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A method is proposed for quickly estimating the sonic boom characteristics from supersonic passenger aircraft under standard atmospheric conditions. The piecewise linear temperature profile and absence of atmospheric wind make it possible to completely reduce the problem of the geometry of sonic boom wave propagation to an algebraic form. For acoustic pressure, an analytical solution is formulated using the nonlinear geometrical acoustics approach. The dependence of the geometry of sonic boom wave propagation on the cruising flight parameters of a supersonic passenger aircraft is analyzed. Under the conditions of SBPW (Sonic Boom Prediction Workshop) 2020, the overpressure signatures on the ground from the X-59 demonstrator were calculated. [ABSTRACT FROM AUTHOR]

This paper introduces a low-boom aircraft optimization design method guided by equivalent area distribution, which effectively improves the intuitiveness and refinement of inverse design. A gradient optimization method based on discrete adjoint equations is proposed to achieve the fast solution of the gradient information of target equivalent area distribution relative to design variables and to drive the aerodynamic shape update to the optimal solution. An optimization experiment is carried out based on a self-developed supersonic civil aircraft configuration with engines. The results show that the equivalent area distribution adjoint equation can accurately solve the gradient information. After optimization, the sonic boom level of the aircraft was reduced by 13.2 PLdB, and the drag coefficient was reduced by 60.75 counts. Moreover, the equivalent area distribution adjoint optimization method has outstanding advantages, such as high sensitivity and fast convergence speed, and can take both the low sonic boom and the low drag force of the aircraft into account, providing a powerful tool for the comprehensive optimization design of supersonic civil aircraft by considering sonic boom and aerodynamic force. [ABSTRACT FROM AUTHOR]

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The conventional sonic boom propagation prediction method widely adopted in supersonic aircraft design involves a two-step procedure. In the first step, a compressible viscous or inviscid Computational Fluid Dynamics analysis is applied to the aircraft geometry at flight conditions to produce a flow field solution near the aircraft. Then in the second step, a one dimensional nonlinear Burgers' equation model is used to propagate sonic boom signature traces from the near field solution at flight altitude to the ground along a ray path. For an accurate ground signature prediction the near field signature must be accurately modeled at a sufficient distance from the aircraft flight path in order to minimize errors in the one dimensional propagation model. This is a very challenging task for general purpose CFD tools in a design environment because the cost of maintaining highly accurate off-body solutions increases dramatically as the radial distance is enlarged in the computational domain. It is also particularly difficult to apply these tools for wave propagation because the algorithms are normally lower order and numerically dissipative and dispersive. In this work a space marching procedure based on an optimized higher order finite difference method is developed and applied in conjunction with a CFD solution concentrated in the close vicinity of the aircraft. This new approach is much more efficient, compared to previous methods, in providing highly accurate near field signatures for full carpet ground predictions. Results indicate that near field signatures retain more waveform shape information farther from the aircraft geometry while reducing the CFD cost significantly. The predicted ground signature is also shown to converge in shape as the radial distance of the near field signature grows, which is indicative of a more ideal initial condition being supplied to the one dimensional wave propagation to ground. This feature is very difficult to replicate in a tractable manner with common CFD approaches used in design. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The most convenient model describing the propagation of a sonic boom wave in the atmosphere is the augmented Burgers equation. In this work, we studied the influence of a numerical scheme on the result of solving an equation that takes into account the nonlinear nature of the propagation of sonic boom waves in the atmosphere. This equation is a key component of the augmented Burgers equation and determines the nature of the transformation of the disturbed pressure profile during its propagation. Two numerical schemes were used for solving: CABARET and WENO—quasi-monotonic end-to-end computing schemes, which make it possible to obtain a solution without significant numerical oscillations. The applicability of these schemes for solving the problem under consideration is analyzed. [ABSTRACT FROM AUTHOR]

