bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical simulation of deformation hysteresis effect of the bristles of brush seals
Authors: Li Pengfei , Hu Yaping , Ji Honghu
Published: May 2024

Because of their good sealing performance, brush seals are used widely in turbomachinery as alternatives to traditional labyrinth seals. However, obstructed by friction, the flexible bristles cannot recover fully after deformation, resulting in a hysteresis effect and decreased sealing performance. In the present study, a three-dimensional multi-row bristle model is established that considers the friction between the neighbouring bristles and back plate. Then the deformation and recovery of the bristles during the radial reciprocating offset of the rotor in the presence of a pressure difference are studied. To evaluate the hysteresis effect, analysis is directed at the unrecovered bristle deformation in the radial direction affected by bristle diameter, bristle lay angle, fence height and width of pressure relief chamber. The results show that the larger the bristle diameter and fence height, the weaker the hysteresis effect and the larger the bristle lay angle, the stronger the hysteresis effect. With increasing width of the pressure relief chamber, the hysteresis effect weakens and then strengthens, meaning that the pressure relief chamber has an optimal axial width that departure from enhances the hysteresis effect. The present results offer a reference for selecting the structural parameters of brush seals in engineering design.
Numerical study on dynamic flow of flexible extension nozzle in rocket motors
Authors: Duanyang He , Zhijun Wei , Xudong Zhang , Dalin Li , Dongsheng Zhao , Chujiu Huang , Haixu Yu
Published: May 2024

The use of extension nozzles in rocket propulsion systems is one of the effective methods to increase the geometric expansion ratio and thrust of the nozzle. As a new type of extension nozzle, the flexible extension nozzle can achieve continuous changes in nozzle expansion ratio. To explore the characteristics of the flow field structure at the “bulge” structure and the step structure in the actual configuration of the flexible extension nozzle, and the impact on the performance of the nozzle, a three-dimensional numerical simulation model of the flexible extension nozzle was first established to study the flow field at the “bulge” structure, and then a two-dimensional unsteady numerical simulation model was established by using the coupling technology of dynamic grid and overlapping grid to study the flow field at the step structure. The results show that during the unfolding of the nozzle surface, a complex flow structure of “expansion fan-mixing layer-shock-vortex” were formed in the step area at the junction of the fixed section and the moving extension section. The specific impulse loss of the 3D model is larger than that of the 2D model due to the consideration of the “bulge” structure. The flow loss of the “bulge” structure and the step structure to the nozzle is 0.73% and 0.65% respectively.
Dynamic modeling of shaping-changing cross parachute
Authors: Wang Chunhui , Zhou Hongmiao , Yu Jianqiao
Published: May 2024

The research explored the dynamic simulation of a cross parachute as an actuator, and proposed a method for dynamic modeling to adjust the configuration of the cross parachute. Initially, based on the method of multi-body dynamics modeling, a coordinate system necessary for system simulation was established. Subsequently, by incorporating the changing configuration parameters as input, a dynamic simulation model of the cross parachute with adjustable configuration was developed. Dynamic simulations were executed for the suggested model under two scenarios: changing configuration and symmetric configuration. The simulation results indicated that the parachute with changing configuration could generate radial forces related to the inflow velocity, with the force significantly increasing as the inflow velocity increased. The modeling approach offers a new perspective for the study of the dynamics of using a cross parachute as a control actuator, while the simulation results provide a degree of reference for research into the control force offered by a variable configuration cross parachute.
Research on dynamic prediction method of temperature environment of unmanned aerial vehicle platform based on physical information and neural network
Authors: Li H , Zhang J J , Fu Y , Xu J , Hao Y J
Published: May 2024

During the flight of an unmanned aerial vehicle, the temperature environment inside the cabin is very harsh, resulting in frequent malfunctions of airborne equipment. Therefore, it is necessary to predict the temperature environment experienced by airborne equipment during its life cycle in the early stages of design to support the formulation of design requirements, determine test verification conditions, used and maintained. In order to accurately predict the temperature environment of the unmanned aerial vehicle platform, this paper proposes a prediction method that integrates physical information and neural networks. In view of the thermal environment characteristics of unmanned aerial vehicle platform, the physical mechanism of the formation and transfer of the unmanned aerial vehicle thermal environment was analyzed. Based on the physical mechanism equations and combined with the measured data of unmanned aerial vehicles, an Elman neural network model was established to achieve high flight speed, speed, etc. parameters are characterized as a function of the temperature inside the unmanned aerial vehicle cabin, and finally the model is verified. The results show that the temperature environment prediction model integrates physical information and neural networks can accurately predict the dynamic changes in the temperature inside the unmanned aircraft cabin. The maximum error of the model is 2.76°C, which meets engineering needs.
Dijkstra algorithm based minimum acceleration/snap quadrotor UAV trajectory planning
Authors: Cai Zizhuo , Selezneva M S , Yang Mo
Published: May 2024

