Article
Engineering, Aerospace
Yu Meng, Wenming Sun, Hongbin Gu, Fang Chen, Ruixu Zhou
Summary: This study investigates the combustion mode and instability characteristics of scramjets using the POD method. Experimental observations of flow and combustion behavior were made on a scramjet model with a cavity stabilizer. The results provide insights into the oscillation characteristics of three typical stabilized combustion modes.
Article
Engineering, Aerospace
Mehdi Mohamadi, AmirMahdi Tahsini
Summary: The purpose of this study is to investigate the combustion of n-Heptane droplets in a supersonic combustor with a cavity-based fuel injection configuration. The results show that using small droplet size achieves complete fuel consumption and combustion efficiency, while using large droplet sizes result in most fuel exiting the combustor in liquid phase. This study is the first of its kind and provides valuable insights for future economic flights.
AIRCRAFT ENGINEERING AND AEROSPACE TECHNOLOGY
(2023)
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
Jianbin Li, Jianhan Liang, Mingbo Sun, Zun Cai, Lin Zhang
Summary: This study experimentally investigates the effect of inlet distortion on the combustion process in a direct-connect test environment. The results show that blockage at the entrance of the isolator can accurately mimic the inlet distortion. Combustion enhancement is achieved in cases with blockage, with wider lean blowoff limits in the combustor. The stronger oblique shock wave and additional background shock wave caused by the inlet distortion are the main causes of combustion enhancement in these cases.
AEROSPACE SCIENCE AND TECHNOLOGY
(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
Metallurgy & Metallurgical Engineering
Zhe Zhang, Xing Jin, Wen-xiong Xi
Summary: The study analyzed the combustion characteristics under different injection conditions, revealing that an increase in total pressure of strut fuel injection leads to a decrease in combustion efficiency. However, increasing the total pressure of strut fuel injection within a proper range can expand the combustion area downstream. Increasing the total pressure of cavity fuel injection within the range of 0.5-2.0 MPa expands the combustion range and improves combustion efficiency, but excessive total injection pressure of cavity fuel can result in a sharp drop in efficiency. Increasing the total injection pressure of the plasma jet raises the height of the cavity shear layer and improves the equivalence ratio of the gas mixture in the cavity, with a maximum combustion efficiency of 82.1% achieved at a total pressure of 1.25 MPa. The combustion-assisted effect of different plasma jet media varies significantly, with O2 having the most significant effect on the combustor.
JOURNAL OF CENTRAL SOUTH UNIVERSITY
(2021)
Article
Engineering, Aerospace
Hongbo Wang, Xiliang Song, Liang Li, Yuhui Huang, Mingbo Sun
Summary: Experiments were conducted to investigate the near blowoff characteristics of cavity-stabilized flames in an ethylene-fueled scramjet combustor. It was found that there exists an optimal cavity size for ignition and flame stabilization near lean blowoff conditions, determined by the competition between flow residence time and local equivalence ratio.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
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
Yakang Kong, Yun Wu, Haohua Zong, Shanguang Guo
Summary: This paper presents an experimental study on supersonic cavity flow control using a spanwise pulsed spark discharge array (SP-PSDA), focusing on its control effect and underlying mechanism. Results show that the SP-PSDA induces thermal bulbs, causing wave-like oscillation in the shear layer. The study finds that SP-PSDA actuation at 5 kHz has a better control effect and enhances the whole hairpin structure's I Rms. Proper orthogonal decomposition reveals the coupling of thermal bulbs with the shear layer to form large-scale coherent structures that excite the Kelvin-Helmholtz instability.
Article
Mechanics
A. A. Dhankarghare, T. Jayachandran, T. M. Muruganandam
Summary: A study was conducted on flow dynamics in strut cavity and wall cavity at different freestream Mach numbers using numerical simulations. The results showed that oscillations occurred in both cavities for low supersonic Mach numbers and decreased for high values, with the strut cavity responding better to the change in Mach number. The study explored wave propagation and interactions inside the cavities, discussed secondary recirculation, revisited the process of wave generation, provided insights into vortex propagation along the cavity length, and described and compared mass exchange between the cavities and freestream.
