scholarly journals Effects of Hydrogen-Enrichment on Flame-Holding of Natural Gas Jet Flames in Crossflow at Elevated Temperature and Pressure

2020 ◽  
Author(s):  
Pankaj Saini ◽  
Ianko Chterev ◽  
Jhon Pareja ◽  
Manfred Aigner ◽  
Isaac Boxx
Keyword(s):  
Natural Gas ◽  
High Speed ◽  
Large Scale ◽  
Compressive Strain ◽  
Stereoscopic Particle Image Velocimetry ◽  
Gas Jet ◽  
Leeward Side ◽  
Jet Flames ◽  
Planar Laser ◽  
The Difference

AbstractThe effect of hydrogen ($$\mathrm {H}_{\mathrm {2}}$$ H 2 ) enrichment on the flame-holding characteristics of two natural gas jet flames in crossflow is investigated here, experimentally. The flame and flowfield measurements are analyzed using simultaneously acquired high-speed (10 kHz) stereoscopic particle image velocimetry, planar laser-induced fluorescence of the hydroxyl radical, and OH* chemiluminescence. The flames, enriched with 20% and 40% $$\mathrm {H}_{\mathrm {2}}$$ H 2 , by volume, are studied at conditions typical of the mixing duct of a modern gas turbine engine; specifically in confinement, at 10 bars, and with a crossflow preheat of 530 K. Consistent with previous findings, the 40% $$\mathrm {H}_{\mathrm {2}}$$ H 2 flame was found to be stabilized on the windward and leeward side of the jet, while the 20% $$\mathrm {H}_{\mathrm {2}}$$ H 2 flame was stabilized only on the leeward side. Analysis of mean and instantaneous velocity fields showed no major differences in the trajectories and principal compressive strain fields of the two flames. The presence of the windward stabilized flame in the 40% $$\mathrm {H}_{\mathrm {2}}$$ H 2 case was, however, found to decrease the centerline velocity decay and greatly reduce or eliminate large scale vortices along the windward shear layer. The difference in the flame-holding here was attributed to the difference in the extinction strain rate from the addition of hydrogen, which would impact the local and global extinction of the flame along the high shear windward region of the flame.

Measurements of Periodic Reynolds Stress Oscillations in a Forced Turbulent Premixed Swirling Flame

2018 ◽  
Author(s):  
Christopher Douglas ◽  
Jamie Lim ◽  
Travis Smith ◽  
Benjamin Emerson ◽  
Timothy Lieuwen ◽  
...  
Keyword(s):  
Reynolds Stress ◽  
High Speed ◽  
Large Scale ◽  
Turbulent Transport ◽  
Stereoscopic Particle Image Velocimetry ◽  
Thermoacoustic Instability ◽  
Image Velocimetry ◽  
Planar Laser ◽  
Swirling Flame ◽  
Dynamics Simulations

This work is motivated by the thermoacoustic instability challenges associated with ultra-low emissions gas turbine combustors. It demonstrates the first use of high-speed dual-plane orthogonally-polarized stereoscopic-particle image velocimetry and synchronized OH planar laser-induced fluorescence in a premixed swirling flame. We use this technique to explore the effects of combustion and longitudinal acoustic forcing on the time- and phase-averaged flow field — particularly focusing on the behavior of the Reynolds stress in the presence of harmonic forcing. We observe significant differences between ensemble averaged and time averaged Reynolds stress. This implies that the large-scale motions are non-ergodic, due to coherent oscillations in Reynolds stress associated with the convection of periodic vortical structures. This result has important implications on hydrodynamic stability models and reduced order computational fluid dynamics simulations, which do show the importance of turbulent transport on the problem, but do not capture these coherent oscillations in their models.

Measurements of Periodic Reynolds Stress Oscillations in a Forced Turbulent Premixed Swirling Flame

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Christopher Douglas ◽  
Jamie Lim ◽  
Travis Smith ◽  
Benjamin Emerson ◽  
Timothy Lieuwen ◽  
...  
Keyword(s):  
Reynolds Stress ◽  
High Speed ◽  
Large Scale ◽  
Turbulent Transport ◽  
Stereoscopic Particle Image Velocimetry ◽  
Thermoacoustic Instability ◽  
Image Velocimetry ◽  
Planar Laser ◽  
Swirling Flame ◽  
Dynamics Simulations

This work is motivated by the thermoacoustic instability challenges associated with ultra-low emissions gas turbine (GT) combustors. It demonstrates the first use of high-speed dual-plane orthogonally-polarized stereoscopic-particle image velocimetry (PIV) and synchronized OH planar laser-induced fluorescence in a premixed swirling flame. We use this technique to explore the effects of combustion and longitudinal acoustic forcing on the time- and phase-averaged flow field—particularly focusing on the behavior of the Reynolds stress in the presence of harmonic forcing. We observe significant differences between ensemble-averaged and time-averaged Reynolds stress. This implies that the large-scale motions are nonergodic, due to coherent oscillations in Reynolds stress associated with the convection of periodic vortical structures. This result has important implications on hydrodynamic stability models and reduced-order computational fluid dynamics simulations, which do show the importance of turbulent transport on the problem, but do not capture these coherent oscillations in their models.

