The Effect from Hole Area on Pressure Waves Produced by a High-Speed Train through Tunnel with Perforated Wall

2011 ◽  
Vol 94-96 ◽  
pp. 1733-1736
Author(s):  
Yuan Gui Mei ◽  
Yong Xing Jia
Keyword(s):  
Numerical Method ◽  
Pressure Wave ◽  
High Speed ◽  
Method Of Characteristics ◽  
Pressure Waves ◽  
High Speed Train ◽  
One Dimensional ◽  
Isentropic Flow ◽  
Perforated Wall ◽  
Hole Area

The perforated wall has great effect on pressure waves produced by high-speed train through a tunnel. In this paper the effect is investigated numerically by the method of characteristics based on one-dimensional unsteady compressible non-isentropic flow theory. The numerical method is validated by experimental results of Netherlands NLR. The effect from hole area in perforated wall is investigated principally and the results shows that the pressure wave is alleviated remarkably in tunnel with perforated wall.

Comparison of Micro-Pressure Wave Radiated Out of Tunnel Exit between Slab Track and Ballast Track

2011 ◽  
Vol 90-93 ◽  
pp. 2183-2187 ◽  
Author(s):  
Feng Geng ◽  
Qian Zhang
Keyword(s):  
Pressure Wave ◽  
High Speed ◽  
High Speed Train ◽  
Tunnel Length ◽  
One Dimensional ◽  
Isentropic Flow ◽  
Calculation Process ◽  
Ballast Track ◽  
Reduction Effect ◽  
The One

Based on the one-dimensional unsteady compressible non-isentropic flow theory, micro-pressure wave radiated out of tunnel exit generated by a high-speed train entering a tunnel was investigated. In calculation process, the track roadbed and tunnel length were considered. The results, which were qualitatively and quantitatively analyzed, show that the ballast track has reduction effect of micro-pressure wave in long tunnel.

Pressure wave characteristics of a high-speed train in a tunnel according to the operating conditions

2017 ◽  
Vol 232 (3) ◽  
pp. 928-935 ◽  
Author(s):  
Joon-Hyung Kim ◽  
Joo-Hyun Rho
Keyword(s):  
Numerical Analysis ◽  
Pressure Wave ◽  
High Speed ◽  
High Reliability ◽  
Rate Of Change ◽  
Operating Conditions ◽  
Pressure Waves ◽  
High Speed Train ◽  
Wave Characteristics ◽  
Pressure Characteristics

The pressure waves of a high-speed train in a tunnel exhibit complicated variations in their characteristics because the waves propagate and reflect with superposition. Studies have been consistently carried out on the pressure waves of a single train since changes in the area of pressure is a key element that influences ride comfort. Recently, the frequency of the operation of coupled trains has increased in order to improve the efficiency of running a train. The cross-sectional area of a train entering a tunnel has a rate of change that greatly influences the pressure characteristics; therefore, a coupled train can have different pressure characteristics when compared to a single train. However, adequate research works have not been done to assess these characteristics. To this end, the pressure characteristics of a train according to the operating conditions are investigated in this study. A high-speed train operating in practice and a tunnel located in a service section were chosen for this study, and the pressure characteristics of a single train were assessed via numerical analysis and an experiment. The numerical analysis was carried out with high reliability by comparing and verifying each result. After the pressure wave characteristics caused by running a coupled train had been assessed by the established numerical analysis, an obvious pressure variation was confirmed to occur at the connecting point. In addition, the maximum pressure applied to a tunnel and a passenger car increased. Thus, the aerodynamic effect of a coupled train should be considered as an important parameter in the early design state of a new high-speed train.

Iterative learning control of air pressure variation inside a high-speed train under the excitation of the tunnel pressure wave with a fixed-morphologic form

2021 ◽  
pp. 095440972110327
Author(s):  
Zhiying He ◽  
Chunjun Chen ◽  
Dongwei Wang ◽  
Chao Deng ◽  
Jia Hu ◽  
...  
Keyword(s):  
Iterative Learning Control ◽  
Pressure Wave ◽  
High Speed ◽  
Learning Control ◽  
Pressure Variation ◽  
Iterative Learning ◽  
Air Pressure ◽  
High Speed Train ◽  
Comfort Index ◽  
Simulation Signal

Based on the characteristics that the tunnel pressure wave has a fixed-morphologic form when the same train passes through the same tunnel, an applicational approach based on the iterative learning control (ILC) is developed, aiming at overcoming the drawbacks of the traditional strategy for controlling the air pressure variation inside a high-speed train carriage. To achieve the goal, the control system is mathematically modelled. Then, the problem is formulated. The task of suppressing the influence of the tunnel pressure wave on the air pressure inside the carriages is shifted as an ILC problem of tracking the comfort index with varying trial length. The algorithm of refreshing the control signal from trial to trial is determined and the process of ILC control is designed. Next, the convergence of the newly-developed applicational ILC algorithm is discussed and the algorithm is simulated by the simulation signal and field-test signal. Results show that the applicational ILC algorithm be more adaptable in handling the control of the air pressure inside carriage under the excitation of varying-amplitude, varying-scale and varying-initial-states tunnel pressure wave. Meanwhile, the matching with tunnel pressure wave makes the applicational ILC algorithm will take both the riding comfort and fresh air into consideration, which upgrades the performances when the high-speed train passing through long tunnels.

