Article
Engineering, Aerospace
Chaoyang Liu, Ning Wang, Kai Yang, Dongpeng Jia, Yu Pan
Summary: This study focuses on the stabilization mechanism of a supersonic lifted jet flame in heated coflows, highlighting the competition between autoignition and the propagation of active kernels at the flame base. Using highly-resolved large eddy simulation, it is found that the characteristics of the lifted hydrogen jet combustion gradually vary along the axial direction, with the evolution of turbulent structures and flameholding mechanism being crucial.
Article
Thermodynamics
Majie Zhao, Zhi X. Chen, Huangwei Zhang, Nedunchezhian Swaminathan
Summary: Large Eddy Simulation with a Perfectly Stirred Reactor model (LES-PSR) is developed to simulate supersonic combustion with high-enthalpy flow conditions. The PSR model considers the viscous heating and compressibility effects on the thermo-chemical state, and is validated through a priori analysis. The model accurately captures shock wave structures, flame characteristics, interactions, and lift-off heights, showing good agreement with experimental data.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
Zhiwei Huang, Matthew J. Cleary, Zhuyin Ren, Huangwei Zhang
Summary: The study successfully simulated the multiple features of a supersonic lifted hydrogen jet flame using the MMC-LES approach, accurately predicting flame structure and characteristics. The importance of pressure work and viscous heating in autoignition induction and flame stabilization was highlighted in this research.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Pavel Panek, Davy Brouzet, Mohsen Talei, Robert L. Gordon
Summary: This paper evaluates flame surface density modeling in the context of large-eddy simulation (LES) using a direct numerical simulation (DNS) dataset. The results suggest that significant improvement is needed for flame surface density modeling, particularly for (rho Sd)s.
COMBUSTION AND FLAME
(2022)
Article
Engineering, Aerospace
Xin Li, Yu Pan, Chaoyang Liu, Xiao Liu
Summary: To avoid the thermal choking problem in scramjet, a wall-expansion scheme is usually adopted, but it poses challenges to flame holding. This paper uses large eddy simulation to study the effect of expansion angle change on the flameout limit in the strut-based supersonic combustor. The numerical results show the establishment of the recirculation zone and the role of reflected shock waves in enhancing combustion.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Engineering, Aerospace
Chong Yan, Yibing Xu, Ruizhe Cao, Ying Piao
Summary: The present study investigated the application of the Very Large Eddy Simulation (VLES) method for supersonic reacting flows. The advantages and characteristics of the VLES model and the Improved Delayed Detached Eddy Simulation (IDDES) method were revealed through a supersonic ramped-cavity cold flow. The accuracy of the VLES method was significantly improved by introducing a hybrid truncation length scale and a resolution control function, allowing it to better predict velocity profiles and wall pressure distribution in a coarser mesh. The modified VLES method, in conjunction with a hybrid combustion model, showed improved consistency with experimental results in simulations of a supersonic flame.
Article
Engineering, Aerospace
Mengcheng Yuan, Ping Wang, Yang Zhang, Ye Tian, Shuang Chen, Subhajit Roy, Kang Cheng
Summary: This study investigates the dual-mode scramjet combustion with different equivalence ratios by quantitatively analyzing flame dynamics. The computational results match well with experimental data and successfully reproduce two typical flame structures, namely cavity shear-layer flame and cavity assisted jet-wake stabilized flame. The focus of the research lies in the continuous flame flashback during mode transition, which involves jet/shear-layer interaction, unsteady heat release, and the establishment of a large-area separation zone. The unsteady jet-wake ram combustion presents three oscillation modes, leading to intermittent flameout of varying levels, mainly caused by coherent-structures motion caused by the combined effects of low-speed separated flow and the fuel-jet.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Thermodynamics
Stephen D. Hammack, Timothy M. Ombrello
Summary: This study experimentally investigated the ignition processes in a scramjet flame holder and found that the location of energy deposition plays a crucial role in successful ignition, affecting flame propagation rates and fuel concentration variations.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Mechanics
S. K. Karthick
Summary: The study numerically investigates the impact of impinging shock waves of varying strengths on the free shear layer in a confined supersonic cavity flow. As the strength of the shock waves increases, the pressure on the cavity wall also increases, exhibiting resonant behavior.
