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PROCEEDINGS OF THE THIRD INTERNATIONAL CONFERENCE ON RAILWAY TECHNOLOGY: RESEARCH, DEVELOPMENT AND MAINTENANCE
Edited by: J. Pombo
Cross-Flow Induced Pressure on Air Outlets
J. Tschepe1, M. Weise2, A. Tietze2, C.N. Nayeri1 and C.O. Paschereit1
1Chair of Fluid Dynamics, Hermann-Föttinger-Institut, Technische Universität Berlin, Germany
J. Tschepe, M. Weise, A. Tietze, C.N. Nayeri, C.O. Paschereit, "Cross-Flow Induced Pressure on Air Outlets", in J. Pombo, (Editor), "Proceedings of the Third International Conference on Railway Technology: Research, Development and Maintenance", Civil-Comp Press, Stirlingshire, UK, Paper 44, 2016. doi:10.4203/ccp.110.44
Keywords: outlet, cross-flow, counter pressure, jet, air-exchange, cooling, railway aerodynamics.
This paper shows that the interaction of an air stream (jet) coming from the outlet of a vehicle with the surrounding flow has an important impact on the pressure distribution in the outlet duct. Based on experimental investigations carried out in a wind tunnel it is shown that this interaction in most cases causes an additional counter pressure that has to be overcome by the acting fan. Depending on the parameter setting pressure differences in the order of several hundred Pascal can appear. Here, the most important parameter for this interaction turned out to be the momentum flux ratio of exhaust jet and cross-flow. This ratio is a result of the streams' fluid densities and velocities and is strongly affected by the near wall flow profile of the cross-flow upstream the outlet. Furthermore, the impact of geometry parameters such as the jet's exit shape is demonstrated.
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