The Experts below are selected from a list of 9987 Experts worldwide ranked by ideXlab platform
Javier Fernandezvilla - One of the best experts on this subject based on the ideXlab platform.
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on the potential of power generation from thermoelectric generators in Gas Turbine Combustors
Energies, 2018Co-Authors: Panagiotis Stathopoulos, Javier FernandezvillaAbstract:Thermoelectric generators (TEGs) offer an attractive power generation option. They have no moving parts, are robust and emit no pollutants. The current work explores the integration of high temperature TEGs in Gas Turbine Combustors. The latter have a thermal shield at their inner surface to protect them against high temperatures. This is supplemented by convective and film cooling. This work studies the replacement of the thermal shield with high temperature TEGs and evaluates their techno-economic potential. A Gas Turbine model is developed and validated to compute the fuel and air flow rate in the combustion chamber. A heat transfer model is subsequently implemented to compute the temperature distribution inside the combustor wall, on which the TEG is constructed. The investment in TEGs is then analyzed for peaker, intermediate load and base load Gas Turbines. The work concludes with a sensitivity analysis of the investment economic performance. It is concluded that, despite the low power generation, the installation of TEGs makes economic sense, even if their price becomes 50% higher than current estimations. It is also concluded that electricity prices have a much stronger effect on the economic viability of the investment than the price of the generators.
Yehia A. Eldrainy - One of the best experts on this subject based on the ideXlab platform.
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large eddy simulation and preliminary modeling of the flow downstream a variable geometry swirler for Gas Turbine Combustors
International Communications in Heat and Mass Transfer, 2011Co-Authors: Yehia A. Eldrainy, Khalid M. Saqr, Hossam S. Aly, Tholudin Mat Lazim, Mohammad Azri Mohd JaafarAbstract:This work presents a novel swirler with variable blade configuration for Gas Turbine Combustors and industrial burners. The flow dynamics downstream the swirler was explored using Large Eddy Simulation (LES). The resolved turbulence kinetic energy in the region where the flow exhibits the main flow phenomena was well above 80% of the total turbulent kinetic energy of the flow. It was evidently shown that the new swirler produces a central recirculation zone and a Rankine vortex structure which are necessary for swirl flame stabilization. Two Reynolds-averaged NavierStokes (RANS) simulation cases utilizing the standard and realizable k-e turbulence models were also conducted for two objectives. The first is to demonstrate the validity of RANS/eddy-viscosity models in predicting the main characteristics of swirling flows with comparison to the LES results. The second objective is to comparatively investigate the flow features downstream the new swirler in both co-rotating and counter-rotating blade configurations. The results show that the counter-rotating configuration produces higher turbulence kinetic energy and more compact recirculation zone compared to the co-rotating configuration.
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a multiple inlet swirler for Gas Turbine Combustors
World Academy of Science Engineering and Technology International Journal of Mechanical Aerospace Industrial Mechatronic and Manufacturing Engineering, 2009Co-Authors: Yehia A. Eldrainy, Khalid M. Saqr, Hossam S. Aly, Mohammad Nazri Mohd. JaafarAbstract:The central recirculation zone (CRZ) in a swirl stabilized Gas Turbine combustor has a dominant effect on the fuel air mixing process and flame stability. Most of state of the art swirlers share one disadvantage; the fixed swirl number for the same swirler configuration. Thus, in a mathematical sense, Reynolds number becomes the sole parameter for controlling the flow characteristics inside the combustor. As a result, at low load operation, the generated swirl is more likely to become feeble affecting the flame stabilization and mixing process. This paper introduces a new swirler concept which overcomes the mentioned weakness of the modern configurations. The new swirler introduces air tangentially and axially to the combustor through tangential vanes and an axial vanes respectively. Therefore, it provides different swirl numbers for the same configuration by regulating the ratio between the axial and tangential flow momenta. The swirler aerodynamic performance was investigated using four CFD simulations in order to demonstrate the impact of tangential to axial flow rate ratio on the CRZ. It was found that the length of the CRZ is directly proportional to the tangential to axial air flow rate ratio.
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CFD insight of the flow dynamics in a novel swirler for Gas Turbine Combustors
International Communications in Heat and Mass Transfer, 2009Co-Authors: Yehia A. Eldrainy, Khalid M. Saqr, Hossam S. Aly, Mohammad Nazri Mohd. JaafarAbstract:We describe the flow dynamics inside a novel swirler conceptualized for Gas Turbine Combustors. The supreme advantage in this swirler is the ability to vary the swirl number for the same value of Reynolds number. The significance of such advantage against contemporary configurations, which have constant swirl number, is quite evident at low Turbine operating loads. The novel geometry and flow pattern are described in details in the present work. The results of four numerical simulations are presented and discussed to study the central recirculation zone, turbulence intensity, and pressure drop at different swirl numbers. The new concept is deemed to enhance the combustion efficiency because of its ability to adjust the swirl number according to the Turbine operating load. The current study reports preliminary results which verify the concept behind the proposed swirler. However, intensive numerical and experimental studies are necessary to be carried out in order to characterize the flow dynamics produced by the novel swirler and its impact on the combustion process.
