A PLATE SOUND RADIATION, RELATED WITH ITS INERTIAL BEHAVIOR IN A NONUNIFORM FIELD OF PRESSURE FLUCTUATIONS

2009 ◽  
Vol 40 (1) ◽  
pp. 87-101
Author(s):  
B. M. Efimtsov ◽  
A. Ya. Zverev
Keyword(s):  
Pressure Fluctuations ◽  
Sound Radiation ◽  
Nonuniform Field

Sound and turbulence modulation by particles in high-speed shear flows

2019 ◽  
Vol 875 ◽  
pp. 254-285 ◽  
Author(s):  
David A. Buchta ◽  
Gregory Shallcross ◽  
Jesse Capecelatro
Keyword(s):  
Gas Phase ◽  
High Speed ◽  
Pressure Fluctuations ◽  
Sound Radiation ◽  
Rate Of Change ◽  
Intensity Increase ◽  
Mass Loading ◽  
Local Pressure ◽  
Time Rate ◽  
Particle Laden Flows

High-speed free-shear-flow turbulence, laden with droplets or particles, can radiate weaker pressure fluctuations than its unladen counterpart. In this study, Eulerian–Lagrangian simulations of high-speed temporally evolving shear layers laden with monodisperse, adiabatic, inertial particles are used to examine particle–turbulence interactions and their effect on radiated pressure fluctuations. An evolution equation for gas-phase pressure intensity is formulated for particle-laden flows, and local mechanisms of pressure changes are quantified over a range of Mach numbers and particle mass loadings. Particle–turbulence interactions alter the local pressure intensity directly via volume displacement (due to the flow of finite-size particles) and drag coupling (due to local slip velocity between phases), and indirectly through significant turbulence changes. The sound radiation intensity near subsonic mixing layers increases with mass loading, consistent with existing low Mach number theory. For supersonic flows, sound levels decrease with mass loading, consistent with trends observed in previous experiments. Particle-laden cases exhibit reduced turbulent kinetic energy compared to single-phase flow, providing one source of their sound changes; however, the subsonic flow does not support such an obvious source-to-sound decomposition to explain its sound intensity increase. Despite its decrease in turbulence intensity, the louder particle-laden subsonic flows show an increase in the magnitude and time-rate-of-change of fluid dilatation, providing a mechanism for its increased sound radiation. Contrasting this, the quieter supersonic particle-laden flows exhibit decreased gas-phase dilatation yet its time-rate-of-change is relatively insensitive to mass loading, supporting such a connection.

Computational Estimation of Fan Casing Noise at Blade Passing Frequency Component Noise

2012 ◽  
Vol 184-185 ◽  
pp. 95-100
Author(s):  
Jian Cheng Cai ◽  
Yong Hai Zhang ◽  
Shuang Li Long
Keyword(s):  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Sound Radiation ◽  
Internal Flow ◽  
Neumann Boundary ◽  
Frequency Component ◽  
Dipole Source ◽  
Centrifugal Fan ◽  
Element Analysis ◽  
Blade Passing Frequency

This paper studies both vibroacoustics and aeroacoustics of a centrifugal fan casing; the aim of this study is to explore a methodology to make quantitative predictions of fan casing noise. The spectra of the fan noise and casing vibration were firstly presented; discrete components related to the rotational frequency protrude in the spectra, especially the blade passing frequency (BPF). Computational fluid dynamics (CFD) technique was used to obtain the three-dimensional unsteady turbulent internal flow. Attention was paid to the pressure fluctuations on the volute wall; the shapes of pressure fluctuation were nearly sinusoidal in nature, with the BPF as the primary frequency. On the vibroacoustic side, Fast Fourier Transform (FFT) was applied to the time series of pressure fluctuations to extract the BPF component. A finite element analysis (FEA) model of the casing structure was constructed, and was validated by experimental modal analysis. The harmonic dynamic response of the casing structure was calculated with the BPF pressure fluctuation component as the excitation. The vibration results were then taken as the velocity (Neumann) boundary condition for the noise radiation model which was built in boundary element method (BEM), and the sound radiation was calculated. On the aeroacoustic side, the BPF component of pressure fluctuations was modeled as acoustic dipole source, and sound radiation was also solved by BEM. Results show that the sound pressure level (SPL) of vibroacoustics is fairly small compared to the aeroacoustic counterpart. This study shows that CFD, FEA together with BEM can be used to numerically predict BPF casing noise of turbomachinery successfully.

