Hasil untuk "Motor vehicles. Aeronautics. Astronautics"

Victor F. Petrenko

Ice accretion along aircraft leading edges, particularly at stagnation line parting strips, remains difficult to remove using conventional electrothermal anti-icing systems. These systems require continuous high-power heating to maintain the stagnation region above the melting point, often exceeding 10–12 kW/m². This study introduces an Ice Cavitation Deicer (ICD) that removes ice through rapid, localized cavitation generated within a thin melt layer formed at the ice–surface interface. In the proposed approach, a short pulse of electric current melts a 1–10 µm interfacial layer and causes a cavitation impulse of approximately 1–10 MPa. This impulse ejects the stagnation-line ice in a direction normal to the surface, often against the external airflow, enabling the immediate aerodynamic removal of the remaining ice. Analytical modeling based on the energy conservation principle was used to determine the optimal foil geometry, thermal pulse parameters, thermal stress, and material selection. Experiments with various metallic foils and substrate materials validated the predicted ejection behavior. The impulses were sufficient to fracture and eject ice 1–10 mm thick. The observed ice fragment velocities varied from 1 m/s to 10 m/s. Compared with conventional thermal anti-icing, the ICD concept reduces power consumption by approximately two orders of magnitude while offering rapid and reliable leading-edge deicing. The low power requirements, rapid response, and compatibility with thin-foil heater architectures make ICD a promising technology for both conventional and electrified aircrafts, UAVs, rotorcrafts, and other platforms where power availability is limited. This manuscript presents the first theoretical and experimental research on the ICD method and is a concept-proof work. Further research and development are required before the ICD is ready to be tested in flight.

Hanxi Zhu, Chengpeng Guo, Tiejun Zhang et al.

The stiffness of flapping wings significantly influences the aerodynamic characteristics and structural response of insects in forward flight. While numerous studies have focused on the fluid-structure interaction of small insect wings, research on butterflies, characterized by large wing areas and low aspect ratios, remains relatively scarce. To investigate the effects of different flexibility distributions on the fluid-structure interaction characteristics of butterfly-like flapping wings in forward flight, a geometric model and kinematic equations were established based on the morphology and motion patterns of Chilasa clytia. A fluid-structure interaction solver combining the lattice Boltzmann method (LBM) and the finite element method (FEM) was developed and validated with benchmark cases. The developed method was then employed to systematically compare the aerodynamic performance and structural responses among isotropic flexible, anisotropic flexible, and rigid butterfly wings during flapping. The results indicate that the isotropic flexible wing exhibits significantly enhanced flight performance compared to the anisotropic and rigid wings. The flapping of the isotropic flexible wing generates more complex vortex structures, including the wingtip secondary flow vortex (WSFV) and the hindwing tip vortex (HTV). These vortices create an additional low-pressure region, thereby improving the aerodynamic performance. This study provides new insights into the vortex dynamics associated with lift enhancement mechanisms in flapping flight and offers valuable references for the design of novel bio-inspired micro flapping-wing aerial vehicles.

Dinh Thang Tran, Van Khiem Pham, Anh Tuan Nguyen et al.

Gliders are engineless aircraft capable of maintaining altitude for extended periods and achieving long ranges. This paper presents an optimal aerodynamic design method for flying wing gliders, leveraging a combination of artificial neural networks (ANNs) as a surrogate model and genetic algorithms (GAs) for optimization. Data for training the ANN is generated using the vortex-lattice method (VLM). The study identifies optimal aerodynamic shapes for two objectives: maximum flight endurance and maximum range. A key finding is the inherent conflict between aerodynamic performance and static stability in tailless designs. By introducing a stability constraint via a penalty function, we successfully generate stable and high-performance configurations. For instance, the stabilized RG15 airfoil design achieves a maximum glide ratio of 24.1 with a robust 5.1% static margin. This represents a calculated 11.5% performance reduction compared to its unstable theoretical optimum, quantitatively demonstrating the crucial trade-off between stability and performance. The methodology provides a computationally efficient path to designing practical, high-performance, and inherently stable flying wing gliders.