Article
Thermodynamics
Sergio Croquer, Olivier Lamberts, Sebastien Poncet, Stephane Moreau, Yann Bartosiewicz
Summary: This study investigates the flow topology in the mixing chamber of a supersonic ejector using Large Eddy Simulation (LES). The results show that the mixing layer transitions from laminar to turbulent and vortices are identified in the first quarter of the mixing chamber. The study also reveals the occurrence of shock train towards the end of the mixing chamber, enhancing mixing.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
David M. Peterson
Summary: Simulations were conducted for a round supersonic combustor using a wall-modeled large eddy simulation approach to model turbulence. Combustion was modeled using a small quasi-global mechanism and a more detailed skeletal mechanism. Sensitivity to grid resolution was investigated and a function for the model constant in the partially-stirred reactor model was found. Different combinations of mechanisms and turbulent combustion models can predict the location of the pre-combustion shock train and peak mean pressure, but there are significant differences in temperature and heat release rate fields.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Engineering, Aerospace
A. A. Dhankarghare, T. Jayachandran, T. M. Muruganandam
Summary: This study combines a strut and a cavity into a strut cavity and compares it with a wall cavity using numerical simulations at different Mach numbers and aspect ratios. The results show that the wall cavity is more prone to oscillations compared to the strut cavity. The generation process of waves inside the cavity is revisited, where both the unstable shear layer and vortex shedding contribute to the wave generation in supersonic flows.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Energy & Fuels
Shijie Xu, Shenghui Zhong, Ahmad Hadadpour, Yan Zhang, Kar Mun Pang, Mehdi Jangi, Hesameddin Fatehi, Xue-Song Bai
Summary: The study used large-eddy simulations coupled with a partially-stirred reactor model and finite-rate chemistry to investigate the impact of n-heptane injection timing on methanol-fueled DF combustion. The results showed that delaying the injection timing of n-heptane led to an increased mass fraction of hydrogen peroxide in the ambient mixture, resulting in early formation of hydroxyl. This caused a decrease in the two-stage ignition delay times of n-heptane and an increase in the ambient methanol ignition delay time.
Article
Thermodynamics
C. Mehl, M. Cailler, R. Mercier, V. Moureau, B. Fiorina
Summary: State-of-the-art LES models have made significant progress in predicting heat release and flame propagation, but predicting pollutants remains a challenge. The COPLES strategy improves the prediction accuracy of CO formation by accounting for the influence of sub-grid scale wrinkling on pollutants formation.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Engineering, Aerospace
Lixing Zhou, Kun Luo
Summary: This paper applies large-eddy simulation (LES) to study swirling spray flames and validates the reliability of the simulation results. The spiral structures formed by swirl intensify combustion.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Aerospace
A. I. Krikunova, A. D. Cheshko, V. V. Krivets
Summary: Fire safety is crucial for the development of efficient and safe energy systems for space objects. This paper focuses on studying the influence of gravity on combustion processes and analyzes the dynamics of inverted conical methane-air flame under external acoustic excitation. The results show that at high excitation frequencies, the intensity of vortex generation is similar to that observed in experiments with normal gravity, indicating the dominance of acoustic mechanism. Additionally, at an external excitation frequency of 240 Hz, significant growth in shear vortex diameters and increased amplitude of perpendicular oscillations of flame branches were observed, indicating the most intensive large scale instability of flow.
Article
Engineering, Aerospace
Liya Huang, Mingquan Gong, Jiarui Zhang, Kun Liang, He Yang
Summary: Metallized gel propellants with exceptional stability and remarkable shear-thinning properties were successfully synthesized by utilizing cooperative hydrogen bonding between polymer octanoyl cellulose and the small Thixatrol ST molecule.
Article
Engineering, Aerospace
Clemence Poirier, Michelle Hermes, Marco Aliberti
Summary: This paper examines the role of space-based data in European climate policies and assesses the barriers to the use of space technology in climate policymaking in European countries. The research findings indicate that while satellite data is crucial for scientific research and climate policies, the role of space is not accurately reflected in European climate policies.
Article
Engineering, Aerospace
Yan-mei Zhou, Ji-ping Wu, Wei Huang, Gautam Choubey
Summary: This study investigates the combustion performance of sinusoidal pulsed jets in supersonic flows using numerical simulations. It is found that the pulsed jets can significantly improve combustion efficiency.
