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21 pages, 8115 KiB

Open AccessArticle

Evaluation of Sonic Boom Shock Wave Generation with CFD Methods

by Samuele Graziani, Francesco Petrosino, Jacob Jäschke, Antimo Glorioso, Roberta Fusaro and Nicole Viola

Aerospace 2024, 11(6), 484; https://doi.org/10.3390/aerospace11060484 - 19 Jun 2024

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Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Sustainable Civil Supersonic and Hypersonic Aircraft: Main Challenges and Latest Developments)

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19 pages, 13878 KiB

Open AccessArticle

Numerical Investigation of Model Support, Closed Engine Nacelle and Scale Effect on a Wind Tunnel Test Model

by Ioan-Laurentiu Padureanu, Dumitru Pepelea, Gilbert Stoican, Marco Marini, Nicole Viola and Matthew Clay

Aerospace 2024, 11(6), 464; https://doi.org/10.3390/aerospace11060464 - 11 Jun 2024

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Abstract

In the frame of the H2020 MORE&LESS project co-funded by European Commission, a test campaign for a hypersonic vehicle demonstrator took place at the INCAS Trisonic Facility. CFD analysis was used to quantify the effects of the wind tunnel model support, the closed [...] Read more.

In the frame of the H2020 MORE&LESS project co-funded by European Commission, a test campaign for a hypersonic vehicle demonstrator took place at the INCAS Trisonic Facility. CFD analysis was used to quantify the effects of the wind tunnel model support, the closed engine nacelle, and to perform the Reynolds number extrapolation. Three sets of simulations were used in order to generate the corrections. The wind tunnel configuration with sting, sting cavity, and closed nacelle was used as the baseline, with the aim of matching the experimental results as precisely as possible. A configuration with a flow-through nacelle and the shock cone in the appropriate position for each Mach number and no sting or cavity was used to determine the effect of the sting and the closed nacelle. For the Reynolds extrapolation, a 1:1 model was used, with the boundary conditions deriving from the theoretical trajectory of the vehicle. The CFD results for the wind tunnel configuration closely align with the experimental data. Significant differences between the three configurations can be observed just for the pitching moment, and those are caused by the presence of the sting and the open nacelle. The difference in Reynolds number does not seem to have a significant effect on the aerodynamic coefficients. Full article

(This article belongs to the Special Issue Sustainable Civil Supersonic and Hypersonic Aircraft: Main Challenges and Latest Developments)

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31 pages, 17080 KiB

Open AccessArticle

Parametric Design Method and Lift/Drag Characteristics Analysis for a Wide-Range, Wing-Morphing Glide Vehicle

by Zikang Jin, Zonghan Yu, Fanshuo Meng, Wei Zhang, Jingzhi Cui, Xiaolong He, Yuedi Lei and Omer Musa

Aerospace 2024, 11(4), 257; https://doi.org/10.3390/aerospace11040257 - 25 Mar 2024

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Abstract

The parametric design method is widely utilized in the preliminary design stage for hypersonic vehicles; it ensures the fast iteration of configuration, generation, and optimization. This study proposes a novel parametric method for a wide-range, wing-morphing glide vehicle. The whole configuration, including a [...] Read more.

The parametric design method is widely utilized in the preliminary design stage for hypersonic vehicles; it ensures the fast iteration of configuration, generation, and optimization. This study proposes a novel parametric method for a wide-range, wing-morphing glide vehicle. The whole configuration, including a waverider fuselage, a rotating wing, a blunt leading edge, rudders, etc., can be easily described using 27 key parameters. In contrast to the typical parametric method, the new method takes internal payloads into consideration during the shape optimization process. That is, the vehicle configuration can be flexibly adjusted depending on the internal payloads; these payloads may be of random amounts and have different shapes. The code for the new parametric design method is developed using the secondary development tools of UG (UG 10.0) commercial software. The lift and drag characteristics over a wide operational range (H = 6–25 km, M = 2.5–8.5, AOA = 0–10°) were numerically investigated, as was the influence of the retracting angle of the morphing wings. It was found that, for the mode of the fully deployed wings, the lift-to-drag ratio (L/D) remained at a high level (≥4.7) over a Mach range of 4.0–8.5 and an AOA range of 4–7°. For the mode of the fully retracted wings, the drag coefficient remained smaller than 0.02 over a Mach range of 4.0–8.5 and an AOA range of 0–5°. A wide L/D of 0.3–4.7 could be achieved by controlling the retracting angle of the wings, thus demonstrating a good potential for flight maneuverability. The flexible change in L/D proved to be a combined result of varying pressure distribution and edge-flow spillage. This will aid in the further optimization of lift/drag characteristics. Full article

