Modal Analysis of Combustion Instabilities in Interacting Swirl Nozzles

2021 ◽  
Author(s):  
Yuvi Nanda ◽  
Ephraim Gutmark
Keyword(s):  
Modal Analysis ◽  
Combustion Instabilities

Mode Shapes and Dominant Frequency Predictions in a Swirl Stabilized Premixed Air-Methane Combustor Using Modal Analysis and Large Eddy Simulations (LES)

2017 ◽  
Author(s):  
Tushar Jadhav ◽  
Stefano Orsino ◽  
Saurabh Patwardhan ◽  
Pravin Nakod
Keyword(s):  
Boundary Condition ◽  
Modal Analysis ◽  
Dominant Frequency ◽  
Large Eddy Simulations ◽  
Combustion Instabilities ◽  
Swirl Number ◽  
Transverse Modes ◽  
Large Eddy ◽  
Emission Regulations ◽  
Inlet Swirl

Stringent emission regulations force the gas turbine combustor community to come up with new designs. Lean Premixed (LPM) combustion is gaining popularity to meet the emission regulations. However, lean combustion process is prone to other issues like combustion instabilities and noise. Self-excited combustion instabilities in a gas turbine play vital role in the life cycle of combustor, noise generation and pollutant formation. If the instabilities in combustor dominate at natural modes, there are risks of resonance which can lead to bursting damage to the combustors. In the present work, modal analysis is carried out to predict the longitudinal and the transverse modes in a swirl-stabilized premixed methane-air combustor. The geometrical details and the boundary conditions used in this work are described in Broda et al. [1]. In addition to the modal analysis, Large Eddy Simulations (LES) with Flamelet Generation Manifold (FGM) combustion model are carried out to find out the instabilities and their sources. In the large eddy simulation, at the inlet of the combustor, a broadband impedance boundary condition is used. This will consider the effect of upstream travelling acoustic waves at the inlet. The outlet of combustor is specified with non-reflecting boundary condition. The inlet mass flow rate and the temperature conditions are consistent with Broda et al. [1]. The longitudinal and transverse modes predicted by the modal analysis and the dominant frequency predicted in the LES case are compared with the experimentally observed values. The predicted first longitudinal mode at ∼1760 Hz compares well with the experimental value of 1760 Hz. Predicted values of first and second tangential modes at 10459 Hz and 17344 Hz are also in good agreement with the experimental measurement. The dominant frequency predicted by the LES simulation is 1940 Hz. After applying the appropriate correction to this value for the wall heat transfer effect, it is in-line with that obtained from the modal analysis and the experiments. The spectral analysis at different probe location in LES simulation shows higher thermo-acoustic coupling at natural frequencies. In this work, the effect of variation in inlet swirl number and the temperature is also studies. The predicted trends in the change in dominant frequency with the increase in inlet swirl number and inlet temperature are captured accurately. For each condition, calculations were performed for about four flow-through times (around 12 ms) after the flow field had reached to its limit cycle to obtain statistically steady condition.

Modal analysis of dielectric-sleeve-loaded circular waveguide for dual-mode radiator applications

1987 ◽  
Vol 134 (4) ◽  
pp. 369 ◽  
Author(s):  
M.S. Leong ◽  
P.S. Kooi ◽  
S.P. Yeo
Keyword(s):  
Modal Analysis ◽  
Circular Waveguide ◽  
Dual Mode ◽  
Dielectric Sleeve

Modal Analysis of Turbulent Flow near an Inclined Bank–Longitudinal Structure Junction

2021 ◽  
Vol 147 (3) ◽  
pp. 04020100
Author(s):  
Nasser Heydari ◽  
Panayiotis Diplas ◽  
J. Nathan Kutz ◽  
Soheil Sadeghi Eshkevari
Keyword(s):  
Turbulent Flow ◽  
Modal Analysis ◽  
Longitudinal Structure

ACTIVE DAMPING OF COMBUSTION INSTABILITIES WITH OSCILLATORY LIQUID FUEL SPRAYS

2002 ◽  
Vol 5 (1-6) ◽  
pp. 814-824
Author(s):  
E. Lubarsky ◽  
Y. Neumeier ◽  
B. T. Zinn
Keyword(s):  
Liquid Fuel ◽  
Active Damping ◽  
Combustion Instabilities ◽  
Fuel Sprays

Effect of Bass Bar Tension on Modal Parameters of a Violin's Top Plate

2015 ◽  
Vol 39 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Ewa B. Skrodzka ◽  
Bogumił B.J. Linde ◽  
Antoni Krupa
Keyword(s):  
Modal Analysis ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Normal Value ◽  
Modal Damping

Abstract Experimental modal analysis of a violin with three different tensions of a bass bar has been performed. The bass bar tension is the only intentionally introduced modification of the instrument. The aim of the study was to find differences and similarities between top plate modal parameters determined by a bass bar perfectly fitting the shape of the top plate, the bass bar with a tension usually applied by luthiers (normal), and the tension higher than the normal value. In the modal analysis four signature modes are taken into account. Bass bar tension does not change the sequence of mode shapes. Changes in modal damping are insignificant. An increase in bass bar tension causes an increase in modal frequencies A0 and B(1+) and does not change the frequencies of modes CBR and B(1-).

Modal analysis of coal mine mobile refuge chamber based on HyperWorks

2014 ◽  
Author(s):  
Jianhua Huang ◽  
Shuyun Jiang ◽  
Zerong Guo ◽  
Yonghe Jiao
Keyword(s):  
Modal Analysis ◽  
Coal Mine

Suppression of fires and combustion instabilities using droplet injection

1998 ◽  
Author(s):  
K. Kailasanath ◽  
E. Chang ◽  
K. Prasad
Keyword(s):  
Combustion Instabilities

Response and Operational Modal Analysis from Wind Tunnel Test of the EOLO Flexible Aircraft

2021 ◽  
Author(s):  
David F. Castillo Zuñiga ◽  
Alain Giacobini Souza ◽  
Roberto G. da Silva ◽  
Luiz Carlos Sandoval Góes
Keyword(s):  
Wind Tunnel ◽  
Modal Analysis ◽  
Wind Tunnel Test ◽  
Operational Modal Analysis ◽  
Flexible Aircraft

MODAL ANALYSIS OF Al-Al2O3 FG THICK PLATE USING GRADED FEM

2019 ◽  
Vol 15 (1) ◽  
pp. 18
Author(s):  
KUMAR P. S. RAVI ◽  
KUMAR P. NANDA ◽  
JANARDHANA G. RANGA ◽  
◽  
◽  
...  
Keyword(s):  
Modal Analysis ◽  
Thick Plate
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