Search

Over the past two decades, there has been a renewed interest in the development of a new generation of supersonic aircraft for civil purposes that could potentially succeed Concorde. However, the noise annoyance is still considered one of the hampering factors to meet public consensus. This paper aims at revealing the potential of numerical simulations to predict sonic boom signature in Near Field at early design stages. In particular, the paper further demonstrates the applicability of the numerical approach proposed by NASA and other partners during the Sonic Boom Prediction Workshops held between 2014 and 2021, to compute the pressure signature of aircraft in the zone close to it. The results highlight the suitability of the approach (1) to capture the impact of aircraft flight condition variations on the sonic boom signature, (2) to enable the characterization of novel aircraft layout, including Mach 5 waverider configuration, (3) to provide near-field shock wave noise predictions that can be used to evaluate shock propagation, on-ground signature analyses, and annoyance assessment.

The eruption in La Palma in 2021 (from September 19th to December 13th) had many phenomena not previously documented nor expected in an eruption of these characteristics in the Canary Islands, such as sonic explosions, although explosions and lightnings were known in ancient chronicles of other eruptions and legends such as that of the «Guayota» devil of the Teide volcano., La erupción de la Palma en 2021 (del 19 septiembre al 13 diciembre) tuvo muchos fenómenos no documentados antes, ni esperados en una erupción de estas características en las islas Canarias, como son las explosiones sónicas, aunque explosiones y rayos si se conocen en antiguas crónicas de otras erupciones y leyendas como la del demonio Guayota del volcán Teide.

An explosive sound was heard over a wide area of Sapporo city, Hokkaido, Japan, on 26 April 2021. It was accompanied by minor shaking and was considered likely to be a sonic boom produced by a fireball. However, no luminous phenomenon was observed. We analyzed seismic data to identify the source of the sonic boom, and estimated the trajectory of the object from the associated signal arrival times. The source was located ∼100 km off the west coast of Hokkaido at an altitude of 50 km. The elevation angle was greater than 66° and the estimated velocity was higher than that of a fighter plane. Although the luminous phenomenon was not observed, the trajectory model suggested that the source of the sonic boom was not an aircraft and most likely a fireball. We compared trajectory models estimated from optical and seismic observations for past sonic boom events, and they were found to be in good agreement. Although our trajectory model is simplified and assumes that sound and the fireball have a constant speed, the model is highly accurate. The results show that seismic data can be used to estimate the trajectory of objects producing sonic booms, even when visual observations are unavailable.

Because of the expected return of civil supersonic flight, research is required to update supersonic noise regulations to allow public acceptance of civil supersonic flights. To advise ICAO on whether future supersonic aircraft will be able to comply with current regulations this thesis predicts the noise production of future supersonic transport aircraft. For this a low-fidelity aircraft design program was created. This program was validated successfully and based on five produced aircraft designs a noise analysis was performed. This analysis shows that supersonic aircraft will be unlikely to meet the subsonic airport noise regulations. The reason for this is that optimisation for supersonic flight inevitably results in changes that produce more noise compared to subsonic aircraft. The sonic boom noise level of future supersonic transport aircraft can be greatly reduced compared to the levels of Concorde by optimising the aircraft’s shape. However, this will result in increased drag, fuel burn and weight. Therefore it is unlikely that near future supersonic transport aircraft will be acceptable in terms of noise., Aerospace Engineering

Because of the expected return of civil supersonic flight, research is required to update supersonic noise regulations to allow public acceptance of civil supersonic flights. To advise ICAO on whether future supersonic aircraft will be able to comply with current regulations this thesis predicts the noise production of future supersonic transport aircraft. For this a low-fidelity aircraft design program was created. This program was validated successfully and based on five produced aircraft designs a noise analysis was performed. This analysis shows that supersonic aircraft will be unlikely to meet the subsonic airport noise regulations. The reason for this is that optimisation for supersonic flight inevitably results in changes that produce more noise compared to subsonic aircraft. The sonic boom noise level of future supersonic transport aircraft can be greatly reduced compared to the levels of Concorde by optimising the aircraft’s shape. However, this will result in increased drag, fuel burn and weight. Therefore it is unlikely that near future supersonic transport aircraft will be acceptable in terms of noise., Aerospace Engineering

There exists no publication currently available to the scholars that address in detail, every aspect of designing a modern supersonic aircraft for civil aviation. This paper aims to resolve that issue. It reviews all the existing work that has been done on the topic so far and builds upon that. It incorporates multiple disciplines and takes into account the closely inter-coupled effects of each component on one-another. It also analyses in detail the various environmental and modern regulatory challenges like sonic boom and means to overcome them. It further addresses the challenges like logistics, cabin crew radiation exposure, and cost sensitivity. The paper also takes into account the progress trends and proposes possible future enhancements. It also combines multiple approaches like higher-order regression, 3D modeling, simulation, neural networks, and genetic algorithms to predict the best-case values for each parameter and thereby finally proposing an extensive set of rules that when obeyed leads to the design of a supersonic aircraft that abides by all the modern civil aviation needs and regulations.