Space-age technology makes it possible to travel faster than the speed of sound from one continent to another one or even to make suborbital flight as a space tourism. The existing technology challenge is to bring this innovative way of travel without damaging the environment to ensure human safety and to preserve environment balance. The sonic boom issue is one of the concerns when flying faster than sound. The issue must be taking into account at the stage of developing environmentally friendly high-speed vehicle. The next generation supersonic transport is fundamentally different from subsonic medium- and long-range aircraft in a breakthrough feature: it ensures a long-term supersonic cruise flight in the range of Mach numbers 1.6–1.8. For a successful implementation of the civil supersonic project at a new stage of technology development, it is necessary to solve a number of scientific and technical problems. In the present paper some of them are under discussion. In particular, the addressed issues are as follows: how to achieve a high level of aerodynamic efficiency at supersonic cruise along with low sonic boom; how to fit into low noise requirements at take-off and landing modes of supersonic aircraft with a moderate-bypass-ratio engine; how to implement a wing with high load factor and fuselage with long nose part to fit into required airframe structural stiffness, etc. Also, new technology approaches in multidisciplinary optimization task to achieve aircraft design goals of low drag, low boom and low noise characteristics are discussed. A few examples of optimal supersonic aircraft configurations along with passenger cabin are given. The paper was presented at the X-th IAA Symposium "Space Flight Safety" in St.-Petersburg on June 2023. • Preliminary aerodynamic design,. • Advanced supersonic transport,. • Sonic boom,. • Multifactor optimization,. • Aerodynamic configuration. [ABSTRACT FROM AUTHOR]

The request for faster and greener civil aviation is urging the worldwide scientific community and aerospace industry to develop a new generation of supersonic aircraft, which are expected to be environmentally sustainable, and to guarantee a high level of protection for citizens. The availability of novel propulsive technologies, together with the development of new civil supersonic passenger aircraft configurations and missions, is pushing international authorities to update the regulatory framework to limit nuisances on the ground and the contribution to climate change. Existing ICAO noise and emissions standards are outdated as they were developed in the 1970s and tailored to Concorde, the only SST that has ever operated in Western airspace. This article provides (i) a comprehensive review of current environmental regulations for SST, encompassing noise and pollutant emissions near airports (LTO cycle) as well as CO2 emissions and sonic booms, and (ii) updated information about the ongoing rulemaking activities by ICAO, FAA and EASA. This review clearly highlights the following findings: (i) the need to revise current rules to better fit future SST design, operations and technologies; (ii) the need to introduce new regulations to cover additional aspects, including stratospheric water vapour emissions and ozone depletion; and (iii) the need to support regulatory activities with solid technical bases, fostering cooperation with academia, research centres and industry in R&D projects. Eventually, a practical example of how SST rulemaking activities are supported by the collaborative research H2020 MORE&LESS is reported. [ABSTRACT FROM AUTHOR]

This paper introduces a low-boom aircraft optimization design method guided by equivalent area distribution, which effectively improves the intuitiveness and refinement of inverse design. A gradient optimization method based on discrete adjoint equations is proposed to achieve the fast solution of the gradient information of target equivalent area distribution relative to design variables and to drive the aerodynamic shape update to the optimal solution. An optimization experiment is carried out based on a self-developed supersonic civil aircraft configuration with engines. The results show that the equivalent area distribution adjoint equation can accurately solve the gradient information. After optimization, the sonic boom level of the aircraft was reduced by 13.2 PLdB, and the drag coefficient was reduced by 60.75 counts. Moreover, the equivalent area distribution adjoint optimization method has outstanding advantages, such as high sensitivity and fast convergence speed, and can take both the low sonic boom and the low drag force of the aircraft into account, providing a powerful tool for the comprehensive optimization design of supersonic civil aircraft by considering sonic boom and aerodynamic force.

In the present, work a modification of the multipole decomposition method is developed, which makes it possible to relate the overpressure distribution in the near-field of a supersonic transport (SST) with a far-field distribution, which is needed for the solution of sonic boom propagation problem from an SST. A generalization of the method for solving the integral equations arising from multipole decomposition is performed. An algorithm for multipole correction of near-field overpressure signatures obtained in numerical simulations has been developed and tested. [ABSTRACT FROM AUTHOR]

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 problem of noise reduction in supersonic aircraft design is one of the key problems, the solution of which largely determines the speed of development of supersonic aviation as a whole. The present study examines the noise generation during flights of supersonic civil aircraft. The effect of a thermally stratified energy source (TSS) used to control the supersonic flow past a pointed cylinder aerodynamic model on the near-field and ground pressure signatures, as well as on the perceived loudness in decibels (PLdB) on the ground, is evaluated. The complex conservative difference schemes, Tomas' waveform parameter method, and Stevens' algorithm Mark VII are used for near-field modeling, obtaining the ground pressure signature, and the evaluation of the PLdB on the ground, accordingly. The fields of flow parameters and the dynamics of a drag force are researched at the variation of temperatures in layers of TSS and for different numbers of layers. Simulations showed that changing the surface pressure due to drag reduction does not necessarily imply a change in the PLdB on the ground. In particular, it has been shown that when performing the flow control at freestream Mach numbers 1.5–2 using TSSs with the number of layers from 2.5 to 7.5 and rarefaction parameters in the layers from 0.15 to 0.3, some weakening of the bow shock wave in the near-field pressure signature due to the effect of TSS occurs, and no additional noise impact on the ground is introduced. [ABSTRACT FROM AUTHOR]

