scholarly journals The Role of Primary Jets in the Dome Region Aerodynamics of a Model Can Combustor

1992 ◽  
Vol 114 (1) ◽  
pp. 20-26 ◽  
Author(s):  
C. D. Richards ◽  
G. S. Samuelsen
Keyword(s):  
Laser Diagnostics ◽  
Combustion Efficiency ◽  
Test Bed ◽  
Gas Turbine Combustor ◽  
Laser Anemometry ◽  
Thermal Fields ◽  
Mixing Patterns ◽  
Thermocouple Probe ◽  
Primary Jets

The role of the primary jets in the aerothermal behavior and overall performance of a gas turbine combustor is explored through an experimental study. The study is performed in a model laboratory combustor that possesses the essential features of practical combustors. The test bed is designed to accommodate optical access for laser diagnostics and overall flow visualization, and is capable of incorporating variable inlet geometries. In the present case, the combustor is operated on JP-4 at atmospheric pressure. A parametric variation in the number of jets per row and axial location of the jet row is performed. The aerodynamic and thermal fields are characterized using laser anemometry and a thermocouple probe, respectively. Species concentrations are acquired via extractive probe sampling. The results demonstrate the importance of primary jet location with respect to the dome swirler. The percent mass recirculated into the dome region, as well as the overall uniformity of mixing and combustion efficiency, are substantially influenced by jet row location. The momentum ratio of the incoming primary jet stream to that of the approaching crossflow of reacting dome gases has a direct impact on the mixing patterns as well. An increase in the number of primary jets leads, in the present case, to more uniform mixing.

scholarly journals The Role of Primary Jets in the Dome Region Aerodynamics of a Model Can Combustor

1990 ◽  
Author(s):  
C. D. Richards ◽  
G. S. Samuelsen
Keyword(s):  
Laser Diagnostics ◽  
Combustion Efficiency ◽  
Test Bed ◽  
Gas Turbine Combustor ◽  
Laser Anemometry ◽  
Thermal Fields ◽  
Mixing Patterns ◽  
Thermocouple Probe ◽  
Primary Jets

The role of the primary jets in the aerothermal behavior and overall performance of a gas turbine combustor is explored through an experimental study. The study is performed in a model laboratory combustor that possesses the essential features of practical combustors. The test bed is designed to accommodate optical access for laser diagnostics and overall flow visualization, and is capable of incorporating variable inlet geometries. In the present case, the combustor is operated on JP-4 at atmospheric pressure. A parametric variation in the number of jets per row and axial location of the jet row is performed. The aerodynamic and thermal fields are characterized using laser anemometry and a thermocouple probe respectively. Species concentrations are acquired via extractive probe sampling. The results demonstrate the importance of primary jet location with respect to the dome swirler. The percent mass recirculated into the dome region, as well as the overall uniformity of mixing and combustion efficiency, are substantially influenced by jet row location. The momentum ratio of the incoming primary jet stream to that of the approaching crossflow of reacting dome gases has a direct impact on the mixing patterns as well. An increase in the number of primary jets leads, in the present case, to more uniform mixing.

The aerodynamic challenges of aeroengine gas-turbine combustion systems

2014 ◽  
Vol 118 (1204) ◽  
pp. 557-599 ◽  
Author(s):  
J. J. McGuirk
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
Great Success ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Lean Burn ◽  
Combustion Systems ◽  
The Rich ◽  
Acoustic Instabilities