This research project aims at obtaining a better understanding of vertically translating the wing and the related wing-body interference effects on the drag and sonic boom. Computational Fluid Dynamics (CFD) analysis using the Euler equations has been used to evaluate an airplane with different vertical wing placements at a lift coefficient of 0.15 at a Mach-number of 1.6 and also in zero-lift conditions. Pressure distributions, drag forces and pressure signatures have been calculated in order to assess the performance in terms of wave drag and sonic booms. These results have been analysed to find out why certain effects are happening for these configurations. The low wing configuration has the highest lift-to-drag ratio due to interference on the upper wing surface close to the fuselage. The lift-to-drag ratio for CL = 0.15 is found to be 4.79% higher compared to the worst performing configuration, the high wing configuration. Due to the local geometry of the low wing configuration it is possible to cre- ate additional suction on the upper wing surface, which positively affects the performance. Pressure signatures are extracted at 1 body-length distance (70푚) from the aircraft for several azimuth angles. These distributions show that the low wing configuration also has the lowest impulse and maximum overpressure. The higher wing configurations show an extra peak in overpressure emanating from the trailing end of the wing, which is created due to interference effects. Below the wing surface there is a large volume of the fuselage, while it is absent for the low wing configuration. Therefore the higher wing configurations show an extra peak in the pressure signature. Next to this discovery, an analysis is presented to relate the geometry of the configurations to the wave drag by assessing the cross-sectional area distribution using different intersection methods. These methods are compared with other methods found in the literature. Two methods which use a single

The Chebarkul meteorite entered Earth's atmosphere over Russia on 3:20 February 15, 2013 (UTC) producing a strong sonic boom throughout Chelyabinsk Oblast. A seismic signal was observed at the same time in the broadband seismic data of the IRIS network. We performed a waveform inversion using 5 broadband seismic records to obtain the source-time function of the Chebarkul meteorite signal. Assuming a single force for the source mechanism, the waveform can be explained well with a point source model. We performed a grid search in space to find the location of the source. The best-fit source location was determined on the meteor track and 40km away from lake Chebarkul, where the large hole from the impact was detected after the meteor fall. We use the modified Friedlander equation to estimate a deconvolved form of the source time function, and the amplitude of the estimated single force is 2.0 *10e11 N and the onset of the pulse is at 3:21:58 (UTC), February 15, 2013. Since the location of the estimated source is separated from the impact point, the single force generating the seismic waves was produced by the blast wave due to the severe fragmentation of the bolide, not the impact of the meteorite on the ground.

The second generation of Supersonic Transport (SST-2) is required to have higher effectiveness than that of SST-1. The SST-2 should be the two-regime plane that has the equal range of flight at subsonic and supersonic cruise M numbers. Further the noise should be reduced at the take-off and landing. The investigation by TsAGI (The Central Aerodynamics Institutes) showed that these contradictory requirements might be satisfied with the CPW (Complex Planform Wings) concept in design. The CPW is consisted of a base wing with moderate aspect ratio and an additional wing (strake) with considerably small aspect ratio. A lifting surface with a given arrangement of the aerodynamic centers can be realized by appropriate choice of geometrical parameters. The SST-2 must be designed to be capable of transporting the passengers of 300 to 350 and have the range of 9,200 km. In order to satisfy these specifications, the aerodynamic designs should be optimized to increase the lift to drag ratio in the whole flight regime. The computational results based on linear theory methods showed that the gain in lift to drag ratios increased with the sweptback angle of strake and reached at a maximum value. It was shown that SST-2 designed as two-regime plane had the same values of range parameter at both subsonic and supersonic regions, which means the same fuel consumption at the both regimes. Further the take-off characteristics and wing devices, and sonic boom levels are described. Finally the main data of the baseline of Russian SST-2 are shown., 第2世代の超音速輸送機(SST-2)にはSST-1より高い効率性が要求されている。SST-2は亜音速および超音速巡航マッハ数で等しい航続距離を持つ2領域機である。また、離着陸時の騒音を低減しなければならない。TsAGI(中央流体力学研究所)の研究は、これらの矛盾する要求を、設計におけるCPW(複合平面型翼)の概念で満たせることを示した。CPWは中程度のアスペクト比をもつ基本形状と非常に小さなアスペクト比をもつ付加翼(ストレーキ)からなる。基本形状と付加翼のパラメータを適切に選定すれば、与えられた空力中心位置配置をもった揚力面を設計することができる。SST-2は乗員300〜350人を輸送し、航続距離が9,200kmであるように設計しなければならない。これらの仕様を満足するためには、空力設計はすべての飛行領域で揚抗比が増大するように最適化を行わなければならない。線形理論に基づいた計算の結果は、揚抗比がストレーキの後退角と共に増大し、最大値に達することを示した。2領域機として設計したSST-2は亜音速と超音速領域とで同じ燃料消費を意味する同じ航行パラメータを持つことである。その他、離陸特性と翼補助装置、およびソニックブーム音圧レベルについて述べた。最後に、ロシアSST-2の基本形状データを示した。

In this research, multiobjective optimization system has been developed to reduce the aerodynamic drag and the sonic boom for SST wing-body configuration. Wing and fuselage are defined by 131 design variables and optimized at the same time. Multiblock grids around SST wing-body configuration are generated automatically and an Euler solver is used to evaluate the aerodynamic performance of SST wing-body configuration boom is evaluated based on the equivalent area distribution by Darden. MOGA is used as an optimizer of the present optimization. To reduce the large computation time, CFD computations are parallelized by a simple master-slave concept on SGI ORIGIN 2000 at The Institute of Fluid Science at Tohoku University., Special Publication of National Aerospace Laboratory, 航空宇宙技術研究所特別資料