Supersonic biplanes can achieve low-boom and low-drag supersonic flights. In the present study, aerodynamic analysis of a two-dimensional stagger Bussmann biplane (staggered upper element by 0.5c) at zero degrees angle of attack with trailing edge flap was investigated with the help of computational fluid dynamics (CFD) tools. Due to the wave cancellation effect, the Busemann biplane delivers a positive drag reduction at design supersonic Mach values. However, when operating outside of its intended parameters, it performs worse, and the wave cancellation effect has no beneficial effects on reducing drag. Another issue with the Busemann biplane is flow chocking, which produces a potent bow shock wave in front of the aircraft. This paper attempts to address low aerodynamics efficiency problems during take-off through numerical simulation of a staggered Busemann biplane with trailing edge flaps at zero degrees angle of attack. It was confirmed that the staggered biplane airfoil with flap has better aerodynamic performance during take-off at lower subsonic free stream Mach numbers. In 2D wings, the effect of flow chocking and hysteresis as starting problems, which arise when the biplanes accelerate from low Mach numbers, is reduced by using the suitable dimension and angle of rotation of the flap, and the flap is effective in settling these issues.

This study aimed to quantify, in situations representative of the daily life of European citizens, the effects of sonic boom exposure on human responses, in the case of a new generation of supersonic commercial aircraft that should emit a reduced (compared to the past generation like Concorde) but perceivable boom while flying overland. Two reduced boom simulators were affixed to the bedrooms’ windows of a house located on our university campus. The simulators were used to study indoor the participants’ responses to realistic “outdoor” booms. Testing took place in both the living room and kitchen because the booms caused different intensities of rattle noise in those two rooms. Participants performed various tasks (communication, working memory, drawing, valence evaluation), took three mandatory rests and filled in various questionnaires about the annoyance caused by the booms and their mood. This paper focuses on the psychophysical and cognitive performance results. The booms resulted in delayed responses in the working memory task and in the valence evaluation task, and in a momentary slowing down in the drawing task. There was no significant effect in the communication task, even though a trend for a worsening of communication efficiency was observed. Taken together, the results suggest that reduced booms can interfere with cognitive and motor tasks by capturing attention, which can momentarily divert cognitive resources away from the task at hand. These results suggest future research directions and may lead to recommendations for future sonic boom regulations.

Full-field direct simulation of sonic boom has only been applied to the analysis of axisymmetric geometries. In this work, a more realistic analysis of complex geometries over buildings is achieved by employing a combination of the following four numerical approaches: (i) a hierarchical structured adaptive mesh refinement method, (ii) a ghost fluid method for incorporating the immersed boundary conditions on the solid–fluid interfaces, (iii) a well-balanced finite volume method to allow stable stratification of the atmosphere, and (iv) a segmentation method of the computational domain to increase the efficiency of the computations. The three-dimensional Euler equations with a gravitational source term are solved over a stratified atmosphere. The simulation is split into two stages. Firstly, the entire flow field that involves a delta wing body is solved without buildings. Thereafter, the flow behaviors near the ground are recomputed considering rectangular and L-type buildings. Computational results show that the near- and far-fields waveforms are comparable to those from the wind tunnel experiment and the waveform parameter method, respectively. The waveform shape behind the shock waves is spiked due to the diffracted waves around buildings, with the spiking effect in L-type buildings being stronger than that in rectangular buildings. The pressure rises for rectangular and L-type buildings are significantly amplified due to double and triple reflections, respectively, each with an amplification factor comparable to the theoretical value. These results indicate that full-field simulation is promising for analyzing three-dimensional characteristics of sonic boom emanating from complex geometries passing over buildings. [ABSTRACT FROM AUTHOR]

