Influence Of Crosswind Research Articles

Numerical Investigation of Large Vehicle Aerodynamics Under the Influence of Crosswind

This paper presents a numerical analysis aimed at estimating the impact of crosswinds on the aerodynamics of large vehicles using ANSYS Fluid Flow and Static Structural, offering insights into the qualitative behaviour of trucks under typical traffic conditions. The cases analysed focus on airflow distribution when a truck, traveling at approximately 100 km/h, passes under a portal while exposed to varying crosswind intensities: weak, moderate, and strong lateral winds. A detailed examination of the truck and portal reveals significant interactions between the induced airflow patterns, affecting truck handling and stability. This is evidenced by shifts in velocity and pressure distributions, changes in drag coefficients, and variations in turbulent kinetic energy, all of which are analysed and discussed in this study.

Unmanned aerial vehicle landing localization technology based on visual dual-channel uniqueness coding

Unmanned aerial vehicle (UAV) mainly uses GPS (Global Positioning System) for positioning, but it is difficult to locate in areas where GPS signal is missing or being disturbed. Therefore, the relative positioning technology based on visual method is also widely used in UAV landing, but due to the influence of cross wind and the motion of the landing plane, the traditional visual landing sign and positioning method is prone to lose the positioning target at the end stage of the landing. Therefore, this article proposes a landing sign based on double-layer unique coding, which can realize continuous positioning in the horizontal direction and accurate positioning of large-scale changes in the vertical direction. Firstly, real-time image acquisition and image processing are carried out through the airborne camera. Based on the flight altitude and encoding extraction effect of the UAV, the red or blue channel component is extracted, and then the image is preprocessed, edge detection, line detection, coding grid extraction, etc. As long as any 5 × 5 small squares of the whole pattern can be extracted, the perspective-n-point algorithm is used to obtain the relative pose estimation between the UAV and the landing sign. Experiments show that the landing sign and recognition algorithm effectively improve the UAV landing reliability.

Numerical Analysis on The Aerodynamic Performance of A High-speed Train Operating on Various Embankment Heights Under The Influence of Crosswinds

Given the unavoidable geographical surface, railings must be raised above ground level in some cases, which is known as an embankment. It was discovered that the height of the embankment had a significant influence on the slipstream on the train's leeward side especially during crosswind conditions. The primary objectives of this study were to investigate the impact of varying embankment heights on the aerodynamic characteristics of a high-speed train under different crosswind conditions using computational fluid dynamics (CFD) analysis. The German Aerospace Center DLR's Next-Generation High-speed Train (NG-HST) model has been used for this study. The yaw angles (ψ) are ranging from 10° to 50° in 10° increments. The Reynolds number based on the model's height and freestream velocity at the computational domain is 1.3 x 106. In the results, it shows that embankment height and crosswind ψ has a significant impact on the aerodynamic characteristics. Essential aerodynamic parameters that have a significant impact on train stability, such as the drag, lift, and side force coefficients, as well as the roll, yaw, and pitch moment coefficients, revealed that the higher the ψ, which included 40° and 50°, produced poor results compared to the lower ψ, which included 10°, 20°, and 30°. In terms of visual appearance, rising of crosswind angles have a greater impact on the formation of vortices on the leeward side of the train body and embankment. Thus, it can be concluded that the embankment heights and crosswind angles are crucial in determining train safety operations.

Effects of rotor–rotor interaction for a small tandem rotor operating in a crosswind

