scholarly journals The Effectiveness of the Suppression of Low Frequency Acoustic Resonances with Porous Sound Absorbing Structures of Multifunctional Upholstery Materials of Car Body Interior

2017 ◽  
Vol 176 ◽  
pp. 159-168 ◽  
Author(s):  
Michael I. Fesina ◽  
Alexander V. Krasnov ◽  
Larisa N. Gorina
Keyword(s):  
Low Frequency ◽  
Car Body ◽  
Acoustic Resonances

Online detection and control of car body low-frequency swaying in railway vehicles

2019 ◽  
Vol 59 (1) ◽  
pp. 70-100 ◽  
Author(s):  
Zhanghui Xia ◽  
Jinsong Zhou ◽  
Jianying Liang ◽  
Sansan Ding ◽  
Dao Gong ◽  
...  
Keyword(s):  
Low Frequency ◽  
Online Detection ◽  
Railway Vehicles ◽  
Car Body ◽  
And Control

Acoustic Resonances of an Industrial Gas Turbine Combustion System

2000 ◽  
Vol 123 (4) ◽  
pp. 766-773 ◽  
Author(s):  
S. Hubbard ◽  
A. P. Dowling
Keyword(s):  
Gas Turbine ◽  
Acoustic Waves ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Nonlinear Effects ◽  
Operating Conditions ◽  
Resonant Frequencies ◽  
Bulk Mode ◽  
Acoustic Resonances ◽  
Industrial Gas Turbine

A theory is developed to describe low-frequency acoustic waves in the complicated diffuser/combustor geometry of a typical industrial gas turbine. This is applied to the RB211-DLE geometry to give predictions for the frequencies of the acoustic resonances at a range of operating conditions. The main resonant frequencies are to be found around 605 Hz (associated with the plenum) and around 461 Hz and 823 Hz (associated with the combustion chamber), as well as one at around 22 Hz (a bulk mode associated with the system as a whole). The stabilizing effects of a Helmholtz resonator, which models damping through nonlinear effects, are included, together with effects of coupled pressure waves in the fuel supply system.

Low‐frequency acoustic resonances from the axi‐symmetrical bubble plume

2007 ◽  
Vol 121 (5) ◽  
pp. 3032-3032
Author(s):  
Michael J. Buckingham ◽  
Thomas R. Hahn ◽  
Thomas K. Berger
Keyword(s):  
Low Frequency ◽  
Bubble Plume ◽  
Acoustic Resonances

scholarly journals Suppression of low-frequency acoustic resonances in integrated optic lithium niobate modulators

2019 ◽  
Vol 1326 ◽  
pp. 012014
Author(s):  
A V Varlamov ◽  
M Yu Plotnikov ◽  
A S Aleinik ◽  
A A Vlasov ◽  
P M Agruzov ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Low Frequency ◽  
Acoustic Resonances

Study on Geometry Filtering Phenomenon and Flexible Car Body Resonant Vibration of Articulated Trains

2013 ◽  
Vol 787 ◽  
pp. 542-547 ◽  
Author(s):  
Dao Gong ◽  
Yue Jia Gu ◽  
Jin Song Zhou
Keyword(s):  
Low Frequency ◽  
Ride Quality ◽  
Green Functions ◽  
Resonant Vibration ◽  
Flexible Coupling ◽  
Car Body ◽  
Articulated Vehicles ◽  
Coupling Dynamic ◽  
Track Irregularity ◽  
Coupling Dynamic Model

A vertical rigid-flexible coupling dynamic model of three articulated vehicles with car body flexibility is established, Green functions are utilized to solve the partial differential equation of each car body, and the mechanism of car body flexible resonance is analyzed. Results show that geometry filtering phenomenon exists in articulated train, when the car body first vertical bending frequency coincides with the frequencies which have the peak values of car body bounce acceleration transmissibility, resonant vibration of flexible car body will happen; The energy of track irregularity decreases rapidly with the increasing frequency, so it is important to avoid the car body resonance at low frequency; If the first vertical bending frequency of car body is greater than a certain value, the flexible resonance will have little effect on the ride quality.

Acoustic Resonances of an Industrial Gas Turbine Combustion System

2000 ◽  
Author(s):  
S. Hubbard ◽  
A. P. Dowling
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Acoustic Waves ◽  
Low Frequency ◽  
Operating Conditions ◽  
Combustion System ◽  
Resonant Frequencies ◽  
Bulk Mode ◽  
Acoustic Resonances ◽  
Industrial Gas Turbine

A theory is developed to describe low frequency acoustic waves in the complicated diffuser/combustor geometry of a typical industrial gas turbine. This is applied to the RB211-DLE geometry to give predictions for the frequencies of the acoustic resonances at a range of operating conditions. The main resonant frequencies are to be found around 605 Hz (associated with the plenum) and around 461 Hz and 823 Hz (associated with the combustion chamber), as well as one at around 22 Hz (a bulk mode associated with the system as a whole).

