Detection and Analysis of Combustion Instability From Hi-Speed Flame Images Using Dynamic Mode Decomposition

2016 ◽  
Author(s):  
Sambuddha Ghosal ◽  
Vikram Ramanan ◽  
Soumalya Sarkar ◽  
Satyanarayanan R. Chakravarthy ◽  
Soumik Sarkar
Keyword(s):  
Gas Turbines ◽  
Internal Combustion Engines ◽  
Structural Integrity ◽  
Combustion Instability ◽  
Complex Problem ◽  
Operating Conditions ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Flame Dynamics ◽  
Mode Decomposition

Flame dynamics and combustion instability is a complex problem involving different non-linearities. Combustion instability has several detrimental effects on flight-propulsion dynamics and structural integrity of gas turbines and any such spaces where combustion takes places internally, primarily in internal combustion engines. The description of coherent features of fluid flow in such cases is essential to our understanding of the flame dynamics and propagation processes. A method that is able to extract dynamic information from flow fields that are generated by a direct numerical simulation or visualized in a physical experiment (like in the case discussed in this paper) is Dynamic Mode Decomposition. This paper presents such a feature extraction and stability analysis of hi-speed combustion flames using Dynamic Mode Decomposition and it’s sparsity promoting variant. Extensive experimental data was collected in a swirl-stabilized dump combustor at various operating conditions (e.g. premixing level and flow velocity) for analysing the flame stability conditions.

scholarly journals From snapshots to modal expansions – bridging low residuals and pure frequencies

2016 ◽  
Vol 802 ◽  
pp. 1-4 ◽  
Author(s):  
Bernd R. Noack
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Orthogonal Decomposition ◽  
Operating Conditions ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Simple Method ◽  
Reduced Order ◽  
Mode Decomposition ◽  
Optimality Property ◽  
Proper Orthogonal

Data-driven low-order modelling has been enjoying rapid advances in fluid mechanics. Arguably, Sirovich (Q. Appl. Maths, vol. XLV, 1987, pp. 561–571) started these developments with snapshot proper orthogonal decomposition, a particularly simple method. The resulting reduced-order models provide valuable insights into flow physics, allow inexpensive explorations of dynamics and operating conditions, and enable model-based control design. A winning argument for proper orthogonal decomposition (POD) is the optimality property, i.e. the guarantee of the least residual for a given number of modes. The price is unpleasant frequency mixing in the modes which complicates their physical interpretation. In contrast, temporal Fourier modes and dynamic mode decomposition (DMD) provide pure frequency dynamics but lose the orthonormality and optimality property of POD. Sieber et al. (J. Fluid Mech., vol. 792, 2016, pp. 798–828) bridge the least residual and pure frequency behaviour with an ingenious interpolation, called spectral proper orthogonal decomposition (SPOD). This article puts the achievement of the TU Berlin authors in perspective, illustrating the potential of SPOD and the challenges ahead.

scholarly journals Dynamic mode decomposition analysis of rotating detonation waves

Shock Waves ◽  
2020 ◽  
Author(s):  
M. D. Bohon ◽  
A. Orchini ◽  
R. Bluemner ◽  
C. O. Paschereit ◽  
E. J. Gutmark
Keyword(s):  
Stable Limit Cycle ◽  
Operating Conditions ◽  
Dynamic Mode Decomposition ◽  
Mode Shapes ◽  
Dynamic Mode ◽  
Stable Limit ◽  
Rotating Waves ◽  
Reduced Order ◽  
Mode Decomposition ◽  
Rotating Detonation

Abstract A rotating detonation combustor (RDC) is a novel approach to achieving pressure gain combustion. Due to the steady propagation of the detonation wave around the perimeter of the annular combustion chamber, the RDC dynamic behavior is well suited to analysis with reduced-order techniques. For flow fields with such coherent aspects, the dynamic mode decomposition (DMD) has been shown to capture well the dominant oscillatory features corresponding to stable limit-cycle or quasi-periodic behavior within its dynamic modes. Details regarding the application of the technique to RDC—such as the number of frames, the effect of subtracting the temporal mean from the processed dataset, the resulting dynamic mode shapes, and the reconstruction of the dynamics from a reduced set of dynamic modes—are analyzed and interpreted in this study. The DMD analysis is applied to two commonly observed operating conditions of rotating detonation combustion, viz., (1) a single spinning wave with weak counter-rotating waves and (2) a clapping operating mode with two counter-propagating waves at equal speed and strength. We show that care must be taken when applying DMD to RDC datasets due to the presence of standing waves (expressed as either counter-propagating azimuthal waves or longitudinal pulsations). Without accounting for these effects, the reduced-order reconstruction fails using the standard DMD approach. However, successful application of the DMD allows for the reconstruction and separation of specific wave modes, from which models of the stabilization and propagation of the primary and counter-rotating waves can be derived.