This study investigates the effects of rotor–rotor interaction on the wake and thrust characteristics of a small tandem rotor operating in a crosswind. Flow velocity and force measurements were conducted in a wind tunnel with two rotors arranged parallel to a crosswind. The results show that the rotor–rotor interaction significantly influences the wake characteristics and thrust generations of the tandem rotor and its effects vary depending on the crosswind speed and distance between rotor tips. In the tandem rotor configuration, the front rotor wake prevents the crosswind flow from reaching the rear rotor wake, thereby reducing the crosswind influence on it. However, under the strong rotor–rotor interaction, such as that caused by high crosswind speeds and short distances between rotor tips, the wakes of both rotors collide with each other and rapidly break down as they proceed downward. Tip-vortex characteristics are also affected by rotor–rotor interaction, which is investigated in terms of variations in the time-averaged tip-vortex trajectory and dissipation ratio with the strength of rotor–rotor interaction. These wake variations by rotor–rotor interaction lead to a decrease in thrust coefficients of the front and rear rotors, with a more significant reduction observed for the rear rotor. The thrust of the rear rotor is more significantly reduced as the crosswind speed increases and the distance between rotor tips narrows. This is mainly attributed to the increased axially induced velocity near the leading tips on the advancing side, retreating side, and centerline.

The influence of crosswinds and leg positions on cycling aerodynamics

This work investigated the influence of crosswinds and leg positions on the aerodynamics of an articulated cycling mannequin on a track bicycle. Force, wake total pressure and wake velocity measurements were made in a low-speed sports wind tunnel of closed-circuit type. The freestream velocity and wheel speeds were kept at 15m/s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$15\\, \\hbox {m/s}$$\\end{document}. The crank angle of the mannequin was varied across a pedal cycle. Yaw angles from 0∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0^{\\circ }$$\\end{document} to 20∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$20^{\\circ }$$\\end{document} were examined. The experimental results reveal that the leg position significantly affects the aerodynamic performance of a cyclist. At high yaw angles, the aerodynamic drag on the cyclist showed noticeable deviations between most leg positions and their 180∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$180^{\\circ }$$\\end{document}-apart pairs. A wake analysis technique effectively captured the influence of leg positions on drag. The total pressure deficit contributes dominantly to the overall drag. The wake pressure contours demonstrate how leg-wheel interaction affects the total pressure distribution and drag under crosswinds. This study offers valuable insights into the flow behavior and drag generation around a cyclist with varying leg positions under crosswinds.

Study of Paired Approach Wake Separation Based on Crosswinds

The effect of crosswinds on paired approach (PA) procedures for Closely Spaced Parallel Runways (CSPR) is investigated in this paper by fully utilizing the crosswind environment to implement a more efficient PA and increase runway capacity. An improved wake dissipation model is used to quickly predict the change in the wake velocity field for the PA procedures. The change in the width of the hazard zone is explored in detail using the roll moment coefficient as a determination index. The calculation method for the hazard zone of a wake encounter in a PA is designed considering the influence of crosswind, turbulence, and ground effect. The results show the diffusion rate of the hazard zone and a decrease in the width of the maximum hazard zone under a breezeless environment with increases in the turbulence intensity. The maximum hazard zone width decreases with an increase in crosswind speed. Favorable crosswinds can reduce wake separation and improve the efficiency of a PA. Lower turbulence intensity has a better crosswind effect under a normal PA. The 3-degree offset PA can accommodate larger unfavorable crosswinds, with a higher turbulence intensity having a better crosswind effect. The 3-degree offset PA can substantially increase the proportion of time when no wake affects the PA procedure.

Study on the Characteristics of Trackside Acoustic Flow Field of High-Speed Train under the Influence of Crosswind.

During the on-track acoustic detection process, a potential flow model and an acoustic finite element mathematical model based on synthetic wind are utilized, taking into account the combined effects of vehicle speed, wind direction angle, and crosswind speed. Simulation and modeling are achieved using Automatic Matching of Acoustic Radiation Boundary Conditions (AML) technology, enabling obtaining a distribution map and sound pressure frequency response curve of the trackside acoustic field under crosswind conditions by setting up field point grids. It is found that sound pressure values at the same location gradually increase as the vehicle speed increases in the frequency range of 10 Hz to 70 Hz, at different vehicle speeds. The sound pressure values and distribution area of the trackside acoustic field are the largest when the crosswind speed is 10 m/s (wind force at level five), allowing for easier location of the sound source when a fault occurs. The study also reveals that under different wind direction angles, the same location's sound pressure value on the trackside gradually decreases as the wind direction angle increases, to lower than that of the non-crosswind condition, severely hindering the reception and diagnosis of acoustic signals.

