Aerodynamic Drag Research Articles

Experimentally detected aerodynamic drag coefficient of the agricultural tractor form considering effects of windshield angle and hood front shape

Agricultural tractors are improving their capacity, speed, and performance. However, the characteristic form of the agricultural tractors is not known in terms of aerodynamics. This is required in modeling transportational duties and their impacts on energy and environment, especially considering tractor-trailer couples. In this work, this characteristic form solely investigated apart from the couple to base a foundation. The geometry was adapted from a commercial model. The model was simplified greatly to isolate numerous parameters yielding a generic shape. Only geometrical features as parameters were selected as the nose shape as the leading surface and the windshield angle. Scaled models were tested in a wind tunnel. Drag coefficients independent from Reynolds number, drag forces, pressure distributions on the symmetry planes and pressure coefficients were obtained. An extrapolation was made in order to predict drag force related fuel consumption and CO2 emission for a full-scale tractor on-road transportation scenario based on experimentally obtained drag coefficient. It is understood that changes in tractor front surface topology and wind shield angle can lead to drag changes up to 3%. A 0.72 value of drag coefficient may be assumed for the generic agricultural tractor form. Based on this value, an on-road agricultural tractor cruising with 70 km h−1 is predicted to have a drag sourced fuel consumption of 3.9 kg h−1 and CO2 emission of 10.19 kg h−1. Tractor trailer couples and their platoons are of interest in terms of research and computational simulations that may utilize present results as validator.

THE KEY ROLE OF MODERN AERODYNAMIC TRENDS IN INCREASING THE ENERGY EFFICIENCY OF HIGH-SPEED VEHICLES

Based on the analysis of typical operating modes of modern high-speed trains and transport aircraft, the influence of various schemes of surface relief modification and blowing through it on aerodynamic drag has been thoroughly investigated. A set of several schemes of the combined effect of these two factors is proposed to create an easy-to-use, cheap-to-produce streamlined surface of the desired structure with a reliable and controllable effect of active influence on aerodynamic drag reduction. The potential effect of reducing aerodynamic drag has been verified by numerical and Particle Image Velocimetry experimental modeling. The proposed technological innovations are encouraging and relevant; by reducing energy costs, they increase the commercial and environmental attractiveness of their implementation.

Development of the Universal Air Collector Design for Measuring the Flow Rate of Swirling Air Flow Using an Integral Thermoanemometer

Measurement of the swirling air flow rate and average speed of air at air distribution units of ventilation systems is a rather difficult task due to the fact that the air flow enters the measuring device at different angles. As a result, significant measurement errors can occur when using point thermoanemometers or other flow meters. The use of integral anemometers facilitates the measurement process. However, it is necessary to eliminate the errors associated with changes in the angle of the air flow to the sensing element of the measuring device. To do this, it is necessary to ensure a rectilinear structure of the air flow using a transitional air collector and rectifier. The aim of this paper is to develop a design of an air collector device that will allow to measure the flow rate of a swirling air flow. The objectives of the paper are to optimize the geometrical parameters of the air collector to ensure a rectilinear flow, minimize its dimensions and aerodynamic drag. The correctness of the air collector design was evaluated by matching the calibration characteristic of the probe of an integral thermoanemometer in the presence of a vortex diffuser in front of the air collector and in its absence. The proposed device has a rectangular shape and consists of a receiver, a rectifying grid, a chamber, an accelerating and stabilizing section, at the outlet of which a thermoanemometer probe is installed. The receiver and the accelerating section are tapered along their length, while the chamber and the stabilizing section have a constant cross-section. The rectifying grid is installed inside the chamber and has a square-shaped honeycomb structure. Several options of the air collector design with different geometrical parameters were studied using computer modelling. The dependence of aerodynamic drag on air flow was plotted. The optimal design of the air collector was chosen, for which a life-size physical model was created. The calibration characteristics of the measuring probe with an air collector were experimentally obtained when a swirling air flow was applied. The developed universal air collector allows the air flow rate measurement at the outlets of almost any air distribution devices of ventilation systems of buildings.

