Dynamic soaring, a special flight mode that enables unpowered long-distance flight by utilizing horizontal wind gradients, holds great potential for enhancing the range and endurance of unmanned aerial vehicles (UAVs). This paper focuses on the parametric design of fixed-wing UAVs, replacing dynamic deformation control with static shape optimization of bionic joint structures to achieve efficient energy harvesting while avoiding complex mechanisms. By calculating and analyzing aerodynamic results corresponding to different design parameters, this study proposes an aerodynamic and wind energy harvesting integrative design method for UAVs. This method employs neural networks to achieve rapid solutions for aerodynamic forces and uses the Gauss pseudospectral method to solve for the optimal wing shape, ultimately obtaining a wing configuration that meets the requirements of efficient energy harvesting. In addition, flight simulations are conducted to compare the energy harvesting efficiency of three different wing shapes during dynamic soaring: basic wing, maximum lift-to-drag ratio wing, and aerodynamic and wind energy harvesting integrative design result. Results show that the UAV with the integrated design achieves the highest energy harvest amount and efficiency, with an increase of 979.04% compared to the basic wing and 10.09% compared to the maximum lift-to-drag ratio wing. The energy gain rate (work) done by the integrated design UAV during the energy harvesting phase is improved by more than 50%, verifying the feasibility of the aerodynamic and wind energy harvesting integrative design method. This design method provides engineering support for breaking through the bottleneck of UAV dynamic soaring energy harvesting.
This article presents in detail the results of the research and development of a unique active electromagnetic weight compensation system created by engineers at JSC «Reshetnev». The primary purpose of this system is to conduct modal testing of modern, weakly damped structures typical of the space industry. The key objective of the system is to create and maintain conditions that accurately simulate zero-gravity conditions on Earth. This effect is achieved through a complex, precisely controlled interaction of electrodynamic forces. The authors describe in detail the system's basic operating principle and its design implementation, paying particular attention to the description of key components. An innovative method for generating the control current dependence on the coordinates of the moving element, which forms the basis for precise control, is proposed and mathematically substantiated. To ensure the highest stability and dynamic accuracy, advanced control algorithms using PID control were integrated and adapted into the system. A significant improvement in control quality was achieved through the implementation of a specialized high-power current amplifier, which eliminated the induced electromotive force and significantly increased the accuracy of the excitation force setting. A series of experimental studies and tests fully confirmed the high operational feasibility and effectiveness of all developed technical solutions. The results also allowed us to identify specific promising areas for further optimization of the system to improve its performance.
The electric vertical take-off and landing fixed-wing (FW-VTOL) unmanned aerial vehicle (UAV) combines the advantages of fixed-wing aircraft and multi-rotor aircraft. Based on the cell discharge characteristics and the power system features, this paper proposes a preliminary design and optimization method suitable for electric FW-VTOL UAVs. The purpose of this method is to improve the design accuracy of electric propulsion systems and overall parameters when dealing with the special power and energy requirements of this type of aircraft. The core of this method involves testing the performance data of the cell inside the battery pack, using small-capacity cells as the basic unit for battery sizing, thereby constructing a power battery performance model. Additionally, it establishes optimization design models for propellers and rotors and develops a brushless DC motor performance model based on a first-order motor model and statistical data, ultimately achieving optimized matching of the propulsion system and completing the preliminary design of the entire aircraft. Using a battery discharge model established based on real cell parameters and test data, the impact of the discharge process on battery performance is evaluated at the cell level, reducing the subjectivity of battery performance evaluation compared to the constant power/energy density method used in traditional battery sizing processes. Furthermore, matching the optimization design of power and propulsion systems effectively improves the accuracy of the preliminary design for FW-VTOL UAVs. A design case of a 30 kg electric FW-VTOL UAV is conducted, along with the completion of flight tests. The design parameters obtained using the proposed method show minimal discrepancies with the actual data from the actual aircraft, confirming the effectiveness of the proposed method.