This paper focuses on path planning using the Dijkstra/A* algorithm and addresses the trajectory generation problem using the minimum acceleration/snap approach. Firstly, the mathematical model of the optimization problem is formulated, specifically utilizing the Euler-Lagrange equation to derive the necessary conditions for achieving minimum acceleration/snap trajectories, which are represented by either 3rd or 7th order polynomials. The coefficients of these polynomials are determined by imposing appropriate constraints on velocity, acceleration, and higher-order derivatives. Subsequently, a detailed comparison of the performances of the two optimization methods in complex environments is conducted, evaluating differences in position and velocity. Based on the deterministic analysis, conclusive results are obtained.
Design and research of an electric unmanned aerial vehicle power system
Authors: Zhao Anmin , Wang Tiancheng , Liu Deshan
Published: May 2024

An Electric power test system of UAVs is presented, which can be applied to validate the efficiency of UAV propulsion systems and provide reliable verification for propeller numerical calculations. The design proposal, working principle, test equipment and test experiment is introducted. Reliability of various functions of the system is examined and assessed through the multiple comparisond tests, which indicates that, when subjected to identical conditions, the numerical solutions for propeller thrust, torque, and motor efficiency exhibit average errors of 1.02%, 10%, and 10.04%, respectively. The results indicate that the power system test platform effectively validates numerical calculation results, providing reliable engineering application value for general UAV propulsion system research. The findings of this study offer support for optimizing power systems of the UAV, providing valuable references for future engineering applications and development.
An overview of icing scaling parameters for supercooled large drop icing conditions in icing wind tunnels
Authors: Sun Mingming , Jie Yuwen , Wang Liping , Zhou Feng
Published: May 2024

Aircraft icing is a serious threat to flight safety, especially the abnormal ice accumulation on the wing surface under the icing conditions of supercooled large droplets (SLD). Icing wind tunnel test is one of the main means of conducting research on aircraft icing, and the icing scaling law is the theoretical basis for selecting the similarity of characteristic parameters. In order to deeply understand the problems related to icing similarity in icing wind tunnel test under SLD icing conditions, the test capabilities on SLD icing conditions for the existing ice wind tunnel and the common similar parameter scaling methods were reviewed. The icing similarity transformation of SLD icing test was emphasized and the advantages, disadvantages, and applicability of each icing scaling law were analyzed. It can provide some references for the SLD icing wind tunnel test for large civil aircraft.
Sensitivity analysis of attack helicopter combat indicators based on machine learning
Authors: Sun L , L q l  , Gao F
Published: May 2024

This paper focuses on sensitivity analysis in the design of Attack helicopter combat indicators, and combines the advantages of machine learning to propose a combat effectiveness oriented sensitivity analysis method for Attack helicopter combat indicators. Firstly, the steps of sensitivity analysis of Attack helicopter combat indicators based on machine learning are introduced. Secondly, through operational scenarios, constructing indicator systems, collecting relevant data, evaluating effectiveness, and using machine learning algorithms for modelling and training, the sensitivity assessment of the damage probability of Attack helicopter to ground armoured weapons can be achieved. This paper is able to provide reference for the sensitivity analysis of weapon equipment system effectiveness, and provide more scientific and reasonable support for the research and application of helicopters in combat systems.
Research on icing scaling technology for large civil aircraft icing wind tunnel test
Authors: Liu Jia , Chen Yingchun , Zhou Feng , Zhao Binbin
Published: May 2024

This article explores the icing scaling technology for large civil aircraft icing wind tunnel tests. Based on the typical critical icing conditions of large civil aircraft and the calibration of icing wind tunnel, and through the similarity analysis of water droplet trajectories, water collection, and energy balance, four similar parameters, namely modified inertia parameter, drop energy transfer parameter, stagnation freezing coefficient, and accumulation parameter, were selected as similarity criteria for icing scaling. Based on this criteria, icing scaling was conducted on the critical icing conditions of large civil aircraft, and the scaling results were evaluated by icing code. The results show that the water droplet collection and the ice shape before and after the scaling are in good agreement, and the similarity criteria used are appropriate. Finally, icing wind tunnel test was conducted in 3m × 2m test section using scaled icing conditions. The test results show that the main characteristics of the experimental ice shape are in good agreement with the calculated ice shape, and the calculated ice shape is more critical. The calculated ice shape can be used as a critical ice for aerodynamic wind tunnel tests and flight tests with simulated ice.
Research on ice shedding experiment for large civil aircraft to exit ice protection mode
Authors: Sun Mingming , Jie Yuwen , Zhao Binbin , Zhou Feng
Published: May 2024