Shuo Li, Gang Wang, Jinyong Chen

Efficient and adaptive mission planning for Earth Observation Satellites (EOSs) remains a challenging task due to the growing complexity of user demands, task constraints, and limited satellite resources. Traditional heuristic and metaheuristic approaches often struggle with scalability and adaptability in dynamic environments. To overcome these limitations, we introduce AEM-D3QN, a novel intelligent task scheduling framework that integrates Graph Neural Networks (GNNs) with an Adaptive Exploration Mechanism-enabled Double Dueling Deep Q-Network (D3QN). This framework constructs a Directed Acyclic Graph (DAG) atlas to represent task dependencies and constraints, leveraging GNNs to extract spatial–temporal task features. These features are then encoded into a reinforcement learning model that dynamically optimizes scheduling policies under multiple resource constraints. The adaptive exploration mechanism improves learning efficiency by balancing exploration and exploitation based on task urgency and satellite status. Extensive experiments conducted under both periodic and emergency planning scenarios demonstrate that AEM-D3QN outperforms state-of-the-art algorithms in scheduling efficiency, response time, and task completion rate. The proposed framework offers a scalable and robust solution for real-time satellite mission planning in complex and dynamic operational environments.

Giancarlo Rufino, Claudia Conte, Pasquale Basso et al.

Climate change is becoming a worldwide emergency. In order to prevent catastrophic levels of climate change, three broad categories of action are ongoing: cutting emissions, adapting to climate impacts, and financing required adjustments. Cutting emissions requires stopping the use of fossil fuels in favor of renewable energy sources. Adapting to climate change and financing required adjustments need instruments for the understanding of the source causes and how effective the potential measures are. In this context, the use of Unmanned Aerial Vehicles for environmental monitoring is continuously increasing thanks to their ability to collect a wide range of environmental data, from the quality of air to the health status of vegetation, waters, and lands. This paper describes the research activities that are being performed for the design and development of a 100 kg Max Take Off Mass prototype zero-emission Unmanned Aerial Vehicle, named Daphne, destined for environmental monitoring, surveillance, and inspection missions. The developed prototype will drive the next industrialization of the vehicle. A particular focus is given to the design of the power system, based on the use of Proton Exchange Membrane fuel cells fueled with green hydrogen, the integration of the sensors allowing for multipurpose observations and measurements, and the design and validation of the relative multi-purpose missions via an innovative approach based on Model-Based System Engineering.

Jason Cornelius, Sven Schmitz, Jose Palacios et al.

This work details the development and validation of a methodology for high-resolution rotor models used in hybrid Blade Element Momentum Theory Unsteady Reynolds Averaged Navier–Stokes (BEMT-URANS) CFD. The methodology is shown to accurately predict single and coaxial rotor performance in a fraction of the time required by conventional CFD methods. The methodology has three key features: (1) a high-resolution BEMT rotor model enabling large reductions in grid size, (2) a discretized set of momentum sources to interface between the BEMT rotor model and the structured URANS flow solver, and (3) leveraging of the first two features to enable highly parallelized GPU-accelerated multirotor CFD simulations. The hybrid approach retains high-fidelity rotor inflow, wake propagation, and rotor–rotor interactional effects at a several orders of magnitude lower computational cost compared to conventional blade-resolved CFD while retaining high accuracy on steady rotor performance metrics. Rotor performance predictions of thrust and torque for both single and coaxial rotor configurations are compared to test the data that the authors obtained at the NASA Langley 14- by 22-ft. Subsonic Tunnel Facility. Simulations were run with both fully turbulent and free-transition airfoil performance tables to quantify the associated uncertainty. Single rotor thrust and torque were predicted on average within 4%. Coaxial thrust and power were predicted within an average of 5%. A vortex ring state (VRS) shielding phenomenon for coaxial rotor systems is also presented and discussed. The results support that this hybrid BEMT-URANS CFD methodology can be highly parallelized on GPU machines to obtain accurate rotor performance predictions across the full spectrum of possible UAM flight conditions in a fraction of the time required by conventional higher-fidelity methods. This strategy can be used to rapidly create look-up tables with hundreds to thousands of flight conditions using a three-dimensional multirotor CFD for UAM.