Enhanced Aerodynamic Performance of a Two-Dimensional Airfoil Using Moving Boundaries

The effects of moving boundary conditions on the aerodynamic performance of a two-dimensional NACA 0012 airfoil at different angles of attack (α) in a uniform freestream at a Reynolds number of 10,000 are numerically studied. The moving boundary conditions are motivated by inviscid potential flow around the airfoil, which also satisfies the viscous equations of motion. In this study, the wall is moved at the slip velocity of the inviscid flow, or a fraction of it. These prescribed moving boundary conditions are shown to suppress vortex shedding, thus allowing the drag to go toward zero and the lift coefficient toward 2πα over a wide range of angles of attack (α≤20°) even in the separated flow regime. It is shown that moving boundary conditions are effective over a wide range of their strengths with respect to the overall power required (required to overcome aerodynamic drag and move the airfoil boundary). This power is shown to attain a minimum near the inviscid flow moving boundary condition, which is around 10% or less of the power required for the stationary boundary condition. Finally, the effectiveness of the moving boundary conditions is demonstrated for fully turbulent flow regimes at Re=6 million as well.

Flow properties of an Ahmed Body with different passive flow control methods

A numerical simulation by utilizing the FloEFD software was carried out in order to investigate the flow topology formed on slant surface and wake region of an Ahmed Body with and without passive flow control techniques. The effects of those flow controllers on flow at the slant surface and wake region by influencing the flow topology as well as aerodynamic drag coefficient examined carefully. The numerical findings clearly revealed that the best performance in terms of providing the drag reduction obtained when sphere and hemispherical shape flow control techniques were applied at the rear part of slant surface of Ahmed Body. Sphere and hemispherical shape flow controllers positioned at the rear part of slant surface led to have drag reduction of 6% and 7%, respectively. Besides, the results of current study compared with the results obtained from published studies in the literature. It was clearly observed that they are consistent with each other even though they were found by different software.

Physico-Mechanical Properties of Pumpkin Seeds in the Context of Drying Processes

The paper highlights the significance of the drying process in post-harvest cucurbit seed treatment technology. To improve the effectiveness of drying high-moisture seeds, a plant construction design was introduced, incorporating the concept of providing varied heat distribution to a vigorously agitated seed layer. The paper validates the necessity of refining the dimensional, frictional, and aerodynamic properties of pumpkin seeds to determine the optimal operating modes for the proposed dryer. (Research purpose) To identify the physical and mechanical properties of pumpkin seeds by defining their dimensional, frictional and aerodynamic characteristics. (Materials and methods) The study employs one-factor experimental research methods with subsequent statistical data processing. An experimental study was conducted on the physical and mechanical properties of Volzhskaya Grey pumpkin seeds possessing a standard moisture content ranging between 9.3 and 9.7 percent. Well-known laboratory apparatuses, namely the «conical tank» and the «inclined plane», were used to determine the natural repose angle and to enhance the accuracy of friction coefficients determination. For analyzing the aerodynamic properties of the seeds, the K-293 Petkus air separator was employed. (Results and discussion) Research methods were developed and experimental plants were described. It was established that with a probability confidence level of 0.95, the static friction coefficients of pumpkin seeds on a solid steel sheet, a perforated steel sieve and on rubber are 0.473, 0.418, 0.481, respectively, and the dynamic friction coefficients under the identical conditions are measured as 0.331, 0.293, 0.337. The average angle of natural repose is found to be 22 degrees, the midsection area is 97.94 square millimeters, the soaring velocity is 7.083 meters per second, the windage coefficient stands at 0.196 and the aerodynamic drag coefficient is 0.136. (Conclusions). The assumption that enhancing the drying efficiency of vegetable seeds can be achieved by implementing a diverse thermal energy supply to continuously moving mass inside the apparatus is confirmed, provided that the seeds do not stick together in layers resulting in blockage of the coolant flow. An improved design of the dryer configurations has been developed and, to validate its optimum design and technological specifications, an in-depth analysis of the seeds' dimensional, frictional, and aerodynamic attributes has been conducted.