While aircraft flying, once the icing detector finds the icing environment, the stall protection system will turn on the icing stall protection mode. After aircraft leaves the icing environment, due to the lack of effective means to determine whether there is still ice on the unprotected surface of the aircraft, it is impossible to exit the icing stall protection mode, which can lead to issues such as high approach speed of the aircraft, affecting landing safety and passenger comfort. To solve this problem, this paper conducts experimental research on ice shedding time under different temperature conditions, simulating the phenomenon of ice shedding during aircraft fight. This work helps formulate the logic of aircraft exiting icing protection mode, and lays a basis for future work of aircraft performance optimization.
Miniaturization design of laser detection device for naval gun composite fuse
Authors: YongqinHuang  , Yang Panxiong , Chen Zuntian
Published: May 2024

Naval gun weapons are the only weapon system on board that can undertake various combat tasks such as shore fire support, sea attack, air defense and missile defense, and rapid response to emergencies. A new type of naval gun laser-radio composite fuse(naval gun composite fuse) is proposed to address the issue of naval gun fuses being susceptible to interference and failure in a single radio proximity system. This improves the multiple operational effectiveness of naval guns and the adaptability of naval gun ammunition to electromagnetic and other interference environments. In response to the limitation of small size of naval gun fuses, the overall structure and miniaturized laser detection device were designed separately. Firstly, a miniaturized 4-channel narrow pulse high repetition frequency laser detection method with uniform forward circumferential distribution is adopted to achieve compatibility with the original naval gun fuse structure, the simulation results indicate that the structural deformation and strength meet the requirements. Secondly, by designing a laser emission collimating lens that is glued together with a small spherical lens and a small concave cylindrical mirror, the outer envelope size is only Φ5x3mm. The simulation results show that at a distance of 20mm from the laser emission window, the spot diameter is 0.66mm and the divergence angle is 1.9 °, achieving good laser collimation and miniaturization of the emission optical system. Finally, the receiving optical system reduces its volume by adding a receiving objective and a field mirror. The effective aperture of the receiving objective is 10mm, the diameter of the field mirror is 5mm, the focal length is 11.1mm, and the receiving field angle is 5 °. The simulation results show that the laser spot radius on the photosensitive surface of the photodetector is 0.06mm, which meets the requirements of photodetectors.
Effects of different deployment strategies on the dynamic characteristics of bidirectional solar array
Authors: Shen Yingyong , Wang Cong , Tan Shiyu , Zhang Ning , Gao Jingbo
Published: May 2024

Based on natural coordinate method, a multi-rigid-body dynamic model of a bidirectional solar array is established. A typical solar array composed of a spacecraft main-body, a yoke, three main solar panels and two side solar panels is utilized as a demonstration case. Three deployment strategies have been designed for bidirectional solar array. Different deployment strategies are evaluated by analysing the attitude and kinetic energy of the spacecraft main-body, angular velocities of deployable components and constraint forces. The simulation results reveal that the strategy of the side panels to be deployed synchronously after the main panels are locked allows the solar arrays to reach a steady state more quickly after entering orbit. The analysis results in this paper can be utilized to aid in the engineering design of solar array deployment.
High-performance subpixel edge location based on FPGA for horizon sensors
Authors: Deng Huajian , Wang Hao , Jin Zhonghe
Published: May 2024

Horizon edge localization accuracy and speed are key factors in the performance of horizon sensors. This paper proposes a high-performance sub-pixel edge localization algorithm base on Field Programmable Gate Array (FPGA) for horizon sensors. The algorithm is carefully designed and simplified according to the computational capabilities and limitations of FPGAs. By making full use of the parallel computing capability of FPGA and carrying out multi-stage pipeline design, the algorithm can complete image acquisition, rough edge localization, sub-pixel edge localization, and projections from pixel points to unit vectors at the same time, which greatly reduces the delay caused by image processing. The experimental results show that FPGA-based image processing shows a significant superiority in terms of speed compared to traditional embedded processors.
A Parameters optimization framework for pose estimation algorithm based on point cloud
Authors: Niu Qun , Wang Ziru , Li Hongkun , Zhao Jieliang
Published: May 2024

Pose estimation using point cloud data is pivotal in robotics. Despite the myriad of algorithms developed for this task, their efficiency is often contingent on optimal parameter settings. Parameters adjustment is a process that traditionally relies on extensive experience and deep understanding of the underlying algorithm. This manual, experience-driven process can hamper the adaptability and performance of pose estimation algorithms. Addressing this limitation, this paper proposes a novel framework for parameter optimization tailored to pose estimation algorithms. The framework introduces an objective function based on pose error, designed to enhance both the algorithm’s number of results and the accuracy. The methodology requires the object model and several scene point clouds with real poses of the objects.By synergistically integrating this objective function with various sampling and pruning algorithms to optimize the pose estimate algorithm, obtaining a set of superior parameters to replace default values becomes a straightforward process. Experimental assessments were conducted on the pose estimation algorithm implemented in Halcon, considering two types of objects within the Industrial 3D Object Detection Dataset (ITODD). The experimental results shown that the number and accuracy of matching results for optimized parameters are better than those proposed by algorithm developers. This not only underscores the framework’s potential as an alternative to conventional manual parameter tuning but also its utility as a foundational configuration for further refinements. Ultimately, the methodology augments the foundational efficiency and versatility of pose estimation algorithms, paving the way for more adept robotic interactions with a myriad of objects.
Scheduling observation tasks for large-scale satellite constellation
Authors: Wen Zhijiang , Liu Yan , Zhang Shengyu , Hu Haiying
Published: May 2024

