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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
Experimental study on noise reduction of ducted fans based on bio-inspired groove arrays
Huang Jinghong;Mo Chongsen;Meng Han;Lu Zhenbo;To address the aerodynamic noise issue of the ducted fan, a core power component of lowaltitude aircraft, and improve its acoustic performance, a bio-inspired herringbone groove structure modeled after bird feathers is investigated and applied to the surface noise reduction design of airfoil and ducted fan. A low-speed anechoic wind tunnel is adopted for experimental verification, and the aeroacoustic responses of the bionic configuration under multiple operating conditions are systematically evaluated. Experimental results show that for the airfoil, discrete mid-frequency noise is modulated into broadband noise by the bionic groove array, and the overall sound pressure level(OASPL) is reduced by up to 24 dBA at high angles of attack. For the ducted fan, the tonal noise at the blade passing frequency and around 1000 Hz is effectively suppressed, and a maximum OASPL reduction of 4.5 dBA is achieved at high-speed and high angle-of-attack conditions. The noise reduction potential of the bionic groove structure on the ducted fan surface is verified, and new insights are provided for the design of low-noise propulsion systems.
An improved MPC-based flight control method for eVTOL tilt transition
Yang Biao;An improved MPC method is used to design the controller for stable flight control of eVTOL with distributed rotor tilt configuration. The eVTOL flight dynamics model of tilt configuration is established considering the tension variation characteristics during distributed rotor tilting. In order to realize the stable control of attitude, velocity, altitude and tilt angle during tilt flight, a tilt transition path tracking controller based on improved MPC method is proposed. Combined with the change of vehicle acceleration performance and tilt angular rate capability in different tilt stages, an adaptive cost function is designed to improve the stability and safety of tilt transition flight control. The simulation results show that the improved MPC method can effectively realize stable tilting flight control, and has better control accuracy and robustness than traditional PID control methods.
A research on 3-DOF trimming of tandem-wing tilt-duct eVTOL
Wu Di;Chen Jinghongju;Zhang Sidong;Li Weibo;Lu Zhenbo;To conduct dynamic modeling of a tandem-wing tilt-duct eVTOL, the trim point for steadylevel flight must first be determined. This study investigates the 3-DOF longitudinal trim process and its determining factors. Aerodynamic parameters are obtained through a combination of ducted-fan static thrust experiments and CFD simulations using the momentum source method. It is proposed that drag and pitching moment effects be considered when calculating the neutral point, and an analytical solution is derived using a binomial approach. Using the control variable method, the effects of freestream velocity, angle of attack, and front and rear duct thrusts on aerodynamic forces and moments are analyzed. Empirical fitting formulas are developed and presented in full expressions. Results show that the neutral point is sensitive to freestream velocity, highlighting the need for accurate determination in this configuration. The four factors' effects on the three aerodynamic forces generally exhibit second-order relationships.
Development of a sub-gram ultralight servo actuator for micro unmanned aerial vehicles
Lv Yafei;Li Fu;Wang Liang;As key actuators for achieving precise position control in small-scale mechanical and electronic systems, micro servos are widely applied in fields such as micro aerial vehicles(MAVs), precision optical pods, robotic joints, and portable communication terminals. To address the design challenges regarding torque density, dynamic response, and disturbance suppression in 0.5-gram class servos, an integrated scheme is proposed and implemented. This scheme is based on a coreless micro DC motor, a hybrid reduction mechanism combining a worm drive and a sectoral gear, an off-axis 3D Hall-effect sensor calibration system, and a 3.3 V single-voltage drive control circuit. Independent third-party testing results of the initial prototype show a rotation range of 149°, a torque density of 2.46 N·m/kg, a total mass of 0.617 g, a dynamic response time of approximately 76 ms, an overshoot of 4.6%, and a steady-state error of 0.8%. These results verify the feasibility and superiority of the design.
Control allocation strategy for tiltrotor UAV based on improved whale optimization algorithm
Chen Jinghongju;Mo Chongsen;Wu Di;Lu Zhenbo;Aiming at the strong nonlinearity and actuator saturation constraints encountered in the thrust vector control allocation of tiltrotor UAV, this paper proposes a control allocation strategy based on an improved whale optimization algorithm(IWOA). Firstly, a six-degree-of-freedom dynamic model of the tiltrotor UAV is established, and attitude and position controllers are designed. The whale optimization algorithm(WOA) is adopted to address the thrust vector control allocation problem. On this basis, three major improvements are implemented to the original WOA: Elite opposition-based learning is introduced to optimize the quality of the initial population; the convergence factor is adjusted to balance the global search and local exploitation capabilities of the algorithm; and the Lévy flight operator is integrated to strengthen the local exploitation performance. Finally, numerical simulation experiments are carried out to compare the proposed algorithm with allocation strategies based on conventional optimization algorithms. The results verify the feasibility and superiority of the presented algorithm for solving control allocation problems, which provides a reliable solution for high-performance maneuvering control of tiltrotor UAV.
Research progress on key technologies of autonomous landing for shipborne vertical take-off and landing unmanned aerial vehicles
Liu Zhongchen;Peng Yiming;Hu Xionglong;Zhang Ming;Chen Xinmin;Wei Xiaohui;Shipborne vertical take-off and landing unmanned aerial vehicles (VTOL UAVs) offer significant advantages， including runway independence， excellent low-altitude and low-speed performance， stable hovering capability， and high mission flexibility. However， the autonomous landing process on naval vessels is characterized by a high accident rate and substantial risks， representing a critical phase in the maritime application of shipborne VTOL UAVs. This paper briefly outlines the technical characteristics distinguishing shipborne VTOL UAVs from their land-based counterparts. It analyzes the technical challenges encountered during the three phases of autonomous landing: return approach， descent and touchdown， and aircraft-ship locking. The study focuses on reviewing key technologies such as autonomous landing guidance， landing platform stabilization， and rapid aircraft-ship securing. Future development trends are also projected. Key directions for advancement include multi-source data fusion-based landing guidance technology， multifunctional integrated landing platform technology， and intelligent adaptive take-off and landing system integration technology.
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