Ebook: Mechanical and Aerospace Engineering

This book is a collection of papers presented at the 15th Asia Conference on Mechanical and Aerospace Engineering (ACMAE 2024), held in Harbin, China from 27-29 December 2024. On behalf of my colleagues on the international advisory, organizing and technical committees, I would like to thank all the authors for their support and the contributions that led to the successful publication of these proceedings.

ACMAE 2024 is sponsored by Harbin Engineering University, China, co-sponsored by the Beijing Institute of Technology, China, and hosted by the College of Aerospace and Civil Engineering, Harbin Engineering University, China, technically supported by Wuhan University of Technology, China, Capitol Technology University, USA and Washington University in St. Louis, USA. This international conference was held over three-days and provided a forum for the discussion of mechanical and aerospace engineering. Submitted papers were received and sent for preliminary and peer review conducted by the technical committees. Professional comments were made in the light of of originality, innovation, applicability, technical merit, organization and writing, and relevance to the conference. After several rounds of review procedure, some excellent papers were accepted for publication in the conference proceedings. This year, we received 130 submissions of which 96 were accepted for presentation and 78 for publication in the proceedings. In this connection, I would like to thank all the committee members, particularly members of the Technical Committee, who worked very hard in reviewing the papers and making valuable suggestions to the authors for improvements to their work. Without a valid peer review, quality cannot be assured and research will be ignored by others. Particular thanks also go to the conference organizer, whose special efforts made the conference such a success. I believe that all those delegates who attended the conference in person had an enjoyable stay in Harbin, where we had the opportunity to forge new friendships and reinforce old ties. I would also like to thank our keynote and invited speakers, who so generously shared their expertise through their presentations.

The papers in these proceedings cover a wide range of topics in mechanical and aerospace engineering, including but not limited to: aircraft wing design and aerodynamic characteristics analysis, engine performance simulation and evaluation in aviation systems, power equipment design and system model in aerospace engineering, fault analysis, equipment defect detection and reliability analysis in aerospace engineering, aviation electronics system control and guidance technology, aviation material analysis and mechanical performance testing, dynamic modeling and fluid mechanics analysis, modern mechanical system design and mechanical analysis, modern aircraft manufacturing process, and automated assembly technology.

We believe that this trend will continue, and we hope to receive more innovative and interesting submissions for this conference in the coming years.

Happy reading and hope to see you in person next year!

Advisory Chair, ACMAE 2024

Prof. Chih-Yung Wen, Hong Kong Polytechnic University, Hong Kong, China

(Head of AAE, PloyU, HKIE Fellow, AIAA Fellow)

Three-dimensional numerical simulations of the flow around the NACA 0015 airfoil were conducted by using the unsteady Reynolds-averaged Navier-Stokes (URANS) and improved delayed detached eddy simulation (IDDES) based on k-ω shear stress transport (SST) turbulence model. The angle of attack range (AoA) is from 0° to 75°. The solver in this paper is developed on an in-house platform HRAPIF based on the finite volume method (FVM) with the elemental velocity vector transformation (EVVT) approach. It uses a density-based method with a low Mach preconditioning technique to accelerate convergence. The inviscid spatial discretization is the 5th-order modified weighted essentially non-oscillatory (WENO-Z) scheme. The results show that the IDDES model can effectively predict lift and drag coefficients at all the studied AoAs and has significant advantages over URANS, both in predicting aerodynamic forces and in simulating flow vortex structures at post-stall AoAs.

Inverse design offers significant advantages in aerodynamic design, such as improved performance and efficiency. In this paper, a denoising diffusion probabilistic model (DDPM) is adopted as a generative model to produce pressure coefficient distribution data for the RAE2822 airfoil. Through the forward noise addition process and the reverse denoising process, the trained DDPM model can sample a large amount of pressure coefficient distribution data from a standard normal distribution. Two neural networks are then employed: one maps the pressure coefficient distribution to geometric parameters, linking the pressure field with geometric parameters, and the other maps the pressure coefficients to lift and drag coefficients. Computational fluid dynamics (CFD) validation of the sampled data shows that the CFD results are close to the generated pressure distributions, demonstrating the effectiveness and reliability of the proposed approach.