With the increasing demand for observations and the development of satellite technology, the scale of the Earth Observation Satellites (EOS) constellation is growing. To make the constellation more efficient during operation, scheduling imaging tasks of large-scale constellations is imperative. To solve the scheduling problem, we designed an allocation strategy for the daily operation and a Deep reinforcement learning (DRL) method for in-orbit emergencies. The results show that both of the method is effective.
High frequency attitude determination of micro satellites based on FPGA
Authors: Yin Chengjin , Meng Tao
Published: May 2024

The accuracy and speed of satellite attitude calculation algorithms are one of the key factors affecting the performance of satellite attitude control. This article proposes a high-performance attitude calculation algorithm for micro satellites based on Field Programmable Gate Array (FPGA). This algorithm is designed and simplified based on the parallel characteristics and abundant computing resources of FPGA. The algorithm fully utilizes the parallel computing power of FPGA and designs a multi-stage pipeline for complex matrix operations in Kalman filtering. It can simultaneously complete data collection and final attitude determination result output, greatly improving the output frequency of attitude information and reducing output delay. The experimental results show that compared to traditional embedded processors, FPGA based attitude calculation has significant advantages in terms of speed.
Equivalent modeling of LSTS and frequency calculation based on dynamic stiffness method
Authors: Li Hongming , Ma Wenlai , Zhao Yang
Published: May 2024

Large space truss structures (LSTS) are quickly becoming a vital type of space structure due to the fast expansion of the outer space field. The equivalent modeling approach has recently attracted the attention of researchers and engineers due to the finite element method’s limitations. In order to solve the equivalent beam model (EBM) in terms of frequency, the Wittrick-Williams algorithm based on dynamic stiffness matrix and the equivalent modeling procedure of large space truss structure are introduced in this study. The frequencies obtained by the equivalent model are good agreement with that obtaied by the finite element model, demonstrating the efficiency of the frequency solution method and equivalent modeling.
Process identification of laser powder bed fusion anomalies based on process-monitored melt pool radiation intensity data
Authors: Yao Chenguang , Zhang Ting , An Zhibin , Dang Mengxiang
Published: May 2024

Laser powder bed fusion (LPBF)) has great application prospects in aerospace and other fields, but low process stability and difficult quality assurance in the process of Laser Powder Bed Fusion are the key problems that restrict its extensive development at present. One of the important ways to solve this problem is to realize online monitoring of molten pool and closed-loop quality control. In this paper, the photodiode sensor is used to collect the radiation signal of the molten pool in real time, and the characteristics of the radiation intensity signal of the molten pool in time domain and frequency domain are extracted. The most appropriate modeling features are selected by comparing and analyzing different features, and XGBoost classical integration algorithm is used to model, and the relationship between the radiation intensity signal of the molten pool and process parameters is established, which provides a new method for abnormal process identification and quality control.
Mechanical property analysis and experimental validation of composite honeycomb sandwich radome considering perforation and impact damage
Authors: Chen X Y , Feng Y W , Song Z C , Zhou C P
Published: May 2024

To carry out the experimental verification of the mechanical properties analysis of the radome considering the damage factors, the test matrix design is carried out according to the finite element analysis method of the equivalent elastic theory and the idea of building block test verification. Firstly, the necessity and basic principle of equivalent elasticity theory in the performance analysis of complex curvature products considering damage factors are explained. Then, combined with the theory, a modular test matrix design is carried out, which should be able to test the correctness of the equivalent elastic modulus. Finally, a case study is carried out, and the difference between the test results and the simulation results is analyzed with the damaged radome as the research object. The results show that the development of the equivalent elasticity theory and the design of the test matrix can make the analysis results meet the engineering requirements.
Global adaptive event-triggered output feedback control for p-normal feedforward nonlinear systems with uncertain output function
Authors: Liu Ce , Zhai Junyong , Li Zeyu
Published: May 2024