The ignition temperature serves as a pivotal parameter for assessing the flame retardancy of high-temperature titanium aluminum alloys（TiAl alloys）. Nevertheless，accurately predicting the ignition temperature of TiAl alloys remains a formidable challenge. Leveraging the Frank-Kamenetskii and Coulomb friction models，this paper develops a computational framework to determine the critical ignition temperature of TiAl alloy. It further investigates the influences of flow velocity，friction contact pressure，and oxygen partial pressure on this critical temperature. The findings reveal that as the flow velocity escalates from 140 m/s to 340 m/s，the critical ignition temperature incrementally rises from 1699.0 K to 1751.6 K. Intriguingly，while friction contact pressure increases from 1.0 MPa to 3.9 MPa，the critical ignition temperature stabilizes at 1710.2 K；however，the threshold ambient temperature necessary for alloy combustion decreases linearly，spanning from 1363.0 K to 537.5 K. Conversely，as the oxygen partial pressure climbs from 21.3 kPa to 96.3 kPa，the critical ignition temperature diminishes from 1719.7 K to 1665.8 K. Under specific conditions of an air flow temperature of 298 K and an air flow rate of 4.1 g/s，the finite volume method calculates a maximum flow velocity of 155.1 m/s near the specimen surface within the combustion chamber. Notably，the computed and experimental values for the critical oxygen partial pressure required for ignition are 93.8 kPa and 88.2 kPa，respectively，exhibiting a relative error of 6.3%.
Francisco Bilendo, Angela Meyer, Hamed Badihi
et al.
In the wind energy industry, the power curve represents the relationship between the “wind speed” at the hub height and the corresponding “active power” to be generated. It is the most versatile condition indicator and of vital importance in several key applications, such as wind turbine selection, capacity factor estimation, wind energy assessment and forecasting, and condition monitoring, among others. Ensuring an effective implementation of the aforementioned applications mostly requires a modeling technique that best approximates the normal properties of an optimal wind turbines operation in a particular wind farm. This challenge has drawn the attention of wind farm operators and researchers towards the “state of the art” in wind energy technology. This paper provides an exhaustive and updated review on power curve based applications, the most common anomaly and fault types including their root-causes, along with data preprocessing and correction schemes (i.e., filtering, clustering, isolation, and others), and modeling techniques (i.e., parametric and non-parametric) which cover a wide range of algorithms. More than 100 references, for the most part selected from recently published journal articles, were carefully compiled to properly assess the past, present, and future research directions in this active domain.
Tianyu Zhao, Jose Escribano-Macias, Mingwei Zhang
et al.
With growing air travel demand, weather disruptions cost millions in flight delays and cancellations. Current resilience analysis research has been focused on airports and airlines, rather than the en-route waypoints, and has failed to consider the impact of disruption scenarios. This paper analyses the resilience of the United Kingdom (UK) air traffic network to weather events that disrupt the network’s high-traffic areas. A Demand and Capacity Balancing (DCB) model is used to simulate adverse weather and re-optimise the cancellation, delay, and rerouting of flights. The model’s feasibility and effectiveness were evaluated under 20 concentrated and randomly occurring extreme disruption scenarios, lasting 2 h and 4 h. The results show that the network is vulnerable to extended weather events that target the network’s most central waypoints. However, the network demonstrates resilience to weather disruptions lasting up to two hours, maintaining operational status without any flight cancellations. As the scale of disruption increases, the network’s resilience decreases. Notably, there exists a threshold beyond which further escalation in disruption scale does not significantly impair the network’s performance.