Article
Chemistry, Physical
Ankit Singh, Sudipto Mukhopadhyay
Summary: In this study, the mixing of fuel and air in a scramjet combustor using strut-based injection is investigated. The effect of strut profile, angled injection, and blunting of the leading edge on mixing efficiency is studied. It is found that the wedge strut with single fuel injection achieves the highest mixing efficiency, reducing the mixing length by 100 mm compared to the diamond strut. Blunting of the leading edge decreases mixing efficiency but also reduces total pressure loss and entropy rise.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Engineering, Aerospace
Kai Yang, Ning Wang, Yu Pan, Zhen-Guo Wang, Chao-yang Liu, Xi-Peng Li
Summary: The experimental study investigates the ignition characteristics and flame stabilization of vaporized kerosene in a direct-connected model engine, showing that the ignition is closely related to the cavity location and configuration. Four ignition modes are classified and studied in relation to injection pressure and temperature variations. Difficulty of ignition and flame stability varies depending on different conditions.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Mechanics
Lin Zhang, Yitao Cao, Jianhan Liang, Yi Wang, Mingbo Sun
Summary: The mixing flow of a sonic transverse jet injection in a supersonic cavity combustor is numerically investigated at two typical inflow velocities. The simulation results show that at low Mach inflow, the separation shock gradually merges with the bow shock, smaller large-scale coherent structures and slower large-scale vortex transport are observed, and narrower range of jet species mass fraction distributions and more upstream large-scale vortices breakdown and dissipation can be observed. The low Mach inflow generates weaker pair of counter-rotating vortices and some trailing counter-rotating vortices, which primarily leads to the weaker jet/cavity interaction.
Article
Engineering, Aerospace
Dai Jian, Zuo Qiuru, Huang Chao
Summary: The study found that the grooved configuration significantly improves supersonic mixing in the scramjet combustor, enhancing fuel uniformity in the downstream region.
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
Engineering, Multidisciplinary
Yibin Wang, Siyang Liu, Ning Qin, Ning Zhao
Summary: The study indicates that random geometric errors introduced into wings during manufacturing and assembly will significantly impact the aerodynamic performance, necessitating the use of uncertainty quantification methods for analysis. The application of adjoint methods with single point Taylor expansion approximation and multi-point Taylor expansion approximation can accurately calculate the aerodynamic performance variation caused by tiny random geometric changes. This shows the noticeable effect of geometric increments on airfoil aerodynamic performance and provides useful error bar information.
JOURNAL OF THE CHINESE INSTITUTE OF ENGINEERS
(2021)
Article
Engineering, Aerospace
Feng Deng, Ning Qin
Summary: In this study, a new hybrid multi-objective EI method is proposed for expensive aerodynamic shape optimization problems, aiming to improve algorithm efficiency and robustness by enhancing the infill criterion. Experimental results show that the proposed method outperforms traditional algorithms and standard optimization algorithms in handling complex design spaces, demonstrating higher efficiency and robustness.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING
(2022)
Article
Engineering, Aerospace
Yonghong Li, Ning Qin
Summary: This study investigates the capability of normal microjet for gust load alleviation through numerical methods and experimental validations on 2D and 3D models. The results show that normal microjet has strong potential for load control, especially under transonic incoming flow conditions.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Aerospace
Feng Deng, Cheng Xue, Ning Qin
Summary: A novel shape parameterization method for airfoil design is proposed, which provides design variables related to aerodynamic characteristics based on linearized aerodynamic theory. The method offers more useful aerodynamic performance parameters.
Article
Mechanics
Feng Xie, Jose D. Perez-Munoz, Ning Qin, Pierre Ricco
Summary: A turbulent drag-reduction method utilizing synthetic jet sheets was investigated through direct numerical simulations. By adjusting the angle and height of the jet sheets, a drag reduction of 10% to 30% was achieved. The study also found that the global skin-friction drag reduction was a result of a finite counter flow induced by the interaction between the jet-sheet flow and the main flow.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Mechanical
Luka Vincekovic, Alistair John, Ning Qin, Shahrokh Shahpar
Summary: This work presents the aerodynamic topology optimization of high-pressure turbine rotor blade tips. Before carrying out the topology optimization on the blade tip, some initial tip design studies were conducted. A winglet tip was optimized first, resulting in a 1.40% increase in aerodynamic efficiency compared to the datum design. Then, a radial basis function-based parametrization was used to create a single squealer rim on the datum blade's tip that could move in the circumferential direction, resulting in a 0.46% increase in efficiency. Afterwards, a combination of winglet and topology free squealer tips was investigated via topology optimization, resulting in better designs compared to the flat tip winglet. However, gradient-based methods struggled to reach an optimum solution due to the flexibility of the design space, which was resolved by optimizing the most promising design subspace.
JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME
(2022)
Article
Engineering, Aerospace
Feng Deng, Haifeng Wang, Cheng Xue, Ning Qin
Summary: This paper presents a combined experimental and numerical investigation on the aerodynamic load reduction using steady blowing on the suction surface of a swept wing. The study reveals that upstream blowing causes a larger reduction in lift and bending moment compared to normal blowing. It is also found that the aerodynamic load reduction increases with the increase in jet momentum. The linear jet velocity distribution with the lowest blowing velocity at the outer end of the jet region achieves the maximum load reduction. Three key flow mechanisms related to load reduction are identified.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Review
Chemistry, Multidisciplinary
Yonghong Li, Ning Qin
Summary: The importance of gust load control and reducing aircraft weight is highlighted in this article. Both conventional and non-conventional techniques for gust load alleviation are reviewed, with a focus on the research progress and performance of fluidic actuators for flow control. The results show that fluidic actuators demonstrate fast response characteristics and are capable of adaptive gust load control.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Aerospace
Cheng Xue, Feng Deng, Haifeng Wang, Ning Qin
Summary: Microjets arranged on the wing surfaces of civil transport aircraft can effectively reduce aerodynamic load on a supercritical airfoil. By solving the Reynolds-averaged Navier-Stokes (RANS) equations, the study simulates subsonic and transonic flowfields around the airfoil with various angled microjets. The results demonstrate that shifting the blowing direction downstream to upstream increases lift reduction and power efficiency.
INTERNATIONAL JOURNAL OF AEROSPACE ENGINEERING
(2023)
Article
Engineering, Aerospace
Feng Deng, Shenghua Zhang, Ning Qin
Summary: In this paper, a closed-loop control using an active shock control bump (SCB) has been proposed to suppress the buffet on a supercritical airfoil flying at transonic speeds. The control law is designed based on the lift coefficient as the feedback signal and the bump height as the control variable. Numerical simulations show that the buffet can be effectively suppressed by optimizing the control law parameters, namely the gain and the delay time. The active SCB has advantages over the reference active trailing edge flap, including less sensitivity to control law parameters and a shorter response time.
Article
Engineering, Aerospace
Siqiang Deng, Yibin Wang, Ning Qin
Summary: This article presents a method for automatically generating feature-aligned anisotropic structured meshes, which is capable of providing high resolution for complex two-dimensional flow features. The method involves extracting dominant flow features and geometric entities, and generating high-quality meshes that are suitable for shock capturing and higher-order reconstruction.
Article
Thermodynamics
Cleopatra Cuciumita, Ning Qin, Shahrokh Shahpar
Summary: This study proposes a novel optimization process to maximize the aerodynamic efficiency of a modern fan blade while satisfying the structural constraint imposed by material limits. The method utilizes the discrete adjoint for evaluating the aerodynamic efficiency sensitivity and a response surface method for the structural stress constraint. A fast, meshless method is used for stress calculations to handle the large number of required sampling points in the response surface generation. The method is applied to the optimization of a practical fan blade, demonstrating an efficiency improvement of 0.6% while keeping the stress below a prescribed value of 500 MPa assuming a titanium alloy material. Without the stress constraint, the efficiency benefit is higher at 0.9%, but the maximum stress exceeds the material's acceptable criterion at almost 1000 MPa. The modular nature of the method allows for adaptation to various turbomachinery blade designs. Flutter analysis of the optimized fan blade has also been conducted due to its practical significance.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY
(2023)
Article
Engineering, Aerospace
Zhaolin Chen, Xiaohui Wei, Tianhang Xiao, Ning Qin
Summary: A 2-D airfoil shape optimization in the transonic low-Reynolds number regime is conducted. The results show that the unconventional airfoil has a significant drag reduction at high Mach numbers and the maximum lift-to-drag ratio is influenced by the Mach number. In contrast, the conventional airfoil experiences an increase in lift fluctuation with an increase in Mach number.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING
(2023)
Article
Engineering, Aerospace
Shenghua Zhang, Feng Deng, Ning Qin
Summary: This paper investigates the effects of buffet caused by the interaction between shock waves and boundary layers on aircraft during transonic flight conditions. It proposes the application of shock control bumps to enhance the robustness of the closed-loop buffet control system. The results indicate that coupling the shock control bumps greatly enhances the closed-loop flap control and improves the aircraft's aerodynamic performance.
Article
Engineering, Aerospace
Zhouwei Fan, Xiongqing Yu, Ning Qin, Maolin Zhu
Summary: The study shows that the low-sweep transonic natural laminar flow wing with shock control bumps has potential benefits in reducing fuel consumption, decreasing maximum takeoff weight, and lowering direct operating costs for commercial aircraft.
JOURNAL OF AIRCRAFT
(2021)