Flame Interaction Characteristics of Two Adjacent Liquid Pool Fires Under the Influence of Cross Wind

Flame Interaction Characteristics of Two Adjacent Liquid Pool Fires Under the Influence of Cross Wind

Study on the aerodynamic performance of nacelle inlet under crosswind

Flow separation will occur in the nacelle inlet under crosswind operation, which will result in engine intake distortion and even engine surge. To study the reference characteristics of the flow field of the short tank inlet separation under the influence of crosswind, this paper observed the cloud map of the total price loss coefficient by changing the flow deflection Angle and flow velocity, made a qualitative analysis of the total pressure distortion degree, then calculated the average total pressure loss coefficient and distortion index, and conducted a quantitative analysis to explore the improvement of the total pressure distortion under different flow field factors. The results show that the degree of total pressure distortion is improved with the increase of incoming flow velocity at a small inlet deflection Angle, but with the increase of incoming flow deflection Angle, the ability of incoming flow velocity to improve the total pressure distortion gradually weakens until it disappears. The inlet deflection Angle plays a decisive role in the improvement effect of incoming flow velocity on the total pressure distortion.

Influence of crosswind on the flow induced vibration profile of high-speed train’s windshield

The high-speed train’s windshield structure is made of high strength rubber. The stagnation pressure under crosswind condition will lead to a large average deformation along with moderate flow-induced vibration of the windshield structure. This deformation and vibration have a vital influence on the servicing life and failure model windshield structures. In this study, the flow-induced deformation and vibration of windshields under crosswind condition are systematically analyzed through an experimentally verified numerical approach. The flow field and aerodynamic load around windshield structure, as well as the deformation of windshield structure are systematically investigated. The results indicate that, compared to the flat ground windless condition, the windshield’s maximum deformation location under crosswind has shifted from the upper half to the lower half. Besides, among all windshield structures throughout the three car formation train, the downstream half of windward windshield between head car and middle car exhibits the largest deformation. When the wind angle shifts from 20° to 30°, the primary frequency of this maximum displacement location is around 30 Hz. In contrast, the primary frequency on the maximum displacement location of windward windshields between middle car and trailing car is 17.5 Hz.

Moving Model Experimental Study on a Slipstream of a High-Speed Train Running on the Bridge Suffering a Crosswind

A running train induces a slipstream around it, which is closely related to its aerodynamic features and crucial for the safety of people and structures near the track. However, the effect of crosswinds is almost inevitable when the train runs on a bridge. In this work, an experimental study using moving model testing technology was conducted to investigate the effects of wind speeds, train speeds, and yaw angles on the aerodynamic performance of a Fuxing Hao high-speed train running on a bridge under the influence of crosswind. The results show that, for the crosswind cases, the slipstream velocities on the leeward side of the train are generally higher than those in the no-crosswind cases. Moreover, the results were compared for the cases with the same effective yaw angle of 21.8° but different wind speeds (6 m/s, 8 m/s) and train speeds (15 m/s, 20 m/s), which suggests the method of the resultant wind’s yaw angle is no longer valid when the train runs on a bridge due to the aerodynamic interactions.

Is the Monsoon climatology observed over the National Capital Region, Delhi indicative of an Urban -Monsoon linkage on rainfall modification?