The request for faster and greener civil aviation is urging the worldwide scientific community and aerospace industry to develop a new generation of supersonic aircraft, which are expected to be environmentally sustainable, and to guarantee a high level of protection for citizens. The availability of novel propulsive technologies, together with the development of new civil supersonic passenger aircraft configurations and missions, is pushing international authorities to update the regulatory framework to limit nuisances on the ground and the contribution to climate change. Existing ICAO noise and emissions standards are outdated as they were developed in the 1970s and tailored to Concorde, the only SST that has ever operated in Western airspace. This article provides (i) a comprehensive review of current environmental regulations for SST, encompassing noise and pollutant emissions near airports (LTO cycle) as well as CO2 emissions and sonic booms, and (ii) updated information about the ongoing rulemaking activities by ICAO, FAA and EASA. This review clearly highlights the following findings: (i) the need to revise current rules to better fit future SST design, operations and technologies; (ii) the need to introduce new regulations to cover additional aspects, including stratospheric water vapour emissions and ozone depletion; and (iii) the need to support regulatory activities with solid technical bases, fostering cooperation with academia, research centres and industry in R&D projects. Eventually, a practical example of how SST rulemaking activities are supported by the collaborative research H2020 MORE&LESS is reported.

Abstract Sonic boom reduction has been an urgent need for the development of future supersonic transport, because of the heavy damage of noise pollution. This paper provides a novel concept for supersonic aircraft to reduce the sonic boom and drag coefficient, wherein a suction slot near the leading edge and an injection slot near the trailing edge on the airfoil suction surface are opened. To make sure of a zero net mass flux flow control, the mass flow sucked in near the leading edge is equal to the mass flow injected near the trailing edge. The diamond and NACA0008 airfoils are adopted as the baseline airfoil to verify the capability of the proposed design method. The effects of the suction and injection location, the suction and injection slot size, the mass flow rate and the attack angle on the ground boom signature and drag coefficient are studied in detail. The results show that the optimized airfoils with the suction and injection have benefits in both sonic boom reduction and wave drag reduction. And the reduction of the sonic boom intensity is more sensitive to the injection near the trailing edge than the suction near the leading edge. From the viewpoint of aerodynamics, opening the suction and injection slots will have no adverse effect on the aerodynamic performances of the supersonic aircraft and even increase the lift-drag ratio under some circumstances. For energy saving, the suction and injection slots can be selectively opened, which are opened when the supersonic aircraft flies over the city but are closed when the aircraft flies over the sea.

An origami sonic barrier composed of cylindrical inclusions attached onto an origami sheet is proposed. The idea allows for tunable sound blocking properties for application in attenuating complex traffic noise spectra. Folding of the underlying origami sheet transforms the periodicity of the inclusions between different Bravais lattices, viz. between a square and a hexagonal lattice, and such significant lattice re-configuration leads to drastic tuning of dispersion characteristics. The wave tuning capabilities are corroborated via performing theoretical and numerical investigations using a plane wave expansion method and an acoustic simulation package of COMSOL, while experiments are performed on a one-seventh scaled-down model of origami sonic barrier to demonstrate the lattice re-configuration between different Bravais lattices and the associated bandgap adaptability. Good sound blocking performance in the frequency range of traffic noise spectra combined with less efforts, required for actuating one-degree of freedom folding mechanism, makes the origami sonic barrier a potential candidate for mitigating complex traffic noise. [ABSTRACT FROM AUTHOR]

Sonic boom reduction has been an urgent need to develop the future supersonic transport, because of the heavy damages of the noise pollution. This paper provides an active control method for the supersonic aircraft to reduce the sonic boom, wherein a suction slot near the leading edge and an injection slot near the trailing edge on the airfoil suction surface are opened, and the mass flow sucked in near the leading edge is equal to the mass flow injected near the trailing edge. The diamond and 566 airfoils are adopted as the baseline airfoil to verify the capability of the active control method, and the effects of the suction and injection location, the mass flow rate and the attack angle on the ground boom signature, the maximum overpressure, the drag coefficients and the ratio of lift to drag are studied in detail. The results show that the proposed active control method can significantly reduce the sonic boom, and the reduction of the sonic boom intensity is more sensitive to the injection near the trailing edge than the suction near the leading edge. Applying this active control method to the diamond (NACA0008) airfoil, when the mass flow rate is 6.5 kg/s(7.5 kg/s), the value of maximum positive overpressure is decreased by 12.87%(12.85%), the value of maximum negative overpressure is decreased by 33.83%(56.77%) and the drag coefficient is decreased by 9.50%(10.96%). It can be seen that the method proposed in this paper has great benefits in the reduction of sonic boom and provides a useful reference for designing a new generation of lower sonic boom supersonic aircraft.