(This article belongs to the Special Issue Sustainable Civil Supersonic and Hypersonic Aircraft: Main Challenges and Latest Developments)

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37 pages, 14400 KiB

Open AccessArticle

Chemical Kinetic Analysis of High-Pressure Hydrogen Ignition and Combustion toward Green Aviation

by Guido Saccone and Marco Marini

Aerospace 2024, 11(2), 112; https://doi.org/10.3390/aerospace11020112 - 25 Jan 2024

Viewed by 1114

Abstract

In the framework of the “Multidisciplinary Optimization and Regulations for Low-boom and Environmentally Sustainable Supersonic aviation” project, pursued by a consortium of European government and academic institutions, coordinated by Politecnico di Torino under the European Commission Horizon 2020 financial support, the Italian Aerospace [...] Read more.

In the framework of the “Multidisciplinary Optimization and Regulations for Low-boom and Environmentally Sustainable Supersonic aviation” project, pursued by a consortium of European government and academic institutions, coordinated by Politecnico di Torino under the European Commission Horizon 2020 financial support, the Italian Aerospace Research Centre is computationally investigating the high-pressure hydrogen/air kinetic combustion in the operative conditions typically encountered in supersonic aeronautic ramjet engines. This task is being carried out starting from the zero-dimensional and one-dimensional chemical kinetic assessment of the complex and strongly pressure-sensitive ignition behavior and flame propagation characteristics of hydrogen combustion through the validation against experimental shock tube and laminar flame speed measurements. The 0D results indicate that the kinetic mechanism by Politecnico di Milano and the scheme formulated by Kéromnès et al. provide the best matching with the experimental ignition delay time measurements carried out in high-pressure shock tube strongly argon-diluted reaction conditions. Otherwise, the best behavior in terms of laminar flame propagation is achieved by the Mueller scheme, while the other investigated kinetic mechanisms fail to predict the flame speeds at elevated pressures. This confirms the non-linear and intensive pressure-sensitive behavior of hydrogen combustion especially in the critical high-pressure and low-temperature region which is hard to be described by a single all-encompassing chemical model. Full article

(This article belongs to the Special Issue Sustainable Civil Supersonic and Hypersonic Aircraft: Main Challenges and Latest Developments)

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0 pages, 6411 KiB

Open AccessArticle

Numerical Modeling of Chemical Kinetics, Spray Dynamics, and Turbulent Combustion towards Sustainable Aviation

by Arvid Åkerblom, Martin Passad, Alessandro Ercole, Niklas Zettervall, Elna J. K. Nilsson and Christer Fureby

Aerospace 2024, 11(1), 31; https://doi.org/10.3390/aerospace11010031 - 28 Dec 2023

Cited by 1 | Viewed by 1229

Abstract

With growing interest in sustainable civil supersonic and hypersonic aviation, there is a need to model the combustion of alternative, sustainable jet fuels. This work presents numerical simulations of several related phenomena, including laminar flames, ignition, and spray flames. Two conventional jet fuels, [...] Read more.

With growing interest in sustainable civil supersonic and hypersonic aviation, there is a need to model the combustion of alternative, sustainable jet fuels. This work presents numerical simulations of several related phenomena, including laminar flames, ignition, and spray flames. Two conventional jet fuels, Jet A and JP-5, and two alternative jet fuels, C1 and C5, are targeted. The laminar burning velocities of these fuels are predicted using skeletal and detailed reaction mechanisms. The ignition delay times are predicted in the context of dual-mode ramjet engines. Large Eddy Simulations (LES) of spray combustion in an aeroengine are carried out to investigate how the different thermodynamic and chemical properties of alternative fuels lead to different emergent behavior. A novel set of thermodynamic correlations are developed for the spray model. The laminar burning velocity predictions are normalized by heat of combustion to reveal a more distinct fuel trend, with C1 burning slowest and C5 fastest. The ignition results highlight the contributions of the Negative Temperature Coefficient (NTC) effect, equivalence ratio, and hydrogen enrichment in determining ignition time scales in dual-mode ramjet engines. The spray results reveal that the volatile alternative jet fuels have short penetration depths and that the flame of the most chemically divergent fuel (C1) stabilizes relatively close to the spray. Full article

(This article belongs to the Special Issue Sustainable Civil Supersonic and Hypersonic Aircraft: Main Challenges and Latest Developments)

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21 pages, 2186 KiB

Open AccessArticle

Analytical Formulations for Nitrogen Oxides Emissions Estimation of an Air Turbo-Rocket Engine Using Hydrogen

by Nicole Viola, Roberta Fusaro, Guido Saccone and Valeria Borio

Aerospace 2023, 10(11), 909; https://doi.org/10.3390/aerospace10110909 - 25 Oct 2023

Cited by 2 | Viewed by 1386

Abstract

According to the latest report of the Intergovernmental Panel on climate change, aviation contributes to only about 2% to anthropogenic global greenhouse gas (GHG) emissions. However, in view of the growing market demand and the dramatic reductions in other transport sectors, including maritime [...] Read more.

