Theoretical Study of Sound Propagation in Lined Duct with Rigid Splices Using Wiener-Hopf Method

The photoacoustic signal generated in a photoacoustic gas cell with rigid wall boundaries is calculated by solving the coupled equations for sound propagation and thermal diffusion in a viscous and relaxing gas. For a cylindrical geometry, monochromatic radiation, and sinusoidal modulation, when a condition of zero heat flow through the lateral walls of the cell is verified, a general expression is found that can be applied whatever the deactivation scheme is for collisional relaxation in the gas. Both resonant and nonresonant modes of operation are considered.

Download Full-text

Control-Oriented Methods for Turbomachinery Noise Simulation

Journal of Turbomachinery ◽

10.1115/1.4038022 ◽

2017 ◽

Vol 140 (1) ◽

Cited By ~ 2

Author(s):

Alex Siu Hong Lau ◽

Siyang Zhong ◽

Xun Huang

Keyword(s):

Stability Analysis ◽

Time Domain ◽

Sound Propagation ◽

Impedance Boundary Condition ◽

Generalized Function ◽

Mean Flow ◽

Impedance Boundary ◽

Analysis And Design ◽

Hopf Method ◽

The Stability

This paper presents an innovative stability analysis and design approach for time-domain impedance boundary conditions to simulate noise propagation and radiation from a lined turbomachinery duct in the presence of a mean flow. A control-oriented model is developed for the stability analysis of the impedance boundary condition by using generalized function at the lining surface. The mean flow effect and sound propagation are considered in the model as well. Then, the numerical stability issue is analyzed by using the Bode plots before stabilized accordingly by employing the phase lead compensator method, which results in a rational transfer function. Finally, the corresponding time-domain implementation is achieved by using the so-called controllable canonical form rather than an inconvenient convolution operation. The performance of the current proposed approach is first validated in an in-duct propagation case by comparing to analytical solutions obtained by employing the Wiener–Hopf method and then demonstrated in a couple of duct acoustic problems with representative turbomachinery setups. The innovative cross-disciplinary nature of the current proposed approach can shed light on impedance problems and is very useful to time-domain acoustic simulations for turbomachinery applications.

Download Full-text