scholarly journals Nonlinear response of composite panels under combined acoustic excitation and aerodynamic pressure

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 1534-1542
Author(s):  
K. Abdel-Motagaly ◽  
B. Duan ◽  
C. Mei
Keyword(s):  
Nonlinear Response ◽  
Acoustic Excitation ◽  
Composite Panels ◽  
Aerodynamic Pressure

Aeroelastic analysis of pre-stressed variable stiffness composite panels

2019 ◽  
Vol 26 (9-10) ◽  
pp. 724-734 ◽  
Author(s):  
Mehnaz Rasool ◽  
Maloy K Singha
Keyword(s):  
Dynamic Pressure ◽  
Variable Stiffness ◽  
Limit Cycle Oscillation ◽  
Composite Panels ◽  
Constant Stiffness ◽  
Aerodynamic Pressure ◽  
Aeroelastic Analysis ◽  
Divergence Type ◽  
Cycle Oscillation ◽  
The Stability

The effect of in-plane stresses on the stability behaviors of constant stiffness and variable stiffness composite panels, exposed to aerodynamic pressure, is studied using the finite element method. The dynamic pressure from the high velocity airflow is evaluated from the first-order piston theory, and the eigenvalue analysis is performed to investigate the flutter or divergence type of instabilities in such composite panels under combined mechanical and aerodynamic loads. Attempt is made to understand the effect of the lamination parameter on the stability characteristics of edge-supported and cantilever composite trapezoidal panels. Finally, the limit cycle oscillation of variable stiffness plates subjected to aerodynamic pressure is investigated.

Nonlinear Flame Transfer Function Characteristics in a Swirl-Stabilized Combustor

2006 ◽  
Vol 129 (4) ◽  
pp. 954-961 ◽  
Author(s):  
Benjamin D. Bellows ◽  
Mohan K. Bobba ◽  
Jerry M. Seitzman ◽  
Tim Lieuwen
Keyword(s):  
Nonlinear Response ◽  
Amplitude Dependence ◽  
Acoustic Excitation ◽  
Acoustic Oscillations ◽  
Flame Dynamics ◽  
Large Velocity ◽  
Planar Laser ◽  
Flame Response ◽  
Test Points ◽  
Unsteady Flame

An understanding of the amplitude dependence of the flame response to acoustic excitation is required in order to predict and/or correlate combustion instability amplitudes. This paper describes an experimental investigation of the nonlinear response of a lean, premixed flame to imposed acoustic oscillations. Detailed measurements of the amplitude dependence of the flame response were obtained at approximately 100 test points, corresponding to different flow rates and forcing frequencies. It is observed that the nonlinear flame response can exhibit a variety of behaviors, both in the shape of the response curve and the forcing amplitude at which nonlinearity is first observed. The phase between the flow oscillation and heat release is also seen to have substantial amplitude dependence. The nonlinear flame dynamics appear to be governed by different mechanisms in different frequency and flowrate regimes. These mechanisms were investigated using phase-locked, two- dimensional OH Planar laser-induced fluorescence imaging. From these images, two mechanisms, vortex rollup and unsteady flame liftoff, are identified as important in the saturation of the flame’s response to large velocity oscillations. Both mechanisms appear to reduce the flame’s area and thus its response at these high levels of driving.

Nonlinear response of buoyant diffusion flame under acoustic excitation

Fuel ◽  
2013 ◽  
Vol 103 ◽  
pp. 364-372 ◽  
Author(s):  
Qian Wang ◽  
Hua Wei Huang ◽  
Hao Jie Tang ◽  
Min Zhu ◽  
Yang Zhang
Keyword(s):  
Diffusion Flame ◽  
Nonlinear Response ◽  
Acoustic Excitation

Nonlinear response of composite panels of high speed aircraft

1993 ◽  
Vol 3 (7-8) ◽  
pp. 645-660 ◽  
Author(s):  
P. Kavallieratos ◽  
R. Vaicaitis
Keyword(s):  
High Speed ◽  
Nonlinear Response ◽  
Composite Panels

Experimental Investigation On Nonlinear Response of a Low-Swirl Flame to Acoustic Excitation with Large Amplitude

2021 ◽  
Author(s):  
Weijie Liu ◽  
Liang Zhang ◽  
Ranran Xue ◽  
Qian Yang ◽  
Huiru Wang
Keyword(s):  
Heat Release ◽  
Nonlinear Response ◽  
High Efficiency ◽  
Axial Direction ◽  
Limit Cycle Oscillation ◽  
Acoustic Excitation ◽  
Driving Frequency ◽  
Thermoacoustic Instability ◽  
Wide Range ◽  
Swirl Flame

Abstract Thermoacoustic instability is a major issue in developing high-efficiency low emission gas turbine combustors. In order to predict the amplitude of limit cycle oscillation, an understanding of the amplitude dependent response of the flame, i.e. the nonlinear response, to large acoustic excitation is needed. In the present study, the nonlinear response of a low-swirl CH4/air premixed flame to acoustic excitation is experimentally studied. Amplitude dependences of flame dynamic at 75 Hz and 195 Hz are discussed in detail over a wide range of excitation level. Experimental results show the gain of flame describing function of the low-swirl flame has a peak value at 65 Hz and a local minimum at 105 Hz which is caused by the destructive (out of phase) and constructive (in phase) of the axial and azimuthal velocity fluctuation. At low perturbation level, flame heat release fluctuation is in linear relationship with the normalized velocity driving level. Heat release fluctuation begins to saturate at a certain level which depends on the driving frequency. The low-swirl flame oscillates mainly in the axial direction at 75 Hz while it is in the radial direction at 195 Hz. The non-linear flame heat release response is a result of combination effect of flame rollup process and harmonic responses.

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