Characterization of flame-shedding behavior behind a bluff-body using proper orthogonal decomposition

Kostka, Stanislav; Lynch, Amy; Huelskamp, Bethany; Kiel, Barry; Gord, James R.; Roy, Sukesh

doi:10.1016/j.combustflame.2012.03.021

Cited by 63 publications

(30 citation statements)

References 26 publications

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“…The observed structures and dynamics of vortex shedding behind the bluff body with ~120 Hz oscillation frequency agree well with those of the chemiluminescence studies reported in Ref. [25]. The detailed American Institute of Aeronautics and Astronautics 9 analysis of the measured combustion-instability phenomena will be discussed elsewhere.…”

Section: Fiber-coupled 10 Khz Simultaneous Oh-plif/pivsupporting

confidence: 82%

Development of fiber-coupled high-speed particle image velocimetry (PIV) for flow fields measurements in gas turbine engine hardware

Hsu

Jiang

Caswell

et al. 2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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We demonstrate the design and implementation of a fiber-optic beam-delivery system using a large-aperture, tapered step-index fiber for high-speed PIV in turbulent combustions flows. The tapered fiber in conjunction with a diffractive-optical-element (DOE) fiber-optic coupler significantly increases the damage threshold of the fiber, enabling fiber-optic beam delivery of sufficient nanosecond, 532-nm, laser pulse energy for high-speed PIV measurements. The fiber successfully transmits 1-kHz and 10-kHz laser pulses with energies of ~5.3 mJ and ~2 mJ, respectively, for more than 25 min without any indication of damage. It is experimentally demonstrated that the tapered fiber possesses the high coupling efficiency (~80%) and moderate beam quality for PIV. Additionally, the nearly uniform output-beam profile exiting the fiber is ideal for PIV applications. Comparative PIV measurements are made using a conventionally ( bulk-optic) delivered light sheet, and a similar order of measurement accuracy is obtained with and without fiber coupling. Effective use of fiber-coupled, 10-kHz PIV is demonstrated for instantaneous 2D velocity-field measurements in turbulent reacting flows. We have also developed and implemented a fiber-coupled, high-speed PIV and PLIF system for measuring hydroxyl radical (OH) concentration and velocity in a realistic 4-MW combustion rig.Simultaneous OH-PLIF and PIV imaging at a data-acquisition rate of 10 kHz is demonstrated in turbulent premixed flames behind a bluff body. Our results show significant promise for the performance of fiber-coupled high-speed PIV and OH-PLIF in harsh laser-diagnostic environments such as those encountered in gas-turbine test beds and the cylinder of a combustion engine. Nomenclature DC= direct current DOE = diffractive optical element LIDT = laser-induced damage threshold NA = numerical aperture OH = hydroxyl radicals PIV = particle image velocimetry PLIF = planar LIF PMT = photomultiplier tube SNR = signal-to-noise ratio UV = ultraviolet

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Section: Fiber-coupled 10 Khz Simultaneous Oh-plif/pivsupporting

confidence: 82%

Development of fiber-coupled high-speed particle image velocimetry (PIV) for flow fields measurements in gas turbine engine hardware

Hsu

Jiang

Caswell

et al. 2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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“…5 The observed flame instabilities at first glance appear similar to the instabilities found in the wake of a bluff body. The objective of this work is to examine the observed similarities between bluff body wake instabilities and flame instabilities.…”

Section: Figure 1 Flow Regimes For a Cylinder In A Cross Flowmentioning

confidence: 58%

Vortex Shedding of Various Bluff Bodies in Cross Flow

Ruscher¹,

Dannenhoffer²,

Glauser³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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The generation of noise in combusting jets is of crucial concern in both military and commercial applications. In order to understand the impact of combustion on the noise generation mechanism, one needs to understand the flow structures. Since the flame structures that are observed experimentally are similar to the flow structures behind a cylinder for a non-combusting flow, a detailed comparison of these is warranted. A large eddy simulation (LES) of a cylinder in a cross flow was performed at different Reynolds numbers to compare the relationship between vortex shedding at various Reynolds numbers with the flame structures at different equivalence ratios. This is done to determine if the proposed analogy is valid. Proper orthogonal decomposition (POD) is performed on the non-combusting flow field and the luminosity of the combusting flow to compare how much energy is contained in symmetric, asymmetric, and uncorrelated modes. The initial study suggests an analogy between Reynolds number and equivalence ratio does not exist in terms of symmetric/asymmetric modal energy distribution despite the visual similarities between the two phenomena. Nomenclature Φ = equivalence ratio m f uel = Fuel mass m oxidizer = Oxidizer mass C(t, t ) = Correlation Matrix T = Number of Snapshots u = Velocity a n = Time dependent POD coefficients λ = eigenvalues φ = POD mode r = correlation f = Frequency D = Diameter U = Free stream Velocity St = Strouhal Number

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“…The Rayleigh criterion has been successfully applied for studying the effect of an acoustic wave on a ñame [5] and, more recently, in the context of fluid dynamic instability [6]. Experimental studies have been carried out in order to study the effects of the Kelvin-Helmholtz vortex shedding mode and the von Karman vortex shedding mode on bluff body stabilized propane flames with the aid of proper orthogonal decomposition by Kostka et al [7]. Three different bluff bodies, a V-gutter, a cylinder, and a plate, were considered.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Combustion Instability in a V-Gutter Stabilized Combustor

Sundaram¹,

Babu

2013

Journal of Engineering for Gas Turbines and Power

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The stability of the combustion process in a V-gutter stabilized combustor is numerically investigated. To this end, 3D compressible turbulent and unsteady reacting flow calculations have been carried out using LES. The time history of the pressure at several locations is used to determine the frequency and amplitude of the oscillations along with the mode shapes. A shift in the dominant mode of the frequency spectra from the acoustic mode to the hydrodynamic mode is observed. A POD analysis of pressure time histories on the symmetry plane also corroborates this trend. The computational domain is divided into several subvolumes in the wake region of the V-gutter and the time histories of pressure, temperature, and heat release are collected in the individual volumes. It is seen that the fluctuation of pressure and heat release tend to oscillate from being in phase to out of phase over a time period. Unstable regions predicted by the Rayleigh index across a plane are shown to be different from those predicted in a volume owing to the three dimensionality of the flame. Quite interestingly, the calculated values of the indices show the combustor to be most unstable for an equivalence ratio of 0.1665 which is not the leanest one considered here. The global Rayleigh index is shown to correlate well with the amplitude of the dominant mode.

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Characterization of flame-shedding behavior behind a bluff-body using proper orthogonal decomposition

Cited by 63 publications

References 26 publications

Development of fiber-coupled high-speed particle image velocimetry (PIV) for flow fields measurements in gas turbine engine hardware

Development of fiber-coupled high-speed particle image velocimetry (PIV) for flow fields measurements in gas turbine engine hardware

Vortex Shedding of Various Bluff Bodies in Cross Flow

Numerical Investigation of Combustion Instability in a V-Gutter Stabilized Combustor

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