Finite-amplitude acoustic waves in liquid3He and4He

1990 ◽  
Vol 79 (5-6) ◽  
pp. 229-250 ◽  
Author(s):  
J. Joffrin ◽  
M. Chapellier ◽  
A. Schuhl ◽  
M. W. Meisel
Keyword(s):  
Acoustic Waves ◽  
Finite Amplitude

Finite amplitude acoustic waves in variable area ducts

2001 ◽  
Author(s):  
Robert Erickson ◽  
Nikos Markopoulos ◽  
Ben Zinn
Keyword(s):  
Acoustic Waves ◽  
Finite Amplitude

Nonlinear self-excited oscillations of a ducted flame

1997 ◽  
Vol 346 ◽  
pp. 271-290 ◽  
Author(s):  
A. P. DOWLING
Keyword(s):  
Linear Theory ◽  
Limit Cycle ◽  
Limit Cycles ◽  
Acoustic Waves ◽  
Bluff Body ◽  
Nonlinear Oscillations ◽  
Function Analysis ◽  
Pressure Fluctuations ◽  
Finite Amplitude ◽  
Flow Disturbances

Self-excited oscillations of a confined flame, burning in the wake of a bluff-body flame-holder, are considered. These oscillations occur due to interaction between unsteady combustion and acoustic waves. According to linear theory, flow disturbances grow exponentially with time. A theory for nonlinear oscillations is developed, exploiting the fact that the main nonlinearity is in the heat release rate, which essentially ‘saturates’. The amplitudes of the pressure fluctuations are sufficiently small that the acoustic waves remain linear. The time evolution of the oscillations is determined by numerical integration and inclusion of nonlinear effects is found to lead to limit cycles of finite amplitude. The predicted limit cycles are compared with results from experiments and from linear theory. The amplitudes and spectra of the limit-cycle oscillations are in reasonable agreement with experiment. Linear theory is found to predict the frequency and mode shape of the nonlinear oscillations remarkably well. Moreover, we find that, for this type of nonlinearity, describing function analysis enables a good estimate of the limit-cycle amplitude to be obtained from linear theory.Active control has been successfully applied to eliminate these oscillations. We demonstrate the same effect by adding a feedback control system to our nonlinear model. This theory is used to explain why any linear controller capable of stabilizing the linear flow disturbances is also able to stabilize finite-amplitude oscillations in the nonlinear limit cycles.

scholarly journals Finite-amplitude standing acoustic waves in a cubically nonlinear medium

2007 ◽  
Vol 53 (4) ◽  
pp. 455-464 ◽  
Author(s):  
O. V. Rudenko ◽  
C. M. Hedberg ◽  
B. O. Enflo
Keyword(s):  
Acoustic Waves ◽  
Nonlinear Medium ◽  
Finite Amplitude
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