Abstract The components of an aeroengine gas-turbine combustor have to perform multiple tasks – control of external and internal air distribution, fuel injector feed, fuel/air atomisation, evaporation, and mixing, flame stabilisation, wall cooling, etc. The ‘rich-burn’ concept has achieved great success in optimising combustion efficiency, combustor life, and operational stability over the whole engine cycle. This paper first illustrates the crucial role of aerodynamic processes in achieving these performance goals. Next, the extra aerodynamic challenges of the ‘lean-burn’ injectors required to meet the ever more stringent NO x emissions regulations are introduced, demonstrating that a new multi-disciplinary and ‘whole system’ approach is required. For example, high swirl causes complex unsteady injector aerodynamics; the threat of thermo-acoustic instabilities means both aerodynamic and aeroacoustic characteristics of injectors and other air admission features must be considered; and high injector mass flow means potentially strong compressor/combustor and combustor/turbine coupling. The paper illustrates how research at Loughborough University, based on complementary use of advanced experimental and computational methods, and applied to both isolated sub-components and fully annular combustion systems, has improved understanding and identified novel ideas for combustion system design.

Combustion Characteristics of Small Size Gas Turbine Combustor Fueled by Biomass Gas Employing Flameless Combustion

2007 ◽  
Author(s):  
Masato Hiramatsu ◽  
Yoshifumi Nakashima ◽  
Sadamasa Adachi ◽  
Yudai Yamasaki ◽  
Shigehiko Kaneko
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Flameless Combustion ◽  
Engine Exhaust ◽  
Micro Gas Turbine

One approach to achieving 99% combustion efficiency (C.E.) and 10 ppmV or lower NOx (at 15%O2) in a micro gas turbine (MGT) combustor fueled by biomass gas at a variety of operating conditions is with the use of flameless combustion (FLC). This paper compares experimentally obtained results and CHEMKIN analysis conducted for the developed combustor. As a result, increase the number of stage of FLC combustion enlarges the MGT operation range with low-NOx emissions and high-C.E. The composition of fuel has a small effect on the characteristics of ignition in FLC. In addition, NOx in the engine exhaust is reduced by higher levels of CO2 in the fuel.

Combustion of Coal/Water Mixtures With Thermal Preconditioning

1987 ◽  
Vol 109 (3) ◽  
pp. 313-318 ◽  
Author(s):  
M. Novack ◽  
G. Roffe ◽  
G. Miller
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
Experimental Program ◽  
Water Mixture ◽  
Gas Turbine Combustor ◽  
Hydrocarbon Gases ◽  
Sampling Probe ◽  
Stable Flame ◽  
Thermal Preconditioning ◽  
Gaseous Form

Thermal preconditioning is a process in which coal/water mixtures are vaporized to produce coal/steam suspensions, and then superheated to allow the coal to devolatilize producing suspensions of char particles in hydrocarbon gases and steam. This final product of the process can be injected without atomization, and burned directly in a gas turbine combustor. This paper reports on the results of an experimental program in which thermally preconditioned coal/water mixture was successfully burned with a stable flame in a gas turbine combustor test rig. Tests were performed at a mixture flowrate of 300 lb/hr and combustor pressure of 8 atm. The coal/water mixture was thermally preconditioned and injected into the combustor over a temperature range from 350°F to 600°F, and combustion air was supplied at between 600°F to 725°F. Test durations varied between 10 and 20 min. Major results of the combustion testing were that: A stable flame was maintained over a wide equivalence ratio range, between φ = 2.2 (rich) and 0.2 (lean); and combustion efficiency of over 99 percent was achieved when the mixture was preconditioned to 600°F and the combustion air preheated to 725°F. Measurements of ash particulates, captured in the exhaust sampling probe located 20 in. from the injector face, show typical sizes collected to be about 1 μm, with agglomerates of these particulates to be not more than 8 μm. The original mean coal particle size for these tests, prior to preconditioning, was 25 μm. Results of additional tests showed that one third of the sulfur contained in the solids of a coal/water mixture with 3 percent sulfur was evolved in gaseous form (under mild thermolized conditions) mainly as H2S with the remainder as light mercaptans.

scholarly journals The Contrasting Role of Water and Acid Within Organic Phase Amphiphile Aggregation