JAXA Special Publication, 宇宙航空研究開発機構特別資料

Brief description is given of the two environmental issues related to the operation of SST (SuperSonic Transport), viz. ozone depletion due to the engine emission and community annoyance caused by the sonic boom. The importance of the aircraft weight reduction is stressed in alleviating the impact of the environmental concernes upon the development of the second generation SST. It is hoped for that fluid dynamicists will contribute in either the weight reduction process or bringing about effective solutions to the environmental issues themselves., 超音速民間輸送機(SST)の運航に係わる2つの環境問題、つまりエンジン排出物によるオゾン層破壊およびソニックブームによる騒音につき概略を述べた。環境問題が第2世代SSTの開発に及ぼす影響を軽減する上での機体重量軽減の重要性を強調した。重量軽減または環境問題それ自体の解決を図る上で流体力学者の寄与する余地が大きいことを指摘した。

A study of the aerodynamic design for the reduction of sonic-boom is conducted by combining a three-dimensional Euler CFD (Computational Fluid Dynamics) code with a least-square optimization technique. This method can consider a nonlinear and a three-dimensional effects of aircraft which cannot be considered by previous low-boom design methods based on linear theory. The fuselage geometry of a low-boom aircraft designed by linear theory is modified by this design method in order to minimize the pressure discrepancies between a target low-boom pressure signature and a calculated signature. It is shown that the sonic-boom intensity of the aircraft designed by this method is smaller than that designed by linear theory. The results of the study indicate that this method is a useful tool for low-boom design., JAXA Special Publication, 宇宙航空研究開発機構特別資料

This paper discusses design optimization of wing for SuperSonic Transport (SST) using Multiple Objective Genetic Algorithm (MOGA). Three objective functions are used to minimize the drag for supersonic cruise, the drag for transonic cruise and the bending moment at the wing root for supersonic cruise. The wing shape is defined by in total of 66 design variables. An Euler flow code is used to evaluate supersonic performance, and a potential flow code is used to evaluate transonic performance. To reduce the total computational time, flow calculations are parallelized on NEC SX-4 computer using 32 PE's. The detailed analysis of the resulting Pareto front suggests a renewed interest in the arrow wing planform for the supersonic wing., JAXA Special Publication, 宇宙航空研究開発機構特別資料

Aerodynamic design system developed in JAXA SST (SuperSonic Transport) project are summarized and a newly developed aerodynamic design system CAPAS (CAD (Computer Aided Design)-based Automatic Panel Analysis System) is introduced in this paper. The CAPAS utilizes the CATIA (Computer Aided Three dimensional Interactive Application) v4 to define an airplane configuration and the A502 panel method for aerodynamic analysis and the Thomas code for sonic-boom analysis. The CAPAS has a java-based GUI (Graphical User Interface) for designers to use it easily. It can be incorporated in optimization tools such as GA (Genetic Algorithm) or gradient-based one easily without its GUI parts. Conceptual design of a scaled low sonic-boom demonstrator is conducted by the CAPAS system and its low-boom characteristics are validated using CFD (Computational Fluid Dynamics) and wind-tunnel test. Both the front and rear part of the ground sonic-boom signature generated by the airplane can be reduced by a non-axisymmetrical low-drag/low-boom nose and the combination of volume and lift with its main wing, lifting aft-fuselage and V-shaped tail wings., JAXA Special Publication, 宇宙航空研究開発機構特別資料

There has been increasing interest in the possibility of an environmentally acceptable and economically viable second generation Super Sonic Transport (SST). This will depend in part on achieving a design that incorporates significant technology gain in both supersonic and transonic aerodynamic efficiency. The CFD (Computational Fluid Dynamics) will play an important role to realize this ambitious goal. This paper attempts to present the expected roles of CFD in the following areas: (1) accurate and precise drag estimation; (2) development of the high performance wing using MDO (Multi Disciplinary Optimization); (3) low boom configuration design; (4) local flow calculation; and (5) flutter analysis. CFD tools are required to be easy operation for designer, to be short turnaround time and to be well correlated with actual phenomena. Those tools should be developed with close coordination between the researcher and end user., 環境適合性、経済的実現可能性のある次世代超音速旅客機(SST)の可能性に対する関心が益々増加しているが、これは、部分的には超音速および遷音速の双方において流体力学的効果を得る重要な技術を取り入れた設計を完成させることに依存するであろう。CFD(計算流体力学)はこの意欲的な目標を実現するために重要な役割を担っている。本稿は、次に示す分野での期待されるCFDの役割について述べた。(1)正確、精密な空気抵抗計算、(2)MDO(多目的最適化)を用いた高性能主翼の開発、(3)低ブーム形状の設計、(4)ローカルフローの計算、および(5)フラッタ解析である。CFDツールは、設計者に対して簡便な操作性、短い計算時間、実際の現象との良好な相関性が求められた。これらのツールを、研究者およびエンドユーザが緊密な協力によって開発した。

