Measurement of fuel mixing and transport processes in gas turbine combustion
TL;DR: In this paper, a survey of the measurement techniques for delineating fuel-air mixing and transport in gas turbine combustion, as well as examples of representative results, are provided in this overview.
Abstract: The measurement techniques for delineating fuel-air mixing and transport in gas turbine combustion, as well as examples of representative results, are provided in this overview. The summary is broken into applications for gaseous fuels and liquid fuels since many diagnostics which are specific to the phase of the fuel have been developed. Many possible methods for assessing the general mixing have been developed, but not all have been applied to practical systems either under scaled or under actual conditions. With respect to gaseous mixing processes, planar laser-induced fluorescence (PLIF) based on acetone is now starting to be successfully applied to actual systems and conditions. In spray-fired systems, the need to discriminate between phases leads to considerable complication in delineating fuel-air mixing. Methods that focus on the discrete phase have successfully provided details relative to the droplets. These include phase Doppler interferometry (PDI), which is becoming ubiquitous in application to practical devices and under practical conditions. PDI is typically being applied to quantify droplet sizes, although the volume flux, which is relevant to fuel-air mixing, in practical systems is also being reported. In addition, PLIF strategies that focus upon the behaviour of the droplets are now being developed. However, PLIF strategies that can discriminate between phases either in the fuel or with respect to the liquid fuel and combustion air are also being developed. In terms of characterizing the vector fields associated with the mixing process, laser anemometry (LA), although it is tedious to apply, has proven reliable even in the presence of droplets. Newer methods such as DPIV and FRS have seen only limited application in practical systems but appear promising. In terms of scalar fields, LIF and PLIF have also been applied successfully to these systems, and examples of the measurements of concentrations of various radical species such as OH are found throughout the literature.
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Journal Article•
793 citations
TL;DR: In this paper, a detailed analysis of the flow-flame interactions associated with acoustically coupled heat-release rate fluctuations was performed for a 10kW, CH4/air, swirl stabilized flame in a gas turbine model combustor exhibiting self-excited thermo-acoustic oscillations at 308 Hz.
283 citations
TL;DR: In this article, the authors present a survey of spray measurement techniques and issues in spray physics and spray engineering, including the need for simultaneous diagnostic measurements under application-relevant conditions, and the effective comparison of spray measurements and numerical simulations.
Abstract: Sprays are among the most intellectually challenging and practically important topics in fluid mechanics. This paper reviews needs, milestones, challenges, and a broad array of techniques for spray measurement. In addition, tabular summaries provide cross-referenced entry points to the vast literature by organizing over 300 citations according to key spray phenomena, physical parameters and measurement techniques for each of the principal spray regions (nozzle internal flow, near-field spray-formation region, far-field developed spray, and spray-wall interaction). The article closes with perspectives on some current issues in spray research, including the cost and complexity of apparatus for spray physics and spray engineering, the need for simultaneous diagnostic measurements under application-relevant conditions, and the effective comparison of spray measurements and numerical simulations.
220 citations
Cites background from "Measurement of fuel mixing and tran..."
...3) are now commercially available and have largely replaced the older technique of collecting liquid in an array of small tubes [15, 26]....
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...droplet size and velocity; vapor-phase concentration) [2, 5, 15, 16] • From single-point to planar to 3D volume measurements • From single-shot to high-speed imaging [1, 17, 18] • From far-field/dilute-spray to near-field/dense-spray and in-nozzle measurements [3, 4, 19]....
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...Reviews of combustion diagnostics with substantial material on planar and volume techniques for sprays include [15, 31, 44]....
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...spray pattern, penetration [14], rate of injection) to microscopic measurements [2, 5, 15] • From qualitative to quantitative characterization (e....
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...Two-wavelength PLIF has been used for near-wall droplet temperature [282], while molecular tagging thermometry based on phosphorescence lifetime has been used to measure surface droplet temperature and size [283]....
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01 Jan 2015
TL;DR: In this article, a partially-premixed turbulent swirl flame is investigated using particle image velocimetry and planar laser-induced fluorescence of OH and acetone with a repetition rate of 10 kHz.
Abstract: Unsteady interactions of flow, fuel–air mixing and reaction in a lean partially-premixed turbulent swirl flame are investigated using simultaneous particle image velocimetry and planar laser-induced fluorescence of OH and acetone with a repetition rate of 10 kHz. The flame is operated with methane and air in a gas turbine model combustor at ambient temperature and pressure. Transport and mixing of fuel is visualized by fluorescence of acetone, which is added with 9% by volume to the methane. The dominant unsteady flow structures are a precessing vortex core (PVC) in the shear layer of the inner recirculation zone and the lower stagnation point (LSP) at the flame root. The measurements show that fuel and air are largely separated at the inlet of the combustion chamber, but are then strongly mixed by the PVC. A well-mixed zone of unburned fuel and air is formed around the vortex, and then ignited by recirculating burned gas. At the flame root, the PVC induces periodic changes in the composition of the unburned gas, which varies between pure air and well-mixed fuel and air. Reaction is locally quenched at the LSP when fresh air without fuel is present, and re-ignition takes place when mixed fuel and air arrive at the boundary of recirculating burned gas. Generally, the results show that the enhancement of fuel–air mixing induced by the PVC contributes significantly to the stabilization of the flame, and that the flame dynamics can only be properly understood when an analysis of transient mixing mechanisms is included.