Article
Engineering, Aerospace
Wang Zhao, Shujun Tan, Yiliang Guo
Summary: This study proposes an adaptive Pogo active suppression controller design method that utilizes measured acceleration as feedback. The eigenspace transformation theory is employed to design dimensional reduced models for observer and adaptive controller, effectively addressing the issues of model parameter uncertainty and time-varying parameters. Simulation analysis of a certain type of rocket demonstrates the effectiveness of the proposed method.
Article
Engineering, Aerospace
A. V. Nebylov, V. A. Nebylov
Summary: This article discusses the safety issues of astronauts during the landing process and investigates how rescuers can effectively carry out rescue missions. The article also takes into account the special maritime conditions of the Vostochny cosmodrome.
Article
Engineering, Aerospace
Pietro Davide Maddio, Rosario Sinatra, Alberto Meschini, Riccardo Rigato, Marco Lapi, Davide Scarozza, Alessandro Cammarata
Summary: This study aims to develop a versatile cable net generation algorithm for designing offset cable nets in parabolic reflectors. The study proposes a methodology that leverages quasi-geodesic curves and introduces two types of these curves. The study also presents various solutions for different cable net layouts and introduces a quality index based on an equilateral triangle cable net.
Article
Engineering, Aerospace
Nahum Melamed, Tom Heinsheimer
Summary: Traditional methods of asteroid trajectory modification rely on impact or nuclear detonation, while centrifugal propulsion offers an alternative approach. The centrifuge system lands on the asteroid and gradually adjusts the trajectory using momentum transfer. This method allows for flexibility in operation parameters and has the potential to be used in planetary defense and other space missions.
Article
Engineering, Aerospace
Andrew Barth, Ou Ma
Summary: As humans continue to explore the surfaces of the Moon and Mars, the use of distributed heterogeneous robot teams can increase the chances of success by utilizing the complementary capabilities and synergy of the team members. Effective cooperation and collaboration between the members of a robot team is crucial, but defining a metric for effective cooperation is challenging. This paper presents a method for determining reward criteria that can be used for training robot swarm through reinforcement learning techniques. The trained robot team exhibits high success rates and cooperative behavior in test environments, demonstrating the robustness and scalability of the training strategies.
Article
Engineering, Aerospace
Kaijie Zhu, Qiquan Quan, Dewei Tang, Yachao Dong, Kaiyi Wang, Bo Tang, Qi Wu, Zongquan Deng
Summary: This study proposes a deployable Mars quadcopter for air patrol and sampling missions. By describing its structure, avionics architecture, and autonomous flight control method, it provides a feasible framework for future Mars flight sampling missions.
Article
Engineering, Aerospace
Avishai Melamed, Adi Rao, Sarah Kreps, Erika Palmer
Article
Engineering, Aerospace
Colin Hunter, Avinkrishnan Vijayachandran, Anthony M. Waas
Summary: Deployable structures inspired by origami have gained significant prominence in space applications. Recent advancements in multi-material additive manufacturing have opened new possibilities for the fabrication of monolithic structures. This paper presents a novel framework for designing deployable structures using viscoelastic hinges incorporated into rigid plates. Experimental results demonstrate the effectiveness and feasibility of these hinge designs in real-world applications.
Article
Engineering, Aerospace
Aleksander V. Efremov, Mikhail S. Tiaglik, Aleksey S. Tiaglik, Iliyas Kh Irgaleev, Tatyana V. Voronka
Summary: Theoretical and experimental studies were conducted to determine the best kind of information presented on a predictive display for the highest accuracy in space mission execution, while considering reduced propellant consumption.
Article
Engineering, Aerospace
Fuwen Liang, Long Miao, Feng Tian, Jiahui Song, Ningfei Wang, Xiao Hou
Summary: This study investigates the influence of deployment friction on the dynamic characteristics of nonconductive space tether through experimental measurement and numerical simulation. The results show that deployment friction significantly limits the uncontrolled tether deployment, while increasing the initial deployment velocity and satellite effective mass, as well as decreasing orbital altitude, can enhance the deployment capability and dynamic stability. In addition, an optimal matching relationship between tether length and satellite total mass is proposed, which is of substantial importance for the design of nonconductive space tether systems.
Article
Engineering, Aerospace
Amirah R. Algethami, Colin R. McInnes, Matteo Ceriotti
Summary: This paper utilizes the Hill's approximation model to manipulate the relative motion of two asteroids by three impulses, resulting in their bound binary motion in Earth's orbit. The feasibility of this strategy is demonstrated, and potential applications for parking small captured near-Earth asteroids in Earth's orbit are discussed.