The PreCICE open-source platform was used for secondary development to achieve multi-physics field coupling between fluid and solid in hypersonic flow processes. The numerical results were compared using circular tube flow experiments, and the numerical results were in good agreement with the experiments. A multi-physics coupling simulation was conducted on an “L” - shaped folding wing under 6 Ma flight conditions using this platform, and the aerodynamic characteristics of the wing under different folding angles and angles of attack were compared. The results showed that the maximum deformation caused by aerodynamic forces on the folding wing itself occurred at the wing tip in hypersonic environments; Fully unfolding the wing at a lower angle of attack could achieve a greater lift to drag ratio, while retracting at a certain angle at a higher angle of attack could increase the lift to drag ratio; As the folding angle increased, the leading edge at the wing axis was less heated while the lower surface was heated more strongly, and the temperature in the high-temperature zone at the end of the axis slightly increased.

Circulation Control (CC) is widely researched because it can generate high lift and create the effect of ‘virtual control surfaces’. Currently, the relationship between the design parameters and the control effects of circulation control is not yet clear. Therefore, this paper establishes the airfoil parametrization method for circulation control airfoils and the effects of different nozzle heights, radii and shapes of Coanda surface, and airfoil thickness and camber on circulation control effect are investigated. The results show that the best equivalent lift-to-drag ratio (K_E) is at a nozzle height of h/c = 0.06%; K_E peak at a Coanda surface radius of a/c = 0.016 and stabilize thereafter; the optimal Coanda surface shape is at b/a = 3/2. Increasing airfoil thickness and camber improves pitch moment but reduces K_E. The best overall performance is achieved at t/c= 15% and w/c= 0%.

Advancement in UAV technology has led to its more widespread role. An emphasis on fuel efficiency and operational range has become a standard operational requirement for UAV designs. As these requirements become more stringent, better structural designs that reduce the weight of UAVs have become increasingly important. However, these structures are often of complicated design which requires advanced manufacturing methods. One such method is additive manufacturing (AM) that is capable of fabricating complex parts with high precision and strength. This manufacturing method is suitable for structure such as IsoTruss which has complex geometries. In this paper, we perform numerical analysis using finite element method on IsoTruss structure and standard I-Beam structure as UAV wing spar. The aim of this analysis is to determine the IsoTruss performance as a viable option for a small UAV wing spar. From the analysis performed, using IsoTruss reduced the weight of the structure by 21.78%. This reduction in weight could be useful for UAV designs that require long duration of flight and wide operational range.

The unsteady flow field of the multi-element airfoil 30P30N at low Reynolds numbers was analyzed using a high-precision CFD method employing the Large Eddy Simulation (LES) turbulence model. Additionally, a reduced-order model (ROM) based on Proper Orthogonal Decomposition (POD) and Galerkin projection was developed and verified. This approach not only deepens our understanding of the aerodynamic performance of multi-element airfoil but also provides an efficient tool of reduced order modeling.

High altitude contra-rotating propellers are increasingly being utilized in High Altitude Long Endurance (HALE) aircraft, due to the significant improvement in aerodynamic efficiency of contra-rotating propellers compared to conventional propellers. This study compares the accuracy of the Multiple Reference Frame (MRF) quasi-steady calculation method with the unsteady calculation method, and employs the MRF quasi-steady method to analysis the effects of axial distance, twist angle, and the rotational speed ratio on the performance of contra-rotating propellers at high altitudes. The results indicate that within the studied range, an increase in axial distance leads to a slight improvement in the efficiency of the contra-rotating propellers, although the overall enhancement is minimal. Additionally, minor variations in the twist angle of the front and rear propellers are advantageous for enhancing the aerodynamic efficiency of the contra-rotating propellers. The maximum efficiency of the contra-rotating propellers is achieved when the rotational speed ratio is 1.05.