This paper concentrates on the global adaptive event-triggered output feedback controller design for a class of p-normal feedforward nonlinear systems with uncertain output function. Due to the existence of unknown growth rate and uncertain output function, the considered uncertain nonlinear systems contain more uncertainties. To overcome this difficulty, a dynamic gain technique is introduced and an elaborate adaptive law of the gain is designed. Then, a completely time-varying event-based strategy is presented, which can effectively eliminate the effects caused by event-triggered errors. Since the presented event-triggered controller is not differentiable, a new analysis manner is developed to prove that the system is Zeno-free. Meanwhile, the closed-loop system(CLS) states are asymptotically convergent with the proposed strategy. Finally, a simulation example is given to illustrate the effectiveness of the proposed control scheme.
Adaptive adjustable performance function based direct prescribed performance control for spacecraft flying around mission
Authors: Wang Kun , Meng Tao , Lei Jiakun
Published: May 2024

The control for spacecraft flying around mission is investigated in this paper based on the prescribed performance control (PPC). Considering the challenges in the traditional PPC framework, we design an adaptive adjustable performance function, which can self-adjust the performance requirement according to the saturation of the control input. Besides, a combined switching controller is designed and the controller behaves as a PPC in the convergence stage, and gradually switches to a nonlinear controller after entering a steady state, which can avoid the over-control problem caused by high-gain PPC after entering the steady state. Finally, the numerical simulations illustrate the effectiveness of the proposed control method.
Artificial potential field-based method for multi-spacecraft loose formation control
Authors: Guan Yue , Zhang Xiang , Chen Danhe , Fan Shuhui
Published: May 2024

This study presents a control strategy based on artificial potential fields to maintain loose formation flying of satellites without a fixed formation, ensuring collision avoidance and stability under various conditions. The approach employs artificial potential fields for obstacle evasion and maintaining relative distances between satellites. Comprehensive simulations validate this method, with Monte Carlo techniques confirming control stability despite variations in initial conditions. The strategy effectively manages the integration of external satellites, maintaining optimal formation even as operational demands increase.
PID controller tuning based on PSO and dominant pole placement
Authors: Kim Yong Su , Hong Kwang Hyok , Yu Hun , Pak Se Yang
Published: May 2024

This paper proposed a new approach for proportional integral derivative (PID) controller tuning. particle swarm optimization (PSO) algorithm and dominant pole placement were used for PID controller tuning. Minimizing the estimation criterion with integral of absolute error (IAE) and overshoot by PSO algorithm, we determined the dominant pole and crossover frequency satisfying the maximum sensitivity and phase margin. This dominant pole and crossover frequency were used in order to design the PID controller. It satisfied robust stability and improves the control effect of the system to balance the trade-off between overshoot and settling time. We simulated this approach for SOPDT model. A simulation results were given to demonstrate the effectiveness of this approach.
Asymptotic consensus tracking control of robotic manipulators with disturbance and dead-zone via adaptive sliding mode control
Authors: Li Zeyu , Zhai Junyong , Liu Ce
Published: May 2024

This article aims at solving the difficulties of robotic manipulator systems with unknown disturbance and dead-zone in consensus trajectory tracking. For the purpose of accelerating the tracking process of leader and follower manipulators, a novel sliding mode control strategy is proposed. For compensating the influence of unknown lumped disturbance and control dead-zone, a novel adaptive law is designed for the construction of controller. With the help of adaptive sliding mode controller, based on the Lyapunov stability theory, the over-estimation is alleviated and the tracking errors converge to zero asymptotically. The simulations demonstrate the validity of the proposed strategy for consensus asymptotic trajectory tracking.
Numerical study on altitude-compensating mechanism of a permeable nozzle
Authors: Xue Yuqin , Bu Yuzhe , Wang Shuai , Guan Ben , Wang Ge
Published: May 2024

A conceptual adaptive altitude compensation nozzle with a permeable wall (permeable nozzle for short) is proposed in the present study. The typical operating states of the nozzle are demonstrated using numerical methods and the underlying mechanism of its altitude compensation is interpreted. The numerical results show that, at low nozzle pressure ratios, the external atmosphere enters the nozzle through its permeable wall section, which inhibits the backflow at the nozzle wall, weakens the strength of the separated oblique shock, thus improves the low-altitude thrust performance of the nozzle. However, at high nozzle pressure ratios, the exhaust gas leaves the nozzle through its permeable wall, which weakens the expansion of the exhaust gas and reduces the thrust performance. The permeable nozzle is considered to possess altitude compensation ability when the enhancement in its low-altitude thrust performance surpasses the deterioration in high-altitude thrust performance. The thrust composition analysis of the permeable nozzle reveals that its altitude compensation ability derives from the internal pressure rise due to the atmospheric air penetration into the nozzle at low nozzle pressure ratios.
A Spacecraft design for mars water survey
Authors: Zhang Yiwen , Huang Hulin , Chen Tiantian , Chen Yulong
Published: May 2024

To probe the possibility of water sources on Mars and research the surface environment of Mars, a Martian spacecraft was designed in detail in this study. Camera PIXL was selected as the payload. The service platform includes an orbit control system, communication system, thermal control system, main computer, energy system, and structure system, which was designed to support the operation of the spacecraft to complete required space missions. The consequence of this research furnishes some guidance for the design of the Martian spacecraft, which discovers water sources on Mars.
Simulation and experiment of the aerodynamic performance of a vane compressor damaged by a bird strike
Authors: Sun Hao , Wang Zhiqiang
Published: May 2024

