The Experts below are selected from a list of 6309 Experts worldwide ranked by ideXlab platform
A R Masri - One of the best experts on this subject based on the ideXlab platform.
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turbulent piloted dilute spray flames flow fields and droplet dynamics
Combustion and Flame, 2012Co-Authors: James Gounder, Agisilaos Kourmatzis, A R MasriAbstract:Abstract This paper presents a comprehensive mapping of the flow and droplet fields in turbulent non-reacting as well as reacting dilute spray jets of acetone and ethanol Fuels. The burner is well-designed such that the boundary conditions are characterized with sufficient details and the stability limits of the flames are known. The flow is intentionally simple so that attention is shifted to the study of flow–droplet interactions with and without heat release. Velocity, turbulence and droplet size data are measured using a conventional LDV/PDA system and measurements are reported at a number of axial locations in the flow. Sequences of conditions are investigated to resolve the effects of increasing the droplet loading (at a fixed carrier flow rate, where the carrier is air) and the effects of increasing the carrier velocity (at a fixed liquid flow rate). It is shown that the decay in the mean axial excess velocity on the centerline of acetone and ethanol flames is significantly slower than in non-reacting spray jets. The centerline rms velocity fluctuations in non-reacting jets peak around x / D = 10 while in the acetone and ethanol flames the peak occurs further downstream at around 80% of the length of the flame. In both reacting and non-reacting jets, large droplets exit the nozzle with negative slip velocities and a changeover occurs further downstream where the slip velocity of large droplets becomes positive. Radial dispersion of droplets decreases with increasing Stokes number while the axial rms fluctuations may remain high due to “memory” effects as well as to droplet shedding from the inner wall of the Fuel Pipe hence leading to high anisotropy. The extensive data base, noting similarities and differences between the non-reacting and reacting jets, will facilitate model development and validation for dilute sprays.
James Gounder - One of the best experts on this subject based on the ideXlab platform.
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turbulent piloted dilute spray flames flow fields and droplet dynamics
Combustion and Flame, 2012Co-Authors: James Gounder, Agisilaos Kourmatzis, A R MasriAbstract:Abstract This paper presents a comprehensive mapping of the flow and droplet fields in turbulent non-reacting as well as reacting dilute spray jets of acetone and ethanol Fuels. The burner is well-designed such that the boundary conditions are characterized with sufficient details and the stability limits of the flames are known. The flow is intentionally simple so that attention is shifted to the study of flow–droplet interactions with and without heat release. Velocity, turbulence and droplet size data are measured using a conventional LDV/PDA system and measurements are reported at a number of axial locations in the flow. Sequences of conditions are investigated to resolve the effects of increasing the droplet loading (at a fixed carrier flow rate, where the carrier is air) and the effects of increasing the carrier velocity (at a fixed liquid flow rate). It is shown that the decay in the mean axial excess velocity on the centerline of acetone and ethanol flames is significantly slower than in non-reacting spray jets. The centerline rms velocity fluctuations in non-reacting jets peak around x / D = 10 while in the acetone and ethanol flames the peak occurs further downstream at around 80% of the length of the flame. In both reacting and non-reacting jets, large droplets exit the nozzle with negative slip velocities and a changeover occurs further downstream where the slip velocity of large droplets becomes positive. Radial dispersion of droplets decreases with increasing Stokes number while the axial rms fluctuations may remain high due to “memory” effects as well as to droplet shedding from the inner wall of the Fuel Pipe hence leading to high anisotropy. The extensive data base, noting similarities and differences between the non-reacting and reacting jets, will facilitate model development and validation for dilute sprays.
Schroer Pierre - One of the best experts on this subject based on the ideXlab platform.
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aerodynamic premixture injection for gas turbines premixes Fuel with primary air from nozzles to impinge on dome and evacuating into swirling air directed to combustion chamber
1992Co-Authors: Sandelis Denis, Schroer PierreAbstract:A cylinder (8) extends into the combustion chamber (3) full gas zone, from its base (6), with a central axis (8a) Fuel Pipe (7) carrying several injection orifices (21). A deflector (18) dome (15) downstream (17) of the cylinder, with an annular wall (14) having radial orifices (22), surrounds first air entries (9), around the Pipe. Upstream, secondary vanes (23) are mounted between the annular wall and the cylinder. The dome chamber (19) receives injected Fuel (20), mixing with the first air flow (F1), forming a very rich premixture, leaving by the radial orifices, to form a less rich mixture with the second air flow (F2). USE/ADVANTAGE - Reduces aero engine pollutants and auto inflammation. Cools dome deflector shield with premixture.
Air Sea - One of the best experts on this subject based on the ideXlab platform.