The Indian Summer Monsoon (ISM) plays a vital role in the lives of the National Capital Region (NCR) - Delhi, the second biggest urban settlement globally. This study attempt to assess the spatio-temporal characters and decadal changes of monsoonal features in detail. The climatology of Monsoonal rainfall and Monsoon Low Level Jet (MLLJ) are investigated. NCR Delhi exhibits a ∼ 28.5% in the recent decade and ∼ 19.7% in the 1997–06 decade reduction in rainfall is noticed compared with 1987–96 decade. The study reveals that the precipitation reduction is alongside the weakening of the MLLJ and marginal reduction of core height over the region. Also, the magnitude of surface wind declined with the directional shift of both MLLJ and surface winds notable in southerlies in the 2007–16 decade. Rainfall islands parallel to the urban heat islands (UHI) are seen likely as coupled monsoon-urban induced effects under the weakened synoptic regime evidenced through MLLJ. The Land Surface Temperature difference (UHI) of ∼ 2.5 °C and more than 3.5 °C is observed from the urban centre to the surrounding cropland during the months of August (core monsoon) and September, respectively. In addition to the rainfall islands during August, islands of rainfall in both the upwind and downwind directions of the urban centre are noted in September. The rainfall patterns point out the signal of monsoon-rainfall modification due to NCR urbanization. Further, the influence of crosswinds with Aravali ridges and the presence of Himalayan foothills are also notable in the NCR rainfall patterns.

Impacts of human movement and ventilation mode on the indoor environment, droplet evaporation, and aerosol transmission risk at airport terminals

The dispersion of the coronavirus pandemic has caused immense damage worldwide, and people have begun to ruminate epidemic prevention strategies for public places. Airport terminals with a high number of occupied passengers have become potentially high-risk regions for aerosol transmission of coronavirus disease 2019 (COVID-19). In this study, the Eulerian–Lagrangian approach and realizable k-ε turbulence model were used to numerically simulate airflow organization and aerosol transmission when passengers are moving slowly in a line. During the aerosol transmission period, evaporation was considered a key factor influencing the particle size distribution at the beginning of aerosol transmission from humans. Moreover, passenger movement at the airport terminal was attained by employing dynamic mesh algorithms. Based on the relative direction of passengers and air vents when queuing in the terminal building, we studied three conditions: windward walking, leeward walking, and crosswind walking. The results of this study showed that the walking has an important influence on droplet distribution. Droplet distribution indicates that individuals standing behind patients during queuing movements have a higher risk of infection than those standing in front of them. A significant aerosol accumulation was discovered at 0.5 m behind the patient when passengers moved simultaneously. An aerosol transmission distance of 15 s aligned with the passenger's walking direction could reach up to 9.32 m. Furthermore, although the evaporation time of the large droplets was longer than that of the small droplets, both large and small droplets evaporated rapidly after exhalation. The crosswind influence caused the droplets to travel farther away in a direction perpendicular to human movement, which increased the distance by approximately 1.26 m compared to the absence of the crosswind influence.

Hydrogen gas dispersion studies for hydrogen fuel cell vessels I: Vent Mast releases

We report modeling results for hydrogen releases associated with deploying hydrogen fuel cell technology on vessels. This first paper (I) considers hydrogen releases through the vessel Vent Mast from 250-bar hydrogen gas storage tanks, the type of tanks being used for the first hydrogen vessels. A manifolded 10-tank hydrogen storage system, holding 278 kg of hydrogen, can be emptied in ∼10 min for maintenance purposes, with a pressure reduction to half the original pressure (125 bar) realized in 2 min if a rapid pressure reduction is needed, for example in the event of a fire. The time profile for filling a tank is also of interest so as not to exceed the tank thermal limits. The calculations show that a manifolded 10-tank array can be filled with hydrogen to 250-bar pressure in ∼2 h from a 350-bar hydrogen refueling trailer without exceeding the 85 °C temperature limit typical of Type IV hydrogen tanks.Computational fluid dynamic (CFD) modeling shows that when the hydrogen is released out of the 10-tank array and into the Vent Mast in a 5-mph wind blowing horizontally, the effect of the wind on the hydrogen dispersion strongly depends on the hydrogen exit speed. For high release speeds (∼800–900 m/s), the hydrogen flow is strongly momentum-driven, and there is modest cross-wind influence. For low hydrogen exit speeds (∼10 m/s), the hydrogen is readily entrained in the wind flow and blown sideways, with the downstream flammable envelope rising at a positive angle to the horizontal due to buoyancy. To capture the influence of a wind with a downward component (e.g., created by a downdraft near a building), a calculation of a low-velocity (8.6 m/s) hydrogen release was performed with a 5-mph wind pointed downward at a 45° angle. The results show that despite the buoyancy of hydrogen, the wind blows the hydrogen substantially downward for low hydrogen speeds exiting the Vent Mast.