The sonic boom problem is a great barrier to the application of supersonic aircraft, and the accurate sonic boom prediction method is the key of the sonic boom problem.Waveform parameter method and augmented Burgers equation method are frequently used for the sonic boom prediction.Compared with the waveform parameter method, the augmented Burgers equation method has more complicated model and higher prediction accuracy.To solve the augmented Burgers equation, an effective nonlinear effect solving method is put forward.A far-field sonic boom signature prediction method based on operator splitting method is established, and verified with examples provided by Second Sonic Boom Prediction Workshop(SBPW-2).The influence of time, space grid density and buffer signal on prediction results are analyzed.The results show that it is unnecessary for the sonic boom solving method to get the required grid density while time and space grid is converged, but to select the suitable grid density according to practical accuracy demand.The buffer signature does not seem to be necessary for small aircraft such as corporate ones, but for bigger aircraft the buffer signature is essential.

To study the feasibility of supersonic commercial airliners, it is essential to better understand the impact of sonic boom caused by the aircraft. For simplicity, a general supersonic airliner concept by Sun et al. was used to conduct this analysis. Using an aircraft model created using Autodesk’s Fusion 360 CAD program, the effects of the aircraft volume and lift in the nearfield of the aircraft was determined using a custom MATLAB script developed in-house. The near-field overpressure was then propagated using NASA’s PC Boom program to determine the ground signature of the airliner. Furthermore, a sensitivity analysis for the geometric and lift properties was conducted. It was determined that an axial step size of 1.2 m (i.e., the spacing between cross-sectional areas obtained from the 3D model used for the numerical differentiation) yields the best results for creating the full ground signature propagated by PC Boom, and that using this step size also results in better computation times compared to smaller step sizes. It was also observed that smaller step sizes for analysis caused noisier/unfiltered data in the F-Function curve which did not change the accuracy of the overall ground signature propagated by PC Boom. Finally, it was determined that a sufficiently large step-size causes the signature propagated by PC Boom to form a different shape compared to step-sizes less than 1.2 m, which should not be considered. [ABSTRACT FROM AUTHOR]

Recent development of the various type of re-entry vehicles for tourism and, in near future, for frequent commercial flights to space as well as coming second generation supersonic transport (SST) rise important issue of flight safety of these vehicles, including sonic boom exposure on ground structures, people and environment. During the space plane descend the sonic boom carpet may cover thousands of kilometers wide territories on the earth or ocean and may cause some discomfort or even danger for people. Proper modelling of shock waves propagation in the non-homogeneous windy atmosphere is important task that should be solved based on the fast calculation methods to provide data to the flight deck in real time, while descending. In this paper the sonic boom modelling is based on augmented Burgers equation. A generalization of this equation is made for the case of a weakly inhomogeneous moving viscous heat-conducting medium with the conservation equations of the second order of approximation. The numerical method of sonic boom propagation and attenuation in real atmosphere and respective computer code "vBoom" have been developed and validated. The calculation data of sonic boom propagation and primary and secondary sonic boom exposure areas on the ground along with comparison with high speed aircraft data are presented. Measurement-based estimation for the loudness of sonic boom for re-entry vehicle at descending has been made. • Re-entry vehicle space safety. • Sonic boom modelling and carpets. • Augmented Burgers equation. [ABSTRACT FROM AUTHOR]

The paper considers practical aspects of mathematical modeling in predictions of the level of near-field pressure pulsations of a near-future prototype supersonic business aircraft. A numerical modeling technique based on the numerical solution of the Navier-Stokes equations is proposed. The method is verified by near-field simulations of the NASA C608 supersonic low-boom demonstrator. We consider a supersonic flight with M=1.4 at a flight altitude of 16,215 m. Good convergence of our predictions with experimental data and results of other researchers is shown. Near-field sonic-boom simulations of the prototype supersonic business aircraft are used to illustrate how the method can be applied in practice for building a second-generation supersonic passenger aircraft. Two aerodynamic configurations of the aircraft are considered: no-tail and canard no-tail. The canard no-tail configuration in the as-is aircraft dimension and design was found to have no advantages over the no-tail configuration in the level of its near-field pressure pulsations because of its nonoptimality. Further recommendations for solving the near-field sonic-boom minimization problem are related to the construction of a comprehensive mathematical model enabling coupled simulations due to smooth integration of a parametrized aircraft geometry, an aerodynamic solver, and an optimizer. [ABSTRACT FROM AUTHOR]