92 citations
TL;DR: In this article, a perfectly-premixed swirl-stabilized combustor was studied using data from S-PIV and planar laser induced fluorescence (PLIF).
74 citations
References
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TL;DR: In this article, the directional ambiguity associated with PIV and LSV is resolved by implementing local spatial cross-correlations between two sequential single-exposed particle images, and the recovered velocity data are used to compute the spatial and temporal vorticity distribution and the circulation of the vortex ring.
Abstract: Digital particle image velocimetry (DPIV) is the digital counterpart of conventional laser speckle velocitmetry (LSV) and particle image velocimetry (PIV) techniques. In this novel, two-dimensional technique, digitally recorded video images are analyzed computationally, removing both the photographic and opto-mechanical processing steps inherent to PIV and LSV. The directional ambiguity generally associated with PIV and LSV is resolved by implementing local spatial cross-correlations between two sequential single-exposed particle images. The images are recorded at video rate (30 Hz or slower) which currently limits the application of the technique to low speed flows until digital, high resolution video systems with higher framing rates become more economically feasible. Sequential imaging makes it possible to study unsteady phenomena like the temporal evolution of a vortex ring described in this paper. The spatial velocity measurements are compared with data obtained by direct measurement of the separation of individual particle pairs. Recovered velocity data are used to compute the spatial and temporal vorticity distribution and the circulation of the vortex ring.
1,976 citations
"Measurement of fuel mixing and tran..." refers background in this paper
...…began in the late 1970s, with the work of Grousson and Mallick (1977), Simpkins and Dudderar (1978), Barker and Fourney (1977) and others, and has been extensively researched since (Meynart 1983, Grant and Smith 1988, Keane and Adrian 1990, Willert and Gharib 1991, Mungal et al 1995, Adrian 1996)....
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Book•
10 Oct 1996
TL;DR: A survey of laser diagnostics can be found in this paper, where the authors present a survey of the field of laser diagnostic tools and their application in various fields, including: 1. Background Physics 3. Experimental Considerations 4. Application Considerations 5. Spontaneous Raman and Rayleigh Scattering 6. Coherent Anti-Stokes Raman Spectroscopy (CARS) 7. Laser-Induced Fluorescence (LIF) 8.
Abstract: 1. Survey of Laser Diagnostics 2. Background Physics 3. Experimental Considerations 4. Application Considerations 5. Spontaneous Raman and Rayleigh Scattering 6. Coherent Anti-Stokes Raman Spectroscopy (CARS) 7. Laser-Induced Fluorescence (LIF) 8. Coherent Methods for Minor Species 9. Field Techniques
1,736 citations
"Measurement of fuel mixing and tran..." refers background or methods in this paper
...Several excellent reviews which provide an overview of the various issues and experiences associated with these diagnostics are available (Eckbreth 1988, Chigier 1991)....
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...Indeed, Raman scattering tends to be limited to applications in which practical geometries and situations do not complicate signal interpretation (Eckbreth 1988)....
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...Many excellent review papers and books are available on these methods and the reader is referred to these offerings for details and discussions of their applications (Eckbreth 1988, Chigier 1991, Daily 1997)....
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...Other strategies including coherent anti-Stokes Raman spectroscopy (CARS) can also be applied (Eckbreth 1988)....
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Journal Article•
793 citations
TL;DR: In this paper, a set of six non-dimensional parameters that are the most significant in optimizing particle image velocimeter performance are identified, which are the data validation criterion, the particle image density, the relative in-plane image displacement, a velocity gradient parameter, and the ratio of the mean image diameter to the interrogation spot diameter.
Abstract: The spatial resolution, detection rate, accuracy and reliability of a particle image velocimeter (PIV) depend critically upon the careful selection of a number of parameters of the PIV system and the fluid motion. An analytical model and a Monte Carlo computer simulation have been developed to analyse the effects of experimental parameters and to optimize the system parameters. A set of six nondimensional parameters that are the most significant in optimizing PIV performance are identified. They are the data validation criterion, the particle image density, the relative in-plane image displacement, the relative out-of-plane displacement, a velocity gradient parameter, and the ratio of the mean image diameter to the interrogation spot diameter. These parameters are studied for the case of interrogation by autocorrelation analysis. By a single transformation, these results can be applied to interrogation by two-dimensional Fourier transform analysis of the Young's fringes.
762 citations
649 citations