Filtering performance and optimization of double-chamber compound hydraulic attenuators

2017 ◽  
Vol 232 (18) ◽  
pp. 3250-3262 ◽  
Author(s):  
Fan Yang ◽  
Bin Deng
Keyword(s):  
Insertion Loss ◽  
Pressure Pulsation ◽  
Low Frequency ◽  
Geometrical Parameters ◽  
Double Precision ◽  
Expansion Chamber ◽  
One Dimensional ◽  
Wave Region ◽  
The One ◽  
Double Chamber

At present, double expansion chamber structures are widely used in the field of acoustic attenuation, and two kinds of double-chamber compound structures for hydraulic attenuators are proposed in this paper. A one-dimensional analytical approach was developed to predict the pressure pulsation attenuation performance of these two structures, and comparisons of insertion loss predictions with experimental results illustrated that the one-dimensional approach is suitable for accurate prediction among the research frequency band. This approach was then used to investigate the effects of porosity and geometrical parameters on the pressure pulsation performance of these two double-chamber compound hydraulic attenuators. To optimize the pressure pulsation attenuation performance at the backwash frequency, parameter optimization was performed for these double-chamber compound structures, and a genetic algorithm based on double-precision floating-point encoding was proposed. The results showed that the range of attenuation frequency bands was widened; however, the effect on low frequency filtering characteristics was limited. The insertion loss of the second structure, which had a partially perforated tube, exhibits a superposition of dome attenuation and axial resonance in the plane wave region. By choosing the length and location of the perforated section to match resonances with the troughs of the pulsation attenuator, a desirable broadband pressure pulsation attenuation can be obtained.

Pulsation Attenuation Analysis of Double-Chamber Composite Hydraulic Suppressors with Inserted Conical Tubes

2019 ◽  
Vol 24 (3) ◽  
pp. 578-585 ◽  
Author(s):  
Fan Yang ◽  
Bin Deng
Keyword(s):  
Insertion Loss ◽  
Parametric Study ◽  
Analytical Approach ◽  
Pressure Pulsation ◽  
Experimental Results ◽  
One Dimensional ◽  
Conical Tube ◽  
Structure Improvement ◽  
Double Chamber

A one-dimensional analytical approach is developed to predict the pulsation attenuation performance of doublechamber compound hydraulic suppressors. The theoretical insertion loss agreed well with experimental results. The need for broadband pressure pulsation attenuation has led to extensive research on the structure improvement. In the present work, the straight-through tube has been replaced by a conical tube and two improved hydraulic attenuator configurations are presented. A parametric study to investigate the effects of different parameters on the research frequencies is included as well. The validity of the models of the improved structures is demonstrated theoretically and experimentally.

ACOUSTIC ATTENUATION CHARACTERISTICS OF STRAIGHT-THROUGH PERFORATED TUBE SILENCERS AND RESONATORS

2008 ◽  
Vol 16 (03) ◽  
pp. 361-379 ◽  
Author(s):  
Z. L. JI
Keyword(s):  
Performance Prediction ◽  
Transmission Loss ◽  
Three Dimensional ◽  
Geometrical Parameters ◽  
Mean Flow ◽  
Acoustic Attenuation ◽  
One Dimensional ◽  
The One ◽  
Attenuation Characteristics ◽  
Perforated Tube

The one-dimensional analytical solutions are derived and three-dimensional substructure boundary element approaches are developed to predict and analyze the acoustic attenuation characteristics of straight-through perforated tube silencers and folded resonators without mean flow, as well as to examine the effect of nonplanar waves in the silencers and resonators on the acoustic attenuation performance. Comparisons of transmission loss predictions with the experimental results for prototype straight-through perforated tube silencers demonstrated that the three-dimensional approach is needed for accurate acoustic attenuation performance prediction at higher frequencies, while the simple one-dimensional theory is sufficient at lower frequencies. The BEM is then used to investigate the effects of geometrical parameters on the acoustic attenuation characteristics of straight-through perforated tube silencers and folded resonators in detail.

