The Asymmetry of the Time History of the High-Speed Train Pass-By Noise

2015 ◽  
Vol 43 (2) ◽  
pp. 169-173
Author(s):  
Di Wu ◽  
Jianmin Ge
Keyword(s):  
High Speed ◽  
Time History ◽  
High Speed Train ◽  
History Of ◽  
The Asymmetry

Analysis of the dynamic response and fatigue reliability of a full-scale carbody of a high-speed train

2018 ◽  
Vol 232 (7) ◽  
pp. 2006-2023 ◽  
Author(s):  
Yaohui Lu ◽  
Linyuan Dang ◽  
Xing Zhang ◽  
Zhen Feng ◽  
Jing Zeng ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Probability Distribution ◽  
Failure Rate ◽  
Surrogate Model ◽  
High Speed ◽  
Time History ◽  
Strength Degradation ◽  
High Speed Train ◽  
Fatigue Reliability ◽  
History Of

For a vehicle operating under different line conditions, coupled with track irregularity and many other factors, the carbody is subjected to extremely complex random loads, and the load mainly exists in the form of an alternating load; therefore, the primary type of failure is fatigue failure. With the continuous improvement in train speed, lightweight designs of carbody structures and the application of high-strength aluminium alloy, the safety and reliability of a carbody require more attention. An investigation of the dynamic fatigue reliability of a full-scale carbody of a high-speed train under random load conditions is carried out. A dynamics model of the vehicle system has been established for acquiring the time history of forces acting on the carbody by each air spring (hereinafter referred to as ‘the load–time history’). A surrogate model (a simple model instead of a complex carbody model) of the carbody is established based on the Box–Behnken matrix design and the polynomial fitting method; then, the load–time history is transformed to the stress–time history of the points of concern, and the results are compared with the results of the transient analysis, which verify the accuracy and effectiveness of the surrogate model. Then, a stress block spectrum is obtained by rain flow counting, and the stress probability distribution is determined. Combined with the probability distribution of fatigue strength, a dynamic stress–strength interference model (the area of interference between strength and stress in the model changes over time) is established. The failure rate and dynamic reliability of the points of concern for two cases are analysed: without considering the strength degradation and considering the strength degradation. The results show that without considering the strength degradation during service, with increased service mileage, the fatigue strength reliability of the points of concern decreases continuously, and the corresponding failure rate of the points of concern decreases with time and reaches a steady value, which has the characteristics of the first two stages of the bathtub curve. By considering the strength degradation during service, the reliability of the points of concern decreases gradually, and the corresponding failure rate of the points of concern decreases and then increases, with all the features of the bathtub curve. In addition, compared with the base metal region, the fatigue resistance of the welded structure decreases due to welding. Under the same service conditions, the reliability of the welded region is relatively low, and fatigue failure is more likely to occur.

Analysis of Liquid Slug Motion in a Voided Line

1998 ◽  
Vol 120 (1) ◽  
pp. 74-80 ◽  
Author(s):  
J. Yang ◽  
D. C. Wiggert
Keyword(s):  
Momentum Transfer ◽  
High Speed ◽  
Time History ◽  
Air Entrainment ◽  
Phase Flow ◽  
Liquid Slug ◽  
Two Phase ◽  
Pressure Time ◽  
History Of ◽  
Good Agreement

A quasi-two-dimensional two-phase flow cylindrical model of slug motion in a voided line is developed that can reasonably predict the change of flow pattern of the slug, air entrainment, “holdup” and the distribution of axial velocity. However, when using the theory of incompressible momentum transfer to estimate the pressure-time history of slug at the elbow, the calculated results are not in good agreement with those of the experiments. Further analysis of the experimental results indicate that an acoustic, or waterhammerlike response may occur immediately upon impact of the high-speed slug with the elbow, and subsequently, the waveform exhibits momentum transfer due to the acceleration of the slug at the elbow.

On the mechanics of high speed liquid jets

1977 ◽  
Vol 357 (1689) ◽  
pp. 143-162 ◽  
Keyword(s):  
Sound Speed ◽  
High Speed ◽  
Supersonic Jet ◽  
Time History ◽  
Taylor Instability ◽  
Liquid Jets ◽  
Late Time ◽  
History Of ◽  
Theoretical Evidence

Both experimental and theoretical methods are used to investigate the mechanics of the emergence and flight of a liquid jet travelling at speeds supersonic relative to the sound speed of the liquid. The experimental work uses an Imacon image converter camera to follow the mechanical events at micro-second framing intervals. The theoretical investigation employs similarity arguments and the Tschaplygin transformation to investigate the role of liquid overcompression in the process of the jet emergence. In addition, simple theoretical arguments are used to examine the effects of Stokes drag on the small liquid particle shroud surrounding the jet and Taylor instability effects in the late time history of the jet’s flight. An evacuated chamber is used to verify the theoretical prediction that subsonic (relative to the liquid sound speed) jets will not undergo the violent decompression process predicted for supersonic jets. The experimental and theoretical evidence are synthesized into an overall picture of the jet’s history from initial decompression of an overdense supersonic jet to the breakup of the resulting liquid slugs by deceleration and Taylor instability.