Based on the purpose of studying the impact of bird strike on compressor aerodynamic performance, this paper takes a single-stage low-speed axial flow compressor as an object to establish a blade model damaged by bird strike, and on this basis, it carries out a three-dimensional full-loop numerical simulation and experiments on the compressor model with damaged blades. Through comparison with the experimental data of undamaged compressors, the results show that after the rotor blades are damaged, the rotor blades are damaged. The aerodynamic performance and stability of the compressor have significantly decreased, which accords with our understanding. The reliability of the numerical simulation method is verified by analyzing the detailed flow field structure of typical working conditions and comparing the experimental data of the compressor, which lays a foundation for the relevant calculation of damaged blades in the future.
The design of a novel two-dimensional deployable mechanism for large-aperture planar antennas
Authors: Liu Xianyi , Zhang Jiarui , Zhang Shuai , Li Wei
Published: May 2024

Large-aperture planar antennas are essential in applications like satellite communication and Earth observation. In order to accommodate them within the constrained storage space of rockets during launch, the development of high-folding-ratio mechanisms becomes imperative. However, most of the existing planar antennas rely on one-dimensional deployable mechanisms, limiting their width and impeding the development of planar antennas with larger apertures. The lack of two-dimensional deployable planar antennas is primarily due to their stringent requirements, including the need for flat reflecting surfaces, regular panel shapes to accommodate electronic devices on the panels’ rear sides and minimal inter-panel gaps. In this paper, we introduce a novel two-dimensional deployable mechanism for the development of large-aperture planar antennas, capable of simultaneously meeting these requirements. Firstly, the architecture of the proposed mechanism and its two-step deployment procedure are described; next, the kinematics on the displacement level are conducted; moreover, a case study is presented to demonstrate its folding performance and frequency response. These studies indicate that the antenna thus obtained can achieve efficient two-dimensional folding while offering a reasonable frequency response, which can be a practical solution for the development of large-aperture planar antennas.
Optimal design of water immersion sensor layout for helicopter emergency flotation system based on the nsgaII algorithm
Authors: Wang Bingqian , Wang Zhe , Sun Zhi , Hou Bin
Published: May 2024

Aiming at the problem of sensor layout in an emergency flotation system, a sensor layout scheme design method based on the NSGAII method is proposed. The ALE method is used to simulate the water landing process of the helicopter on different pitch angles. The logic relationship of the 4/5 voting system is used to improve the sensor module reliability. Further, a mathematical model of layout scheme is established to maximize the detection coverage and minimize the force acting on the water immersion sensors when helicopter emergent water landing as the objective functions. Based on the mathematical model of water immersion sensor layout optimization constructed in this paper, NSGAII is used to solve this problem. The results show that the proposed method can realize the optimization of the layout of the water immersion sensor, the detection coverage of optimized schemes is increased by 3.26% on average compared with the value under the original scheme, and the force acting on the water immersion sensors is reduced by 61.86%.
Parameter identification of disk-gap-band parachute during steady descent
Authors: Jiang Tian , Ge Sicheng
Published: May 2024

In light of the challenges associated with acquiring the display model for identifying parachute aerodynamic parameters, this study aims to establish a correlation model for the aerodynamic parameters of a specific type of disk-gap-band parachute during the steady drop stage of transonic and subsonic speeds. This will be achieved by employing the genetic algorithm and utilizing observed data from airdrop experiments. The findings indicate that the genetic algorithm can accurately calculate the aerodynamic parameters in dynamic simulation with a high level of precision. Additionally, the numerical distribution state of the parameters to be identified exhibits similarity in the multiple disk-gap-band parachute airdrop experiments, thereby confirming the accuracy of the model and methodology. Finally, the numerical ranges for the drag coefficient and the stable equilibrium angle of attack of this particular type of disk-gap-band parachute are provided. The results are compared with both the airdrop experiments and the wind tunnel experiment. The errors in question satisfy the criteria of engineering precision, and the verification process confirms the accuracy of the identification outcomes.
Effects of fuselage shape on helicopter aerodynamic performance in case of intermeshing-rotor interference
Authors: Ma Cunwei , Li Jingyang , Yu Hao , Baoyin Hexi
Published: May 2024