Intelligent variant aircraft is an important development trend in the future aerospace field, which is of great significance to improve the comprehensive performance of aircraft. Most of the current deformable wing schemes are mainly mechanical or rigid-flexible coupled mechanisms, but it is difficult to meet the practical engineering needs in terms of continuous deformation and load bearing at multiple target points. Intelligent deformed wing based on mechanical metamaterial structure and traditional driving mechanism is the easiest and most potential scheme at present. In view of this, a lightweight distributed variable thickness structure based on reversible assembly of mechanical metamaterial is proposed in this paper. The structure consists of three basic deformed lattice, one active deformed cell and one transitional cell. Firstly, the deformation mechanism of the three types of basic cells were analyzed through simulation and related mechanical properties characterization experiments. The results show that the rigidity of the three base voxels is very different, and the Poisson’s ratio covers the range from negative to positive, which verifies its rationality as the base voxels of deformed structures. Secondly, according to the actual curved airfoil profile, the transition cell structure is designed and manufactured to complete the structural design and verification of intelligent deformed wings. The experimental results show that the deformation increment of the deformed wing is about 5% of the chord length and the deformation error is about 3.95%, which lays a foundation for the accurate deformation of the distributed deformed wing structure.

Sandpaper ice has a detrimental impact on the stall characteristics of aircraft. In this paper, numerical simulation method is used to study the aerodynamic characteristics of supercritical airfoils and high-lift airfoils with sandpaper ice. Different roughness heights and ranges of the sandpaper ice are considered. For the supercritical airfoil, it is found that within the leading-edge region, the adverse effects on lift characteristics increase with the roughness range, and the impact stabilizes when the ice accretion reaches 1% chord length. However, the degradation of lift characteristics becomes more pronounced when there is sandpaper ice on the mid to aft sections of the supercritical airfoil. For the high-lift airfoil, within the slat leading-edge region, the adverse effects on lift characteristics increase with the roughness range, and the impact stabilizes when the ice accretion reaches 1% chord length. However, the lift characteristics deteriorate when there is sandpaper ice on the main wing of the high-lift airfoil, especially on the mid to aft sections of the main wing. For both supercritical airfoils and high-lift airfoils, the higher the ice roughness height in the leading-edge region, the more detrimental the impact on their lift characteristics.

This experimental study investigates the influence of geometric parameters, specifically the expansion ratio, on combustion pressure oscillations within a solid fuel ramjet (SFRJ). Experiments were conducted under controlled conditions with a total incoming flow temperature of 540K, total pressure of 0.78 MPa, and air mass flow rate of 0.3 kg/s. The main geometric configurations of the engine included the combustion chamber length, afterburner chamber length, inlet diameter, and fuel grain inner diameter, with the expansion ratio defined as the ratio of the fuel grain inner diameter to the inlet diameter. By analyzing the pressure data during stable operation, it can be observed that as the expansion ratio increases, the average pressure in the combustion chamber significantly decreases. Fourier transform analysis identified varying frequencies and amplitudes of pressure oscillations across different expansion ratios. The results indicate that the increase in expansion ratio has little effect on the first-order primary frequency. As the expansion ratio rises from 1.75 to 2.0 and ultimately to 2.57, the amplitude of pressure oscillation increases from 1.89 kPa to 2.0 kPa and then to 2.3 kPa. These findings validate the experimental design and provide important insights for optimizing the performance and stability of SFRJ.

The structural integrity analysis of propellant grain is very important for Solid Rocket Motor(SRM). In this paper, a new semi-dumbbell ring groove grain is proposed, and the structural integrity of this new structure is studied by the finite element method. The results showed that the maximum equivalent strain of the semi-dumbbell ring groove grain can be reduced by about 19.8% under temperature loading and by 19.4% under pressure loading compared with the traditional ring groove grain. This new grain structure can provide some reference for the design of high-loading ratio SRM.