Numerical simulation of rigid-flexible coupled dynamics for an inflatable sphere deorbiting device

Inflatable spheres can be applied to the aerodynamic drag deorbiting device for satellites. It may bring about a complicated dynamic problem under the disturbance from the lightweight large-volume inflatable sphere to the satellite. In order to explore this problem, rigid-flexible coupled dynamics behaviors of satellite-sphere system during inflating process are numerically studied in this paper. The folding pattern of inflatable sphere is designed to obtain the parametric model in the folded state. The dynamic analysis model of this system is established to analyze dynamic behaviors, including the dynamics of the satellite-sphere system, the gas state of the airbag and the disturbance to the satellite, during the inflating process. Parameter effects on the attitude disturbance are studied. The results show that the satellite mass, inflating mass rate and control torque have a great impact on the attitude disturbance. These works provide theoretical bases and technical supports for the engineering development of inflatable sphere deorbiting devices.

Magnetic Attitude Control Scheme for Drag Sail Deorbiting with Limited Sensors

As concerns over space debris in the Low Earth orbit (LEO) intensify, deorbit strategies for small satellites becomes evident because many lack an effective deorbit mechanism. After successfully demonstrating their effectiveness in flight tests, aerodynamic drag sails emerge as a superior deorbit solution, significantly reducing the time required for deorbiting. To maximize the aerodynamic drag, it is crucial to maintain the drag sail perpendicular to the atmospheric flow. This becomes especially challenging with the potential threat of sensor failure. This paper introduces a magnetic control scheme for deorbiting using drag sails. Relying solely on magnetometers as sensors, the control scheme uses magnetorquers, bias momentum wheels, and an onboard geomagnetic field model to keep the sail perpendicular to the satellite’s velocity. Furthermore, a backup control scheme that does not require the onboard geomagnetic field model is proposed. This control scheme uses magnetometers in conjunction with just another common small satellite sensor, such as the GPS, gyroscopes, or sun sensors as sensors. A stability criterion, based on a linearized analytical model, validates the feasibility of this backup control scheme. Numerical simulations confirm the efficacy of both control schemes. Both schemes reduce the deorbit time by approximately 40% compared to the uncontrolled satellite deorbiting.

Experimental and numerical investigations of austenitic stainless steel semi-oval hollow sections under combined compression and bending

Semi-oval hollow section is an innovative cross-section profile, including one semi-circular flange, one flat flange and two flat webs. While the semi-circular flange (exposed to fluid or wind) offers a low level of hydrodynamic or aerodynamic drag, the flat elements facilitate connections with other members. This paper presents experimental and numerical investigations into the local buckling behaviour and resistances of austenitic stainless steel semi-oval hollow sections under combined compression and bending. A testing programme was firstly conducted and included initial local geometric imperfection measurements and ten eccentric compression tests. In conjunction with the testing programme, a numerical modelling programme was performed, where finite element models were developed to validate against the test results and conduct parametric studies for expanding the test data pool over a wider range of cross-section dimensions and loading combinations. The obtained test and numerical data were used to evaluate the applicability of the relevant design interaction curves for austenitic stainless steel rectangular hollow sections, as prescribed in the European code and American specification, to austenitic stainless steel semi-oval hollow sections. On the basis of the evaluation results, the codified design interaction curves were found to provide conservative resistance predictions. Finally, an improved design interaction curve, with more accurate end points and suitable shape, was developed and led to more accurate and consistent resistance predictions for austenitic stainless steel semi-oval hollow sections under combined compression and bending.

