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Introduction of Aerospace Technology
Chinese Name:空天技术
English Name: Aerospace Technology
Publication cycle: Bimonthly
Language: Chinese
Director: China Aerospace Science and Industry Corporation Limited (CASIC)
Sponsor: Beijing HIWING Scientific and Technology Information Institute
Editor in chief: LIU Haifeng
Study on the interfacial properties between plasma-treated fiber surfaces and thermoplastic resin
Hu Yiyun;Liao Zhenhao;Yang Lei;To improve the interfacial adhesion between ultra-high molecular weight polyethylene fiber(UHMWPE), carbon fiber, and thermoplastic Elium resin, the fibers are subjected to surface treatment using atmospheric plasma. The interfacial bonding performance of the composite materials is characterized by transverse tensile strength testing. Various plasma treatment powers and durations are set to explore the effect of plasma treatment parameters on the interfacing performance between fibers and resin, and the interfacial failure mode is studied in conjunction with the transverse tensile fracture morphology of fibers/resin. Research shows that under the influence of plasma etching, the interfacial bonding strength between the carbon fiber and UHMWPE fiber and the resin is enhanced. When the treatment conditions are set at 200W for 3 minutes, the transverse tensile strength of the UHMWPE fiber/resin increased by 87%; When the treatment power conditions are 300W-5min and 300W-10min, the transverse tensile strength of the carbon fiber/resin increased by 14.7% and 30.2%, respectively. Further investigation of the tensile fracture surfaces reveals that before plasma treatment, there is a more pronounced fiber pull-out phenomenon on the fracture surface,reflecting a significant enhancement in the wettability of the fiber after plasma treatment. The study on the thermal stability of plasma-treated fibers indicates that plasma treatment alters the decomposition rate of fibers by decomposing surface materials and affecting their molecular structure, and the highly reactive ions also have a certain impact on the molecular structure of the fibers. Further research on the surface functional groups of the carbon fibers before and after modification found that the number of oxygen-containing functional groups increased after plasma treatment, improving the surface polarity of the fibers.
Study on drag reduction and heat prevention characteristics of opposing jet on the leading edge of high-speed air rudder
Feng Yuan;Guo Qingyang;Gang Dundian;Ma Rui;Li Shibin;During the flight of high-speed aircraft, its head, wing/rudder leading edge, etc. produces huge resistance and severe aerodynamic heating, which poses a great challenge to the design of high-speed aircraft.Theoretical analysis and numerical simulation are used to systematically study the flow field characteristics and aerodynamic/thermal characteristics of the leading edge of high-speed air rudder. By changing the jet angle, jet hole position and spacing, the drag reduction and heat prevention mechanism of the reverse jet at the rudder leading edge is studied. The results show that when the jet conditions are the same, the drag reduction effect of the reverse jet perpendicular to the wall spray is better. The closer the jet hole is to the root of the rudder, the smaller the resistance coefficient of the rudder leading edge, and the better the drag reduction and heat protection effect. Under the condition of 0 ° sweep angle, when using a porous jet, the drag coefficient decreases as the distance between jet holes decreases.
Optimization of fixed altitude cruise trajectory for powered aircraft based on convex optimization
Liu Xiaohang;Chu Xianying;Shui Zunshi;Yang Ting;To solve the altitude-constrained cruise trajectory optimization problem for powered vehicles, a sequential convex optimization approach is presented. The dynamic model of the powered vehicle is simplified under the constant-altitude constraint, and the mapping relationships between thrust, angle of attack, and bank angle are derived, resulting in an optimized vehicle motion model. To overcome the issue of non-convex control constraints, the angle of attack rate and bank angle rate are introduced as new control variables, and an expanded state model is constructed. A first-order Taylor expansion is then used to convexify the path constraints. Additionally, continuous linearization is applied to approximate the non-convex terms in the dynamics, transforming the original non-convex nonlinear optimization problem into a convex optimization problem. Simulation calculations are performed to verify the algorithm, and the optimization results under different scenarios are analyzed and compared. Numerical simulation results demonstrate that this method effectively solves the trajectory optimization problem for constant-altitude cruising of powered vehicles.Furthermore, under unpowered flight conditions, this method shows improved bypassing capabilities and superior computational performance compared to traditional unpowered convex optimization methods.