To solve the problem of aero-engine multi-performance degradation modeling and reliability evaluation, an evaluation method based on data fusion of active component and stochastic process was proposed. First, multivariate performance degradation data are reduced to low-dimensional key variables through data fusion techniques; then, based on the above variables, the reliability of the product is evaluated using the Gamma process or multivariate Gamma process model; finally, the product life distribution is predicted based on the reliability results at different time. The proposed method improves the efficiency of complex data processing and improves the applicability and practicability of the model.

To effectively monitor the performance status and early warning of engine starting system, the multi-indicator fusion strategy for health monitoring of engine starting system is proposed by comprehensively considering the starting valve and starter performances. Combined with the operation principle of starting valve and starter in the starting system, the quick access recorder (QAR) parameters that can reflect the performance change of starting process are selected; the pressure value at the entrance of the starter is obtained by using the auxiliary power units (APU) pressure attenuation coefficient, and then the work energy is determined by integrating the starting process pressure; the operating time of the valve is calculated by the starting valve air volume-time curve, and the health indicator threshold of the valve and starter is obtained by using the regression fitting method and three-parameter Burr distribution, to realize the health state monitoring of the engine starting system. The results show that the accuracy of proposed method for engine health status monitoring can reach 90%, which can effectively reflect the performance changes of engine starting system, and can provide a reference for engine health management and predictive maintenance formulation strategies.

In order to achieve the verification work of jet vanes in the aerodynamic design phase at a low cost, a six-component force test system for a cold gas motor using nitrogen as the working medium has been developed. High-pressure nitrogen is used to replace the high-temperature gas produced by the combustion of solid propellants as the working gas for the cold gas motor, and to construct a semi-physical simulation experimental platform for six-component forces. By constructing a jet vane-type actuator to achieve vector thrust, data collection of six-component forces is carried out with different actuation deflection angles as examples. The results indicate that, compared to experiments using actual solid rocket engines, this system is safe and stable, with lower costs for individual experiments.

This paper presents a rock sampling system designed for the slopes of Valles Marineris on Mars, utilizing a quadrotor vehicle. The study begins with an overview of Mars exploration and the potential applications of rotorcraft in this context. A novel sampling process tailored for the challenging slopes of Valles Marineris is proposed, integrating a Mars Unmanned Vehicle (MUV) with a Mars Sampling Quadcopter (MSQ). The rock sampling mechanism features a single-degree-of-freedom, double-link structure, which employs a synchronous belt and gear drive to enable effective rock sample collection on complex terrains. A comprehensive stress analysis of the system is conducted to validate the feasibility and robustness of the design.

To enhance the load disturbance suppression of electric fuel pumps and the operational safety of aviation engines, analysis and experimental research were conducted from three aspects: carrier frequency, control structure, and control parameters. under the dual-loop control structure, the carrier frequency is positively correlated with load disturbance rejection. The speed fluctuation at a carrier frequency of 20KHz is not more than 88% of that at 10KHz; The load disturbance rejection performance of the single speed loop control structure is significantly better than that of the dual-loop control structure, making it a major influencing factor on load disturbance rejection. The primary factors affecting the load disturbance suppression of electric fuel pumps were investigated, and the main measures for load disturbance suppression were formulated, thereby improving the operational safety of aviation engines.

This paper derives the dynamic equations for a dumbbell-shaped spacecraft equipped with control moment gyroscopes. Using the theory of gyroscopic flexible bodies, a modal analysis is conducted on the constrained boundary of the dumbbell-shaped spacecraft, leading to the determination of its natural frequencies and mode shapes. Zero-input response analyses are conducted for both the constrained-boundary spacecraft and a cantilever beam model, under two conditions: with and without damping. The results are then thoroughly analyzed. A comparison between the direct method and the modal superposition method shows that truncating after the fifth mode yields higher accuracy. This research provides a foundation for further studies on free-boundary modal analysis of dumbbell-shaped spacecraft and the optimization of control moment gyroscope installation positions.