Experimental study on the aerodynamic characteristics of combined angle transmission tower subject to skew wind

The transmission towers served as crucial carriers in the process of power transmission. The combined angle transmission tower of dual-angle steel with cruciform section are relatively a novel type of angle tower, which is being more widely used in transmission lines. The studies on aerodynamic characteristics of combined angle tower in skewed wind are limited. In this paper, the wind tunnel tests are conducted to investigate the aerodynamic characteristics of the combined angle tower, and the high frequency force balance (HFFB) test is introduced to obtain the transverse and longitudinal forces on the tower using the direct force measurement (DFM) method. The drag coefficients and wind load-distribution factors of the combined angle tower are obtained from the wind tunnel tests, and the effects of interference and tower leg spacing on the wind loads of the tower legs are fully explored. It can be found that the aerodynamic coefficients and drag coefficients of the combined angle steel tower leg tend to decrease with the increase of interference members and it also decreases with the decrease of the tower leg spacing. The test wind load-distribution factors of the isolated leg are generally larger than those defined by seven typical codes (e.g., US, EU, Japanese, and Chinese codes) and significantly exceed the code-specified values under partial wind angles. The observations obtained from this study may provide helpful guidance on the wind-resistant design of this relatively novel type of combined angle tower.

A stacking-based ensemble prediction method for multiobjective aerodynamic optimization of high-speed train nose shape

A stacking-based ensemble prediction method is proposed in order to improve the efficiency and accuracy of aerodynamic shape optimization. This can be divided into a two-level model. The first-level model uses various base learners to predict the training dataset and obtain various combinations of predictions. In the second-level model, the meta-learner is trained using various combinations of predictions as inputs and the true response values as outputs. The RMSE and R-Square metrics results show that the performance metrics of the stacked models are significantly better than those of the original surrogate models, except for the stacked RBFNN model. The stacked Kriging model and LSSVR model achieved the best results with RMSE and R-Square index values of 0.0039 and 0.8418 for aerodynamic drag coefficient, respectively. The stacked Kriging model, RBFNN model, and LSSVR model achieved the best results with RMSE and R-Square index values of 0.0024 and 0.76 for aerodynamic lift coefficient, respectively. Four state-of-the-art multiobjective optimization algorithms are used to perform the optimization process. The results of hypervolume and Pareto fronts demonstrate the effectiveness of the selected FDV-NSGAII algorithm. After optimization, the drag and lift coefficients before and after optimization are reduced by 1.9% and 12.7%, respectively.

Erosion characteristics of water droplet machining

Water Droplet Machining (WDM) is a new manufacturing process, which uses a series of high-velocity, pure-water droplets to impact and erode solid workpieces, for the purpose of through-cutting, milling and surface profiling. The process is conducted within a vacuum environment to suppress aerodynamic drag and atomization of the waterjet and droplet train. This preserves droplet momentum and allows for a more efficient transfer of energy between the water and workpiece, than in standard atmospheric pressure. As a new manufacturing technique, parameter-specific details and characteristics of this process are absent from the scientific literature. Therefore, this study aims to elucidate the capabilities of WDM, and uncover its erosion characteristics. Experiments are performed using a custom-fabricated machine, where a range of waterjet-types (and droplet trains) are produced. The experiments are performed on two industrial-relevant metals: stainless steel SS 316 L and aluminum AA 6022-T4. The target shape is a partial-cut through the material, i.e., a trench. A parametric study investigates the effects of stand-off distance, orifice diameter, and feed-rate on the trench shape, material-removal-rate, and reveals the conditions which render WDM an effective machining process. It was found that, for orifice diameters of 100 μm, an effective stand-off distance is between 457 and 686 mm; below that, no material removal is observed. In this configuration, accurate through-cuts are produced and can be used for manufacturing purposes. For large orifice diameters, e.g., 250 μm, an atomized spray is produced, which features a comparatively large material removal rate, and can be used for surface profiling and milling.

