The aerodynamics of freight trainsDavid Soper, Chris Baker and Mark Sterling - School of Civil Engineering

The aerodynamics of freight trainsDavid Soper, Chris Baker and Mark Sterling - School of Civil Engineering

BackgroundBackgroundBackgroundBackgroundThe UK rail freight industry is a growing sector with increasing volumes of international trade. Within an already over crowded network this creates economic and sustainability challenges. Solutions include increasing freight train lengths and speeds, however these have implications on efficiency and safety. The movement of a vehicle creates transient aerodynamic effects called slipstreams. There is extensive research of passenger train slipstreams, but little work has been untaken for freight trains.

Containers blown from freight trains near Cheddington and Containers blown from freight trains near Cheddington and HardendaleHardendale

ResultsResultsResultsResults

MotivationMotivationMotivationMotivation

MethodMethodMethodMethod

AimAimAimAimThe aim of the research was to create an understanding of slipstream velocities created by various container freight train configurations using full and model scale experiments.

Induced slipstream forces can interact with trackside objects potentially destabilising them. In the last forty years there have been twenty four train slipstreams incidents, the majority caused by freight trains. Transient air flows created by freight trains when coupled with outside effects such as crosswinds can also have serious consequences. On 1st March 2008 near Cheddington and Hardendale containers were blown from a train, causing damage to the track and overhead line equipment, creating delays.

Contacts

Experiments were conducted at the Transient Aerodynamic Investigation (TRAIN) facility in Derby. A purpose built 1/25th scale moving model train was designed and built to simulate a Class 66 and 4 FEA-B wagons with detachable containers. Different loading configurations were tested to understand the affect of container spacing on slipstream velocities.

container spacing was clearly seen in the pressure plots by a positive then negative pressure peak, caused by the passing of the front and rear of each container. The effect of container spacing in the velocity plots is seen by pronounced peaks caused by the container passing.

Pressure and velocity plots for a sparsely loaded container freight consistPressure and velocity plots for a sparsely loaded container freight consist

David Soperemail: DXS020@bham.ac.uk

Results from the model scale experiments are compared to full scale data collected during the RAPIDE and AeroTRAIN projects.

Model scale resultsModel scale results

Ensemble pressure and velocity plots were compared for varying distances from the train side. The effect of

Full scale resultsFull scale results

Maximum 1 second moving averages for a container freight train travelling at 75mph at trackside and platform conditions were compared to UK safety standards. It was shown that a shorter time scale should be used to fully assess slipstream velocities and safety positions should be moved further from platform edges and the nearest rail for freight passage.

Wavelet analysis on ensemble velocities highlighted the effect of averaging and the existence of high frequencies created within the boundary layer due to container passage.