Large-caliber and long-barrel weapons are important experimental devices for exploring the impact resistance and reliability of warheads. The force of impact of the muzzle jet has a significant influence on the overload resistance of the warhead and surrounding devices. The mechanism of motion of the body inside the tube cannot be ignored owing to the high kinetic energy at the muzzle. In this study, we designed the relevant experiment and a simulation model to analyze the structural characteristics and mechanism of evolution of the shock wave and the vortex structure in a muzzle jet. The aim was to examine the evolution of the shock wave with initial jet-induced interference. And we established three other simulation models to compare the similarities and differences between the results of the models. The results showed that, in the original complex model, the initial jet restricted the free expansion of the muzzle jet, and this led to many shock–shock collisions that retarded the development of the shock waves. Multiple reflected shock waves were thus formed under a high local pressure that distorted the shock structure, while the structure of the shock wave in the simplified models was clear and simple. The parameters of motion of the body changed by a little when the initial jet-induced interference was ignored. The difference in values of the strongest impact force measured at monitoring points far from the muzzle was small, with an error of about 2%, such that the simplified model without the initial jet could be used in place of the original complex model. The other simplified models yielded significant differences. Our results provide an important theoretical basis for further research on the muzzle jet and its applications in engineering.
The room temperature tensile properties and elevated temperature tensile properties of peak aged Al-Cu-Mg-Ag hub forgings after different heat exposure temperatures and heat exposure time were tested，and the thermal stabilities of the forgings at different temperatures were compared and analyzed. The results show that Al-Cu-Mg-Ag forgings exhibit good thermal stability. After exposure at 150 ℃ for 1 to 100 h，there were no significant changes in room temperature tensile properties and elevated temperature tensile properties. Short time heat exposure at 150-200 ℃ for 1 h does not reduce the overall performance，but the strength of Al-Cu-Mg-Ag forgings decreases with the increase of heat exposure temperature and the extension of heat exposure time. After 100 h of exposure at 200 ℃ and 250 ℃，the room temperature yield strength remains 61.1% and 37.2 %，and the room temperature tensile strength remains 77.8% and 60.8%，the elevated temperature yield strength remains 61.6% and 42.8%，and the elevated temperature tensile strength remains 67.5% and 47.6%，respectively. The main precipitates of Al-Cu-Mg-Ag forgings are Ω phase and θ′ phase. Under the experimental conditions of Kt=1 and R=0.1，the room temperature fatigue limit after 200 ℃/10 h heat exposure is 278 MPa，which is 10.6% lower than the fatigue limit of 311 MPa before heat exposure.
In this paper, the detached eddy simulation (DES) method is used to calculate the aerodynamic characteristics of NACA0015 airfoil by combining the Riemann approximate solution HLLC (Harten–Lax–van Leer Contact) with the high-order weighted essentially non-oscillatory (WENO) scheme and the weighted compact nonlinear scheme (WCNS), respectively. By comparing the calculation results of the two different numerical schemes with the wind tunnel test results, it is found that both numerical schemes can accurately calculate the aerodynamic parameters at small angles of attack. However, in the range of near-stall angle (in the range of 10–15°), the calculation results of various numerical schemes have a certain degree of deviation. The calculation results of the fifth-order WCNS and the fifth-order WENO scheme are closer to the experimental values. The fifth-order WCNS predicts the stall angle of attack more accurately than the fifth-order WENO scheme. The calculation accuracy of the fifth-order WCNS is better than that of the fifth-order WENO scheme under the post-stall condition (where the angle of attack is greater than 15°). By comparing the vorticity contours calculated by different numerical schemes, it is found that the numerical dissipation of the fifth-order accuracy is smaller than that of the third-order accuracy, and the vortex capture ability is stronger. WCNS captures the small vortex structure that the WENO scheme does not.