Analysis on Load Spectrum of Bogie Frame for High-Speed EMU

2014 ◽  
Vol 633-634 ◽  
pp. 1166-1173
Author(s):  
Yu Guang Wang ◽  
Da Fu Zhang
Keyword(s):  
Fatigue Life ◽  
Dynamic Model ◽  
High Speed ◽  
Estimation Method ◽  
Time History ◽  
Load Spectrum ◽  
Safe Operation ◽  
Bogie Frame ◽  
Key Factor ◽  
History Of

The load spectrum, on which there is not a thorough research, is the key factor of the safe operation of EMU. A dynamic model of some high-speed EMU is established and the load time history of main load on frame is obtained through simulation and analysis based on the Beijing-Tianjin route. The load spectrum for main load is calculated by rain-flow counting, the crossing contrast of load spectrum in basic and fault conditions is proceeded as well, the extent of impact of all kinds of fault conditions to bogie main load is analyzed and a brief introduction of estimation method of the frame fatigue life is put forward in this paper.

Analysis and Selection of Fluid-Film Bearings for Spool-Shaft Gas Turbines

1970 ◽  
Vol 92 (4) ◽  
pp. 597-606
Author(s):  
W. Shapiro ◽  
R. Colsher ◽  
O. Decker
Keyword(s):  
Gas Turbines ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Ambient Pressure ◽  
Time History ◽  
Fluid Film ◽  
Fluid Film Bearings ◽  
High Speed Rotation ◽  
History Of ◽  
Speed Rotation

The mechanical simplicity and damping qualities of fluid-film bearings makes them attractive possibilities for spool-shaft bearings of gas turbines. The simultaneous high-speed rotation of journal and bearing, however, causes whirl stability to be a major problem. Computerized analysis was utilized to screen a spectrum of practical candidate configurations. Stability threshold plots were expeditiously generated using accurately determined cross-coupled spring and damping coefficients to represent the bearings. Performance of each bearing type was determined as a function of configuration, ambient pressure, and machined clearance. The selected three-lobe design was further tested with a “time-transient” analysis that accurately traced a complete time history of the motions of the system in its various degrees of freedom.

Experimental Observations of the Microlayer in Vapor Bubble Growth on a Heated Solid

1983 ◽  
Vol 105 (3) ◽  
pp. 625-632 ◽  
Author(s):  
L. D. Koffman ◽  
M. S. Plesset
Keyword(s):  
High Speed ◽  
Time History ◽  
Laser Interferometry ◽  
Nucleate Boiling ◽  
Thickness Change ◽  
Transfer Rates ◽  
High Speed Cinematography ◽  
History Of ◽  
Microlayer Evaporation ◽  
Fringe Patterns

Experimental measurements of microlayer formation and of the time history of microlayer thickness change have been obtained for nucleate boiling of water and ethanol. These detailed measurements were obtained using laser interferometry combined with high-speed cinematography. The measurement technique is discussed in detail with emphasis on the difficulties encountered in interpretation of the fringe patterns. The measurements for water can be reasonably applied to the data of Gunther and Kreith, in which case it is concluded that microlayer evaporation alone cannot account for the increased heat transfer rates observed in highly subcooled nucleate boiling. It appears that microconvection must play at least an equal role.

scholarly journals AN INVERSE DYNAMICS METHOD FOR RAILWAY VEHICLE SYSTEMS

Transport ◽  
2013 ◽  
Vol 29 (1) ◽  
pp. 107-114 ◽  
Author(s):  
Tao Zhu ◽  
Shoune Xiao ◽  
Guangwu Yang ◽  
Weihua Ma ◽  
Zhixin Zhang
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Inverse Dynamics ◽  
Time History ◽  
Inverse Model ◽  
Contact Forces ◽  
Railway Vehicle ◽  
Inverse Dynamic ◽  
Multibody Model ◽  
History Of