Combustion Instability Analysis of a Model Gas Turbine by Application of Dynamic Mode Decomposition

2019 ◽  
Vol 24 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Yuangang Wang ◽  
Yuangang Wang ◽  
Chae Hoon Sohn ◽  
Jisu Yoon ◽  
Jinhyun Bae ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Combustion Instability ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Instability Analysis ◽  
Mode Decomposition

scholarly journals Mixed acoustic–entropy combustion instabilities in gas turbines

2014 ◽  
Vol 749 ◽  
pp. 542-576 ◽  
Author(s):  
Emmanuel Motheau ◽  
Franck Nicoud ◽  
Thierry Poinsot
Keyword(s):  
Gas Turbines ◽  
Transfer Functions ◽  
Combustion Instability ◽  
Low Frequency ◽  
Acoustic Mode ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Reacting Flow ◽  
Exit Nozzle ◽  
Low Order

AbstractA combustion instability in a combustor terminated by a nozzle is analysed and modelled based on a low-order Helmholtz solver. A large eddy simulation (LES) of the corresponding turbulent, compressible and reacting flow is first performed and analysed based on dynamic mode decomposition (DMD). The mode with the highest amplitude shares the same frequency of oscillation as the experiment (approximately 320 Hz) and shows the presence of large entropy spots generated within the combustion chamber and convected down to the exit nozzle. The lowest purely acoustic mode being in the range 700–750 Hz, it is postulated that the instability observed around 320 Hz stems from a mixed entropy–acoustic mode, where the acoustic generation associated with entropy spots being convected throughout the choked nozzle plays a key role. The DMD analysis allows one to extract from the LES results a low-order model that confirms that the mechanism of the low-frequency combustion instability indeed involves both acoustic and convected entropy waves. The delayed entropy coupled boundary condition (DECBC) (Motheau, Selle & Nicoud, J. Sound Vib., vol. 333, 2014, pp. 246–262) is implemented into a numerical Helmholtz solver where the baseline flow is assumed at rest. When fed with appropriate transfer functions to model the entropy generation and convection from the flame to the exit, the Helmholtz/DECBC solver predicts the presence of an unstable mode around 320 Hz, in agreement with both LES and experiments.

Local and Global Stability Analysis of an Academic Rotor/Stator Cavity

2018 ◽  
Author(s):  
Matthieu Queguineur ◽  
Thibault Bridel-Bertomeu ◽  
Laurent Gicquel ◽  
Gabriel Staffelbach
Keyword(s):  
Structural Integrity ◽  
Flow Instability ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Cavity Flows ◽  
Space Applications ◽  
Sustained Oscillations ◽  
Mode Decomposition ◽  
Large Eddy ◽  
The Stability

Self-sustained oscillations of rotor/stator cavity flows are well known to industry. This unsteady phenomenon can be very dangerous and jeopardize the structural integrity of aeronautical engines by damaging turbomachinery components or turbopumps in the context of space applications. Today, the origin of such flow instability and resulting limit-cycle is not well understood and still difficult to predict numerically. In order to have more insight of this phenomenon dynamic, an academic rotor/stator cavity is investigated in the present paper. The main motivation of this study is to highlight the benefit of conjunct numerical strategies relying on Large Eddy Simulations (LES) and flow stability analyses to understand driving instability mechanisms. More specifically, results of a local and global methods are devised and compared to a Dynamic Mode Decomposition (DMD) of LES predictions. Good agreements between the stability methods studied and the present features in the LES limitcycle are found. On this basis, a sensitivity and receptivity analysis of the flow is realized to point the origin of the two most unstable modes: i.e the position within the flow where the problem issues.

Experimental Measurement of In-Plane Rolling Nonpneumatic Tire Vibrations Using High-Speed Imaging

2019 ◽  
Vol 47 (3) ◽  
pp. 196-210
Author(s):  
Meghashyam Panyam ◽  
Beshah Ayalew ◽  
Timothy Rhyne ◽  
Steve Cron ◽  
John Adcox
Keyword(s):  
High Speed ◽  
Image Correlation ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
High Speed Imaging ◽  
Correlation Algorithm ◽  
Mode Decomposition ◽  
Series Of Experiments ◽  
Plane Deformations ◽  
Dominant Frequencies

ABSTRACT This article presents a novel experimental technique for measuring in-plane deformations and vibration modes of a rotating nonpneumatic tire subjected to obstacle impacts. The tire was mounted on a modified quarter-car test rig, which was built around one of the drums of a 500-horse power chassis dynamometer at Clemson University's International Center for Automotive Research. A series of experiments were conducted using a high-speed camera to capture the event of the rotating tire coming into contact with a cleat attached to the surface of the drum. The resulting video was processed using a two-dimensional digital image correlation algorithm to obtain in-plane radial and tangential deformation fields of the tire. The dynamic mode decomposition algorithm was implemented on the deformation fields to extract the dominant frequencies that were excited in the tire upon contact with the cleat. It was observed that the deformations and the modal frequencies estimated using this method were within a reasonable range of expected values. In general, the results indicate that the method used in this study can be a useful tool in measuring in-plane deformations of rolling tires without the need for additional sensors and wiring.

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