A Numerical Study of the Unsteady Flow Field and Tonal Hydrodynamic Sound of a Centrifugal Pump

2015 ◽  
Author(s):  
Jian-Cheng Cai ◽  
Jie Pan ◽  
Andrew Guzzomi
Keyword(s):  
Centrifugal Pump ◽  
Cfd Simulation ◽  
Numerical Study ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Broad Band ◽  
Sound Radiation ◽  
Acoustic Analogy ◽  
Eddy Simulation ◽  
Surface Dipole

In this paper, the 3-D unsteady turbulent flow inside a centrifugal pump is investigated by computational fluid dynamics (CFD) in ANSYS CFX, using Detached Eddy Simulation (DES) as the turbulence approach. The pump has a single end-suction and a single volute discharge. The impeller is semi-open (unshrouded with baseplate) and has five backswept blades and pump-out back blades. The CFD model of the pump consists of the inlet, the impeller, and the volute. A sliding mesh technique has been applied to the interfaces in order to allow unsteady interactions between the rotating impeller and the stationary parts. These unsteady interactions generate pressure fluctuations over the volute casing and blade surfaces that are hydroacoustic dipoles according to Lighthill’s acoustic analogy theory. The pressure fluctuation spectra at the volute tongue show that pressure fluctuations are generated mainly by the discrete components related to the impeller rotation at low frequencies, especially the blade-passing frequency (BPF) component. This component is approximately 1% of the reference dynamic pressure 0.5ρν22 where ν2 is the circumferential velocity at the impeller outlet. The discrete components with frequency larger than 4 times BPF are no longer obvious in the spectra. Compared to the experimental results, the CFD simulation predicts much lower amplitudes for the broad band pressure fluctuations. This is reasonable, because DES combines a classical Reynolds averaged Navier Stokes (RANS) simulation with elements of Large Eddy Simulation (LES), and both RANS and LES use average methods which filter out the high frequency fluctuations. Nevertheless, CFD is capable of accurately predict the BPF component. The pressure fluctuations on the casing and blade surfaces are extracted and modelled as the stationary and rotary dipoles, respectively, according to the Ffowcs Williams and Hawkings (FW-H) equation of the acoustic analogy theory. After Fast Fourier Transform, the spectra of the pressure fluctuations are obtained, and are used to predict the tonal hydrodynamic sound radiation at BPF and its low order harmonics. The sound radiation of casing surface dipoles is calculated by extracting the tonal components, and performing a surface integration with the fundamental solution to Helmholtz equation as the kernel. A frequency domain formulation of the FW-H equation with the moving surface dipole is employed to predict the tonal blade noise. The results from these acoustical simulations show that the sound power generated by the casing surface dipole is three orders of magnitude higher than that of the blade surface dipole, and the main hydroacoustic sources are located at the volute tongue.

PRESSURE FLUCTUATIONS OF LIQUID-LIQUID SLUG FLOW IN CROSS-JUNCTION SQUARE MICROCHANNELS

2018 ◽  
Author(s):  
Jin-yuan Qian ◽  
Min-rui Chen ◽  
Zan Wu ◽  
Zhen Cao ◽  
Bengt Sunden
Keyword(s):  
Slug Flow ◽  
Pressure Fluctuations ◽  
Liquid Slug

Separated flow surface pressure fluctuations and pressure-velocity correlations on prolate spheroid

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 266-274
Author(s):  
Michael C. Goody ◽  
Roger L. Simpson ◽  
Christopher J. Chesnakas
Keyword(s):  
Surface Pressure ◽  
Pressure Fluctuations ◽  
Separated Flow ◽  
Prolate Spheroid ◽  
Flow Surface

Time-series analyses of wall pressure fluctuations in plume-induced separated flowfields

AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 1817-1824
Author(s):  
R. J. Shaw ◽  
J. C. Dutton ◽  
A. L. Addy
Keyword(s):  
Time Series ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Wall Pressure Fluctuations ◽  
Time Series Analyses

Large eddy simulations of sound radiation from subsonic turbulent jets

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 1469-1477
Author(s):  
W. Zhao ◽  
S. H. Frankel ◽  
L. Mongeau
Keyword(s):  
Sound Radiation ◽  
Turbulent Jets ◽  
Large Eddy Simulations ◽  
Large Eddy
Sign in / Sign up

Export Citation Format

Share Document