To study the influence of fuselage shape on the aerodynamic performance of a helicopter under the interference of an intermeshing-rotor, a numerical simulation method of flow field under the forward flight state of Synchropter is established based on the lattice Boltzmann method. Firstly, the Maryland helicopter was calculated to verify the scientific validity of the method. Then, the simplified S-97 fuselage was used as the object of analysis to analyze the aerodynamic data such as surface pressure, friction, and lift resistance of the fuselage with different head curvature, cross-section shapes, and transition segments under Synchropter interference with different attack angles in forward flight. The results show that increasing the radius of curvature of the nose can reduce the total drag of the fuselage; the fuselage with a circular cross-section shape has better aerodynamic characteristics of lift resistance, and the fuselage with rhombic cross-section shape has better transverse stability; the transition section with backward position, smaller upward dihedral angle, and smooth transition can avoid serious airflow separation and achieve the purpose of drag reduction.
Strength performance simulation and testing of pontoon component cabin
Authors: Yang Li , Sun Libing , Zhu Yuanchun , Feng Zhijie , Zhang Dongxiao
Published: May 2024

The helicopter emergency flotation system consists of a buoy installation mechanism, a high-pressure gas bottle, and an electronic control starting device. The buoy assembly cabin is an important part of the buoy installation mechanism. During the flotation test, openings and cracks appeared in the pontoon assembly cabin due to insufficient strength. To avoid the occurrence of openings and cracks, methods such as rounding corners at the locations of openings and cracks, carbon fiber cross-laying technology, and changing cross-sections at stress concentration locations are adopted. The improved method was applied to the buoy cabin of the emergency flotation system, and the damage coefficient in the front and back states was simulated. The simulation results showed that the damage coefficient was reduced by 59%. After the improved cabin was subjected to the emergency flotation system flotation test, the openings and cracks in the pontoon assembly cabin disappeared, indicating that the improvement method was effective and could improve the strength and performance of the cabin.
Parameters design for feel system of aircraft active inceptor controller
Authors: Wei Hongwei , Liu Xiaoyu , Cui Haiwei , Xu Shuting , Tan Wenqian
Published: May 2024

To provide the pilot with feedback on flight states, aircraft active inceptor controllers deliver appropriate tactile feedback through the feel system. Current research on the feel system often relies on conventional models, with limited analysis of its unique characteristics. Investigating the dynamic properties of the feel system and their impact on flying quality can inform the parameters design of the feel system. In this paper, we designed various feel system parameters with different natural frequencies and damping ratios and selected three typical aircraft dynamic models. A human-vehicle closed-loop system model is established, including the pilot model, feel system model, and aircraft dynamic model. Combining different flying quality criteria, including bandwidth criterion, Neal-Smith criterion, and Open-Loop Onset-Point (OLOP) criterion, the flying qualities of Type I and Type II pilot-induced oscillations (PIO) are evaluated separately. The influence of aircraft configuration, feel system natural frequency and damping ratio on flying quality is explored. Finally, design recommendations for the feel system are proposed, aiming to reduce the adverse aircraft pilot coupling and improve flying quality.
Aerodynamic optimization design of low reynolds number aerofoils based on induced laminar separation
Authors: Liu Haoji , Di Weicheng , Wei Zixing , Li Daochun , Xiang Jingwu , Tu Zhan
Published: May 2024

At low Reynolds numbers, the design of aerofoils with a high lift-to-drag ratio (RLD) is crucial for enhancing the aerodynamic performance of Micro Air Vehicles (MAVs). However, the transition from laminar to turbulent flow plays a dominant role in the aerodynamic performance of aerofoils at Low-Reynolds-Numbers (LRN). The laminar separation bubbles formed in laminar flow alter the effective aerofoil shape, reducing aerodynamic efficiency. Additionally, predicting the shape and location of the laminar separation bubbles becomes challenging due to its sensitivity to the flight environment. To design aerofoils suitable for low Reynolds number MAV applications, we optimize a high RLD aerofoil by inducing transition to improve the effective aerofoil shape in the flow field. The study reveals that excessive curvature can suppress the formation of laminar separation bubbles at the leading edge, redirecting separation to the midsection. This results in reduced aerofoil drag and enables a high lift distribution at the leading edge.
Structural response analysis of a solid rocket motor charge under temperature and internal pressure loads
Authors: Liu Fangyi , Ba Shuhong
Published: May 2024

To study the structural integrity of a solid rocket motor under low temperature load, internal pressure load, and two combined loads, based on the linear viscoelastic model, the structural response of a solid rocket motor under low temperature load, internal pressure load and two combined loads were analyzed by ANSYS finite element software, and the temperature field and strain field of charge loading were obtained. The Von Mises strain distribution of the solid rocket motor along the axial characteristic line is obtained. The results are: Under the combined action of low temperature load, internal pressure load, and two kinds of loads, the maximum Von Mises strain appears at the transition position between the blade joint and the barrel section, which is the most dangerous position for charging.
Non-geodesic winding design method for the composite shell of unequal-pole-hole solid rocket motor
Authors: Sun Xiaoliang , Ma Hu , Li Jing
Published: May 2024