Andrii Morozov

The subject matter of this article is the dynamic characteristics of a composite propeller blade. Determination of the modes and frequencies of natural vibrations is necessary to predict the dangerous resonance modes of aircraft engines and to identify the most stressed local zones of the blade surface. The goal of this study is to develop a verified method for determining the dynamic characteristics of composite rotor parts of aircraft engines based on the known properties of the structural components of the composite material. A general mathematical statement of the problem of elasticity theory for the analysis of the dynamic characteristics of composite structures is described. A complete system of equations that describes the mechanical state of the body within the framework of the continuum mechanics approach was developed. Geometric modeling of the propeller blades was performed. Modeling and numerical investigation of the natural frequencies and mode shapes of the propeller blade were performed using the finite element method using the ANSYS software package. Based on the results of numerical research of the stressed and deformed state of the propeller blade, the first five natural vibration frequencies and the distribution of the local stress field were determined. The most stressed local zones on the blade surface were determined for each form of natural vibration. The propeller blade model was verified using an experimental study of the first five forms and frequencies of natural blade vibrations. The eigenfrequencies of the blade vibration were experimentally determined using the method of free (natural) vibrations. The resonance method was used to experimentally determine the resonant frequencies and vibration modes of the blade. The distribution of the blade deformation field was investigated using the strain gauge method. The highest error in the verification of numerical and experimental research is 4.11% for the fourth vibration frequency. Conclusions. The scientific novelty of the results obtained is that the effective elastic properties of the composite material for calculations should be determined using the procedure of numerical homogenisation of composite materials of different reinforcement structures by the properties of the matrix and fibers. The method does not require experimental determination of the effective elastic constants for the layers of blade components of different weave architecture patterns.

Oliver Pohling, Lorenz Losensky, Sandro Lorenz et al.

Historically, higher airspace has been used for military exercises and as transit for space vehicles. Riding on commercial space operations’ coattails, more and more vehicles are under development that will make use of higher airspace resources. This will lead to increasing interactions with conventional air traffic since these new vehicles will have to transit through lower airspaces. The management of these operations is necessary to ensure the safe and practicable shared usage of these airspaces. This paper outlines an assessment of the impact of higher airspace operations on conventional air traffic in Europe. Initially, a synthesis of possible use cases was performed, and demand scenarios were developed that served as input to a fast-time simulation. The impact on air traffic was measured by means of flight efficiency parameters. The simulation results showed that the impact is dependent on the type of operation. High-altitude platform system flights and orbital launches cause the largest deviations in flight distance, flight duration and fuel consumption. Higher airspace operation parameters, including location, time, and duration, strongly affect the impact on the conventional air traffic.

Eric Töpel, Alexander Fuchs, Kay Büttner et al.

In this work, a method is developed for the component design of chassis bushings with contoured inner cores, aided by artificial neural networks (ANNs) and design optimization. First, a model of a physical chassis bushing is generated using the finite element method (FEM). To determine the material parameters of the material model, a material parameter optimization is conducted. Based on the bushing model, different samples for a design study are generated using the design of experiments method. Due to invalid areas of the geometrical model definitions, constraints are established and the design parameter space is cleaned up. From the cleaned design parameter space, a database of several design parameter samples and three associated quasi-static stiffnesses, calculated with FEM simulations, is generated. The database is subsequently used for the training and hyper-parameter optimization of the ANN. Subsequently, the feed-forward ANN is employed in a design study, where stiffnesses are prescribed and design parameters identified. The design process is inverted with the help of a constrained design parameter optimization (DO), based on particle swarm optimization (PSO). Two usecases are defined for the evaluation of the design accuracy of the entire method. The design parameters found are validated by corresponding FEM simulations.

