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Research Papers: Flows in Complex Systems

Aerodynamic Forces on Multiple Unit Trains in Cross Winds

[+] Author and Article Information
Christopher J. Baker

School of Civil Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK

Mark Sterling

School of Civil Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, UKm.sterling@bham.ac.uk

J. Fluids Eng 131(10), 101103 (Sep 18, 2009) (14 pages) doi:10.1115/1.3222908 History: Received February 26, 2009; Revised August 05, 2009; Published September 18, 2009

This paper describes the results of wind tunnel tests that were carried out to measure the aerodynamic characteristics of an electrical multiple unit (EMU) vehicle in a cross wind. The measurements were made on a 1/30 scale model of the Class 365 EMU in a simulation of the natural wind. The time histories of surface pressures were measured at a large number of points over the vehicle from which the aerodynamic characteristics and force coefficients were determined. This paper describes the complex fluctuating pressure field over the vehicle, through a consideration of the mean and fluctuating pressure coefficients and their spectra, and through a proper orthogonal decomposition analysis, which identifies the major modes of this distribution. The mean, fluctuating, and extreme aerodynamic side and lift forces are also discussed. It is shown that the flow pattern around the vehicle is dominated by large windward roof corner pressure fluctuations.

Copyright © 2009 by American Society of Mechanical Engineers
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References

Figures

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Figure 10

Probability distributions for the pressure time series data shown in Fig. 9: (a) tap 1-windward wall, (b) tap 3-roof corner, and (c) tap 5-roof

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Figure 11

Pressure coefficient POD mode 1 on the leading car

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Figure 12

Pressure coefficient POD mode 2 on the leading car

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Figure 13

Pressure coefficient POD mode 3 on the leading car

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Figure 14

Pressure coefficient mode spectra plotted in normalized form (spectral density×frequency/variance): (a) mode 1, (b) mode 2, and (c) mode 3

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Figure 15

Mean force coefficients for the leading car

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Figure 16

Standard deviations of the force coefficients for the leading car

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Figure 17

Force coefficient spectra for the leading car plotted in normalized form (spectral density×frequency/variance): (a) side and (b) lift force coefficients

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Figure 18

An illustration of the variation in the side force coefficient on car A with respect to yaw angle (NB the time has been expressed in terms of full-scale equivalent time)

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Figure 19

Overall cross-correlation force coefficient with respect to the yaw angle (cs×cl).

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Figure 20

Instantaneous plots of the lift force coefficient versus the side force coefficient for a range of yaw angles.

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Figure 21

Probability distributions relating to the force coefficient time series: (a) side and (b) lift force coefficients

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Figure 22

99.67th percentile filter applied to the side force coefficient data

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Figure 23

99.67th percentile filter applied to the lift force coefficient data

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Figure 24

Ensemble average pressure distribution corresponding to a side force peak event

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Figure 25

Ensemble average pressure distribution corresponding to a lift force peak event

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Figure 26

Instantaneous pressure distributions resulting in a maximum value of the lift force coefficient occurring for a peak value of the side force coefficient

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Figure 27

Instantaneous pressure distributions resulting in a minimum value of the lift force coefficient occurring for a peak value of the side force coefficient

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Figure 1

The Class 365 EMU wind tunnel model

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Figure 2

The simulated velocity profile and target value for a full-scale surface roughness=0.03 m

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Figure 3

The simulated turbulence intensity profile and target value for a full-scale surface roughness=0.03 m

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Figure 4

The simulated velocity spectrum at z=100 mm (3 m full scale) plotted in normalized form (spectral density×frequency/variance)

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Figure 5

Pressure tapping notation: (a) pressure tap identification and (b) tapping loop distribution

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Figure 6

Pressure coefficient distribution at 90 deg yaw on loop E (solid line represents datum, dotted line represents the pressure coefficient, and negative values are between the datum and the train sketch)

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Figure 7

Mean pressure coefficients on the leading car

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Figure 8

Standard deviation of the pressure coefficients on the leading car

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Figure 9

Pressure coefficient spectra on the leading car (loop E) plotted in normalized form (spectral density×frequency/variance)

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