Large-scale structure and entrainment in the supersonic mixing layer

1995 ◽  
Vol 284 ◽  
pp. 171-216 ◽  
Author(s):  
N. T. Clemens ◽  
M. G. Mungal
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Large Scale ◽  
Mixture Fraction ◽  
Mixing Layer ◽  
Mie Scattering ◽  
Planar Laser ◽  
The Cross ◽  
Convective Mach Number ◽  
Stream Direction

Experiments were conducted in a two-stream planar mixing layer at convective Mach numbers,Mc, of 0.28, 0.42, 0.50, 0.62 and 0.79. Planar laser Mie scattering (PLMS) from a condensed alcohol fog and planar laser-induced fluorescence (PLIF) of nitric oxide were used for flow visualization in the side, plan and end views. The PLIF signals were also used to characterize the turbulent mixture fraction fluctuations.Visualizations using PLMS indicate a transition in the turbulent structure from quasi-two-dimensionality at low convective Mach number, to more random three-dimensionality for$M_c\geqslant 0.62$. A transition is also observed in the core and braid regions of the spanwise rollers as the convective Mach number increases from 0.28 to 0.62. A change in the entrainment mechanism with increasing compressibility is also indicated by signal intensity profiles and perspective views of the PLMS and PLIF images. These show that atMc= 0.28 the instantaneous mixture fraction field typically exhibits a gradient in the streamwise direction, but is more uniform in the cross-stream direction. AtMc= 0.62 and 0.79, however, the mixture fraction field is more streamwise uniform and with a gradient in the cross-stream direction. This change in the composition of the structures is indicative of different entrainment motions at the different compressibility conditions. The statistical results are consistent with the qualitative observations and suggest that compressibility acts to reduce the magnitude of the mixture fraction fluctuations, particularly on the high-speed edge of the layer.

scholarly journals Characteristics of Large-Scale Structures in Supersonic Planar Mixing Layer with Finite Thickness

2014 ◽  
Vol 6 ◽  
pp. 878679
Author(s):  
Hailong Zhang ◽  
Jiping Wu ◽  
Jian Chen ◽  
Weidong Liu
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Finite Thickness ◽  
Mixing Layer ◽  
Mixing Enhancement ◽  
Laser Scattering ◽  
Large Scale Structures ◽  
Eddy Simulation ◽  
Planar Laser ◽  
Scale Structures

Nanoparticle-based planar laser scattering (NPLS) experiments and large eddy simulation (LES) were launched to get the fine structure of the supersonic planar mixing layer with finite thickness in the present study. Different from the turbulent development of supersonic planar mixing layer with thin thickness, the development of supersonic planar mixing layer with finite thickness is rapidly. The large-scale structures of mixing layer that possess the characters of quick movement and slow changes transmit to downriver at invariable speed. The transverse results show that the mixing layer is strip of right and dim and possess 3D characteristics. Meanwhile the vortices roll up from two sides to the center. Results indicate that the higher the pressure of the high speed side is, the thicker the mixing layer is. The development of mixing layer is restrained when the pressure of lower speed side is higher. The momentum thickness goes higher with the increase of the clapboard thickness. Through increasing the temperature to change the compression can affect the development of the vortices. The present study can make a contribution to the mixing enhancement and provide initial data for the later investigations.

Visualizations of Flow Structures in the Rotor Passage of an Axial Compressor at the Onset of Stall

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Huang Chen ◽  
Yuanchao Li ◽  
David Tan ◽  
Joseph Katz
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Incidence Angle ◽  
Axial Compressor ◽  
Leading Edge ◽  
Suction Side ◽  
Stereoscopic Particle Image Velocimetry ◽  
High Speed Imaging ◽  
Vortical Structures ◽  
Flow Phenomena

Experiments preformed in the JHU refractive index matched facility examine flow phenomena developing in the rotor passage of an axial compressor at the onset of stall. High-speed imaging of cavitation performed at low pressures qualitatively visualizes vortical structures. Stereoscopic particle image velocimetry (SPIV) measurements provide detailed snapshots and ensemble statistics of the flow in a series of meridional planes. At prestall condition, the tip leakage vortex (TLV) breaks up into widely distributed intermittent vortical structures shortly after rollup. The most prominent instability involves periodic formation of large-scale backflow vortices (BFVs) that extend diagonally upstream, from the suction side (SS) of one blade at midchord to the pressure side (PS) near the leading edge of the next blade. The 3D vorticity distributions obtained from data recorded in closely spaced planes show that the BFVs originate form at the transition between the high circumferential velocity region below the TLV center and the main passage flow radially inward from it. When the BFVs penetrate to the next passage across the tip gap or by circumventing the leading edge, they trigger a similar phenomenon there, sustaining the process. Further reduction in flow rate into the stall range increases the number and size of the backflow vortices, and they regularly propagate upstream of the leading edge of the next blade, where they increase the incidence angle in the tip corner. As this process proliferates circumferentially, the BFVs rotate with the blades, indicating that there is very little through flow across the tip region.