Defei Hou, Qingran Su, Yi Song et al.

Drones are widely used in a number of key fields and are having a profound impact on all walks of life. Working out how to improve drone safety through fault detection is key to ensuring the smooth execution of tasks. At present, most research focuses on fault detection at the component level as it is not possible to locate faults quickly from the global system state of a UAV. Moreover, most methods are offline detection methods, which cannot achieve real-time monitoring of UAV faults. To remedy this, this paper proposes a fault detection method based on a fault mode database and runtime verification. Firstly, a large body of historical fault information is analyzed to generate a summary of fault modes, including fault modes at the system level. The key safety properties of UAVs during operation are further studied in terms of system-level fault modes. Next, a monitor generation algorithm and code instrumentation framework are designed to monitor whether a certain safety attribute is violated during the operation of a UAV in real time. The experimental results show that the fault detection method proposed in this paper can detect abnormal situations in a timely and accurate manner.

Jubilee Prasad-Rao, Olivia J. Pinon Fischer, Neil C. Rowe et al.

The cost to train a basic qualified U.S. Navy fighter aircraft pilot is nearly USD 10 M. The training includes primary, intermediate, and advanced stages, with the advanced stage involving extensive flight training, and, thus, is very expensive as a result. Despite the screening tests in place and early-stage attrition, 4.5% of aviators undergo attrition in this most expensive stage. Key reasons for aviator attrition include poor flight performance, voluntary withdrawals, and medical reasons. The reduction in late-stage attrition offers several financial and operational benefits to the U.S. Navy. To that end, this research leverages feature extraction and machine learning techniques on the very sparse flight test grades of student aviators to identify those with a high risk of attrition early in training. Using about 10 years of historical U.S. Navy pilot training data, trained models accurately predicted 50% of attrition with a 4% false positive rate. Such models could help the U.S. Navy save nearly USD 20 M a year in attrition costs. In addition, machine learning models were trained to recommend a suitable training aircraft type for each student aviator. These capabilities could help better answer the need for pilots and reduce the time and cost to train them.

Pavlo Lukianov, Lin Song

The subject of this study is the flow development region of laminar incompressible fluid flow in the boundary layer. This flow is an example where a direct application of the Navier-Stokes equations of gradient-free laminar incompressible fluid flow, in which the molecular viscosity is assumed to be a constant value independent of spatial coordinates, leads to a redefinition of the mathematical model. It is about the fluid boundary layer in the region of flow establishment in the motion problem of a semi-infinite plane, where the pressure gradient is zero. There is a situation when the number of equations is equal to three (two equations of momentum conservation and the equation of continuity), and the number of unknowns is equal to two - the number of the speed component. As a logical solution to the obtained inconsistency, it is proposed, as was already done for the problem of stationary motion of a plane and the problem of acceleration of a plane, to depart from the false statement about the constancy of molecular viscosity in the gradient-free boundary layer of an incompressible flow and consider molecular viscosity as a function of spatial coordinates. The need to consider the variable nature of molecular viscosity led to the discovery of another flaw in the Navier-Stokes theory. This non-trivial flaw was discovered during the application of the original numerical analytical method for solving the flow development region problem. The Navier-Stokes equations are supplemented by boundary conditions. The most important condition is the condition of fluid non-slipping on the surface of a solid body, which, by the way, does not follow any physical law. As a result, on the surface of a half-plane (or a moving body), the component of the velocity, which coincides with the direction of motion, has a constant value equal to the velocity of the body.  It immediately follows from the continuity equation that the normal derivative of the normal component of the velocity must be equal to zero along the surface of the plane (body), since the longitudinal derivative of the velocity becomes zero. However, it is quite obvious that the velocity component normal to the surface of the plane (body) changes across the boundary layer in the region of current development, which indicates the presence of a normal gradient (both components) of the velocity. The conflict or contradiction is overcome by moving away from the generally accepted condition of non-slipping to the condition of partial non-slipping, or essentially the presence of sliding. Even with the sudden braking of any vehicle, the complete stop does not occur instantly, but after some finite time and distance, so in the case of the motion of a body in a stationary fluid, there is not an instant sticking, but a gradual one - from complete sliding, when a particle of liquid has just met a moving plane (body), to complete non-slipping at the end (and further) of the flow development region. Research methods. This work uses purely theoretical methods based on the use of calculus of variations, laws of physics, and ideas from everyday life. Conclusions. An improved model of a viscous Newtonian fluid in the area of flow development in the boundary layer was derived. On the basis of assumptions about the variable nature of the molecular viscosity, which already has two components, and the departure from the non-slipping condition, analytical solutions for both components of the velocity and both components of the molecular viscosity were obtained. A comparison of the obtained results with the results of other studies is presented.

