Detached-Eddy Simulations of the Effects of Different Wind Gust Models on the Unsteady Aerodynamics of Road Vehicles

2010 ◽  
Author(s):  
Tristan Favre ◽  
Gunilla Efraimsson
Keyword(s):  
Unsteady Aerodynamics ◽  
Vertical Direction ◽  
Wind Gust ◽  
Deterministic Models ◽  
Aerodynamic Loads ◽  
Simulation Techniques ◽  
Wind Gusts ◽  
Pitch Moment ◽  
Vehicle Shape ◽  
Yaw Angle

The relative flexibility of nowadays simulation techniques offers an alternative way to experiments in order to investigate unsteady crosswind aerodynamics in an industrial framework. In this study, time-accurate simulations, Detached-Eddy Simulations (DES), are used to simulate the flow around a simple vehicle shape, the so-called Windsor model. The ReL of the corresponding flow case is 2.0 · 106. The influence of different deterministic models of wind gusts on the aerodynamic loads and moments are studied. The wind gusts are varied in the stream-wise and the vertical direction. The magnitude of the gusts models corresponds to a yaw angle of 20°. The aerodynamic loads calculated show a large excess of drag coupled with a reduction of the pitch moment. In addition, although the side force has a smooth variation in the gust, overshoots up to 18% higher than the steady value of yaw moment are also observed.

Effect of wind gusts on the dynamics of railway vehicles running on a curved track

2017 ◽  
Vol 232 (4) ◽  
pp. 1103-1120 ◽  
Author(s):  
Wonhee You ◽  
Hyukbin Kwon ◽  
Joonhyuk Park ◽  
Yujeong Shin
Keyword(s):  
Dynamic Characteristics ◽  
Wind Tunnel Test ◽  
Simulation Software ◽  
Scale Model ◽  
Railway Vehicle ◽  
Wind Gust ◽  
Railway Vehicles ◽  
Wind Gusts ◽  
Pitch Moment ◽  
Curved Track

Due to global warming, there is an increasing number of wind gusts that affect the stability of railway vehicles. A railway vehicle running on a curved track during a wind gust is subjected to multiple forces simultaneously, which include the centrifugal force and forces exerted by the wind gust and cant, and they significantly affect the vehicle’s dynamic characteristics as well as its safety. The forces increase the vibration of carbodies and the risk of derailment and overturning of cars; the effect is worse on irregular tracks. In order to review the phenomenon in detail, a 1/20 scale model of a railway vehicle was built to measure the aerodynamic coefficients in five directions—side force, lift force, roll moment, pitch moment, and yaw moment—through a wind tunnel test. The data collected were applied as external forces to a full-scale railway vehicle model traveling on a curved track. Using a multibody simulation software program, SIMPACK, a railway vehicle was modeled, which was then used in the simulation of the dynamic characteristics and safety of vehicles while traveling on a curved track during a wind gust. Using the actual measured track data from the curved zone, a comparison was made on the dynamic characteristics of the car traveling, with and without a wind gust, on a curved track with a railway curve radius of 599 m; also, the difference was analyzed with the direction of the wind gust blowing from inside and toward the center of curvature. The results showed that in the presence of a wind gust blowing from outside the curvature with an average speed of 25 m/s it is advisable to stop train services on grounds of safety.

scholarly journals Wind Gust Measuring at Low Altitude Using An Unmanned Aerial System

2021 ◽  
Author(s):  
Alton Yeung
Keyword(s):  
Turbulence Models ◽  
Satellite System ◽  
Data System ◽  
Measurement Unit ◽  
Wind Gust ◽  
Wind Gusts ◽  
Low Altitude ◽  
And Performance ◽  
Global Navigation Satellite ◽  
Aerial Platform