Advanced composite materials have the advantages of high specific strength, high specific modulus, good fatigue resistance, good shock absorption performance, and strong designability. They are widely used in the fields of national defense science and technology and civil engineering. To make a more accurate winding design of the composite shell of the non-equidistant solid rocket motor, based on the ANSYS ACP composite structure design and analysis software, this paper uses the cubic spline function method to design the fiber winding thickness of the shell head section for a solid rocket motor. The Runge-Kutta method is used to calculate the changing winding angle of the non-geodesic line, and the changing winding angle and winding thickness on the head are simulated based on the look-up table interpolation table module in ACP. Finally, the mechanical properties of the designed shell under certain internal pressure are simulated and analyzed. Through the simulation analysis of the designed engine model, it is found that the connection between the front head and the barrel section is a weak profit, and the follow-up study should reinforce this area.
Mission analysis and design of launch vehicle based on MBSE
Authors: Zhang Longxi , Guo Xiang , Ren Zhengfei , Ma Xiao
Published: May 2024

A reusable launch vehicle is the basis for carrying out large-scale space activities and reducing the cost of space entry. It will greatly enhance the ability to enter space independently and come up with higher requirements for mission planning, demonstration, overall design, and system development of launch vehicles. Based on the model-based system engineering (MBSE) method, the forward process of model-based launch vehicle mission analysis and design is proposed first. Then, taking a launch vehicle as an example, the mission analysis and design are carried out, the mission is defined, the stakeholder requirements and mission requirements are identified, the mission application scenario is analyzed, the mission architecture is built, and the mission requirements model is established. Finally, by establishing the traceability relationship of mission requirements, the forward process of launch vehicle mission analysis is preliminarily realized, and the feasibility of the process is verified. It is of great engineering significance to improve the efficiency of launch vehicle mission analysis and system design.
LPT rotor speed after low-pressure shaft failure
Authors: Meng Xianghai , Wang Chengen , Yu Naijiang , Wei Yumin
Published: May 2024

When designing engine safety and compliance with airworthiness regulations, it is important to determine the variation of rotor rotational speed and other parameters of aero-engine under shaft failure scenarios. In this paper, a transient process simulation model is established using the component method for a high bypass ratio two-shaft direct-drive turbofan engine. It helps analyze the response of engine rotor speed and key temperature parameters after the failure of the low-pressure shaft, the influence of the fuel supply, low-pressure turbine efficiency, and rotor resistance torque on the response of the parameters. The results demonstrate that the sudden increase of the low-pressure shaft speed at the turbine end after the failure of the low-pressure shaft is the most important factor affecting the engine safety design. The fuel supply, LPT efficiency, and resistance torque have significant effects on this sudden increase in speed.
Measurement uncertainty of vertical combustion test of civil aircraft interior materials
Authors: Wu Shuang
Published: May 2024

The civil cabin interior materials vertical combustion test is the necessary test to verify the flame retardancy ability of the floor coverings, textiles, seat cushions and cushions. It is an inspection step required for cabin interior materials before installation, which is of great significance for the safe flight of civil aircraft. During the experiment process, variable factors such as personnel and equipment are highly likely to impact the test results. To ensure the reliability of test results, it is necessary to summarize and evaluate the factors that may affect the results of the test process. Thus, in this paper, the test method, measurement model, and sources of measurement uncertainty have been analysed, and the calculation case of experimental measurement uncertainty has been introduced.
An experimental study on gas-solid two-phase rotating detonation ramjet engine based on aluminum powder fuel
Authors: Jing Jianing , Ma Hu
Published: May 2024

In order to explore the feasibility of solid powder detonation technology, the ground direct connection test of aluminum powder/hydrogen/air fuel detonation engine was carried out in this paper. The experimental results show that hydrogen is needed to achieve detonation combustion of aluminum powder with a diameter of 1 μm. A series of tests were carried out in the range of equivalence ratio of 0.8-1.2. With the increase of equivalence ratio, the mean value of steady pressure, average peak pressure, and average wave velocity of rotating detonation combustion increased first and then decreased gradually, and reached the maximum at the equivalence ratio of 0.9. The maximum propagation frequency of the detonation wave is 2653 Hz, and the average wave velocity is 1667 m/s.
Analysis of the correction process for the initial field iteration calculation of the stability analysis program
Authors: Wang Ruilin , Li Chuanpeng
Published: May 2024

As the heart of aircraft, the performance requirements of aviation engines are increasing, and analyzing the aerodynamic stability of engines has become an essential part. The methods for analyzing the stability boundary of engines at home and abroad are also gradually improving. When using a domestic engine stability analysis program, it was found that the turbine drop pressure ratio changed during the calculation process, which was inconsistent with the initial given. This article focuses on this issue and analyzes the process of parameter correction during the calculation process by analyzing the parameter changes discovered during its use. This program ensures power balance and duct and bypass outlet static pressure balance. The calculation accuracy is improved through these correction processes.