The application of virtual testing technology for aircraft structural strength can effectively verify the rationality of physical test designs and predict the dynamic responses of physical tests. The primary step in this process is rigid-flexible coupling dynamics modeling, which encompasses the modeling of both the rigid lever loading system and the flexible aircraft body. To address the issue of the heavy workload involved in designing the lever loading system, a parametric design approach is adopted, combining MATLAB and Adams to establish a rigid model of the lever loading system that is adjustable in parameters and data-driven. Using the finite element software HyperWorks, the Craig-Bampton method is applied to construct a flexible body model based on Adams software. Finally, coupling interactions are created to connect the flexible body with the rigid model of the lever loading system, achieving rigid-flexible coupling dynamic modeling of aircraft loads based on Adams.

Maneuverability is an important indicator for evaluating the comprehensive performance of aircraft, and the researchers have increasingly high requirements for the maneuverability of fighters. As target simulators, drones must possess corresponding maneuvering capabilities to replicate real combat scenarios. Based on the requirements of modern weapon testing systems and current trends in target drone technology, investigations into the development of supersonic high-maneuverability target drones was considered. Key performance metrics such as aerodynamic characteristics, structural integrity, and flight performance were tested. As a preliminary validation, development and flight testing of high-maneuverability, overload-capable target drones were conducted. For a drone with a total weight of 248 kg and a maximum flight speed of 0.8 Ma, the goal is to achieve a stable overload capability of over 6g and a maximum overload of over 9g. Firstly, CFD and CSD techniques were used to simulate the key performance of the aircraft, then flight tests were conducted for verification. The results indicate that the flight performance meets the overall design requirements and the simulation results agrees with it. The drone achieved complete autonomous control from take off to landing. The entire system performed reliably, and the drone maintained stable flight, with normal attitude, speed, altitude, and flight path tracking.

The lift fan is a critical component in vertical short takeoff and landing (VSTOL) fighters, enhancing thrust and offering significant applications in aerospace. To streamline airflow and optimize flow field distribution, guide vanes are often incorporated into lift fans to improve efficiency. However, studies on the aerodynamic impact of inlet and outlet guide vanes remain limited. This research examines the effects of inlet guide vane number and deflection angle, as well as the influence of outlet guide vanes on flow characteristics, using a two-stage counter-rotating lift fan as the subject. Findings indicate that fan lift increases steadily with the number of inlet guide vanes until reaching ten, after which additional vanes cause a rapid decrease in lift. The total pressure loss coefficient initially remains constant and then rises with increased inlet guide vane deflection angle. As adjustable vanes, the inlet guide vanes can pivot from approximately 80° to 20° to achieve gradual lift improvement. Compared to configurations without outlet guide vanes, the addition of outlet guide vanes significantly enhances airflow uniformity near the fan’s exit, reducing aerodynamic losses and stabilizing the overall flow.

In order to improve the ballistic performance of dual-pulse guided rockets, the medium-range guided rocket and long-range rocket are taken as the research objects, A multi-stage and multi-constraint optimization model of pulse energy allocation-external ballistic trajectory is established, and the optimization procedure is programmed based on hp-adaptive pseudospectral method to solve the problem. The impacts of pulse energy allocation, the angle-of-attack control and the endpoint constraints on the ballistic performance are analyzed in detail. The results show that the pseudospectral method can solve the ballistic optimization problem of the dual-pulse guided rockets. Besides, the optimization results of the angle of attack control combined with pulse energy distribution are not much different from those of the separate optimization results. Under the zero-angle-of-attack case, the dual-pulse motor can effectively increase the range of long-range rockets, but has less effect on the range of medium-range rockets. Under the angle-of-attack control case, the ranges of both types of rockets can be greatly increased, and are less affected by the energy distribution.