Research into sonic booms is indispensable for the future supersonic flight. In particular, the issue of sonic boom becomes a crucial problem when supersonic flights are over thickly populated areas. The TsAGI (Russia Central Aerohydrodynamic Institute) has been studying the sonic boom problem theoretically, experimentally and numerically since 1960. Prof. Zhirin of this institute has developed a theory of sonic boom by aircraft flying along any specified trajectory in non-homogeneous atmosphere. Based on this theory, computational methods have been developed for the analysis of sonic boom in stratified non-homogeneous atmosphere with three-dimensional wind. This paper reports recent results achieved at TsAGI, particularly techniques for prediction and reduction of sonic boom. The calculation of pressure signature and ray paths for both primary and secondary sonic boom areas provided pressure distributions of areas on the ground exposed to sonic boom, focusing boom, and super boom. The function F was calculated using the near field pressure distributions derived from panel methods or solutions of the Euler equation. Effects of distribution of aerodynamic forces, flight trajectory and atmospheric conditions on sonic boom were investigated. The concept of minimum boom and the main trends in SST sonic boom reduction have been investigated., 将来の超音速飛行にあたって、ソニックブームの研究は不可欠である。特に、人口が密集している地域の上を飛行するときには重要な問題である。TsAGIでは1960年代以降、理論的・実験的・数値的な研究を行っている。ツイリン教授(Prof.Zhirin)は非一様大気を任意の経路に沿って飛行する航空機からのソニックブームに対する理論を開発した。この理論を基にして、3次元風のある層状非一様大気中におけるソニックブーム解析のために、計算方法を発展させてきた。本報告では最近TsAGIで得られた成果について、特に、ソニックブームの予測技術やその解析法、ソニックブームの低減法について報告した。1次および2次ソニックブーム領域についての圧力特性および圧力線跡の計算は、収束ブーム、スーパブームおよびソニックブーム領域を含めた地上でのソニックブームを受けた領域の圧力分布を与えた。パネル法またはオイラー方程式の解に基づいた近傍場の圧力分布を用いて、F関数を計算した。空力配置、飛行経路、大気条件がソニックブームに与える影響を調べた。SSTソニックブーム減少における最小ブームの概念および主な傾向を調べた。

For validating “low-boom” supersonic aircraft design concepts and techniques in flight tests, sonic booms must be measured accurately. This paper discusses the systems and methods for accurate sonic boom measurement both on and above the ground. Requirements and issues for sonic boom measurement systems are considered and possible solutions are shown with the measurement systems and methods the authors have developed as examples. For the aerial measurement, the system and method for recording sonic booms at multiple altitudes up to about 1000 m above the ground by using a tethered blimp have been developed. The sonic boom data measured in the recent flight tests demonstrated the validity of the systems and methods for aerial and ground-based sonic boom measurement., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations

JAXA conducted D-SEND#1 Test in May 2011, whose main objective was to demonstrate the low-sonic-boom aircraft design concept by measuring sonic booms created by two types of test bodies designed with and without the concept. D-SEND#1 was successful, and distinct sonic boom signatures from the differently shaped test bodies were captured as designed. The collected sonic boom data is reported in this study. The data were collected at several microphone locations: at multiple (three or four) altitudes up to about 1000 m above the ground, on the ground surface, and in a small house., Physical characteristics: Original contains color illustrations, 形態: カラー図版あり

A study of impulsive noise propagation and its effect on structures has been performed. Propagation and response measurement were conducted on eleven buildings at three military facilities. Sources included artillery and tank gun firing and explosive ordinance disposal. Propagation measurements demonstrated that the primary path is airborne, not groundborne. Frequency Response Functions were developed for the measured structures, and a general single degree of freedom model for structural velocity response was prepared. A model for Probability of Damage from impulsive noise sources was developed and is presented. That model addresses a wide range of structure types, and provides guidance for impulsive noise criteria in communities., The original document contains color images.

Recent progresses by the aircraft industry in the development of a quieter supersonic transport have opened the possibility of overland supersonic flights, which are currently banned by aviation authorities in most countries. For the ban to be lifted, the sonic booms the aircraft generate at supersonic speed must be acceptable from a human-perception point of view, in particular inside buildings. The problem of the transmission of sonic booms inside buildings can be divided in several aspects such as the external pressure loading, structure vibration, and interior acoustic response. Past investigations on this problem have tackled all these aspects but were limited to simple structures and often did not account for the coupled fluid-structure interaction. A more comprehensive work that includes all the effects of sonic booms to ultimately predict the noise exposure inside realistic building structures, e.g. residential houses, has never been reported. Thus far, these effects could only be investigated experimentally, e.g. flight tests. In this research, a numerical model and a computer code are developed within the above context to predict the vibro-acoustic response of simplified building structures exposed to sonic booms, at low frequency. The model is applicable to structures with multiple rectangular cavities, isolated or interconnected with openings. The response of the fluid-structure system, including their fully coupled interaction, is computed in the time domain using a modal-decomposition approach for both the structural and acoustic systems. In the dynamic equations, the structural displacement is expressed in terms of summations over the â in vacuoâ normal modes of vibration. The interior pressure is expressed in terms of summations over the acoustic modes of the rooms with perfectly reflecting surfaces (hard walls). This approach is simple to implement and computationally efficient at low frequency, when the modal density is relatively low. The numerica

In this thesis, an output-only experimental modal testing and analysis technique known as the Natural Excitation Technique (NExT) is examined for use with large residential structures and interior cavities. The technique which assumes a random, stationary input causing the response data is reviewed and extended for the first time to include the assumption of an impulse input. This technique is examined with respect to the experimental modal analysis of single and two room residential structures. Each structure is first tested using conventional modal testing methods. Then, NExT is applied using each structure's response to a simulated sonic boom, an impulsive input. The results of these analyses along with the results obtained from a finite element model are compared. Then, the interior cavities enclosed by the residential structures are examined using NExT. Therefore, this thesis also demonstrates the successful use of NExT on acoustic systems for the first time. Three configurations of the interconnected cavities enclosed by the two room structure are considered to study physical phenomena. Both interior pressure response to random, stationary inputs and the sonic boom response are used with NExT to determine modal properties. The results of these analyses are compared to a theoretical analysis. Advantages to using NExT with both the response to a random, stationary input and an impulsive input are demonstrated for structural and acoustic systems.