Study of the Discharge Pressure Pulsation Within Twin Screw Compressors

2001 ◽  
Author(s):  
Ziwen Xing ◽  
Xueyuan Peng ◽  
Xiaojun Zhang ◽  
Tiansheng Cui
Keyword(s):  
Gas Flow ◽  
Pressure Pulsation ◽  
Theoretic Analysis ◽  
One Dimensional ◽  
Flow Equations ◽  
Twin Screw ◽  
Flow Through ◽  
The One ◽  
Discharge Pressure ◽  
Unsteady Gas Flow

Abstract Even in the absence of valves, flow through the discharge port of a screw compressor is oscillatory in nature. This unsteady but periodic flow variation at the discharge port excites the pressure pulsation. In this paper, the one-dimensional unsteady gas flow equations describing the discharge pressure pulsation are established, which allow for the effects of the viscosity friction and heat transfer between the gas and the pipe, and the boundary conditions of discharge pressure pulsation are considered. With Two-Step Lax-Wendroff scheme used, the one-dimensional unsteady gas flow equations are solved. In order to verify the theoretic analysis, the discharge pressure pulsation at variable working conditions is measured. It is shown that the model established in this paper is valid for getting a better understanding of the mechanism governing the behavior of the pressure pulsation in discharge pipe. It is found that the most important factor that affects the discharge pressure pulsation is the pressure difference between the actual discharge pressure and the design discharge pressure.

Study on Mechanism of One-Dimensional Phononic Crystals with Locally Resonant Structures

2011 ◽  
Vol 287-290 ◽  
pp. 650-653
Author(s):  
Zhuo Fei Song ◽  
Qiang Song Wang ◽  
Zi Dong Wang
Keyword(s):  
Phononic Crystal ◽  
Low Frequency ◽  
Phononic Crystals ◽  
Bragg Scattering ◽  
Scattering Mechanism ◽  
One Dimensional ◽  
Resonant Structures ◽  
Low Frequency Vibration ◽  
Lower Frequency Band ◽  
The One

Comprehensive study is performed for the one-dimensional phononic crystals with locally resonant structures mechanism and Bragg scattering mechanism. Found locally resonant mechanism is same as Bragg scattering mechanism on one-dimension phononic crystal. The reasons of producing lower frequency band gap are still stiffness decrease and quality increase. So the theory that locally resonant structure is better than Bragg scattering in low frequency vibration reduction is inexact.

NUMERICAL CALCULATIONS OF AC RESPONSE IN AHARONOV-BOHM RINGS

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2853-2858
Author(s):  
SHUN HE ◽  
GUOJUN JIN ◽  
XUEAN ZHAO ◽  
YUQIANG MA
Keyword(s):  
Low Voltage ◽  
Coupling Parameter ◽  
Low Frequency ◽  
External Perturbation ◽  
Incident Electron Energy ◽  
One Dimensional ◽  
The One ◽  
Ac Response ◽  
Scattering Matrix Method ◽  
Aharonov Bohm

We present a detailed theoretical investigation on the transport properties of the one dimensional quantum rings. The Aharonov-Bohm effects under the low-voltage and low-frequency perturbation have been carefully studied. Scattering matrix method is adopted to obtain the ac response at external perturbation. The results show that the dc and ac parts of the conductance are dependent on the incident electron energy, magnetic field strength, and the coupling parameter. Some impressive characteristics of the emittance have also been discussed.

scholarly journals One-Dimensional Propagation

2020 ◽  
pp. 453-512
Author(s):  
Steven L. Garrett
Keyword(s):  
Sound Propagation ◽  
Impedance Matching ◽  
Low Frequency ◽  
Absolute Calibration ◽  
Sound Waves ◽  
Quality Factors ◽  
Electrical Measurements ◽  
One Dimensional ◽  
The One ◽  
The Waves

Abstract Having already invested in understanding both the equation of state and the hydrodynamic equations, only straightforward algebraic manipulations will be required to derive the wave equation, justify its solutions, calculate the speed of sound in fluids, and derive the expressions for acoustic intensity and the acoustic kinetic and potential energy densities of sound waves. The “machinery” developed to describe waves on strings will be sufficient to describe one-dimensional sound propagation in fluids, even though the waves on the string were transverse and the one-dimensional waves in fluids are longitudinal. These results are combined with the thermal and viscous penetration depths to calculate the frequencies and quality factors in standing wave resonators. The coupling of those resonators to loudspeakers will be examined. The introduction of reciprocal transducers that are linear, passive, and reversible will allow absolute calibration of transducers using only electrical measurements (i.e., currents and voltages) by the reciprocity method, if the acoustic impedance that couples the source and receiver is calculable. Reflection and transmission at junctions between multiple ducts and other networks will be calculated and applied to the design of filters. The behavior of waves propagating through horns will provide useful impedance matching but introduce a low-frequency cut-off.