Numerical Analysis on the Crosswind Influence Around a Generic Train Moving on Different Bridge Configurations

In this article, a numerical approach is applied to study the flow regimes surround a generic train model travelling on different bridge configurations under the influence of crosswind. The bridge is varies based on the different geometry of the bridge girder. The crosswind flow angle (Ψ) is varied from 0° to 90°. The incompressible flow around the train was resolved by utilizing the Reynolds-averaged Navier-Stokes (RANS) equations combined with the SST k-ω turbulence model. The Reynolds number used, based on the height of the train and the freestream velocity, is 3.7 × 105. In the results, it was found that variations of the crosswind flow angles produced different flow regimes. Two unique flow regimes appear, representing (i) slender body flow behaviour at a smaller range of Ψ (i.e. Ψ ≤ 45°) and (ii) bluff body flow behaviour at a higher range of Ψ (i.e. Ψ ≥ 60°). As the geometries of the bridge girder were varied, the bridge with the wedge girder showed the worst aerodynamic properties with both important aerodynamic loads (i.e. side force and rolling moment), followed by the triangular girder and the rectangular girder. This was due to the flow separation on the windward side and flow structure formation on the leeward side, both of which are majorly influenced by the flow that moved from the top and below of the bridge structures.

Influence of Cross-Wind on CO2 Arc Welding of Carbon Steel

The purpose of this study is to develop a novel welding torch with high wind resistance, which can be used for welding outside a building under strong cross-wind. In this paper, a parametric study was carried out using different torch nozzle designs and shield gas flow rates for their optimization. The gas flow around the torch nozzle exit was visualized through the shadowgraph method to evaluate the interaction between the shielding gas flow and the cross-wind. Nitrogen fraction in a weld bead was measured for confirming the shielding effect. Furthermore, CFD simulation was also carried out for obtaining shielding gas flow velocity at the torch nozzle exit. From the result of the above experiments and simulation, effective parameters for improving the shielding effect against the cross-wind were comprehensively discussed. As a result, the nitrogen fraction was found to be decreased by increasing the averaged vertical gas velocity at the torch nozzle exit. For achieving this, it is especially effective to decrease the nozzle diameter or increase the gas flow rate.

Optimization on the Crosswind Stability of Trains Using Neural Network Surrogate Model

Under the influence of crosswinds, the running safety of trains will decrease sharply, so it is necessary to optimize the suspension parameters of trains. This paper studies the dynamic performance of high-speed trains under crosswind conditions, and optimizes the running safety of train. A computational fluid dynamics simulation was used to determine the aerodynamic loads and moments experienced by a train. A series of dynamic models of a train, with different dynamic parameters were constructed, and analyzed, with safety metrics for these being determined. Finally, a surrogate model was built and an optimization algorithm was used upon this surrogate model, to find the minimum possible values for: derailment coefficient, vertical wheel-rail contact force, wheel load reduction ratio, wheel lateral force and overturning coefficient. There were 9 design variables, all associated with the dynamic parameters of the bogie. When the train was running with the speed of 350 km/h, under a crosswind speed of 15 m/s, the benchmark dynamic model performed poorly. The derailment coefficient was 1.31. The vertical wheel-rail contact force was 133.30 kN. The wheel load reduction rate was 0.643. The wheel lateral force was 85.67 kN, and the overturning coefficient was 0.425. After optimization, under the same running conditions, the metrics of the train were 0.268, 100.44 kN, 0.474, 34.36 kN, and 0.421, respectively. This paper show that by combining train aerodynamics, vehicle system dynamics and many-objective optimization theory, a train’s stability can be more comprehensively analyzed, with more safety metrics being considered.

