Wind tunnel tests on railway vehicles in the presence of windbreaks: Influence of flow and geometric parameters on aerodynamic coefficients

2022 ◽  
Vol 220 ◽  
pp. 104838
Author(s):  
E. Brambilla ◽  
S. Giappino ◽  
G. Tomasini
2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Li Xin-min ◽  
Nie Xiao-chun ◽  
Zhu Yong-kun ◽  
You Yi ◽  
Yan Zhi-tao

Wind tunnel tests were carried out to obtain the static aerodynamic characteristics of crescent iced 4-bundled conductors with different ice thicknesses, initial ice accretion angles, bundle spaces, and wind attack angles. The test models were made of the actual conductors and have a real rough surface. Test results show that the influence of wake interference on the drag coefficients of leeward subconductors is obvious. The interference angle range is larger than 20° and the drag coefficient curves of leeward subconductors have a sudden decrease phenomenon at some certain wind attack angles. The absolute value of the lift and moment coefficient increases with the increase of the ice thickness. In addition, the galloping of the iced subconductor may occur at the angle of wind attack near ±20° and the wake increases the moment coefficient. The variation of initial ice accretion angle has a significant influence on the aerodynamic coefficients. The aerodynamic coefficient curves exhibit a “moving” phenomenon at different initial ice accretion angles. The bundle spaces have a great influence on the moment coefficient of leeward thin ice-coated conductors. With the increase of ice thickness, the bundle spaces generally have little influence on the aerodynamic coefficients.


2009 ◽  
Vol 34 (1) ◽  
pp. 24-29 ◽  
Author(s):  
Tatsuo MAEDA

2020 ◽  
Vol 23 (13) ◽  
pp. 2882-2897
Author(s):  
Xuhui He ◽  
Fanrong Xue ◽  
Yunfeng Zou ◽  
Suren Chen ◽  
Yan Han ◽  
...  

Accurately quantifying the aerodynamic forces acting on vehicles and long-span bridges is critical for assessing the safety of moving vehicles on bridges which are subjected to strong wind. It is necessary to consider the aerodynamic interference between vehicles and the bridge, especially for this with the bluff body section and wind barriers. However, very few investigations have been carried out to find aerodynamic coefficients of vehicles on a bridge with the bluff body section and considering the effect of wind barrier. This article therefore carried out wind tunnel tests to determine aerodynamic coefficients of container truck on a bridge with a π-cross section and wind barriers. The influence of vehicle position in different road lanes of the bridge deck and the aerodynamic interference between vehicles on the aerodynamic characteristics of the vehicle and the bridge are investigated. Different heights and ventilation ratios of wind barrier are taken into consideration to examine variations of aerodynamic coefficients with different wind barriers. Furthermore, the change mechanism in the aerodynamic coefficients of the vehicles is observed by analyzing the wind pressure distribution on the surface of the vehicles. The test results show that the different lane locations of the vehicle affect the aerodynamic coefficients significantly, as well as the aerodynamic interference between vehicles with transverse arrangement or longitudinal arrangement, especially for the side force coefficient. The existence of wind barrier reduces the side force coefficients of the vehicle remarkably. Such effects also vary with the ventilation ratio and height of wind barrier.


Author(s):  
Elia Brambilla ◽  
Gisella Tomasini ◽  
Stefano Giappino

Abstract In the present paper the force aerodynamic coefficients measured, according the European Standard Specifications, by means of wind tunnel tests carried out on a 1:15 scaled model of ETR1000 train in presence of different windbreaks configurations, are presented. In particular, 3m high band barriers (40% of porosity) have been tested with different gaps (from 0,5m to 30m, full scale) in the windbreaks and considering different positions of the train with respect to the gaps. The results shown in this paper allow to evaluate the effect of different windbreak parameters (gap amplitude, train position) on the train overturning risk and they represent a complete database for validation of CFD analyses.


2019 ◽  
Vol 91 (6) ◽  
pp. 905-914 ◽  
Author(s):  
Wojciech Grendysa

Purpose The purpose of this paper is finding the optimal geometric parameters and developing of a method for optimizing a light unmanned aerial vehicle (UAV) wing, maximizing, at the same time, its endurance with the assumed parameters of aircraft mission. Design/methodology/approach The research is based on the experience gained by the author’s contribution to the project of building medium-altitude, long-endurance class, light UAV called “Samonit”. The author was responsible for the structure design, wind tunnel tests and flight tests of the “Samonit” aircraft. Based on the experience, the author was able to develop an optimization process considering various disciplines involved in the whole aircraft design topics such as aerodynamics, flight mechanics, structural stiffness and weight, aircraft stability and maneuverability. The presented methodology has a multidisciplinary nature, as in the process of optimization both aerodynamic aspects and the influence of wing geometric parameters on the wing structure and weight and the aircraft payload were taken into account. The optimal wing configuration was obtained using the genetic algorithms. Findings As a result, a set of wing geometrical parameters has been obtained that allowed for achieving twice as long endurance as compared with the initial one. Practical implications Using the methodology presented in the paper, an aircraft designer can easily find the optimum wing configuration of a designed aircraft, satisfying the mission requirements in a best way. Originality/value An original procedure has been developed, based on the actual design, wind tunnel tests and numerical calculations of “Samonit” aircraft, enabling the determination of optimum wing configuration for a small unmanned aircraft.


Author(s):  
F. Cheli ◽  
F. Fiocco ◽  
S. Giappino ◽  
G. Tomasini

Embankment is a typical layout for rail infrastructures and train aerodynamic coefficients in this scenario are necessary for the analysis of cross wind effects. Nevertheless wind tunnel tests on scale models with the embankment scenario presents difficulties in the reproduction of the boundary conditions, that is the simulation of a “pseudo-infinite” full scale embankment. To investigate this topic we have performed wind tunnel tests on an ETR500 1:45 scale model using a finite length embankment, with and without an upwind nose and a “pseudo-infinite” embankment, reproduced by the extension wall-to-wall of the scenario. The paper presents the tests results in terms of aerodynamic force coefficients and surface pressures. Guidelines for wind tunnel tests on embankment are than discussed.


2021 ◽  
Vol 11 (4) ◽  
pp. 1642
Author(s):  
Yuxiang Zhang ◽  
Philip Cardiff ◽  
Jennifer Keenahan

Engineers, architects, planners and designers must carefully consider the effects of wind in their work. Due to their slender and flexible nature, long-span bridges can often experience vibrations due to the wind, and so the careful analysis of wind effects is paramount. Traditionally, wind tunnel tests have been the preferred method of conducting bridge wind analysis. In recent times, owing to improved computational power, computational fluid dynamics simulations are coming to the fore as viable means of analysing wind effects on bridges. The focus of this paper is on long-span cable-supported bridges. Wind issues in long-span cable-supported bridges can include flutter, vortex-induced vibrations and rain–wind-induced vibrations. This paper presents a state-of-the-art review of research on the use of wind tunnel tests and computational fluid dynamics modelling of these wind issues on long-span bridges.


2021 ◽  
Vol 215 ◽  
pp. 104685
Author(s):  
An Miao ◽  
Li Shouying ◽  
Liu Zhiwen ◽  
Yan Banfu ◽  
Li Longan ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document