Transient aerodynamic behavior of a high-speed Maglev train in plate braking under crosswind

The test speed of high-speed maglev trains (HSMT) exceeds 600 km/h, requiring higher braking performance and technology. Plate braking technology, which is a suitable choice, has been applied for engineering the high-speed test vehicles. However, the unsteady aerodynamic response during the opening process of HSMT under crosswind needs to be studied. This study explores the unsteady aerodynamic characteristics of a HSMT with a train speed of 600 km/h during plate braking at different crosswind speeds. The plate motion is achieved based on the dynamic grid technology, and the unsteady flow field around the train is simulated using the unsteady Reynolds time averaged equation and the shear stress transport k-omega (SST k–ω) turbulence model. This calculation method was verified using wind tunnel test data. The peak aerodynamic drag (AD) of the braking plates overshot during opening. Under a crosswind of 20 m/s, the AD peak of the first braking plate was 11% larger than that without crosswind. The middle braking plates were significantly affected by upstream vortex shedding, and the AD fluctuation was the most severe. The AD of the head and tail coaches is significantly affected by crosswind. With an increase in the crosswind speed, the AD of the head and tail coaches decreased and increased, respectively. Compared with no crosswind, under a crosswind of 20 m/s, the AD of the head coach decreased by 43%, and the AD of the tail coach increased by a factor of approximately 1.1 times. Furthermore, the AD fluctuation of the tail coach was the most severe.

Primary breakup model development for trajectory prediction of liquid jets in subsonic crossflow

A comprehensive theoretical model for the primary breakup of liquid jets in subsonic crossflow was developed. The model theoretically analyzed the jet deformation process, mass stripping process, and the influence of several critical forces and consequently provided highly accurate predictions of the jet trajectory. Deformation of the liquid jet cross section was considered as a two-stage process based on the physical characteristics, including the spring-mass analogy deformation and the mass stripping induced deformation. The mass stripping process was modeled as an exponential function of time based on experimental findings for liquid jets and droplets. Balance of critical forces acting on the jet were analyzed, both along the gas and jet flow directions, which included aerodynamic drag, viscous force, surface tension, and gravitation. The model provided precise prediction to the jet trajectory against experimental data without any initial jet velocity assumption across a wide range of gaseous Weber numbers and gas to liquid momentum ratios. In addition, quantitative effects of viscous force, surface tension force, and aerodynamic drag on jet trajectory were fully investigated based on the new model, which provided more insight into jet breakup characteristics and the effects of fuel properties on jet trajectory and deformation. Furthermore, the three-dimensional structure of the jet was reconstructed through the present model, which matched well against numerical results. Importantly, the current mathematical primary breakup model could be integrated with Lagrangian methods, obtaining more detailed vortex structures and accurate droplet dispersion with reduced computational time.

Kriging-based multi-objective optimization on high-speed train aerodynamics using sequential infill criterion with gradient information

For models with large numerical simulation costs, such as high-speed trains, using as few samples as possible to construct a high-precision surrogate model during aerodynamic multi-objective optimization is critical to improving optimization efficiency. This study proposes a sequential infill criterion (SIC) appropriate for the Kriging surrogate model to address this issue. Three multi-objective functions are employed to test the feasibility of constructing a surrogate model based on SIC, and the SIC surrogate model then performs multi-objective aerodynamic optimizations on the high-speed train. The findings indicate that the expected improvement infill criterion (EIC) in the first stage can enhance the global prediction accuracy of the SIC. An infill criterion based on EIC that fuses gradient information (PGEIC) in the second stage is proposed to seek samples in the Pareto front. The PGEIC surrogate model achieves the lowest generational distance and prediction error. The performance of EIC for global search, EIC for Pareto front search, and infill criterion for Pareto front search using only gradient information is poor. The final PGEIC–SIC surrogate model of train aerodynamics has less than 1% prediction error for the three optimization objectives. The optimal solution reduces the aerodynamic drag force of the head car and the aerodynamic drag and lift force of the tail car by 4.15%, 3.21%, and 3.56%, respectively, compared with the original model. Furthermore, sensitivity analysis of key parameters revealed that the nose height v1, cab window height v3, and lower contour line have a greater impact on aerodynamic forces. Moreover, the nose and cab window heights of the optimal model have been reduced, and the lower contour line is concave. Correspondingly, the streamlined shape appears more rounded and slender.