WAVE PROPAGATION THROUGH HOLLOW BODIES AND NOISE REDUCTION

2001 ◽  
Vol 09 (03) ◽  
pp. 853-868
Author(s):  
SYLVAIN GERMÈS ◽  
CHRISTOPHE STAWICKI ◽  
DENIS AUBRY
Keyword(s):  
Wave Propagation ◽  
Low Frequency ◽  
Frequency Noise ◽  
Finite Element Models ◽  
Body Frame ◽  
Reflection And Transmission ◽  
Car Industry ◽  
Car Body ◽  
The Past ◽  
Good Agreement

Low frequency noise (2–200 Hz) reduction in the passenger compartment has emerged in the past few years as a crucial subject of research in the car industry. This kind of noise is mainly due to the panels' vibrations, therefore our aim is to decrease the part of structural energy that reach them, i.e., we want to increase the part of energy that dissipates while propagating in the car body frame. This approach requires the understanding of structural wave propagation through the beam like structure (pillar, cross members…) as well as reflection and transmission at the structural joints. This is the physical problem that we want to address in this paper. Since car body frames are much too complex for physical understanding, we focused on simpler representative academic structures. We developed a numerical tool for the prediction and visualization of wave propagation, based on finite element models (FEM). Our FEM are first validated by comparison with experimental modal analysis, and then used for transient analysis. In both cases, the good agreement between calculations and experiments shows the reliability of our model and allows us to use it for wave propagation visualization. We illustrate our results by making a movie that helps to understand how waves propagate through a two hollow bodies junction.

Empirical Modeling of a Rail Tank Car for Struck Coupler Force Estimation

2014 ◽  
Author(s):  
Brad M. Hopkins ◽  
Dan Maraini ◽  
Andrew Seidel ◽  
Parham Shahidi
Keyword(s):  
Low Frequency ◽  
Real Data ◽  
Empirical Modeling ◽  
Data Sets ◽  
Force Estimation ◽  
Computationally Efficient ◽  
Car Body ◽  
Parametric Studies ◽  
Added Uncertainty ◽  
Identification Techniques

Freight rail cars may experience high input forces during a coupling event, which could potentially cause damage to the car body and/or lading. The AAR recommended practice states that cars should not be coupled at speeds greater than 4 mph. However, this recommendation is not always followed and cars are often coupled at much higher speeds. As a result, accelerometers on the car body are sometimes used to monitor impact events. Threshold levels may be set to determine if an over-speed or high-force impact event has occurred. However, a single acceleration value can be difficult to interpret because its relationship to impact force is dependent on many factors, including car type, end-of-car device type, lading type, and loading condition. Dynamic modeling and parametric studies may be used to determine these relationships which can be applied in practice. This paper presents a study on the relationship between struck coupler force and car body acceleration for a series of impacts on a tank car in both loaded and unloaded states. For the loaded condition, the tank was filled with water. The simplest change from an unloaded tank to a loaded tank is the decrease in acceleration for a given force due to the added mass. However, there is additional complexity added to the system due to the sloshing liquid inside the tank. When attempting to model this dynamic system there is added uncertainty in struck coupler force estimation because of the non-linearity in low frequency car body oscillations. Several example data sets are presented in the time and frequency domains to illustrate this point. The data is then used to generate an empirical model using system identification techniques. The results show that the proposed model offers improved characterization of the system as compared to conventional techniques by accounting for the uncertainties introduced by the sloshing liquid in the tank. The proposed technique is computationally efficient and can potentially be implemented in real time. The model is used to estimate struck coupler force and is validated with real data.

scholarly journals Influence of electrical part of traction transmission on dynamic characteristics of railway vehicles based on electromechanical coupling model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xun Wang ◽  
Tiefeng Peng ◽  
Pingbo Wu ◽  
Litong Cui
Keyword(s):  
High Speed ◽  
Electromechanical Coupling ◽  
Low Frequency ◽  
Traction Force ◽  
Coupling Model ◽  
Transmission System ◽  
Transmission Model ◽  
Rail Transit ◽  
Mechanical Coupling ◽  
Car Body

AbstractWith the continuous development of rail transit industry and the acceleration of train speed, higher requirements are established for the operation quality of high-speed trains and the reliability of transmission system. In the process of train running, speed fluctuation and vibrations from various parts of the driving devices are common, which could be greatly affected by the traction torque. During traction transmission, the harmonic vibration torque exists in traction motor due to that the motor is connected with non-sinusoidal alternating current. In order to study the vibration influence of the electrical component of traction transmission system on the rail vehicles, i.e., bogie and car-body, an electro-mechanical coupling dynamic model for rail transit vehicles was established by explicitly incorporating the electric-induced traction into the transmission model. The dynamics responses of the vertical, lateral and longitudinal acceleration on vehicle components, such as axle box and car-body were quantitative analyzed. By comparison with field test, it was observed that there was a vibration peak of 12-times of the fundamental rotor frequency on the bogie frame and axle box, which existed at conditions of traction, uniform speed and braking. However, the vibration acceleration exhibit nearly little difference with or without traction force, especially at low frequency domain < 100 Hz.

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