Optimal cross-sectional area distribution of a high-speed train nose to minimize the tunnel micro-pressure wave

2010 ◽  
Vol 42 (6) ◽  
pp. 965-976 ◽  
Author(s):  
Yo-Cheon Ku ◽  
Joo-Hyun Rho ◽  
Su-Hwan Yun ◽  
Min-Ho Kwak ◽  
Kyu-Hong Kim ◽  
...  
Keyword(s):  
Pressure Wave ◽  
High Speed ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
High Speed Train ◽  
Cross Sectional ◽  
Area Distribution

scholarly journals Numerical method of characteristics for one-dimensional blood flow

2015 ◽  
Vol 294 ◽  
pp. 96-109 ◽  
Author(s):  
Sebastian Acosta ◽  
Charles Puelz ◽  
Béatrice Rivière ◽  
Daniel J. Penny ◽  
Craig G. Rusin
Keyword(s):  
Blood Flow ◽  
Numerical Method ◽  
Method Of Characteristics ◽  
One Dimensional

Active Attenuation of Low Frequency Noise Radiated from Tunnel Exit of High Speed Train

1994 ◽  
Vol 13 (2) ◽  
pp. 39-47
Author(s):  
Min Liang ◽  
Toshiya Kitamura ◽  
Katsushi Matsubayashi ◽  
Toshifumi Kosaka ◽  
Tatsuo Maeda ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Pressure Wave ◽  
High Speed ◽  
Outer Space ◽  
Low Frequency ◽  
Close Relation ◽  
Frequency Noise ◽  
High Speed Train ◽  
Low Frequency Noise ◽  
Active Cancellation

A pressure wave occurs at the instant when a high speed train enters into a long tunnel. The wave propagates downstream to the tunnel exit and low frequency noise is radiated from the exit to outer space. The low frequency noise causes a lot of problems1 to the residents living near the exit and has a close relation with the pressure gradient of the pressure wave. To attenuate the low frequency noise, an active cancellation system rather than a passive one is developed. This research uses a model tunnel to examine the characteristic of the pressure wave and investigates the possibility to reduce the low frequency noise by reducing the pressure wave gradient with active cancellation.

Numerical Method for Studying Bearing Gap Pressure Wave Development and Subsequent Performance Mapping of Externally Pressurized Gas Journal Bearings

2019 ◽  
Author(s):  
Tom M. Lawrence ◽  
Marvin D. Kemple
Keyword(s):  
Numerical Method ◽  
Cross Section ◽  
Mass Flow ◽  
Pressure Wave ◽  
Design Space ◽  
Numerical Study ◽  
Pressure Waves ◽  
Wide Range ◽  
Wave Development ◽  
Static Instability

Abstract In previous work, numerical methods were developed to determine the pressure waves (pressure distribution) in the bearing gap of round externally pressurized gas bearings (EPB’s) that were pressurized through porous liners (PL bearings) or through liners with rows of feedholes (FH bearings). When integrated and differentiated these pressure portraits yield the net hydrodynamic force (FH) between the shaft and the bushing and the mass flow rates through the bearing gap. These results successfully replicated force-deflection curves and mass flow rate data for experimentally tested prototype FH and PL bearings over a wide range of mass flow constriction and clearances. Subsequently the numerical study was expanded to a broader design space of clearance and mass flow compensation. Also, a bearing performance mapping method of mapping the normalized bearing load over the clearance-eccentric deflection plane was developed for different levels of mass compensation. These performance maps produced a very interesting result as they indicated certain areas in the design space of FH bearings where static instability (negative stiffness) would be encountered. This static instability was not observed in the experimental data but is noted in references as known to occur in practice. Because this numerical method is based on the development of pressure wave portraits, the FH pressure wave could then be “dissected” in the areas of the onset of static instability which gave much insight as to the possible causes of static instability. This initial work, then, was perhaps the first to predict where in design space static instability would occur and yield some insight via examination of the corresponding pressure waves as to the cause. The numeric techniques developed, however are in no way limited to non-rotating bearings but are extensible to rotating bearings. The method is also easily extensible to examination of any configuration of feedholes or orifices. Nor is it limited to parallel deflections but can yield results for unbalanced loads. The method is also not limited to round bearings but can be applied to any cross-section configuration of bearing gap cross section such as a 3 lobed bearing or a slotted 3 lobed bearing. Examination of the resulting pressure wave development patterns for different scenarios can be examined to garner insight as to the causes of differing performance that can be applied to alterations towards optimization. Thus sharing in detail the developed numerical method underlying these studies seems worthwhile.

Simulation Models of the Complex Type Pressure Wave Supercharger

2016 ◽  
Vol 823 ◽  
pp. 341-346
Author(s):  
Sebastian Radu ◽  
Marius Hârceagă ◽  
Gheorghe Alexandru Radu ◽  
Cristian Leahu ◽  
Horia Abăităncei ◽  
...  
Keyword(s):  
Pressure Wave ◽  
Rotation Speed ◽  
Three Dimensional ◽  
Simulation Models ◽  
Pressure Waves ◽  
Complex Type ◽  
One Dimensional ◽  
Fluent Software ◽  
Type Pressure ◽  
Made In

In order to efficiently supercharge Diesel engines with pressure wave superchargers it is necessary to correlate the superchargers rotation speed with certain parameters of the supercharged engine. For this purpose, to reduce the research costs and duration, simulation models can be used which help to determine the parameters which have a major impact on the supercharger's rotational speed and efficiency. In this paper there are presented two simulation models: a one-dimensional (made in AMESim software) and a three dimensional (made in Fluent Software). This simulation models offer the possibility to visualize some dynamic phenomenon within the supercharger, like the evolution of the pressure waves or the turbulent flow inside the rotor channels. These phenomena are difficult and expensive to study with conventional methods.

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