient shape optimization for the purpose of minimizing the impact of loudness. The accuracy of the adjoint-based sensitivities is verified against sensitivities obtained using an independent complex-variable approach. The adjoint based optimization methodology is applied to a configuration previously optimized using alternative state of the art optimization methods and produces additional loudness reduction. The results of the optimizations are reported and discussed.
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advanced Sonic Boom prediction using augmented burger s equation
Journal of Aircraft, 2011Co-Authors: Sriram K. RallabhandiAbstract:This paper presents an approach to predict the Sonic Boom ground signatures accurately by numerically solving the Augmented Burgers’ equation entirely in the time domain. The method is capable of predicting the shock thicknesses, thus improving the frequency spectrum of the ground signatures. This also improves the loudness calculation when compared to linear theory methods because the shock rise times are computed and not empirically adjusted or corrected. The method is capable of predicting under-track and off-track ground signatures, with or without wind effects, along with consideration for aircraft maneuvers. This method is very efficient and accurate, making it a very useful design tool in the development of superSonic cruise aircraft.
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advanced Sonic Boom prediction using the augmented burgers equation
Journal of Aircraft, 2011Co-Authors: Sriram K. RallabhandiAbstract:This paper presents an approach to predict the Sonic Boom ground signatures accurately by numerically solving the Augmented Burgers’ equation entirely in the time domain. The method is capable of predicting the shock thicknesses, thus improving the frequency spectrum of the ground signatures. This also improves the loudness calculation when compared to linear theory methods because the shock rise times are computed and not empirically adjusted or corrected. The method is capable of predicting under-track and off-track ground signatures, with or without wind effects, along with consideration for aircraft maneuvers. This method is very efficient and accurate, making it a very useful design tool in the development of superSonic cruise aircraft.
Kojiro Suzuki - One of the best experts on this subject based on the ideXlab platform.
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effects of vibrational relaxation on Sonic Boom waveforms in a stratified atmosphere
AIAA Journal, 2020Co-Authors: Rei Yamashita, Kojiro SuzukiAbstract:This paper describes the effects of vibrational relaxation on Sonic Boom waveforms in a stratified atmosphere. Full-field direct simulations with vibrational nonequilibrium are performed over unifo...
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lateral cutoff analysis of Sonic Boom using full field simulation
Aerospace Science and Technology, 2019Co-Authors: Rei Yamashita, Kojiro SuzukiAbstract:Abstract This paper describes the world's first successful simulation for lateral cutoff phenomena of Sonic Boom far from the flight path due to variation in atmospheric temperature with altitude. A flow field around an axi-symmetric paraboloid has been analyzed by the full-field simulation method that solves the three-dimensional Euler equations with a gravity term to create a horizontally stratified atmosphere. A solution-adapted structured grid is constructed to align the grid lines with the front and rear shock-wave surfaces in the entire domain, including the near field around a superSonic body and far field reaching the ground beyond lateral cutoff. The flight is assumed to have a speed of Mach 1.2 at an altitude of 10 km, and the computational domain ranges over a distance of 30 km from the axis of symmetry. The computational results show that the evanescent wave in the shadow zone beyond lateral cutoff decays exponentially and changes into a progressive rounding waveform. The characteristics of the waveform transition are in good agreement with those observed in the flight tests. Therefore, the full-field simulation is recognized as a promising approach for investigating Sonic Boom strength in the full extent of Sonic Boom noise, including lateral cutoff and evanescent waves. Moreover, the computational results clarify that Sonic Boom focusing occurs above the ground, except for the vicinity of the ground, and the focusing strength along the lateral cutoff curve detected from the three-dimensional shock-wave surface increases with altitude. The results of ray tracing analysis collaborate the reasonability of the simulation results, and the caustic of downward convex agrees well with the lateral cutoff curve. In the shadow zone, the magnitude of exponential decay increases with altitude, and the lateral distance where the pressure rise decreases rapidly shortens with altitude.
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full field Sonic Boom simulation in stratified atmosphere
AIAA Journal, 2016Co-Authors: Rei Yamashita, Kojiro SuzukiAbstract:This paper discusses the usefulness of a full-field simulation as a Sonic Boom prediction method, wherein the analysis of the entire flowfield as a single computational domain is presented, including both the near field around a superSonic body and the far field reaching the ground. The three-dimensional Euler equations with a gravity term to create a realistic atmospheric model stratified with altitude are numerically solved by solution-adapted structured grids. Computations are made to reproduce the Drop test for Simplified Evaluation of Non-symmetrically Distributed Sonic Boom (D-SEND) #1, conducted by the Japan Aerospace Exploration Agency. As a result, this paper describes the world’s first successful reproduction by direct flight-test simulation of the evaluation of a Sonic Boom strength. The computational results clarify the Sonic Boom propagation, including the three-dimensional structure of the shock wave in the real environmental condition. Moreover, the results of the full-field simulations are...
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full field Sonic Boom simulation in real atmosphere
32nd AIAA Applied Aerodynamics Conference, 2014Co-Authors: Rei Yamashita, Kojiro SuzukiAbstract:As the Sonic Boom prediction method, the usefulness of the full-field simulation, in which the whole flow field including both the zone around a superSonic body and that on the ground is analyzed as a single computational domain, is assessed in this paper. The three dimensional Euler analyses including the gravity term have been numerically conducted to take into account the variation of the atmospheric properties with the altitude. The solutionadaptive structured grids are constructed by advancing the computational domain sector by sector for the grid lines to be aligned with the shock wave surfaces. The computations are made to reproduce the D-SEND#1 flight test by Japan Aerospace Exploration Agency (JAXA). The computational results are validated by comparing with the results of the waveform parameter method and the flight test data taken from the D-SEND database provided by JAXA. The maximum pressure rises of the present full-field simulations agree well with those of the waveform parameter method and the flight test data. Consequently, the present full-field simulations seem promising to analyze the natures of the Sonic Boom propagation in the realistic atmosphere model.