2021 ◽  
Author(s):  
Biswajit Sadhu ◽  
Aurora E. Clark
Keyword(s):  
Self Assembly ◽  
Dynamics Simulation ◽  
Test Bed ◽  
Network Analyses ◽  
Liquid Liquid Extraction ◽  
Polar Media ◽  
Polar Solutes ◽  
Local Aggregation ◽  
The Individual

Hypothesis: Amphiphile self-assembly in non-polar media is often enhanced by polar co-solutes, as observed upon amphiphile mediated transport of water and acid into organic solution. Such co-extraction precludes understanding the individual roles of polar solutes upon self-assembly. Using this liquid-liquid extraction (LLE) system as a test-bed, we hypothesize that co-solute competition and hydrogen bond (HB) characteristics cause different size/shape distributions of assembled amphiphiles and alter self-assembly mechanisms in non-polar solvents. Experiments: Concentration dependent classical molecular dynamics simulation and intermolecular network analyses identified the correlating relationships between HB properties of H2O and HNO3 upon the aggregation of N,N,N,N-tetraoctyl-3-oxapentanediamide (TODGA), a prevalent LLE amphiphile extractant. Findings: Concentration dependent competition of hydrogen bonding fundamentally impacts amphiphile self-assembly in non-polar media. H2O bridges TODGA and enhances self-assembly, however as [H2O]org increases, preferential self-solvation leads to large (H2O)n clusters that cause TODGA clusters to sorb to the (H2O)n periphery and form extended aggregation. HNO3 restricts the (H2O)n size by disrupting the HB network. At large [H2O]org, HNO3 modulates TODGA self-assembly from extended to local aggregation. We attribute prior experimental observations to the role of water rather than co-extracted HNO3, thus providing valuable new insight into the means by which extractant aggregation can be tuned.

Influence of fuel volatility on combustion and emission characteristics in a gas turbine combustor at different inlet pressures and swirl conditions

2002 ◽  
Vol 216 (3) ◽  
pp. 257-268 ◽  
Author(s):  
N. Y. Sharma ◽  
S. K. Som
Keyword(s):  
Gas Turbine ◽  
Gas Phase ◽  
Combustion Efficiency ◽  
Inlet Pressure ◽  
Emission Characteristics ◽  
Spray Parameters ◽  
Gas Turbine Combustor ◽  
Spray Cone ◽  
Emission Level ◽  
Inlet Swirl

The practical challenges in research in the field of gas turbine combustion mainly centre around a clean emission, a low liner wall temperature and a desirable exit temperature distribution for turboma-chinery applications, along with fuel economy of the combustion process. An attempt has been made in the present paper to develop a computational model based on stochastic separated flow analysis of typical diffusion-controlled spray combustion of liquid fuel in a gas turbine combustor to study the influence of fuel volatility at different combustor pressures and inlet swirls on combustion and emission characteristics. A κ-ɛ model with wall function treatment for the near-wall region has been adopted for the solution of conservation equations in gas phase. The initial spray parameters are specified by a suitable probability distribution function (PDF) size distribution and a given spray cone angle. A radiation model for the gas phase, based on the first-order moment method, has been adopted in consideration of the gas phase as a grey absorbing-emitting medium. The formation of thermal NO x as a post-combustion reaction process is determined from the Zeldovich mechanism. It has been recognized from the present work that an increase in fuel volatility increases combustion efficiency only at higher pressures. For a given fuel, an increase in combustor pressure, at a constant inlet temperature, always reduces the combustion efficiency, while the influence of inlet swirl is found to decrease the combustion efficiency only at higher pressure. The influence of inlet pressure on pattern factor is contrasting in nature for fuels with lower and higher volatilities. For a higher-volatility fuel, a reduction in inlet pressure decreases the value of the pattern factor, while the trend is exactly the opposite in the case of fuels with lower volatilities. The NOx emission level increases with decrease in fuel volatility at all combustor pressures and inlet swirls. For a given fuel, the NOx emission level decreases with a reduction in combustor pressure and an increase in inlet swirl number.