Crosswind influence on heat and mass transfer performance for wet cooling tower equipped with an axial fan

To enhance the thermal performance and relieve the impact of crosswind on the super large-scale natural draft wet cooling towers (SLWCTs), based on our previous research, through the three-dimensional numerical simulation of the SLWCT equipped with an axial fan, the impact of the fan positions on the thermal performance was investigated at various crosswind velocities (1–9 m/s) when the fan power was fixed to 200 kW. It is obtained that the optimized fan diameter and the installation height are 20 m and 18 m. Additionally, the characteristics of the aerodynamic and temperature field inside the tower with different fan positions were discussed based on the above results, subsequently, the change rules of water temperature drop, evaporation loss, and heat transfer coefficient are analyzed. The results manifested that the optimization scheme efficiently relieves the adverse effects of the crosswind, and the air velocity near the fan is significantly increased. By comparison with the case of no fan, the heat transfer coefficient and water temperature drop increase by 4.79% and 0.226 °C, respectively, and the evaporation loss increases by 2.86% at the utmost.

Research on the ground vortex and inlet flow field under the ground crosswind condition

The ground vortex field and nacelle inlet flow field under ground crosswind condition are investigated experimentally and numerically. A test rig with ground plane and crosswind blowing devices have been built, the experiments have been carried out by DSA3217 Pressure Scanner and Hot Wire Anemometer to get inlet total pressure distribution and the unsteady characteristics of ground vortex, respectively. The characteristics of ground vortex are quantitatively analyzed respect to vortex intensity, frequency, and dynamics, then the study crosswind interact on ground vortex is conducted, by considering the direct influence of crosswind on inlet distortion and the indirect effect of crosswind on ground vortex. Finally, it is found that due to the ground vortex, the process that inlet distortion increases with crosswind is unsteady and unstable. According to the variation of vortex intensity and the influence level that ground vortex acted on the inlet flow field, the process of blowing away the ground vortex from the beginning to the end can be divided into four phases, the encouraging phase, the initial blowing phase, the rapid blowing phase and the end blowing phase.

Near-to-Far Wake Characteristics of Road Vehicles Part 2: Influence of Cross Winds and Free-Stream Turbulence

<div class="section abstract"><div class="htmlview paragraph">Conventional assessments of the aerodynamic performance of ground vehicles have, to date, been considered in the context of a vehicle that encounters a uniform wind field in the absence of surrounding traffic. Recent vehicle-platooning studies have revealed measurable fuel savings when following other vehicles at inter-vehicle distances experienced in every-day traffic. These energy savings have been attributed in large part to the air-wakes of the leading vehicles. This set of three papers documents a study to examine the near-to-far regions of ground-vehicle wakes (one to ten vehicle lengths), in the context of their potential influence on other vehicles.</div><div class="htmlview paragraph">Part two of this three-part paper documents the influence of the ambient winds on the development of the wake behind a vehicle. A series of scaled-model wind-tunnel measurements, supplemented by some high-fidelity numerical simulations, based on a Lattice-Boltzmann approach, are presented to examine the effects cross-wind magnitude, by means of changes in yaw angle, on the wakes behind four vehicle shapes: a sedan, an SUV, a pickup truck, a medium-duty vehicle and a heavy-duty vehicle. The influence of road-representative freestream turbulence is also examined.</div><div class="htmlview paragraph">The results of these investigations show that, under yaw conditions, the distinct differences between the wake structures of slant/step-back and square-back shapes, documented in Part 1, are eliminated. At yaw, the moderate-to-far wake region is dominated by a large vortex structure of similar size to the vehicle itself that generates significant sidewash, analogous to the downwash in the wake of a wing in pitch. All vehicle shapes studied demonstrate this vortex structure which increases in strength with yaw angle. For vehicles following in the wake, not only do they experience a wind-speed deficit associated with the wake, but they experience a twisted wind profile with reduced yaw angles near the ground. The introduction of freestream turbulence is shown to generate a large wake with reduced shear, but without changing the dominant flow characteristics.</div></div>