According to the latest report of the Intergovernmental Panel on climate change, aviation contributes to only about 2% to anthropogenic global greenhouse gas (GHG) emissions. However, in view of the growing market demand and the dramatic reductions in other transport sectors, including maritime and automotive, the aviation sector’s percentage impact on global GHG emissions is expected to reach 50% of the transport share by 2040. High-speed aviation exploiting liquid hydrogen as the propellant can represent a valuable solution toward the decarbonization of the sector. However, to avoid jeopardizing the dream of a new generation of high-speed aircraft, it will be necessary to introduce non-CO₂ emissions estimations beginning with the design process. To unlock the possibility of anticipating the nitrogen oxides emissions estimation, the authors developed the hydrogen and high-speed P₃-T₃ methodology (H2-P₃T₃), an evolution of the widely used P₃-T₃ method, properly conceived to support (i) innovative air-breathing propulsive systems for supersonic and hypersonic flights and (ii) greener fuels, such as hydrogen. This paper presents a step-by-step approach to developing novel analytical formulations customized for an Air Turbo-Rocket engine and discusses the discovered correlation of nitrogen oxides production with the fuel-to-air ratio (FAR), the Mach number, and the Damköhler number (Da), the last being a nondimensional variable directly related to hydrogen/air combustion, considering the matching between the residence time and the ignition delay times. The most complete formulation allows for reduction in the prediction errors below 5%. Full article

(This article belongs to the Special Issue Sustainable Civil Supersonic and Hypersonic Aircraft: Main Challenges and Latest Developments)

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24 pages, 9359 KiB

Open AccessArticle

Study on Ground Experimental Method of Stagnation Point Large Heat Flux of Typical Sharp Wedge Leading Edge Structure

by Ri Wang, Fengfei Lou, Bin Qi, Rong A, Yuanye Zhou and Sujun Dong

Aerospace 2023, 10(10), 871; https://doi.org/10.3390/aerospace10100871 - 6 Oct 2023

Viewed by 1228

Abstract

In this paper, aimed at the problem of large temperature gradient thermal testing with the typical sharp wedge leading edge structure of a hypersonic vehicle, a subsonic high-temperature combustion gas heating (SHCH) test device is used to conduct a series of experiments on [...] Read more.

In this paper, aimed at the problem of large temperature gradient thermal testing with the typical sharp wedge leading edge structure of a hypersonic vehicle, a subsonic high-temperature combustion gas heating (SHCH) test device is used to conduct a series of experiments on the heat flux simulation ability of subsonic high-temperature combustion gas in the stagnation point region. Firstly, for a hypersonic vehicle with a flying height of 24 km and Mach number range of 4~6.5, the stagnation point heat flux in the head area is obtained by numerical calculation of a typical leading edge structure, which is used as the experimental target of the thermal structure test. Secondly, an experimental specimen with a Gardon heat flux meter is designed with the same shape and size as the specimen in the numerical simulations to prepare for the subsequent SHCH test. Thirdly, a method to determine the combustion gas temperature based on a Kriging surrogate model is proposed. CFD numerical simulation is conducted using the SHCH test model, and the numerical calculation results are used as the training dataset. The Kriging surrogate model is used to establish an approximate fitting relationship between the stagnation point heat flux and experimental parameters under SHCH conditions. The corresponding combustion gas temperature values are found, respectively, with the hypersonic aerodynamic heat flux at Mach 5.0~5.4 as the target value. Finally, stagnation point heat flux testing of low-speed and high-temperature combustion gas is performed at different combustion gas temperatures. The experimental and target values obtained from hypersonic aerodynamic thermal simulations are compared and analyzed to verify the heating capacity of SHCH and the feasibility of hypersonic aerothermal simulation testing. Full article

(This article belongs to the Special Issue Sustainable Civil Supersonic and Hypersonic Aircraft: Main Challenges and Latest Developments)

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Review

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23 pages, 677 KiB

Open AccessReview

A Review of the Current Regulatory Framework for Supersonic Civil Aircraft: Noise and Emissions Regulations

by Thomas Rötger, Chris Eyers and Roberta Fusaro

Aerospace 2024, 11(1), 19; https://doi.org/10.3390/aerospace11010019 - 25 Dec 2023

Viewed by 1696

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Sustainable Civil Supersonic and Hypersonic Aircraft: Main Challenges and Latest Developments)

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