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GT2004-53496 NUMERICAL PREDICTION OF NON-REACTING AND REACTING FLOW IN A MODEL GAS TURBINE COMBUSTOR GT2004-53496
2020Co-Authors: Power For Land, Air SeaAbstract:ABSTRACT INTRODUCTION The three-dimensional, viscous, turbulent, reacting and non-reacting flow characteristics of a model gas turbine combustor operating on air/methane are simulated via an unstructured and massively parallel Reynolds-Averaged Navier-Stokes (RANS) code. This serves to demonstrate the capabilities of the code for design and analysis of real combustor engines. The effects of some design features of combustors are examined. In addition, the computed results are validated against experimental data. Computational fluid dynamics (CFD) has become an integral part in the design process of aeropropulsion engines, and a viable tool in understanding complex physical features of flowfields associated with various components of these engines. Use of CFD allows experimentation with new innovative design ideas that was not possible before, due to the excessive cost associated with manufacturing and testing of the prototypes. Thus CFD is able to improve design, reduce development cost, contribute to improved performance, and increase understanding of flowfield induced in yet not fabricated configurations. The numerical model encompasses the whole experimental flow passage, including the flow development sections for the air annulus and the Fuel Pipe, twelve channel air and Fuel swirlers, the combustion chamber, and the tail Pipe. A cubic non-linear low-Reynolds number K-e turbulence model is used to model turbulence, whereas the eddy-breakup model of Magnussen and Hjertager is used to account for the turbulence combustion interaction. Several RANS calculations are performed to determine the effects of the geometrical features of the combustor, and of the grid resolution on the flow field. The final grid is an all-hexahedron grid containing approximately two and one half million elements. In particular, gas turbine combustion modeling involves many complex physical processes that occur simultaneously such as combustion, turbulence, turbulence chemistry interaction, reaction kinetics, turbulence spray interaction, heat transfer, and radiation. In addition to solving the ReynoldsAveraged Navier-Stokes equations with a turbulence model, one may need to solve tens of individual species mass balance. The required partial differential equations to be solved could easily add up to 30 to 40 equations, depending on the number of species involved in the reaction kinetics. Considering various physical processes that are modeled and the resolution required for the grid to resolve scales of these processes, computational resources needed may become extensive and costly. In addition the complexities of the geometries of the combustors raise the daunting task of curvilinear grid generation. To provide an inlet condition to the main combustion chamber, consistent with the experimental data, flow swirlers are adjusted along the flow delivery inlet passage. Fine details of the complex flow structure such as helicalring vortices, recirculation zones and vortex cores are well captured by the simulation. Consistent with the experimental results, the computational model predicts a major recirculation zone in the central region immediately downstream of the Fuel nozzle, a second recirculation zone in the upstream corner of the combustion chamber, and a lifted flame. Further, the computed results predict the experimental data with reasonable accuracy for both the cold flow and for the reacting flow. It is also shown that small changes to the geometry can have noticeable effects on the combustor flowfield. However, to apply CFD in real-world design applications, the complex 3-D geometries, and many of the physical processes involved need to be resolved. With decreasing computing cost, increasing CPU speed, and the development of the parallel computing platform, computational cost and time is reduced to a level that fit in the design cycle time frame. Furthermore, with the advance of the numerical schemes using unstructured or Chimera meshes, mesh generation is becoming less intimidating than it used to be. The major task still remains
Agisilaos Kourmatzis - One of the best experts on this subject based on the ideXlab platform.
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turbulent piloted dilute spray flames flow fields and droplet dynamics
Combustion and Flame, 2012Co-Authors: James Gounder, Agisilaos Kourmatzis, A R MasriAbstract:Abstract This paper presents a comprehensive mapping of the flow and droplet fields in turbulent non-reacting as well as reacting dilute spray jets of acetone and ethanol Fuels. The burner is well-designed such that the boundary conditions are characterized with sufficient details and the stability limits of the flames are known. The flow is intentionally simple so that attention is shifted to the study of flow–droplet interactions with and without heat release. Velocity, turbulence and droplet size data are measured using a conventional LDV/PDA system and measurements are reported at a number of axial locations in the flow. Sequences of conditions are investigated to resolve the effects of increasing the droplet loading (at a fixed carrier flow rate, where the carrier is air) and the effects of increasing the carrier velocity (at a fixed liquid flow rate). It is shown that the decay in the mean axial excess velocity on the centerline of acetone and ethanol flames is significantly slower than in non-reacting spray jets. The centerline rms velocity fluctuations in non-reacting jets peak around x / D = 10 while in the acetone and ethanol flames the peak occurs further downstream at around 80% of the length of the flame. In both reacting and non-reacting jets, large droplets exit the nozzle with negative slip velocities and a changeover occurs further downstream where the slip velocity of large droplets becomes positive. Radial dispersion of droplets decreases with increasing Stokes number while the axial rms fluctuations may remain high due to “memory” effects as well as to droplet shedding from the inner wall of the Fuel Pipe hence leading to high anisotropy. The extensive data base, noting similarities and differences between the non-reacting and reacting jets, will facilitate model development and validation for dilute sprays.
