Noise suppression effect of a linear predictor and a coding scheme for narrow‐band speech communications

The structure of cavity flow field with high mach number is very complex, in which pressure and velocity pulsate seriously, leading a seriously noise about almost 170dB. The noise poses a great threaten to the safety of the missile in the cavity and the structure of the cavity. The active control method (jet flow) by applying the CFD technology based on Scale-Adaptive Simulation (SAS) model developed from two-equation SST turbulent model is used to simulate the changing of the dynamic noise in the standard cavity M219(the ratio of the length to the depth is 5), and studied the flow character, flow field structure and noise mechanism. First, the accuracy of the noise prediction method is validated. Base on above-mentioned method, the suppression effect on the noise in the cavity of jet flow is analyzed and the conclusion is that jet flow has a great influence on the aerodynamic noise suppression in the cavity.

Download Full-text

Prediction of Aeroacoustic and Control over a Cavity by Delayed Detached Eddy Simulation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.598.505 ◽

2014 ◽

Vol 598 ◽

pp. 505-509 ◽

Cited By ~ 1

Author(s):

Yu Liu ◽

Ming Bo Tong

Keyword(s):

Sound Pressure ◽

Noise Suppression ◽

Cfd Simulation ◽

Leading Edge ◽

Pressure Level ◽

Detached Eddy Simulation ◽

Suppression Effect ◽

Eddy Simulation ◽

Delayed Detached Eddy Simulation ◽

And Control

In the present study CFD simulation with delayed detached eddy simulation (DDES) are performed to investigate an open cavity at Mach 0.85. Two cavity configurations, clean cavity and cavity with a leading-edge saw tooth spoiler, are modeled. The results obtained from clean cavity prediction are compared with experimental sound pressure level (SPL) data from QinetiQ, UK. Furthermore, comparisons are made with the predicted SPL between the two configurations. The main focuses of this investigation are to obtain a further understanding of the cavity aeroacoustics and test the noise suppression effect by a saw tooth spoiler.

Download Full-text

Aeroacoustic Characteristics of Cavity and Effect Study of Mesh on Noise Suppression

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.421.104 ◽

2013 ◽

Vol 421 ◽

pp. 104-109

Author(s):

Jing Sun ◽

Guang Jun Yang ◽

Jian Jun Liu

Keyword(s):

Noise Reduction ◽

Noise Suppression ◽

Flow Characteristics ◽

Leading Edge ◽

Cavity Flow ◽

Noise Spectrum ◽

Effect Study ◽

Suppression Effect ◽

Reduction Effect ◽

Suppression Effects

To explore the noise suppression effect of mesh on cavity, the wind tunnel experiment is carried out based on the analysis of clean cavity flow characteristics. The meshes are arranged both in the cavity and at the leading edge of the cavity. Through the analysis of pressure distribution on the cavity bottom and the noise spectrum monitored at front and rear walls respectively, noise suppression effects of mesh programs relative to the clean cavity and changes in the flow field are studied, the results show that the mesh inside the cavity has a better noise reduction effect. The work in this paper provides an effective way for cavity noise reduction.

Download Full-text