The request for faster and greener civil aviation is urging the worldwide scientific community and aerospace industry to develop a new generation of supersonic aircraft, which are expected to be environmentally sustainable and to guarantee a high-level protection of citizens. A key aspect to monitor the potential environmental impact of new configurations is the aerodynamic efficiency and its impact onto the real mission. To pursue this goal, this paper discloses increasing-fidelity aerodynamic modeling approaches to improve the conceptual design of high-speed vehicles. The disclosed methodology foresees the development of aerodynamic aerodatabases by means of incremental steps starting from simplified methods (panels methods and/or low-fidelity CFD simulations) up to very reliable data based on high-fidelity CFD simulations and experimental measurements with associated confidence levels. This multifidelity approach enables the possibility of supporting the aircraft design process at different stages of its design cycle, from the estimation of preliminary aerodynamic coefficients at the beginning of the conceptual design, up to the development of tailored aerodatabases at advanced design phases. For each design stage, a build-up approach is adopted, starting from the investigation of the clean external configuration up to the complete one, including control surfaces’ effects and, if any, the effects of the integration of the propulsive effects. In addition, the applicability of the approach is guaranteed for a wide range of supersonic and hypersonic aircraft, and the developed methodology is here applied to the characterization of Mach 2 aircraft configuration, a relevant case study of the H2020 MORE&LESS project.
Positioning and mapping technology is a difficult and hot topic in autonomous driving environment sensing systems. In a complex traffic environment, the signal of the Global Navigation Satellite System (GNSS) will be blocked, leading to inaccurate vehicle positioning. To ensure the security of automatic electric campus vehicles, this study is based on the Lightweight and Ground-Optimized Lidar Odometry and Mapping on Variable Terrain (LEGO-LOAM) algorithm with a monocular vision system added. An algorithm framework based on Lidar-IMU-Camera (Lidar means light detection and ranging) fusion was proposed. A lightweight monocular vision odometer model was used, and the LEGO-LOAM system was employed to initialize monocular vision. The visual odometer information was taken as the initial value of the laser odometer. At the back-end opti9mization phase error state, the Kalman filtering fusion algorithm was employed to fuse the visual odometer and LEGO-LOAM system for positioning. The visual word bag model was applied to perform loopback detection. Taking the test results into account, the laser radar loopback detection was further optimized, reducing the accumulated positioning error. The real car experiment results showed that our algorithm could improve the mapping quality and positioning accuracy in the campus environment. The Lidar-IMU-Camera algorithm framework was verified on the Hong Kong city dataset UrbanNav. Compared with the LEGO-LOAM algorithm, the results show that the proposed algorithm can effectively reduce map drift, improve map resolution, and output more accurate driving trajectory information.
Lighting in aircraft cabin is an important part of the aircraft interior lighting system. A reasonable cabin lighting design can improve the quality of flight services and enhance passenger satisfaction and comfort. In this paper, an aircraft cabin lighting design method is proposed based on the DIALux calculation and simulation software. Based on a quantitative evaluation, calibration and analysis of average illuminance, glare and uniformity of illuminance from the perspectives of travel safety, visual comfort and high quality service, the method explores and proposes an innovative approach to the design of aircraft cabin lighting. Finally, based on this method, an optical simulation model is established and visual simulation calculations are carried out to verify the feasibility of the method.
Carlo E.D. Riboldi, Marco Belan, Stefano Cacciola
et al.
When it comes to computing the values of variables defining the preliminary sizing of an airship, a few standardized approaches are available in the existing literature. However, when including a disruptive technology in the design is required, sizing procedures need to be amended, so as to be able to deal with the features of any additional novel item. This is the case of atmospheric ionic thrusters, a promising propulsive technology based on electric power, where thrusters feature no moving parts and are relatively cheap to manufacture. The present contribution proposes modifications to an existing airship design technique, originally conceived accounting for standard electro-mechanical thrusters, so as to cope with the specific features of new atmospheric ionic thrusters. After introducing this design procedure in detail, its potential is tested by showing results from feasibility studies on an example airship intended for a high-altitude mission. Concurrently, the so-obtained results allow the demonstration of the sizing features corresponding to the adoption of atmospheric ionic thrusters at the current level of technology, comparing them to what is obtained for the same mission when employing a standard electro-mechanical propulsion system.