The Vorbix Burner: A New Approach to Gas Turbine Combustors

1975 ◽  
Author(s):  
S. J. Markowski ◽  
R. P. Lohmann ◽  
R. S. Reilly
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
High Rate ◽  
Rayleigh Instability ◽  
Gas Turbine Combustor ◽  
New Approach ◽  
High Power Operation ◽  
Power Operation ◽  
Definition Of ◽  
Excellent Stability

The vorbix burner (acronym for Vortex Burning and Mixing) represents a new approach to a practical gas turbine combustor design. The concept exploits the Rayleigh instability of swirling flows to enhance the mixing and combustion rates. The combination of a two-stage fuel system with a piloted combustor leads to a unique high rate technique for fuel prevaporization within the combustor proper. This paper presents the fundamental concepts in the definition of the vorbix combustor and the results of exploratory tests conducted on can (tubular) and annular vorbix combustors. The results indicate that this type of combustor has unique performance characteristics that include excellent stability and high combustion efficiency over wide excursions in operating fuel air ratios in addition to substantially reduced emission levels during high power operation.

scholarly journals Testing structural and relational embeddedness in collaboration risk

2020 ◽  
Vol 32 (1) ◽  
pp. 67-92
Author(s):  
Minsun Song ◽  
Kyujin Jung ◽  
Namhoon Ki ◽  
Richard C Feiock
Keyword(s):  
Emergency Management ◽  
Network Governance ◽  
Test Bed ◽  
Relational Uncertainty ◽  
Structural Embeddedness ◽  
Institutional Collective Action ◽  
Seoul Metropolitan Area ◽  
Relational Embeddedness ◽  
Relational Risk

The study investigates the effect of embeddedness, defined as a property of interdependent relations in which organizations are integrated in a network, on collaboration risk emerging from relational uncertainty. Despite efforts to understand the structural effects of network governance, embedded relationships and their influence on collaboration remain relatively unexplored. A case of intergovernmental collaboration for emergency management is used as a test bed to examine the role of embeddedness in disaster networks and to extend the knowledge of collaboration risk within the institutional collective action framework. We hypothesize and test the effect of relational and structural embeddedness on the level of collaboration risk that an organization perceives. Our analysis of 69 organizations engaged in emergency management operations in the Seoul Metropolitan Area, South Korea reveals that both structural and relational embeddedness facilitate organizations to mitigate perceived collaboration risk. The results suggest that reachability secures relief of relational risk, and that commitment relationships bind participants.

Comparison of Numerical and Experimental Results of a Premixed DLE Gas Turbine Combustor

2001 ◽  
Author(s):  
Ruud L. G. M. Eggels ◽  
Christopher T. Brown
Keyword(s):  
Reaction Mechanism ◽  
Gas Turbine ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Gas Turbine Combustor ◽  
Cfd Modelling ◽  
Recirculation Length ◽  
Global Reaction ◽  
Presumed Pdf ◽  
Pdf Model

A numerical and experimental study on a premixed DLE gas turbine combustor has been performed. Experiments and CFD modelling have been carried out at isothermal and combusting conditions. The measurements were obtained at ERC using two component Laser Doppler Velocimetry. To be able to access the inner part of the combustor, the liners of the combustion chamber were outfitted with quartz windows. Temperature measurements were obtained at a few planes using a thermocouple. Modelling of the combustor has been performed using an in-house CFD code. The combustion process has been modelled using a global reaction mechanism and a Flame Generated Manifold reaction mechanism in combination with a presumed PDF model to incorporate the effect of turbulent fluctuations. The Flame Generated Manifold method uses a flame library, which has been generated by performing a number of laminar one-dimensional flame calculations at representative conditions. Comparing the numerical and experimental quite some differences are observed. The CFD model is able to predict the main features of the flow and combustion process, but does not predict the recirculation length accurately. Both combustion models, however, are able to predict the low combustion efficiency measured at the 1atm test condition.

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