The measurement of train aerodynamic phenomena in operational conditions

与列车设计和运营相关的空气动力学影响有多种--空气动力阻力的确定、侧风对列车稳定性的影响、轨旁结构上的压力瞬变载荷、隧道压力瞬变的生理影响、列车滑流和尾流对候车乘客和轨旁工作人员的影响等。这些影响的大小随着车速的平方而广泛增加，因此随着高速列车线路的不断发展，空气动力学影响在设计和运营方面将变得更加显著。现在可以假设，过去用于预测空气动力效应的技术(风洞和CFD方法)可能会确定比实际观测到的压力、速度、力等大小更高的压力、速度、力等，而其他影响--如轨道粗糙度、气象条件的可变性等--通常在某种程度上可能会掩盖空气动力效应，因此，目前的一些设计方法具有不必要的限制性和/或保守性。因此，本项目的目的是调查和测量在实际列车运行中观察到的一系列空气动力学现象，无论是相对于列车还是相对于轨道边的某个固定点，并比较这些影响如何与模型比例尺测量和各种类型的CFD计算相匹配，从而检验上述假设的有效性。这将通过Network Rail高速测量列车的仪器来实现，以测量空气动力效应，因为列车在英国铁路网中执行其正常的负载循环。此外，轨旁仪器将安装在合适的位置，以便测量列车下的现象。校准风洞、CFD和运动模型试验将按常规方式进行，以便与全尺寸测量数据进行比较。全尺度、模型尺度和计算试验将由经验丰富的RFS进行，并将为两项博士研究提供数据，其中一项将调查基于列车的横风力、压力瞬变等测量与传统方法预测的结果如何比较，另一项将调查轨道侧测量与传统测试结果的比较。研究人员将综合结果，并对未来的空气动力测试方法提出建议。

There are a variety of aerodynamic effects associated with train design and operation - the determination of aerodynamic drag, the effect of cross winds on train stability, pressure transient loading on trackside structures, the physiological effect of tunnel pressure transients, the effect of train slipstreams and wakes on waiting passengers and trackside workers etc. The magnitude of these effects broadly increases as the square of the vehicle speed and thus with the continued development of high speed train lines aerodynamic effects will become more significant in terms of design and operation. Now it can be hypothesised that the techniques that have been used to predict aerodynamic effects in the past (wind tunnel and CFD methods) are likely to determine magnitudes of pressures, velocities, forces etc. that are higher than those observed in practice, where other effects - such as track roughness, variability in meteorological conditions etc. are likely to usually obscure aerodynamic effects to some extent and, because of this, some of the current design methodologies are unnecessarily restrictive and/or conservative. Thus the aim of the current project is to investigate and measure a range of aerodynamic phenomena observed in real train operation, both relative to the train and relative to a fixed point at the trackside, and to compare how such effects match model scale measurements and various types of CFD calculation, and thus to test the validity, or otherwise, of the above hypothesis. This will be achieved through the instrumentation of the Network Rail High Speed Measuring Train to measure aerodynamic effects, as the train carries out its normal duty cycle around the UK rail network. Also trackside instrumentation will be installed at a suitable site that will allow off-train phenomena to be measured. Calibration wind tunnel, CFD and moving model tests will be carried out in the conventional way for comparison with data measured at full scale. The full scale, model scale and computational trials will be carried out by experienced RFs and will provide data for two doctoral studies, one of which will investigate how the train based measurements of cross wind forces, pressure transients etc compare with those predicted by conventional methodologies, and one of which will investigate how the track side measurements compare with conventional test results. The investigators will synthesise the results and make recommendations for future aerodynamic test methods.