Recent progresses by the aircraft industry in the development of a quieter supersonic transport have opened the possibility of overland supersonic flights, which are currently banned by aviation authorities in most countries. For the ban to be lifted, the sonic booms the aircraft generate at supersonic speed must be acceptable from a human-perception point of view, in particular inside buildings. The problem of the transmission of sonic booms inside buildings can be divided in several aspects such as the external pressure loading, structure vibration, and interior acoustic response. Past investigations on this problem have tackled all these aspects but were limited to simple structures and often did not account for the coupled fluid-structure interaction. A more comprehensive work that includes all the effects of sonic booms to ultimately predict the noise exposure inside realistic building structures, e.g. residential houses, has never been reported. Thus far, these effects could only be investigated experimentally, e.g. flight tests. In this research, a numerical model and a computer code are developed within the above context to predict the vibro-acoustic response of simplified building structures exposed to sonic booms, at low frequency. The model is applicable to structures with multiple rectangular cavities, isolated or interconnected with openings. The response of the fluid-structure system, including their fully coupled interaction, is computed in the time domain using a modal-decomposition approach for both the structural and acoustic systems. In the dynamic equations, the structural displacement is expressed in terms of summations over the "in vacuo" normal modes of vibration. The interior pressure is expressed in terms of summations over the acoustic modes of the rooms with perfectly reflecting surfaces (hard walls). This approach is simple to implement and computationally efficient at low frequency, when the modal density is relatively low. The numerical

Commercial aircraft are subject to noise regulations imposed by the Federal Aviation Administration. Currently, the FAA limits overland flight of supersonic airplanes due to the negative effect of the sonic boom on communities. The annoyance produced by the impulsive signature of sonic booms, particularly indoors, cannot exceed that of the broadband, low-overpressure noise produced by subsonic airplanes for the restriction to be lifted. Therefore, the ability to understand and accurately reproduce the acoustic response of a sonic boom is important for psychoacoustic classification of their tolerability within residences. This thesis presents and interprets results of the propagation and transmission of simulated sonic booms incident on wood-framed structures. The testing environment, sonic boom simulation method, and associated instrumentation are described. The effects of the traveling blast on the structure are investigated through pressure loading and structural response measurements. The ensuing interior acoustic responses for several different configurations are presented, including the effects of room cavity interaction and exposure of the room cavities to the traveling wave through an open door. Calculated transfer functions between the interior acoustic response and the free-field incident wave are computed to assess the extent to which wood-framed buildings transmit energy to their cavities. In all cases tested, significant transmission of the sonic boom's low frequency content into the structures was apparent through direct apertures and the excitation of structural components. The data show that sonic booms provide significant excitation of structural and acoustic modes that drives the interior acoustic response in residential structures.

This EA documents the potential environmental impacts of conducting two Hypersonic Technology Vehicle 2 (HTV-2) flight tests to support development and demonstration of hypersonic technologies. Both HTV-2 missions would be launched from Vandenberg Air Force Base, California, using existing rocket booster systems. Following booster separation, the HTV-2 would glide at hypersonic velocities in the upper atmosphere, prior to an ocean impact near US Army Kwajalein Atoll/Ronald Reagan Ballistic Missile Defense Test Site in the Republic of the Marshall Islands., The original document contains color images. Sponsored in part by DARPA, Tactical Technology Office, Arlington, VA.

This report analyzes the potential environmental affects and consequences for conducting up to 48 annual flight tests by one of a kind research aircraft that would use scramjet engines to fly at altitudes up to 264,000 feet above sea level. These flights would reach speeds faster than the speed of sound and land at Edwards Air Force Base, California., Task order 68, task 7. The original document contains color images.

The purpose of this presentation is to briefly outline the progress and achievements that have occurred in some areas of nonlinear acoustics during recent years. © 2008 American Institute of Physics.

Preliminary results on shape optimization of a wing-body configuration aiming at reducing sonic boom overpressure will be discussed. The optimization process uses a CAD modeler and an Euler CFD code with adjoint. Thickness, scale, twist and camber at section level were used to obtain gains in ground pressure signature.

This paper presents an accurate approach to simulate the sonic boom of a supersonic aircraft. The near field flow is modeled by the conservative Euler equations and is solved using a finite volume approach on adapted unstructured tetrahedral meshes. Then, from the CFD solution, the pressure distribution under the aircraft is extracted and used to set up the initial conditions of the propagation algorithm in the far field. The pressure distribution is propagated down to the ground in order to obtain the sonic boom signature using a ray tracing algorithm based upon the Thomas waveform parameter method. In this study, a sonic boom sensitivity analysis on the SSBJ geometry provided by Dassault Aviation is carried out.

Preliminary results on shape optimization of a wing-body configuration aiming at reducing sonic boom overpressure will be discussed. The optimization process uses a CAD modeler and an Euler CFD code with adjoint. Thickness, scale, twist and camber at section level were used to obtain gains in ground pressure signature.

This paper presents an accurate approach to simulate the sonic boom of a supersonic aircraft. The near field flow is modeled by the conservative Euler equations and is solved using a finite volume approach on adapted unstructured tetrahedral meshes. Then, from the CFD solution, the pressure distribution under the aircraft is extracted and used to set up the initial conditions of the propagation algorithm in the far field. The pressure distribution is propagated down to the ground in order to obtain the sonic boom signature using a ray tracing algorithm based upon the Thomas waveform parameter method. In this study, a sonic boom sensitivity analysis on the SSBJ geometry provided by Dassault Aviation is carried out.