There has been a worldwide interest to develop a supersonic business jet (SSBJ) for a minimum range of 4000 nm with low sonic boom intensity and high fuel efficiency. An SSBJ design model is developed in the GENUS aircraft conceptual design environment. With the design model, a low-boom low-drag SSBJ concept is designed and optimized. This article studies the design concept for its operational performances. The sustained supersonic cruise flight is studied to find out the fuel-efficient Mach number and altitude combinations. The combined supersonic and subsonic cruise flight scenarios are studied to evaluate the feasibility of boom-free flight routes. The one-stop supersonic cruise flight scenario is studied to compare the fuel consumption and time advantage over subsonic airliners. The off-design sonic boom intensity is studied to explore the operational space assuming there would be a sonic boom intensity limit in the future. Through the studies, it is revealed that there is a corresponding most fuel-efficient operating altitude for a specific cruise Mach number. To operate the aircraft near the cutoff Mach number leads to both increases in the fuel consumption (6.3%–8.1%) and the mission time (11.7%–13.1%). The business-class supersonic transport (231 g/PAX/km) consumes nearly three times fuel as the economic-class supersonic transport (77 g/PAX/km), which is still far more than the economic-class subsonic transport (20 g/PAX/km). Off-design sonic boom intensity studies reveal different trends against the common understanding: the sonic boom intensity does not necessarily decrease as the altitude increases; the sonic boom intensity does not necessarily decrease as the Mach number decreases. [ABSTRACT FROM AUTHOR]

It is key points to improve the aerodynamic efficiency and decrease the sonic-boom intensity for the supersonic aircraft design. Sonic-boom prediction method with high precision combining the near-field sonic-boom prediction based on Reynolds-Averaged Navier-Stokes equations and the far-field sonic-boom prediction based on waveform parameter method is firstly established. Then the gradient of sonic boom with respect to the design variables is calculated by the finite difference method and is combined with the gradient of the aerodynamic object by the discrete adjoint technique, acting as the gradient of the weighed object function. Assembling two gradients, the optimization system couples Free Form Deform method、the dynamic mesh technique based on Inverse Distance Weighting interpolation method、the gradient-based optimization algorithm based on the sequential quadratic programming. Using the aerodynamic optimization system considering the sonic boom intensity, the paper conducts a nose angle deflection optimization design and an elaborate aerodynamic optimization including huge design variables and constraints on a supersonic business jet, while the optimization objects are the weighed object and the supersonic cruise drag coefficient. The results show that the nose is deflected downward and the shock wave pattern is changed, leading to a lower far-field maximum overpressure; the drag is decreased by 15.8 counts, and the wing load is moved inboard, also, the pressure drag of the outer wing reduces. Meanwhile, the pressure distribution in the outer wing has a weaker adverse pressure gradient and a more gentle pressure recovery. After optimization, the low-drag and low-sonic boom configuration is obtained, which verified the effectiveness of the optimization system.

The renewal of civil supersonic aviation is partly conditioned by the establishment of an international regulation on sonic boom level. Human perception of booms from future aircraft creating sound disturbances of lower level than past ones can currently be evaluated only through boom simulators in laboratory setups with predicted signatures from numerical simulations. To reach sufficient ecological validity, it is necessary that perception studies take place in an environment as familiar as possible to participants. With this in view, a simulator has been designed to reproduce sonic booms of low amplitude with the highest possible fidelity and control, while adapting to an existing house. The article presents the challenges and design solutions chosen to reach this objective. A double optimisation of the input signal, successively in the frequency and in the time domain, is described. Observed performances are presented for different boom exposures and in various rooms of the house.