Aerodynamic means of reducing the influence of warning accessories on drag and emissions, for intervention vehicles

Aerodynamic performance of passenger vehicles is one of the most efficient methods to further reduce the CO2 emissions and comply with the increasing constraints in the legislation. Previously performed studies on exterior warning accessories (systems with visual alerting signals that may be found on intervention vehicles e.g. ambulances), indicate a significant degradation of aerodynamic coefficient (Cd). Even if this category of vehicles does not have to comply with the standard emission rules, it is important to study and discover the means to reduce aerodynamic drag for this type of vehicles considering the general aim to reduce air pollution. The target would be to have a Cd level equal to that found in the base vehicles, before transformation (i.e. often, intervention vehicles are obtained by converting a vehicle available to general customers - multistage vehicle transformation).The current paper’s purpose is to continue the investigation on methods to improve the aerodynamic performance of intervention vehicles. This will be done by compensating the shape and dimensions of the warning devices with the addition of supplementary body elements or by adapting existing parts. The Cd value of the different configurations is assessed using computational fluid dynamics (CFD) software based on Lattice Boltzmann mathematical model. 3D models of different generic body type vehicles (sedan, hatch back, SUV) were created and immersed in a virtual wind tunnel. To simulate the real-world measurement method specific boundary conditions on walls, inlets, outlets were set while the fluid environment was defined with a network from fine (2mm length, near the studied model), to coarse (20mm length, near exterior walls).The results indicate that there is great potential in reducing the aerodynamic drag and, by extension, fuel consumption and CO2 emissions for all body types studied. Deviations could exist due to different make designs, or diversity of warning devices for example so the results obtained have a general nature. Nevertheless, the conclusion remains the same: if one’s aim is to improve air quality or prepare for new legislation (that will also apply to intervention vehicles), the aerodynamic optimization should be further scrutinized as it can prove to be a robust method to obtain the targeted results.

Various Blowing-Suction Schemes for Manipulating Turbulent Boundary Layers

ABSTRACT The methodology of efficiency analysis of turbulent flow modification by making permeable sections in the streamlined wing surface with the aim to reduce aerodynamic drag is the principal subject of the presented research. The numerical analysis of the effect of laterally and longitudinally located permeable sections on boundary-layer properties showed the following flow features: (1) the most effective place for permeable surface is an upwind side of the wing; (2) multi-sectional blowing can simply be organised as non-uniform (especially in the case of laterally arranged permeable sections) that brings additional flexibility to change the blowing intensity depending on flight mode and, first of all, on angle of attack; and (3) arrays of longitudinal permeable sections allow to intensify turbulent vortical structures exchange in the lateral direction and improve flow stability to stall. Moreover, due to creating the regular anisotropy of the boundary layer in the lateral direction, this modified blowing technique can potentially have some synergistic properties, which can give the additional benefit. All these effects are too delicate and their experimental study cannot be performed with the use of directed measurements of aerodynamic forces. The comparison of the obtained flow properties with the corresponding experimental data demonstrates an appropriate level of agreement.

Backspin in Ruellia ciliatiflora does not maximize seed dispersal range, but provides moderate dispersal range thatisrobust to launch conditions.

Ruellia ciliatiflora is a perennial herb whose fruits explosively dehisce, launching their thin disc-like seeds over 6 m with a backspin up to 1660 Hz. Whileithas been previously shown that the backspin launch orientation minimizes the aerodynamic drag experienced by the seeds, it is not immediately obvious whether backspin is also the range-maximizing launch orientation. Here the three-dimensional equation of motion of a thin, spinning disc flying through a fluid medium was derived and solved numerically to simulate the flight of seeds of R. ciliatiflora under different launch conditions. Simulations of seed flights reveal that the range-maximizing launch orientation lies between sidespin and topspin, far from the backspin that is observed in nature. While this range-maximizing orientation results in dispersal ranges of nearly 10 m, the precise orientation is highly sensitive to other launch parameters, chiefly spin rate and launch angle. By contrast, backspin, which yields moderate dispersal ranges about 60% of the range-maximizing orientation, is robust to perturbations in launch parameters that the plant cannot precisely control.