The paper reviews recent studies of supersonic/hypersonic flow and shock wave control using plasma energy addition and magnetohydrodynamics (MHD), focusing on the work by the Princeton University group and their collaborators. Applications include sonic boom mitigation and optimization of scramjet inlets. Experimental and computational studies of interaction of oblique shocks with laser-generated blast wave and thermal wake demonstrate the possibility of shock mitigation in a repetitive-pulse mode. Analysis of interaction parameter for MHD control of cold hypersonic flows with external ionization shows that significant interaction can be achieved with energy-efficient ionization by electron beams. The maximum achievable interaction parameter sharply increases with increasing Mach number and altitude; however, interelectrode arcing may limit the performance. For MHD control of scramjet inlets, nonequilibrium electrical conductivity is created by electron beams injected into the gas along magnetic field lines. At Mach numbers higher than the design value, the shocks that would otherwise enter the inlet can be moved back to the cowl lip by a short MHD generator at the first compression ramp. To increase air capture at Mach numbers below the design value, a heated region is used to create a"virtual cowl" and to deflect flow streamlines into the inlet. The best location of the energy addition region is near the intersection of the nose shock of the vehicle with the continuation of the cowl line, and slightly below that line. Stretching and tilting the energy addition region improves performance. By spending only a few percent of the enthalpy flux into the inlet, the air capture and engine thrust can be increased by 15-20%, with no loss in specific impulse., See also ADM001739. Presented at The Conference Proceedings on Thermochemical Processes in Plasma Aerodynamics (Final) held in Saint Petersburg, Russia on 28-31 July 2003. The original document contains color images. Sponsored in part by DARPA and the Air Force Research Laboratory.

A "sonic boom wavy surface" computer code was developed by HKC Research at the University of Southern California (USC) over the last few years. It was distributed in April 2003 via CD through PARSONS, Pasadena, to the Air Force. A final report was also distributed. The problem addressed by this code is that of a sonic boom passing over a wavy ocean surface. The pressure wave transmitted through the wavy interface is the primary output of this code. The theory upon which this code is based is presented in a USC Report authored by H. K. Cheng and C. J. Lee. The purpose of the current report is to document the code by explaining the calculations performed therein, and placing the numerical routines in correspondence with the equations which appear in the USC Report. Code results from a sample input set are also presented in order to provide a benchmark for future users and against which to compare possible future releases of this code by Cheng and Lee. The emphasis of this report is on code documentation. No assessment nor interpretation of the theory is offered. Although the Cheng and Lee code is not currently in standard use for predicting sonic boom transmission into the ocean, this document may hasten its adoption as a standard tool for this purpose.

A laboratory experiment was designed and performed to ascertain the difference in underwater response to sonic boom laboratory between flat and wavy surface models and their depth-dependent rule overpressure attenuation. Waveforms of overpressure were recorded in a water-filled tank, fitted with a surface-wave maker, during over-flight of the supersonic projectiles. Sawyers' (1968) theory for the flat interface has been validated to a depth of at least four signature lengths. The theory of Cheng and Lee (2000) for a wavy surface has been confirmed in several respects. Firstly, the predicted overpressure attenuation with depth to the one-half power has been found to be correct over depths up to four signature lengths. Secondly, the predicted frequencies and the fore-to-aft frequency shift have been confirmed by these laboratory-scale experiments., The original document contains color images.

The Russian space station, Mir, was actively deorbited to impact in the South Pacific on 23 March 2001. Mir was the largest body in Earth orbit ever to be deorbited in a controlled fashion. As such, it provided a unique opportunity to observe, at a known time and location, what happens to such a large object as it re-enters the earth's atmosphere. The reentry and breakup were videotaped from the Fiji Sheraton hotel by a CNN cameraman. About four to five minutes after the streaking Mir debris left his view, he described hearing a number of sonic booms which were generated by pieces of the wreckage. This report contains the cameraman's description of what he heard and a calculation of the sonic boom amplitude and duration which would have been generated by a single Mir module on its reentry trajectory. Results of the calculation are consistent with the reported estimated time of boom arrival past visual sighting. However, no actual measurements were made at the hotel of the boom strength (sound level.) Thus the code results for boom amplitude cannot be quantitatively verified.

The sonic Boom Analysis and Measurement (BAM) system is portable, user configurable and is rapidly deployable. The BAM system user's manual is designed to familiarize the user by providing concise steps so that the system can be properly installed and operated. The manual also contains information that will allow the operator to confirm that the system is functioning properly before deployment and contains some basic field-level maintenance information. The system has been developed for and with the assistance of the Air Force Research Laboratory at Wright-Patterson AFB, OH. The BAM system has been designed to detect sonic booms. The system was developed to have superior performance to the existing Boom Event Analyzer Recorder (BEAR) system.

The effects of simulated subsonic (94.6-114.2 dB CSEL) and supersonic (0.25-6 psf) aircraft noise on 14 desert tortoises, Gopherus Agassizii were studied. Auditory thresholds of the most sensitive individuals at 250 Hz were 17.5 dB SPL. Thresholds averaged 34 dB SPL at 250 Hz for the 11 individuals tested. No significant temporary threshold shift (TTS) was detected after worst-case exposure to subsonic aircraft noise or 2-6 psf simulated booms. TTS ranging from 5-20 dB was measured in 5 of 9 individuals after exposure to 10-6 psf booms (recovery >45 min and <48 hr). Tortoises were trained to walk voluntarily on a treadmill and fitted with small mask for measurements of O2 consumption. V02 at rest averaged 1.472 1.472 ml/min/kg/ (s.d.=0.410). Resting heart rate averaged 11.82 BPM (s.d. = 3.91). Exercising heart rate ranged from 10 BPM to 42 BPM, averaging 30 BPM. There was no increase in blood lactate levels during or post-exercise. The most extreme response to simulated subsonic aircraft noise was a typical reptilian defensive response - freezing - for up to 113 minutes. After the initial exposure, bouts were short (<^5 min); thereafter, the tortoise entered a milder defensive state (head withdrawals, alerting, less climbing or digging). Averaged heart rate declined 7-8% decrease during exposures, corresponding to the shift in behavior. Responses to sonic booms were limited to brief bouts of alerting.

