Article
Engineering, Aerospace
Yi Han, Chibing Shen, Zhaobo Du, Haoran Tang
Summary: This research investigates the impact of induced shock waves on fuel mixing in supersonic flow and finds that symmetric setting of shock wave generators achieves the highest mixing efficiency.
Article
Engineering, Aerospace
Wei Huang, Han Wu, Zhao-bo Du, Li Yan, Gautam Choubey
Summary: A novel mixing enhancement scheme combining oblique shock wave and step has been proposed to promote the mixing process between supersonic airflow and fuel. Experimental results show that this scheme can effectively prolong the residence time of hydrogen in the flow and enhance the mixing effect between fuel and air.
Article
Mechanics
Charles T. Haddad, Joseph Majdalani
Summary: This work investigates traveling and standing vorticoacoustic waves in circular tubes induced by axisymmetric headwall injection using perturbation tools, field decomposition, and boundary-layer theory. An explicit formulation for arbitrary headwall injection is obtained and validated numerically. The characteristics of the evolving vorticoacoustic wave and the velocity features of the vortical field are systematically explored using four canonical cases, revealing the significant amplitudes of the standing modes compared to traveling waves. A uniformly valid wave approximation is achieved by extending the boundary-layer analysis from the headwall to the sidewall.
Article
Engineering, Aerospace
Zhangming Zha, Zhengyin Ye, Zheng Hong, Kun Ye
Summary: The study introduces a new method for enhancing mixing efficiency in supersonic mixing layers using unsteady shock waves. Findings show that unsteady shocks have a significant impact on mixing efficiency, causing periodic flow field changes, vortex evolution, increased turbulence intensity, and overall improved mixing efficiency.
Article
Engineering, Aerospace
Guoyan Zhao, Jianhui Du, Hongxi Yang, Tao Tang, Mingbo Sun
Summary: An approach combining numerical, experimental, and theoretical analyses was used to study the effects of injection parameters on the flame flashback phenomenon. The simulations showed good agreement with experimental observations. Higher fuel equivalence ratios, sharper injection degrees, longer premixing distances, and multiple injectors promoted fuel-flow interactions, enhancing mixing efficiency and fuel penetration. Changes in thermally choked flow and temperature fluctuation thresholds were found to be important factors influencing flame flashback.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Aerospace
Tushar Sikroria, Richard Sandberg, Andrew Ooi, Shahram Karami, Julio Soria
Summary: Flow unsteadiness in supersonic impinging jets can cause practical issues such as ground erosion and high noise levels. Studying shear-layer instabilities requires time-resolved measurements of flow velocity fields, which can be challenging in high-speed flow applications. A novel approach using time-unresolved dual-time digital PIV coupled with dynamic mode decomposition analysis is being applied to investigate the dynamics of shear-layer instabilities in supersonic impinging jets.
Article
Engineering, Aerospace
S. Vaisakh, T. M. Muruganandam
Summary: An experimental study was conducted to understand the near flowfield of an over-expanded supersonic wall-jet. The study focused on capturing flow features using shadowgraphy, oil flow visualization, and infrared thermography, with a comparative analysis between the two methods. The research also looked at the ability of these methods to capture supersonic surface flow features and listed their merits and demerits.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Aerospace
Kalyani Bhide, Kiran Siddappaji, Shaaban Abdallah
Summary: This study numerically investigates the internal flow and exit flow of rectangular nozzles with low to high aspect ratios, and explores factors related to supersonic jet mixing. Results show that as the aspect ratio increases, shock waves weaken, boundary layer thickness increases, and significantly affect the characteristics of the exit flow.
Article
Engineering, Aerospace
Robin Sebastian, Anne-Marie Schreyer
Summary: Forced jet injection can effectively control flow separation by enhancing mixing and lateral spreading, leading to improved separation control. The injection induces periodic oscillations and large-scale rotation of the major vortex. High-frequency forced jet injection is more efficient in controlling flow separation, but periodic oscillations can cause faster dissipation and breakdown of the vortical structures.
Article
Mechanics
Chandrasekhar Medipati, S. Deivandren, R. N. Govardhan
Summary: Liquid jet injection into supersonic crossflow can result in unsteady flow and spray formations. This study experimentally investigates the self-induced fluctuations in flow and spray caused by liquid jet injection into supersonic crossflow. The results show significant variations in windward spray edge and penetration, which are influenced by fluctuations in mass flow rate and shocks.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2023)
Article
Mechanics
Tongbiao Guo, Jian Fang, Ji Zhang, Xinliang Li
Summary: In this study, the effect of secondary flow induced by riblets on supersonic turbulent boundary layers over a compression ramp is investigated. The results show that the secondary flow leads to an increase in the size and intensity of the rolling motion, contributing to the increase of mean momentum flux and turbulent fluctuations. The separation area is also reduced by the presence of riblets, and the frequency of low-frequency motion is higher in the presence of riblets compared to the baseline case.
Article
Engineering, Multidisciplinary
Gautam Choubey, Om Patel, Malhar Solanki, Antonella Ingenito, Yuvarajan Devarajan, Sumit Tripathi
Summary: In this study, the effect of different geometric parameters of a splitter plate-based scramjet combustor, including the cavity's aft wall angle, the bottom wall's divergence angle, and the splitter plate's angle of attack, on the mixing performance of the supersonic combustor was investigated. The results showed that geometric modifications significantly affect the performance of the combustor, with an increase in the cavity's aft wall angle improving combustion efficiency. Furthermore, the study found that an increase in the divergence angle of the bottom wall led to a decrease in combustion performance due to the expansion of the separation region on the top wall. Finally, it was observed that a negative angle of attack of the splitter plate (-1 degrees) resulted in a recirculation region and sufficient shear mixing layer, promoting adequate air-fuel mixing for combustion.
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2023)
Article
Mechanics
R. Sebastian, A-M Schreyer
Summary: This study investigates the influence of jet spacing on the control effectiveness of air-jet vortex generators in supersonic flow. Using large-eddy simulations and experimental visualizations, the study analyzes the effects of different jet spacings on flow structures, vortical structures, and boundary-layer statistics. The insights gained from this study are crucial for the development of efficient control setups.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Dongdong Zhang, Peng Cui, Jianguo Tan, Xiao Yao, Yao Liu, Jie Song
Summary: This paper proposes a novel strategy of plate jet actuation to enhance the mixing process in scramjet engines. The results show that Kelvin-Helmholtz (K-H) vortices induced by K-H instability coexist with T-shaped structures induced by jet actuation instability. The interaction between adjacent T-shaped structures improves the interfaces of upper and lower streams. The introduction of plate jet actuation leads to more intense fluctuations and a significant increase in mixing thickness.
Article
Chemistry, Physical
Zhao-bo Du, Chi-bing Shen, Wei Huang, Xiang-yu Zhong
Summary: This study numerically investigates the effect of the combined strategy of oblique shock wave and secondary recirculation jet on fuel-air mixing in supersonic crossflow. The results show that this strategy can effectively improve mixing speed and efficiency, and reduce the peak heat flux.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(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.