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. Plain Language Summary: An unexplained explosive sound was heard around Sapporo city, Hokkaido, Japan at 20:00 JST on 26 April 2021. The sound and the resulting minor tremors were widely felt throughout the densely populated city. To determine the source of the explosive sound, we analyzed the data obtained by seismometers and found that the signals of the tremors had been recorded. The explosive sound represented a sonic boom, which is a loud sound generated by an object traveling faster than the speed of sound. Based on the arrival pattern of the signal, we estimated the location and moving direction associated with the source of this sound. The source was located about 100 km off the west coast of Hokkaido and the estimated velocity was higher than that of a fighter plane. Although no luminous phenomenon was observed, we believe the sonic boom was generated by a fireball. Key Points: We analyzed seismic data to identify the source of an explosive sound heard in Sapporo city, Hokkaido, Japan, on 26 April 2021A trajectory model was established, and the source was identified as an object producing a sonic boom that was most likely a fireballSeismic data can be used to estimate the trajectory of objects producing sonic booms, even those not visually observed [ABSTRACT FROM AUTHOR]

Sonic boom reduction has been an urgent need for the development of future supersonic transport, because of the heavy damage of noise pollution. This paper provides a novel concept for supersonic aircraft to reduce the sonic boom and drag coefficient, wherein a suction slot near the leading edge and an injection slot near the trailing edge on the airfoil suction surface are opened. To make sure of a zero net mass flux flow control, the mass flow sucked in near the leading edge is equal to the mass flow injected near the trailing edge. The diamond and NACA0008 airfoils are adopted as the baseline airfoil to verify the capability of the proposed design method. The effects of the suction and injection location, the suction and injection slot size, the mass flow rate and the attack angle on the ground boom signature and drag coefficient are studied in detail. The results show that the optimized airfoils with the suction and injection have benefits in both sonic boom reduction and wave drag reduction. And the reduction of the sonic boom intensity is more sensitive to the injection near the trailing edge than the suction near the leading edge. From the viewpoint of aerodynamics, opening the suction and injection slots will have no adverse effect on the aerodynamic performances of the supersonic aircraft and even increase the lift-drag ratio under some circumstances. For energy saving, the suction and injection slots can be selectively opened, which are opened when the supersonic aircraft flies over the city but are closed when the aircraft flies over the sea. [ABSTRACT FROM AUTHOR]

Reducing the sonic boom to a community-acceptable level is a fundamental challenge in the configuration design of the next-generation supersonic transport aircraft. This paper conducts a survey of recent progress in developing efficient low-boom design and optimization methods, and provides a perspective on the state-of-the-art and future directions. First, the low- and high-fidelity sonic boom prediction methods used in metric of low-boom design are briefly introduced. Second, efficient low-boom inverse design methods are reviewed, such as the classic Jones–Seebass–George–Darden (JSGD) method (and its variants), the high-fidelity near-field-overpressure-based method, and the mixed-fidelity method. Third, direct numerical optimization methods for low-boom designs, including the gradient-, surrogate-, and deep-learning-based optimization methods, are reviewed. Fourth, the applications of low-boom design and optimization methods to representative low-boom configurations are discussed, and the challenging demands for commercially viable supersonic transports are presented. In addition to providing a comprehensive summary of the existing research, the practicality and effectiveness of the developed methods are assessed. Finally, key challenges are identified, and further research directions such as full-carpet-low-boom-driven multidisciplinary design optimization considering mission requirements are recommended. [ABSTRACT FROM AUTHOR]

Abstract The article represents the discussion of several separate directions of investigations, which are performed by TsAGI flight vehicles aerodynamics specialists at the time. There are some major trends of classical layout of route aircraft and also peculiarities of some prospective flight vehicles. Also there are some hypersonic vehicles aerodynamics questions examined along with problems of creation of civil supersonic transport aircraft. There is a description given for well-known and some newer methods of flow control for drag reduction.

While automatized content identification of audio data, in critical discourse analysis, is bound to the symbolic order of monitoring, control, surveillance, censorship and copyright protection, the very tools and algorithms which have been developed for such purposes can be turned into instruments of knowledge production in the scientific sense. Audio content identification is not simply an extension of cultural taxonomies to machine listening, but an operation with its own eigen knowledge. Audio content identification is not simply a continuation of analog techniques for monitoring sonic objects. From a media-epistemological perspective, new forms of audio content identification open different orders of the sonic archive. What is practiced in the online domain has been preceded by experimental investigations of archival storage. The real l'archive, though, are the technological (hardware) and mathematical (software) criteria defining content identification. A media archaeology of audio content identification reveals the technological l'archive governing such forms of enunciation. [ABSTRACT FROM AUTHOR]