Determination of the features of integrated design of civil long-range aircraft with transonic truss-braced wing at the preliminary design stage

The object of research is a civil mainline aircraft with a transonic truss-braced wing. The problem of designing an aircraft of this scheme at the preliminary design stage is being solved in the work. The results of the work include the concept of designing aircraft with a transonic truss-braced wing, the main advantages of such a scheme, the process of determining the geometric parameters of the truss-braced, features of the preliminary design of an aircraft with an extremely high aspect ratio truss-braced wing, possible approaches to the arrangement of units and their mutual arrangement. The results are explained by the difference in the design model (the cantilever beam is replaced by a beam on two supports) in mass analysis and the increased wing aspect ratio in aerodynamic calculation. The final data are based on a statistical study to determine the basic geometric parameters of assemblies of modern mainline passenger aircraft, synthesis of parameters of analog aircraft. For example, an aircraft capable of carrying 250 passengers over a distance of 13.000 km is considered. In the design process, values of aspect ratio, taper ratio, wing area, vertical tail and horizontal tail area ratio, and fuselage dimensions are accepted. Drawings of the general appearance of the aircraft have been developed and, based on it, a master geometry of the theoretical contour has been constructed. Graphs of first-order polar and maximum lift-to-drag ratio have been plotted, the reduction of aerodynamic drag in percentage terms has been determined, and the increase in aerodynamic lift-to-drag ratio in percentage terms for an aircraft with an extremely high aspect ratio truss-braced wing compared to similar characteristics of an aircraft with a conventional non-braced wing has been calculated. The approximate mass savings when using a truss-braced wing on the aircraft are determined in percentage terms. The expediency of using wings of greater aspect ratio, than modern aircraft currently have, has been justified. The expediency of using a brace for the aircraft with an extremely high aspect ratio wing has been justified. The obtained results can be used in practice in the process of developing the preliminary design of an aircraft with a truss-braced wing or in the modifications of existing aircraft to increase their fuel efficiency or increase the durability of wing elements due to reduced loads acting on them.

Вплив геометричних параметрів автопоїзда на його аеродинамічні характеристики

In the article, the authors analyzed the relevance of the research topic, defined the goal, task, subject and object of the research. They also provided an analysis of well-known studies related to the study of the peculiarities of the formation of air resistance during the movement of motor vehicles. On the basis of the analysis of known studies on the factors affecting the geometric parameters of road trains on aerodynamic resistance, the relevance of the studies is substantiated, and their purpose and tasks are formulated.The purpose of the article is to determine the influence of geometric parameters of road trains on their aerodynamic characteristics and, as a result, on fuel consumption, and therefore on the cost of transport work. The tool for researching this issue is software, which will be used to conduct a number of experiments. Every year, road trains move millions of kilometers of various goods, and on such a scale, the price of each individual kilometer plays a very important role. Based on the analysis of the power balance equation, it can be concluded that a significant part of the engine power is spent on overcoming air resistance, and the higher the speed of the road train, the greater this resistance.The relevance of research lies in the possibility of reducing costs through the adoption of a number of decisions to reduce the aerodynamic resistance of road trains.The mechanism of air resistance is considered. It has been found that reducing aerodynamic drag is a very important task, as every 2% reduction in vehicle drag results in a 1% improvement in fuel economy. Compared to passenger cars, trucks have a much larger cross-section and more clumsy outlines. This is caused by the specifics of their purpose and use. When creating a universal truck, they try to get as much volume as possible to accommodate cargo with the minimum area occupied by the car on the road, and since part of this area is the engine and cabin, it is natural that the body is high. So, if one of the ways to reduce the aerodynamic resistance of a passenger car is to reduce its cross-section, first of all, its height, then another option should be found for a highway truck or road train.