Wind tunnel study of a cone-like shaped roof: Reynolds number effects

This paper describes the results of windtunnel tests performed on acone-likeshaped roof characterised by multiple curved surfaces. Surface pressure measurements were carried out by high-frequency scanners. In particular, Reynoldsnumber and surface roughness effects on the mean pressure distribution and on its unsteady components have been analysed. Methodologies were found in order to validate the windtunnelwind load measures performed on scale models having the typology of building roofs with curved surfaces

High-speed freight trains for intermodal transportation: Wind tunnel study on the aerodynamic coefficients of container wagons

The paper investigates the response to crosswind of a high-speed freight train for intermodal transportation, through wind tunnel tests. A 1:20 model of a freight train composed by an engine and two flat-car vehicles was instrumented with force balances to measure the aerodynamic coefficients of the flat-car plus container assembly and of the container alone. Aerodynamic coefficients strongly affects the train stability and the anchorage limits of the container itself. During the wind tunnel tests, eight different loading configurations were considered and aerodynamic coefficients were determined for yaw angles (i.e. angle between train and wind) ranging from 0° to 90°. Experimental results show the benefits in terms of drag reduction due to the presence of a laden vehicle upstream. As far as the rollover risk is concerned, the less critical condition is found for a vehicle preceded by a fully laden wagon and followed by an empty one. More in particular, at low yaw angles, the worst condition for a vehicle occurs when the wagon ahead is empty while, for yaw angles between 45° and 55° which are the most critical for ‘low speed’ trains, the differences with respect to the other configurations reduce significantly

Turbulence effects on the aerodynamic forces acting on railway vehicles by means of wind tunnel experimental study

The present research work is based on an experimental campaign of wind tunnel tests aimed at investigating the crosswind aerodynamic of a lightweight railway vehicle. The performed tests allow to measure the aerodynamic forces on the vehicles for different wind exposures and over a wide range of Reynolds number. In particular the aerodynamic admittance functions are computed for different wind conditions by varying the turbulence intensity indexes and the integral length scales of the simulated wind flow; the final aim of the paper is to validate a numerical model which is able to reproduce the equivalent forces exerted on the vehicle in presence of turbulent flow conditions