A small unmanned aerial vehicle (UAV) was developed with the specific objective to explore atmospheric wind gusts at low altitudes within the atmospheric boundary layer (ABL). These gusts have major impacts on the flight characteristics and performance of modern small unmanned aerial vehicles. Hence, this project was set to investigate the power spectral density of gusts observed at low altitudes by measuring the gusts with an aerial platform. The small UAV carried an air-data system including a fivehole probe that was adapted for this specific application. The air-data system measured the local wind gusts with an accuracy of 0.5 m/s by combining inputs from a five-hole probe, an inertial measurement unit, and Global Navigation Satellite System (GNSS) receivers. Over 20 flights were performed during the development of the aerial platform. Airborne experiments were performed to collect gust data at low altitudes between 50 m and 100 m. The result was processed into turbulence spectrum and the measurements were compared with the MIL-HDBK-1797 von K´arm´an turbulence model and the results have shown the model underpredicted the gust intensities experienced by the flight vehicle. The anisotropic properties of low-altitude turbulence were also observed when analyzing the measured gusts spectra. The wind and gust data collected are useful for verifying the existing turbulence models for low-altitude flights and benefit the future development of small UAVs in windy environment.

scholarly journals Characterizing wind gusts in complex terrain

2019 ◽  
Vol 19 (6) ◽  
pp. 3797-3819 ◽  
Author(s):  
Frederick Letson ◽  
Rebecca J. Barthelmie ◽  
Weifei Hu ◽  
Sara C. Pryor
Keyword(s):  
Wind Turbines ◽  
Complex Terrain ◽  
Probability Distributions ◽  
Wind Loading ◽  
Wind Gust ◽  
Wind Gusts ◽  
Sonic Anemometers ◽  
Vertical Displacements ◽  
Structural Loading ◽  
Good Agreement

Abstract. Wind gusts are a key driver of aerodynamic loading, especially for tall structures such a bridges and wind turbines. However, gust characteristics in complex terrain are not well understood and common approximations used to describe wind gust behavior may not be appropriate at heights relevant to wind turbines and other structures. Data collected in the Perdigão experiment are analyzed herein to provide a foundation for improved wind gust characterization and process-level understanding of flow intermittency in complex terrain. High-resolution observations from sonic anemometers and vertically pointing Doppler lidars are used to conduct a detailed study of gust characteristics with a specific focus on the parent distributions of nine gust parameters (that describe velocity, time, and length scales), their joint distributions, height variation, and coherence in the vertical and horizontal planes. Best-fit distributional forms for varying gust properties show good agreement with those from previous experiments in moderately complex terrain but generate nonconservative estimates of the gust properties that are of key importance to structural loading. Probability distributions of gust magnitude derived from vertically pointing Doppler lidars exhibit good agreement with estimates from sonic anemometers despite differences arising from volumetric averaging and the terrain complexity. Wind speed coherence functions during gusty periods (which are important to structural wind loading) are similar to less complex sites for small vertical displacements (10 to 40 m), but do not exhibit an exponential form for larger horizontal displacements (800 to 1500 m).

Large Eddy Simulation on the Unsteady Aerodynamics of a Heavy Duty Truck in Wind Gust

2011 ◽  
Author(s):  
Makoto Tsubokura ◽  
Prasanjit Das ◽  
Tomofuyu Matsuuki ◽  
Takuji Nakashima
Keyword(s):  
Large Eddy Simulation ◽  
Numerical Method ◽  
Unsteady Aerodynamics ◽  
Static Condition ◽  
Wind Tunnels ◽  
Wind Gust ◽  
Heavy Duty ◽  
Heavy Duty Truck ◽  
Eddy Simulation ◽  
Large Eddy

Unsteady aerodynamic forces acting on a full-scale heavy duty truck were investigated using a large-eddy simulation technique. The numerical method adopted was first validated on a static condition measured at the DNW German-Dutch wind tunnels. After the correction of the blockage ratio in the wind tunnel, the drag coefficient obtained by our numerical method showed good agreement with the experimental data within the errors of less than 5%. Effect of an air deflector mounted on the top of a cabin was also discussed. Then the method was applied to non-stationary conditions in which the truck was subjected to ambient perturbation of approaching flow. The perturbation of the flow is a model of atmospheric turbulence and sinusoidal crosswind velocity profiles were imposed on the uniform incoming flow with its wavelength comparable to the vehicle length. As a result, it was confirmed that when the wavelength of the crosswind is close to the vehicle length, averaged drag increases by more than 10% and down-force decreases by about 60%, compared with the case without perturbation.

