scholarly journals Numerical Study of Galerkin–Collocation Approximation in Time for the Wave Equation

2020 ◽  
pp. 15-36
Author(s):  
Mathias Anselmann ◽  
Markus Bause
Keyword(s):  
Wave Equation ◽  
Numerical Study

scholarly journals Numerical study using ADM for the modified regularized long wave equation

2008 ◽  
Vol 32 (12) ◽  
pp. 2962-2972 ◽  
Author(s):  
A.K. Khalifa ◽  
K.R. Raslan ◽  
H.M. Alzubaidi
Keyword(s):  
Wave Equation ◽  
Numerical Study ◽  
Long Wave ◽  
Regularized Long Wave Equation

Investigation of Fan Casing Aerodynamic Noise at the Blade Passing Frequency

2009 ◽  
Author(s):  
Jian-Cheng Cai ◽  
Da-Tong Qi ◽  
Fu-An Lu
Keyword(s):  
Wave Equation ◽  
Flow Rate ◽  
Sound Propagation ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Sound Field ◽  
Noise Model ◽  
Aerodynamic Noise ◽  
Centrifugal Fan ◽  
Blade Passing Frequency

From our previous studies of fan casing vibroacoustics, it was found that noise caused by casing vibration was fairly small compared to its aeroacoustic counterpart. In the present work, a numerical study on the aerodynamic tonal noise of a centrifugal fan casing was carried out. A 3-D numerical simulation of turbulent unsteady flow on the whole impeller-volute configuration was performed using computational fluid dynamics (CFD) technique in order to obtain the pressure fluctuations on the casing wall which serve as aeroacoustic dipole sources. Three different flow rates were simulated: the best efficiency point (BEP), 1.382×BEP and the maximal flow rate (2.104×BEP). Fast Fourier Transform (FFT) was applied to the time series of pressure fluctuations to extract the blade passing frequency (BPF) component constituting the source term of the wave equation. Boundary element method (BEM) was used to solve the inhomogeneous frequency-domain wave equation. The influence of the casing on the sound field was taken into account in simulating the noise radiation by taking it as a rigid body. Results showed that the presence of the casing could greatly affect sound propagation. With the increase of flow rate, the radiated sound power rose drastically. The tonal blade noise was also investigated using Lowson’s formulation of rotor noise model, and the results showed that it’s smaller than the tonal casing noise.

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