The wheel–rail action will obviously be increased during the vehicles in high-speed operation state. However, in many practical cases, direct measurement of the wheel–rail contact forces cannot be performed with traditional procedures and transducers. An inverse mathematical dynamic model for the estimation of wheel–rail contact forces from measured accelerations was developed. The inverse model is a non-iteration recurrence method to identify the time history of input excitation based on the dynamic programming equation. Furthermore, the method overcomes the weakness of large fluctuations which exist in current inverse techniques. Based on the inverse dynamic model, a high-speed vehicle multibody model with twenty-seven Degree of Freedoms (DOFs) is established. With the measured responses as input, the inverse vehicle model can not only identify the responses in other parts of vehicle, but also identify the vertical and lateral wheel–rail forces respectively. Results from the inverse model were compared with experiment data. In a more complex operating condition, the inverse model was also compared with results from simulations calculated by SIMPACK.

scholarly journals Anti-sunward high-speed jets in the subsolar magnetosheath

2013 ◽  
Vol 31 (10) ◽  
pp. 1877-1889 ◽  
Author(s):  
F. Plaschke ◽  
H. Hietala ◽  
V. Angelopoulos
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
High Speed ◽  
Dynamic Pressure ◽  
Time History ◽  
Data Set ◽  
Wind Variability ◽  
History Of ◽  
Favorable Conditions ◽  
Upstream Solar Wind

Abstract. Using 2008–2011 data from the five Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft in Earth's subsolar magnetosheath, we study high-speed jets identified as intervals when the anti-sunward component of the dynamic pressure in the subsolar magnetosheath exceeds half of its upstream solar wind value. Based on our comprehensive data set of 2859 high-speed jets, we obtain the following statistical results on jet properties and favorable conditions: high-speed jets occur predominantly downstream of the quasi-parallel bow shock, i.e., when interplanetary magnetic field cone angles are low. Apart from that, jet occurrence is only very weakly dependent (if at all) on other upstream conditions or solar wind variability. Typical durations and recurrence times of high-speed jets are on the order of tens of seconds and a few minutes, respectively. Relative to the ambient magnetosheath, high-speed jets exhibit higher speed, density and magnetic field intensity, but lower and more isotropic temperatures. They are almost always super-Alfvénic, often even super-magnetosonic, and typically feature 6.5 times as much dynamic pressure and twice as much total pressure in anti-sunward direction as the surrounding plasma does. Consequently, they are likely to have significant effects on the magnetosphere and ionosphere if they impinge on the magnetopause.

Effects of Mechanical and Pneumatic Return Springs on Valve Train Dynamics

2006 ◽  
Author(s):  
Stefano Pastorelli ◽  
Andrea Almondo ◽  
Massimo Sorli
Keyword(s):  
High Speed ◽  
Dynamic Stiffness ◽  
Time History ◽  
Pressure Control ◽  
Valve Train ◽  
Cam Mechanism ◽  
Distributed Parameters ◽  
Return Spring ◽  
History Of ◽  
Mechanical Spring

The dynamic analysis of a cam transmission derived from an engine valve train is performed in frequency and time domain, by means of a combined lumped-distributed parameters models, capable of predicting the effects of the higher harmonics of the cam lift profile on system performances, in particular as concerning the return spring device. Dynamic stiffness of the transmission in frequency domain and time history of contact force between cam and follower are evaluated, highlighting the limits of the transmission at high-speed camshaft operations caused by the spring behavior. The aim of the study is to developed a comparison on the performances of the cam mechanism working with the original mechanical spring from design or with a pneumatic return device based on a pneumatic spring and a pressure control circuit.

Fractal Properties of a Falling Particle Curtain in Air

2021 ◽  
Author(s):  
Josh S. Ludwigsen ◽  
Patrick Wayne ◽  
Daniel Freelong ◽  
Gregory Vigil ◽  
Carolina Shaheen ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
High Speed ◽  
Multiphase Flows ◽  
Initial Conditions ◽  
Numerical Models ◽  
Time History ◽  
Dense Particle ◽  
History Of ◽  
Gravity Driven ◽  
Evolutionary Growth

Abstract The formation of a gravity-driven falling particle curtain is important for many problems, including solar tower particle receivers and setting the correct initial conditions for modeling shock interaction with multiphase media. One important characteristic of the curtain is the time history of its fractal dimension that characterizes the evolutionary growth of perturbations along the curtain's extent. For multiphase flows, fractal dimension can be used to help predict the types of instabilities that will occur within the flow. Our experiment aimed to establish the transient and steady-state fractal dimension of a dense particle curtain containing particles with a density of 1.4416 gm/cm3 and nominal diameter ranging from 30 to 50 microns. High-speed video of the curtain was captured and analyzed. This data from this experiment, besides providing insights into the relevant physical processes, will be used to validate numerical models for multiphase flows.

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