HPC-LES for Unsteady Aerodynamics of a Heavy Duty Truck in Wind Gust - 1st report: Validation and Unsteady Flow Structures

2010 ◽  
Author(s):  
Makoto Tsubokura ◽  
Kaito Takahashi ◽  
Tomofuyu Matsuuki ◽  
Takuji Nakashima ◽  
Takeshi Ikenaga ◽  
...  
Keyword(s):  
Unsteady Flow ◽  
Unsteady Aerodynamics ◽  
Flow Structures ◽  
Wind Gust ◽  
Heavy Duty ◽  
Heavy Duty Truck

The Impact of Wind Gusts on the Ocean Thermal Skin Layer by Capillary-Gravity Waves

2020 ◽  
Author(s):  
Christopher J Zappa ◽  
Nathan Laxague ◽  
Sophia Brumer ◽  
Steven Anderson
Keyword(s):  
Infrared Imaging ◽  
Wind Waves ◽  
Ocean Surface ◽  
Skin Layer ◽  
Wind Gust ◽  
Thermal Infrared Imaging ◽  
Wind Gusts ◽  
Transient Forcing ◽  
The Impact ◽  
Depth Water

<p><span>The thermodynamic and emissive properties of the ocean thermal skin layer are crucial contributors to air-sea heat flux. In order to properly observe ocean surface temperature without disturbing any delicate fluid mechanical processes, thermal infrared imaging is often used. However, wind impacting the ocean surface complicates the extraction of meaningful information from thermal imagery; this is especially true for transient forcing phenomena such as wind gusts. Here, we describe wind gust-water surface interaction through its impact on skin layer thermal and emissive properties. Two key physical processes are identified: (1) the growth of centimeter-scale wind waves, which increases interfacial emissivity and (2) microscale wave breaking and shear, which mix the cool skin layer with warmer millimeter-depth water and increase the skin temperature. As more observations are made of air-sea interaction under transient forcing, the full consideration of these processes becomes increasingly important.</span></p>

337 Aerodynamic Loads on Horizontal Axis Wind Turbine Rotors Exerted by Wind Gust

2005 ◽  
Vol 2005.2 (0) ◽  
pp. 245-246
Author(s):  
Shinya HOTTA ◽  
Yutaka HASEGAWA ◽  
Hiroshi IMAMURA ◽  
Junsuke MURATA ◽  
Koji KIKUYAMA
Keyword(s):  
Wind Turbine ◽  
Horizontal Axis ◽  
Wind Gust ◽  
Horizontal Axis Wind Turbine ◽  
Aerodynamic Loads ◽  
Turbine Rotors

Numerical Simulation of Unsteady Aerodynamic Loads over an Aircraft

2014 ◽  
Vol 908 ◽  
pp. 264-268
Author(s):  
Xiao Jun Xiang ◽  
Yu Qian
Keyword(s):  
Mach Number ◽  
Euler Equations ◽  
Unsteady Aerodynamics ◽  
Periodic Motions ◽  
Aerodynamic Loads ◽  
Unsteady Aerodynamic ◽  
Sinusoidal Motion ◽  
A Cell ◽  
Rigid Body Motions ◽  
Volume Method

The unsteady aerodynamic loads are the basic of the aeroelastic. This paper focuses on the computation of the unsteady aerodynamic loads for forced periodic motions under different Mach numbers. The flow is modeled using the Euler equations and an unsteady time-domain solver is used for the computation of aerodynamic loads for forced periodic motions. The Euler equations are discretized on curvilinear multi-block body conforming girds using a cell-centred finite volume method. The implicit dual-time method proposed by Jameson is used for time-accurate calculations. Rigid body motions were treated by moving the mesh rigidly in response to the applied sinusoidal motion. For an aircraft model, a validation of the unsteady aerodynamics loads is first considered. Furthermore, a study for understanding the influence of different Mach number was conducted. A reverse of the trend of hysteretic loops can be observed with the increasing of the Mach number.

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