The coherence function of a sound field propagating in a turbulent atmosphere

2006 ◽  
Vol 119 (5) ◽  
pp. 3264-3264
Author(s):  
Vladimir E. Ostashev ◽  
Sandra L. Collier ◽  
D. Keith Wilson
Keyword(s):  
Turbulent Atmosphere ◽  
Coherence Function ◽  
Sound Field

Study on Modeling Method of Vortex Shedding Synchronization in Heat Exchanger Tube Bundles II: Experimental Verification

2011 ◽  
Author(s):  
Eiichi Nishida ◽  
Hiromitsu Hamakawa
Keyword(s):  
Vortex Shedding ◽  
Experimental Verification ◽  
Coherence Function ◽  
Sound Field ◽  
Modeling Method ◽  
Resonance Level ◽  
Simple Method ◽  
Critical Flow Velocity ◽  
Wake Oscillator ◽  
Tube Bundles

Acoustic resonance may occur in heat exchangers such as gas heaters or boilers which contain tube bundles. This resonance is classified in self-excited oscillation, and feedback effect in vortex shedding and sound field plays important role. The purpose of this study is to develop a modeling method of the resonance level dependence of vortex shedding synchronization because this is the most essential part of critical flow velocity prediction. The level of synchronization is expressed by a coherence function between vortex shedding in any two locations in the tube bundle. Here, we introduce the wake oscillator model of vortex shedding, and based on this model, a simple method to estimate the resonance level dependence of the coherence function is proposed. In this method, the relationship of vortex shedding and the sound field in an arbitrary tube is expressed by a statistical model where the effect of resonance on the wake-oscillator is expressed by the width of the fluctuation range of phase between wake-oscillator and acoustic particle velocity. From this model, the resonance level dependence of the coherence function is derived in simple form. This method gives the result that when the resonance level increases, the synchronization level in the tube bundles also increases, which seems to be a reasonable conclusion. The results of experimental verification showed the validity of the proposed modeling method.

scholarly journals Coherence of vortex pseudo-Bessel beams in turbulent atmosphere

2019 ◽  
Vol 43 (6) ◽  
pp. 926-935 ◽  
Author(s):  
I.P. Lukin
Keyword(s):  
Root Mean Square ◽  
Turbulent Atmosphere ◽  
Coherence Function ◽  
Theoretical Research ◽  
Mean Square ◽  
Integral Scale ◽  
Integral Scales ◽  
Highly Sensitive ◽  
Mutual Coherence Function ◽  
Coherence Degree

Theoretical research of coherent properties of vortex conic waves propagating in a turbulent atmosphere was developed. The analysis was based on the analytical solution of the equation for the transverse second-order mutual coherence function of a light field. The following characteristics of coherence of vortex conic waves were considered: the coherence degree, the coherence radius, the root-mean-square and the integral scale of coherence degree. Dependence of these characteristics on the parameters of optical radiation and turbulent atmosphere was analyzed. Unlike the coherence radius, the root-mean-square and integral scales of the coherence degree of vortex conic waves were found to be highly sensitive to the influence of atmospheric turbulence.

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