Sonic boom noise from overwater supersonic aircraft operations penetrates into the water. The present work developed an algorithm to simulate this penetrating sonic boom noise for realistically shaped sonic booms, predictions previously unavailable. The new algorithm assumes that the water surface is fairly flat and that the water is deep enough so that bottom reflections can be ignored. The algorithm was used to model the underwater sonic boom noise for the cases of incident sonic boom waves distorted by atmospheric effects and by common aircraft maneuvers. It was found that certain aircraft maneuvers and atmospheric effects can increase the penetration of the sonic boom noise, while others decrease it.

In April 1994, the USAF Armstrong Laboratory in cooperation with USAF Test Pilot School conducted a measurement study of controlled focus boom generated by supersonic maneuvers. The objective of this study was to collect focus and post focus booms and to assess the ability of aircrews to control the placement of the focal region during basic maneuvers. Forty-nine supersonic passes were flown and included level linear acceleration, level turn, accelerating dives and climbout/ pushover maneuvers. These flights were flown under calm and turbulent atmospheric conditions. Turbulent conditions had a defocusing effect which caused distortions in the focus region and resulted in smaller maximum overpressures. Sonic booms were collected by up to 25 Boom Event Analyzer Recorders (BEARs) placed in a 13,000 ft. linear array. The BEAR units were spaced 500 to 2,000 feet apart with the denser spacing at the expected focal region. This spacing was chosen to evaluate the thickness of both the focal and post-focal regions. Of the 49 flights, a docus boom was placed within the array 37 times and within approximately 3,000 feet of the target point 27 times demonstrating the ability to place controlled focus booms.

For the past two decades in the United States, blast sounds and sonic booms both have been assessed using C weighted day and night average sound level. Based almost exclusively on blast sound research, a new method which replaces the C weighted day and night average sound level recently has been recommended, reviewed, and incorporated into a new American National Standard. As in the previous method, the new method includes and assesses sonic boom sounds in a like manner to blast sounds. However, while available evidence suggested that in an indoor setting sonic boom could be treated in a similar fashion to blast sounds, experimental evidence was lacking. To provide the lacking comparison data, this study tested the responses of subjects to sonic booms to determine if they were consistent with the previous blast response data presented by Schomer in 1994, since these data formed the basis for the new method. A key factor in the design of this study was the presentation of real blasts and booms to subjects situated in real structures in the field. The new data resulting from this study show good general agreement with the previous data.

It has been suggested that sonic booms caused a mass hatching failure of Sooty Terns on the Dry Tortugas, Florida. Notwithstanding that the evidence was circumstantial, this hypothesis is often quoted as proof that sonic booms harm wildlife. The mathematical analysis reported herein is performed at two levels of idealization. The first model is that of a spherical elastic shell with the embryo represented as an inertial concentric sphere and the albumen as an acoustic fluid that completely fills the intervening volume. The second, higher fidelity, model accounts for the "egg shape" and allows for an air sac. In both cases the sonic boom is taken to be an incident acoustic wave with the classic N-wave signature. The peak responses of the egg, specifically the peak shell stress, embryo acceleration, and reactive force at the substrate upon which the egg rests, are computed as a function of the incident sonic boom overpressure and compared with damage criteria taken from the literature. It is concluded that the overpressures from supersonic military operations with existing aircraft are of insufficient level to cause avian egg damage in general and the 1970 Sooty Tern hatching failure in particular.

During November 1996 a series of tests was performed in and around Caliente, NV. These tests, performed by the firms of Cambridge Acoustical Associates, Inc., and Wyle Laboratories, Inc., are part of a Small Business Innovative Research (SBIR) project, being sponsored by the Armstrong Laboratory of the United States Air Force. The project objective is to perfect measurement techniques that simulate structural response to sonic booms, and in turn allow one to assess potential damage, especially to unconventional structures. The goals of the Caliente tests were twofold. The first was to provide additional data for the validation of the techniques. The second was to demonstrate the process by which such measurements may be used to perform an environmental (structural) damage assessment. This report focuses on the latter. To limit the overall environmental impact on Caliente, supersonic operations from Nellis AFB have recently been prohibited within five miles of the town. To evaluate the adequacy of this restriction with respect to avoiding structural damage, window damage to be exact, a part of our test plan was devoted to a measurement survey of various windows throughout the town. From these data we have simulated their peak response (stress) to the sonic boom environment evaluated under the above mentioned flight restriction. Twenty windows were tested, including those of a number of commercial buildings, the library, train station, and one of the auxiliary hospital buildings. (Window installations with a noticeable rattle are not readily simulated and were excluded from the ensemble.) Based on our simulations (Table 3), the least susceptible to damage is a window of the Bureau of Land Management (BLM) Building and a train station window is the most vulnerable. For all windows, no additional breakage is anticipated under current flight restrictions.