FU Xiaowei, XU Zhe, WANG Hui

UAVs pursuit evasion game is a research hotspot in the field of air combat. Traditional solutions have many limitations to this problem, such as the difficulty of the model to adapt to complex dynamic environments to quickly make decisions, and the poor generalization of different mission scenarios. Based on the DDPG(deep deterministic policy gradient) algorithm, a mathematical model of UAVs pursuit and evasion countermeasures is established in this paper. On this basis, this research designs a variety of countermaneuver strategies for escaping UAV, and uses the training method of course learning ideas. In the training process, the intelligence of the escaping UAV is gradually improved, so as to progressively train the confrontation strategy of the chasing UAV. The simulation results show that compared with direct training, the pursuit strategy of the chasing UAV trained by the research method of course learning can converge faster, and can better perform the hunting mission of enemy aircraft, and can be applied to a variety of enemy aircraft with a variety of maneuvering strategies, which effectively improved the generalization of the UAV′s pursuit and escape confrontation decision model.

Quanbing Sun, Zhiwei Shi, Weilin Zhang et al.

Circulation control (CC) is used extensively to control the attitude of rudderless aircraft experiencing ground effect in take-off and landing phases. The investigation of ground effect on airfoil CC is necessary to improve flight performance and quality in proximity to the ground. The aerodynamics and flow field of a modified NACA0012 airfoil with CC in ground effect are investigated with numerical simulations. The compressible Reynolds-averaged Navier–Stokes equations with the shear-stress transport k−ω turbulence model equations are solved using the Finite Volume Method (FVM). Simulation results show that the ground effect changes the lift increment per unit jet momentum coefficient, and CC can reverse the polarity ground effect. The effective angle of attack αE and the downwash space downstream airfoil are altered by the ground effect resulting in variations of airfoil surface pressure and lift. Unlike the unbounded flow field, the jet attachment distance is not only determined by the jet momentum coefficient but it can change with the ride height, which is the distance from the ground to the center of the semicircular Coanda surface, for the same jet momentum coefficient.

Dmitrii LOMONOSOV, Dmitrii ZHURAVLEV, Mikhail SHAPAR et al.

The relevance of the study is conditioned by the wide occurrence of situations in which diesel fuel, during its storage and transportation, reacts with the environment, resulting in its oversaturation with moisture and a decrease in a number of characteristics that are of fundamental importance in the process of practical use, which necessitates the development and practical implementation of a special device that allows determining the moisture content in diesel fuel before its use. The purpose of this study is a theoretical assessment of the prospects for the development of such a device and its practical use, including an assessment of its main technical characteristics that are essential from the standpoint of practical use for measuring the moisture content of diesel fuel in various branches of its application. The leading approach is a combination of a theoretical investigation of the prospects for the development and technical improvement of a device for measuring the moisture content of diesel fuel with a systematic analysis of the main aspects of the effectiveness of its practical application. The results obtained indicate the significant importance of qualitative measurement of the parameters of the moisture content of diesel fuel and the need to use special devices to ensure the high quality of such control. The results and conclusions of this study are of significant importance for developers of special devices designed to measure the moisture content of diesel fuel and for employees of technical services whose duties include monitoring the condition of diesel fuel before its direct use and evaluating its parameters that are of fundamental importance from the standpoint of the safety of its further use.

