Crosswind Angle Research Articles

On the optimal model configuration for aerodynamic modeling of open cargo railway train

This study is concerned with the optimal model configuration for aerodynamic modeling of long open cargo railway trains. Frontal air drag of several train configurations was studied using numerical modeling and physical i.e. wind tunnel testing of 1:40 scale railcar models in a range of cross-wind angles. In a long train, the locomotive and the last railcar influence the aerodynamic characteristics of the first three and the last three railcars only. Aerodynamic performance of all other railcars in the long train is similar and can be represented by two inner-train railcars only. A model train configuration combining the shortest computation time with the lowest experimental error was determined from numerical modeling and this was then used for wind tunnel testing. It has been shown that, for long open cargo railway trains the model consisting of six railcars with two streamlined bodies is the optimal configuration, with both the numerical modeling and wind tunnel testing results in good agreement.

Measurements of Intake Separation Hysteresis in a Model Fan and Nacelle Rig

A 1/20-scale, low speed model rig representing the fan and nacelle of a high bypass ratio jet engine has been tested under crosswind conditions. The flow conditions under which the intake flow separates and reattaches have been found to exhibit considerable hysteresis. This phenomenon has been examined by a careful test procedure in which the crosswind angle has been slowly increased and then decreased. Measurements of the hysteresis associated with separation and reattachment are presented for independent variations in stream-tube contraction ratio, ground clearance, fan operating point and Reynolds number. The results reveal that particular care must be taken to allow for any hysteresis when testing intakes under crosswind conditions. They also indicate that separation hysteresis is particularly sensitive to fan operating point and the position of the ground plane. These findings suggest that it is important for high Reynolds number intake tests and calculations to include a ground plane and a model of the downstream turbomachinery. © 2002 by the author(s).

The assessment of wind tunnel testing techniques for ground vehicles in cross winds

This paper sets out the various types of wind induced problems experienced by ground vehicles, and discusses the nature of the experimental data required for appropriate vehicle safety assessments to be made. In particular the adequacy of various types of wind tunnel testing to obtain aerodynamic data is considered. By means of a correlation of experimental results and various theoretical approaches the requirements for adequate wind tunnel testing become apparent. It is concluded that to obtain the data required for wind induced suspension effects to be assessed and also for vehicle force histories to be determined from wind speed histories, it is necessary, except at low crosswind angles, to fully model both the upstream atmospheric turbulence simulation may be used together with some simulation of model motion.