PCBoom3 is a PC-based program that computes single-event sonic boom footprints from any supersonic vehicle exercising any maneuver in a real atmosphere, including winds. The user specifies the aircraft, the maneuver, and the atmosphere. The primary output is the sonic boom footprint in terms of contours of equal overpressure (or other amplitude metric) on the ground, relative to the aircraft's position. PCBoom3 also generates sonic boom signatures, the pressure-time history of the boom at a particular location on the ground. Spectra of these signatures are also computed. The program is operated through a menu interface, which simplifies its use and the presentation of results. The program is designed for use by personnel who are planning specific supersonic missions where sonic boom will be an issue or who are investigating sonic boom incidents. While the program is relatively simple to operate, it provides access to analysis which requires an understanding of sonic boom phenomena. A copy of this program can be obtained by contacting AFRL/HECB at (937) 255-3605 x423 or downloading the file directly from the public website at www.afcee.brooks.af.mil/EC/noise/noisemodels.htm.

For the past two decades, blast sounds and sonic booms have been assessed in a like manner in the United States using a C-weighted day-night level. Recently, a new method which replaces the C-weighted day-night level had been recommended (Schomer, Nov. 1994), and reviewed and recommended (NRC, 1996). In this new method, as in the old, blast sounds and boom sounds are once again assessed in a like manner. However, while available evidence suggested that in an indoor setting, blast sounds and sonic booms could be treated similarly, evidence in the form of a side-by-side comparison was lacking. The purpose of the study reported herein was to provide the lacking side-by-side data. The study tested if subjects indoors responded in a like manner to both blast and boom sounds. This study also tested if the response of subjects to sonic booms followed the new method suggested in Schomer (Nov. 1994)., Prepared in collaboration with Eagle Aeronautics, Inc., Newport News, VA.

Three types of tests were employed: static tests, fatigue tests, and tests inside the Sonic Boom Test Facility (SBTF). Uniform loads across the glass surface were applied to glass panes in all tests. In the static tests, the panes were subjected to increasing pressure until they failed (typically between 30 and 90 sec loading). Fatigue tests sinusoidally loaded the panes at 3 Hz frequency until they failed or 24 hrs had elapsed (259,200 cycles). SBTF tests involved exposing the panes to up to 5000 sonic booms or until failure, Static tests were used to establish the strength of panes under a variety of conditions and to assess the variation of the glass strength for any particular condition. This included assessing the strength of new glass, after aging, with different edge conditions, flawed glass, and after other tests. Fatigue tests allowed testing at a significant fraction of the anticipated breaking strength and loading the panes more slowly than in the SBTF. These two factors increased the chance of breaking and, thus, of detecting glass fatigue behavior. The SBTF provided the most realistic simulation of repetitive sonic booms and, thus, the most credible demonstration of the importance of cumulative damage to the assessment of sonic boom damage to glass., Prepared in cooperation with BBN Acoustic Technologies, Canoga Park, CA.

Eggs of domestic white leghorn chickens were exposed to simulated sonic booms in the Sonic Boom Test Facility at BBN Systems and Technologies in Canoga Park CA. Two-hundred and fifty-two fertile eggs in four groups were exposed to booms with levels of 3 psf (group A), 20 psf (group B), 0 psf (control group C) and 30 psf (group D). Ten exposures were given daily separated by 10 sec intervals (day 2-19 of incubation). Chicks were held for four days after hatching for observation. By chance, the mean egg weight at laying of groups A and C differed from groups B and D. Differences in survivorship among the groups during incubation were explained by this difference, with survivorship significantly lower in the least exposed groups (A and C; Time series analysis, Mantel-Cox criterion; c2 = 5.67; df = 1,245; p < 0.05). Final counts of the numbers of eggs pipped and hatched did not differ (c2=1.21; df= 3; p >/= 0.05), nor did weekly weights and weight at hatching (ANOVA, p > 0.05). None of the exposed eggs cracked during exposure and all chicks hatched were normal. Resonance frequencies of 23 chicken eggs ranged between 468 and 1036 Hz, and of4 quail eggs between 1274 and 1475 Hz, 6-7 octaves above the peak energy in the simulated sonic booms.

Seasonal variations in wind and temperature gradients are known to influence the propagation of sonic booms. This report examines predictive techniques in current use which may be refined for application to seasonal Environmental Impact Statements. The effects of seasonally averaged refractive atmospheres on the sonic boom carpet predictions for an example flight of an F-111 at Mach 1.3 and 10,000 feet above Mean Sea Level (MSL) were documented. The effect of such atmospheres on predicted noise exposures due to a real-world mix of supersonic flights was estimated. The example boom environment was chosen to be that near Edwards Air Force Base (EAFB) where sonic booms are known to affect the public. Two distinct atmospheric averaging techniques were applied seasonally and the resulting sonic boom predictions compared to each other and to those predictions obtained using the U.S. Standard Day Atmosphere and the Annual reference Atmosphere for Edwards AFB. The results show the potential benefit of conducting seasonal sonic boom predictions in forecasting the effects which supersonic flight operations have on the public. (AN)

In recent works we have formulated a new approach to compressible flow simulation, combining the advantages of shock-fitting and shock-capturing. Using a cell-centered Roe scheme discretization on unstructured meshes, we warp the mesh while marching to steady state, so that mesh edges align with shocks and other discontinuities. This new algorithm, the Shock-fitting Lagrangian Adaptive Method (SLAM) is, in effect, a reliable shock-capturing algorithm which yields shock-fitted accuracy at convergence. Shock-capturing algorithms like this, which warp the mesh to yield shock-fitted accuracy, are new and relatively untried. However, their potential is clear. In the context of sonic booms, accurate calculation of near-field sonic boom signatures is critical to the design of the High Speed Civil Transport (HSCT). SLAM should allow computation of accurate N-wave pressure signatures on comparatively coarse meshes, significantly enhancing our ability to design low-boom configurations for high-speed aircraft. (MM)