Kirsty Veale, Sarp Adali, Jean Pitot et al.

Paraffin wax has been identified as a hybrid rocket motor fuel, which offers enhanced regression rates and improved combustion performance. While various investigations into the performance of this class of fuels are being conducted around the world, the consideration of its structural performance is often overlooked. The research presented here establishes a simplified, yet accurate method of defining the structural performance of a paraffin wax hybrid fuel grain to be introduced early in the design phase of a motor. The use of the Johnson–Cook (J–C) material model has been verified to work within the “low speed” ignition range experienced in paraffin wax/N2O hybrid motors, and therefore is used to predict failure in a variety of motors. The resultant stress profiles within the grains indicate that the grain outer to inner diameter (OD/ID) ratio, as well as the outer diameter (OD) itself, play an important role in the grain ability to withstand the loading conditions applied. Additionally, the grain structural properties, and the stiffness of the combustion chamber affect the severity of the internal stresses in the grain. The feasibility of large-scale pure paraffin wax grains without structural enhancement additives is thus found to be poor. Fuel additives should be considered for structural enhancement.

I. L. Krikunov, K. E. Gaipov

Nowadays many modern industries depend on satellite technologies to a greater or lesser extent. To build such satellite communication systems it is necessary to have estimated parameters of high service quality, one including the information delay time. To implement a mathematical model of traffic distribution in a satellite network, such analytical expressions for time delays are used, which have a discontinuity of the second kind at the moment when the arrival rate becomes equal to the service rate. Removal of this discontinuity can reduce the time required for calculating optimal routes. To achieve this goal, a piecewise linear approximation is used. As a way of specifying line segments, two approaches are considered, which are compared using the integral least squares method and the issue of the number of lines used in the conditions of the problem is also considered. As a result, approximation dependences were obtained, which allows plotting a piecewise-linear function of the mean waiting time in the buffer for the M/M/1 system. The procedure for finding the optimal parameters for this function is described and the analytical method was used to obtain approximate formulas for finding the tangency points of depending on the incoming traffic intensity.

Juan G. Arango, Robert W. Nairn

The purpose of this study was to create different statistically reliable predictive algorithms for trophic state or water quality for optical (total suspended solids (TSS), Secchi disk depth (SDD), and chlorophyll-a (Chl-a)) and non-optical (total phosphorus (TP) and total nitrogen (TN)) water quality variables or indicators in an oligotrophic system (Grand River Dam Authority (GRDA) Duck Creek Nursery Ponds) and a eutrophic system (City of Commerce, Oklahoma, Wastewater Lagoons) using remote sensing images from a small unmanned aerial system (sUAS) equipped with a multispectral imaging sensor. To develop these algorithms, two sets of data were acquired: (1) In-situ water quality measurements and (2) the spectral reflectance values from sUAS imagery. Reflectance values for each band were extracted under three scenarios: (1) Value to point extraction, (2) average value extraction around the stations, and (3) point extraction using kriged surfaces. Results indicate that multiple variable linear regression models in the visible portion of the electromagnetic spectrum best describe the relationship between TSS (R² = 0.99, <i>p</i>-value = &lt;0.01), SDD (R² = 0.88, <i>p</i>-value = &lt;0.01), Chl-a (R² = 0.85, <i>p</i>-value = &lt;0.01), TP (R² = 0.98, <i>p</i>-value = &lt;0.01) and TN (R² = 0.98, <i>p</i>-value = &lt;0.01). In addition, this study concluded that ordinary kriging does not improve the fit between the different water quality parameters and reflectance values.

G. A. Kryzhanovskii, V. P. Maslakov, I. A. Ilinykh

The necessity of using of heuristic methods take account of uncertainties in each of the transport company activities when choosing a rational variant of the vector control of dynamic processes related to performance indicators, built on the basis of poly-criteria evaluation.

D. B. Rychenkov

The article discusses the selection of functionally important elements of aircraft avionics using the procedures of MRB and AVPO.