A Simplified Transient CFD Model to Support the Development of a Low Cost Self-Monitoring Railway Damper

The purpose of this thesis was to conduct preliminary modelling and analysis of primary vertical dampers in railway vehicle suspension systems to support the development of a low cost condition monitoring system. Currently damper maintenance is calendar based, but with implementation of a continuous condition monitoring system, the damper’s health status will be known and hence it will become possible for maintenance intervals to be extended. This in-turn will reduce costly downtime and increase vehicle availability.
Of particular interest are the failure modes of primary vertical dampers, and the determination of sensor type and placement within the damper to support the wider future plans to develop a complete condition monitoring solution. The simulation and analysis work to support the derivation of sensor type and placement will be achieved with the aid of computational fluid dynamics modelling (CFD).
The research questions are established, followed by an overview of railway vehicles and the functions of their suspension systems, including primary and secondary dampers. A literature review of existing research in the field of condition monitoring of rail vehicle dampers and the use of computational fluid dynamic modelling in analysis of dampers is then conducted. Primary damper failure modes are identified and the most prominent modes established using existing data provided by Unipart Rail Ltd. A brief overview of computational fluid dynamic methods is conducted, followed by a selection of approach. A fluid dynamic model is created and compared with an existing damper.
It is proposed that it may be possible to detect the majority of failure modes, with effective processing of data provided by an appropriate sensor. The results of the fluid dynamic modelling show that sensors are best placed on the top and bottom of the piston head or within the compression and extension chambers of the damper. A pressure sensor with a
measuring range corresponding to the CFD is also suggested (between 25 Pa and 117,000 Pa). Further work is suggested, which consists of further CFD modelling and employing vehicle dynamics simulation techniques to further characterise the operating environment of the damper. This information could then be further employed to specify an advanced testing regime, which would explore the degradation modes of the damper in more detail and ultimately lead to the development of failure mode algorithms for integration within a remote condition monitoring architecture for remaining life predictions.