Industrial-scale processing of granite surfaces by natural gas jet flames

2002 ◽  
Vol 22 (4) ◽  
pp. 393-405 ◽  
Author(s):  
H.H. Liakos ◽  
M.K. Koukou ◽  
M.A. Founti ◽  
N.C. Markatos
Keyword(s):  
Natural Gas ◽  
Gas Jet ◽  
Industrial Scale ◽  
Jet Flames

Lift-off heights in underexpanded natural gas jet flames

1989 ◽  
Vol 22 (1) ◽  
pp. 825-831 ◽  
Author(s):  
A.D. Birch ◽  
G.K. Hargrave
Keyword(s):  
Natural Gas ◽  
Gas Jet ◽  
Jet Flames ◽  
Lift Off

Flow and Mixture Distribution in a High-Speed Five-Valve Direct Injected Gasoline Engine

2006 ◽  
Vol 7 (2) ◽  
pp. 143-166 ◽  
Author(s):  
N Kampanis ◽  
C Arcoumanis ◽  
S Kometani ◽  
R Kato ◽  
H Kinoshita
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Gasoline Engine ◽  
Flow Instability ◽  
Direct Injection ◽  
Mixture Distribution ◽  
Direct Injection Engines ◽  
Planar Laser ◽  
Performance And Emissions ◽  
Cylinder Flow

The in-cylinder flow, spray dynamics, air-spray interaction, and fuel vapour distribution have been characterized in a motorcycle five-valve gasoline engine in terms of their effect on performance and emissions. A five-valve single-cylinder optical engine was employed which operated at speeds up to 3000 r/min in the close spacing configuration, with an early induction injection strategy using a centrally mounted swirl pressure atomizer. Particle image velocimetry, spray imaging in a spray chamber and in the engine, and planar laser-induced fluorescence revealed the importance of a strong and ordered in-cylinder flow for the efficient distribution of the liquid fuel throughout the cylinder volume and its complete evaporation prior to combustion, especially in the relatively low speed regime investigated. Furthermore, in the absence of a large-scale vortex structure during compression, incomplete mixing may still occur, resulting in mixture inhomogeneities and flow instability. Consequently, in contrast to port fuel injected engines, where good mixing could be achieved at high revolution rates, even with an unstructured flow, in direct injection engines an ordered flow structure is a prerequisite for efficient combustion and low exhaust emissions.

scholarly journals Development of an Intermittent High-Speed Natural Gas Jet

2005 ◽  
Vol 25 (Supplement1) ◽  
pp. 449-452
Author(s):  
Kenji KIKUCHI ◽  
Mikiya ARAKI ◽  
Seiichi SHIGA ◽  
Hisao NAKAMURA ◽  
Tomio OBOKATA
Keyword(s):  
Natural Gas ◽  
High Speed ◽  
Gas Jet

Key Technologies of Rebuilding Underground Natural Gas Storages from Carbonate Buried Hill Gas Reservoirs

2011 ◽  
Vol 347-353 ◽  
pp. 1561-1567 ◽  
Author(s):  
Shu Jun Huang ◽  
Hui Zhang ◽  
Cui Juan Shang ◽  
Shu Long Jing
Keyword(s):  
Natural Gas ◽  
Large Scale ◽  
Gas Storage ◽  
Gas Reservoirs ◽  
Research Results ◽  
Key Technologies ◽  
The Difference ◽  
Buried Hill ◽  
The Impact ◽  
Gas Supply

In this paper, according to research difficulties of rebuilding underground natural gas storages from carbonate buried hill gas reservoirs, we select a variety of relevant technologies and methods to study. Considering the reservoir geologic features geology, the impact of water intrusion, the difference of reserve calculations and many other factors, we carry out the research and determine the key parameters of rebuilding underground natural gas storages, and finally get a reasonable understanding of the study. Upon completion of large-scale gas storage for research results, further to form the distinctive key technologies of rebuilding underground natural gas storages from carbonate buried hill gas reservoirs. The research results will provide the appropriate technical reference for similar future rebuilding underground gas storages and also provide the technical assurance for a safe and stable gas supply to Beijing, Tianjin and Hebei region.

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