Research on optimal intelligent control method of boundary layer pumping in isolated section based on the combination of reinforcement learning and ADRC
Peng Jiahuan;Liang Shuang;Tian Ye;Yang Maotao;Aiming at the optimal control issue of boundary layer suction in the isolator of a ramjet facing a wide range of conditions, the research on multi-objective optimization and boundary layer suction control strategy is carried out. Using a self-developed high-speed internal and external flow coupling calculation program, 2D numerical simulations of the ramjet internal flow are conducted at Ma=2, 4, and 8. Kriging mathematical models linking suction back pressure to isolator performance indicators(suction mass flow rate,separation zone scale, and shock-train front position) are established. Multi-objective optimization via the particle swarm algorithm is carried out to achieve optimal shock-train front positioning and minimal suction flow while ensuring a ≥20% reduction in separation zone scale. Control effects of PID, ADRC, and TD3-ADRC are compared, with TD3-ADRC showing strong disturbance rejection and PID-matching speed.Comprehensive simulations confirm that after optimal suction control, the model-output separation zone scale,suction flow, and shock-train front position align with the optimal-parameter performance state, proving the feasibility and advancement of the proposed method.
Numerical investigation of shock wave drag reduction on a blunt body with plasma synthetic jet
Xu Zhengyang;Chen Yanjun;Hu Xijing;Luo Zhenbing;Zhou Yan;Unit 91362 of the PLA;In order to solve the high drag problem caused by the strong bow shock of the blunt head of the supersonic/hypersonic aircraft, the shock wave drag reduction based on reverse plasma synthetic jet(PSJ)actuator is studied. The effects of the outlet length, the discharge energy and the Mach number of the inflow on the drag reduction are investigated by numerical simulation. The results show that, under the action of PSJ, the bow shock at the head of the blunt body is pushed away, and the high-temperature and high-pressure regions will also be far away from the blunt head body, thus the shock wave intensity is weakened. The drag reduction ratio can reach more than 40%. When the dimensionless outlet length of PSJ actuator increases from 3 mm to 9 mm, the time for the drag reduction to reach 20% increases from 180 μs to 350 μs. The increase of discharge energy of PSJ actuator does not necessarily lead to the increase of drag reduction effect. In the case of same action time, PSJ only brings more than 5% drag reduction in the hypersonic flowfield, while it can bring more than 50% drag reduction in the supersonic flowfield. The results show that the effect of PSJ on the control of blunt body bow shock is weakened when the incoming flow crosses from supersonic to hypersonic.
Investigation on the ground proximity separation of a parallel arrangement vehicle based on CFD/RBD coupled method
Luo Xingdong;Hou Zihao;Yuan Ya;Bo Jinglong;Zhai Maochun;Li Shaowei;Zhang Shenrong;To meet the safety analysis requirements for ground proximity separation of parallel configuration vehicles during maglev electromagnetic boost launch， a multi-body separation prediction method based on CFD/RBD coupling is established， a constrained separation strategy with auxiliary separation mechanism is developed， and the flow field structure， aerodynamic load and constrained load characteristics during constrained separation and free separation are explored. The effect of attitude control engine working time on the separation characteristics is also studied. The results show that the ground proximity shock wave interference structure is basically unchanged in the constrained separation stage， and the ground reflected shock wave of the head of the vehicle directly interferes with the vehicle wings in the free separation stage. With the vehicle's head up， the supersonic ground effect gradually weakens， the aerodynamic lift gradually approaches the free stream state， and the vertical constraint load decreases continuously. With the release of constraints and the free separation stage， the head reflected shock wave enhances the lift force and the nose-down moment of the vehicle. When the dimensionless working time of the attitude control engine is 280， the vertical displacement of the vehicle gravity center will meet the safety distance condition at the dimensionless time 1466， when the pitch Angle is 6.1° and the constraint time is just right， safe separation can be better realized.
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