Design of an Axial Impulse Turbine for Enthalpy Drop Recovery

2014 ◽  
Author(s):  
Gaetano Morgese ◽  
Marco Torresi ◽  
Bernardo Fortunato ◽  
Sergio Mario Camporeale
Keyword(s):  
Industrial Process ◽  
Geometrical Parameters ◽  
Impulse Turbine ◽  
One Dimensional ◽  
Analytical Functions ◽  
Process Plants ◽  
The One ◽  
Definition Of ◽  
Turbine Design ◽  
Work Done

In industrial process plants, often there is the need to reduce the pressure of the operating flow. Generally this is performed by means of valves which expand the flow without any work done. The same operation could be performed by replacing these valves with turbines, with the advantage of energy recovery, hence improving the overall efficiency of the system. In this work, a simple and rapid method is shown in order to design a single stage, straight bladed, axial impulse turbine for enthalpy recovery. Assigned the desired flow rate and the minimum power output, the turbine design is performed according to a one-dimensional study into which loss effects are considered by means of appropriate coefficients. From the one-dimensional analysis the heights, the pitch angle, the inlet and outlet angles of both rotor and stator blades are obtained. Actually, the rotor and stator blade profiles are defined by means of several analytical functions. The blade design is then validated by means of CFD simulations. The definition of loss coefficients and blade geometrical parameters is clearly an iterative process, which needs to be repeated until convergence is reached. Furthermore, by means of fully 3D simulations, the effect of the rotor-stator distance is investigated in order to maximize the turbine performance.

scholarly journals Violent Relaxation and Mixing in 1-D Gravitational Systems

1987 ◽  
Vol 127 ◽  
pp. 523-524
Author(s):  
Marc Luwel
Keyword(s):  
Surface Density ◽  
Gravitational Force ◽  
Equations Of Motion ◽  
Dimensional System ◽  
Double Precision ◽  
One Dimensional ◽  
Gravitational Systems ◽  
Gravitational Model ◽  
The One

The one dimensional gravitational model consists of N mass sheets with surface density mi, parallel to the (y, z)–plane and constrained to move along the x-axis under influence of their mutual gravitational force Fij = −2πGmimj sgn(xi – xj). in order to study the evolution of this one–dimensional system, the N Newtonian equations of motion are integrated numerically, using an “exact” double precision algorithm.

Hybrid radial plate-type elastic metamaterials for lowering and widening acoustic bandgaps

2018 ◽  
Vol 32 (26) ◽  
pp. 1850286
Author(s):  
Yinggang Li ◽  
Qingwen Zhou ◽  
Ling Zhu ◽  
Kailing Guo
Keyword(s):  
Phononic Crystal ◽  
Low Frequency ◽  
Geometrical Parameters ◽  
The Finite Element Method ◽  
Displacement Fields ◽  
One Dimensional ◽  
Relative Bandwidth ◽  
Elastic Metamaterials ◽  
Plate Type ◽  
Radial Plate

In this paper, we present theoretical investigation on the wave propagation and acoustic bandgap characteristics in hybrid radial plate-type elastic metamaterials constituted of periodic double-sides composite stubs deposited on one-dimensional binary radial phononic crystal plate. The dispersion relations and the displacement fields of the eigenmodes are calculated by using the finite element method on the basis of two-dimensional axial symmetry models. Numerical results show that the proposed hybrid radial plate-type elastic metamaterial can generate lowering and widening acoustic bandgaps and yield a significant expansion of the relative bandwidth by a factor of 5 compared to the traditional radial plate-type elastic metamaterial with double-sided composite stubs. The displacement fields of the eigenmodes are applied to reveal the formation mechanism of lowering and widening acoustic bandgaps. In addition, the influences of the physical and geometrical parameters on the bandgaps are further performed. These low-frequency broadband acoustic bandgap properties in the radial plate-type elastic metamaterials can probably be applied to vibration and noise reduction in the rotary machines and structures.

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