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Augmentation of turbulence and mixing in Gas Turbine Combustors by introducing unsteady effects
Proceedings of the 2010 International Conference on Mechanical Industrial and Manufacturing Technologies (MIMT 2010), 1Co-Authors: Yehia A. Eldrainy, Khalid M. Saqr, Hossam S. Aly, Mohammad Nazri Mohd. JaafarAbstract:Turbulence production and mixing are crucial for flame stability in Gas Turbine Combustors. Designers have relied on fixed geometry swirlers to introduce a tangential component to the inlet air flow in order to sustain a central recirculation zone able to enhance the mixing process and stabilize the flame. In this paper we propose a novel swirler for Gas Turbine Combustors. The new swirler concept is composed of a conventional vane swirler and a rotating element which interrupts the swirling flow. Such unsteady interruption enhances the turbulence and mixing characteristics of the swirling flow. The novel concept is assessed by performing four numerical simulations at four different angular velocities for the rotating element which are 0, 240, 480, and 960 rpm. A trend of increasing turbulence kinetic energy with the rotating element angular velocity was observed.
Keith Robert Mcmanus - One of the best experts on this subject based on the ideXlab platform.
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real time equivalence ratio measurements in Gas Turbine Combustors with a near infrared diode laser sensor
Proceedings of the Combustion Institute, 2011Co-Authors: Shawn D Wehe, Keith Robert McmanusAbstract:Abstract A rapid (2 kHz) near-infrared tunable diode laser (TDL) absorption sensor is developed for real-time measurements of methane concentration (and thus equivalence ratio) in Gas Turbine Combustors. The non-intrusive sensor is based on fixed-wavelength laser absorption of methane near 1.65 μm using a single fiber-coupled diode laser. This CH4 absorption wavelength is free of interference from the absorption of other species in air. Wavelength modulation spectroscopy (WMS) is combined with second-harmonic detection to improve the sensor sensitivity and accuracy. WMS-1f signal is used to normalize the 2f signal to remove the need for calibration and account for the laser transmission variations in Gas Turbine Combustors. The near-IR TDL sensor is first calibrated in a static cell with CH4 and N2 mixture to determine the line-strength and find the laser setpoint. Test with a Gas Turbine combustor operating at atmospheric pressure is then conducted to demonstrate the sensor accuracy and response time. The TDL sensor is used to characterize equivalence ratio fluctuations in the combustor before the fuel/air mixtures enter the combustion chamber. The gain between heat release and equivalence ratio fluctuation is measured when the fuel flow rate is modulated at different levels. The combustion test results demonstrate the utility of the TDL sensor as a useful diagnostic tool to study flame characteristics and evaluate different combustor designs.
Mohammad Nazri Mohd. Jaafar - One of the best experts on this subject based on the ideXlab platform.
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a multiple inlet swirler for Gas Turbine Combustors
World Academy of Science Engineering and Technology International Journal of Mechanical Aerospace Industrial Mechatronic and Manufacturing Engineering, 2009Co-Authors: Yehia A. Eldrainy, Khalid M. Saqr, Hossam S. Aly, Mohammad Nazri Mohd. JaafarAbstract:The central recirculation zone (CRZ) in a swirl stabilized Gas Turbine combustor has a dominant effect on the fuel air mixing process and flame stability. Most of state of the art swirlers share one disadvantage; the fixed swirl number for the same swirler configuration. Thus, in a mathematical sense, Reynolds number becomes the sole parameter for controlling the flow characteristics inside the combustor. As a result, at low load operation, the generated swirl is more likely to become feeble affecting the flame stabilization and mixing process. This paper introduces a new swirler concept which overcomes the mentioned weakness of the modern configurations. The new swirler introduces air tangentially and axially to the combustor through tangential vanes and an axial vanes respectively. Therefore, it provides different swirl numbers for the same configuration by regulating the ratio between the axial and tangential flow momenta. The swirler aerodynamic performance was investigated using four CFD simulations in order to demonstrate the impact of tangential to axial flow rate ratio on the CRZ. It was found that the length of the CRZ is directly proportional to the tangential to axial air flow rate ratio.
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CFD insight of the flow dynamics in a novel swirler for Gas Turbine Combustors
International Communications in Heat and Mass Transfer, 2009Co-Authors: Yehia A. Eldrainy, Khalid M. Saqr, Hossam S. Aly, Mohammad Nazri Mohd. JaafarAbstract:We describe the flow dynamics inside a novel swirler conceptualized for Gas Turbine Combustors. The supreme advantage in this swirler is the ability to vary the swirl number for the same value of Reynolds number. The significance of such advantage against contemporary configurations, which have constant swirl number, is quite evident at low Turbine operating loads. The novel geometry and flow pattern are described in details in the present work. The results of four numerical simulations are presented and discussed to study the central recirculation zone, turbulence intensity, and pressure drop at different swirl numbers. The new concept is deemed to enhance the combustion efficiency because of its ability to adjust the swirl number according to the Turbine operating load. The current study reports preliminary results which verify the concept behind the proposed swirler. However, intensive numerical and experimental studies are necessary to be carried out in order to characterize the flow dynamics produced by the novel swirler and its impact on the combustion process.
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Augmentation of turbulence and mixing in Gas Turbine Combustors by introducing unsteady effects
Proceedings of the 2010 International Conference on Mechanical Industrial and Manufacturing Technologies (MIMT 2010), 1Co-Authors: Yehia A. Eldrainy, Khalid M. Saqr, Hossam S. Aly, Mohammad Nazri Mohd. JaafarAbstract:Turbulence production and mixing are crucial for flame stability in Gas Turbine Combustors. Designers have relied on fixed geometry swirlers to introduce a tangential component to the inlet air flow in order to sustain a central recirculation zone able to enhance the mixing process and stabilize the flame. In this paper we propose a novel swirler for Gas Turbine Combustors. The new swirler concept is composed of a conventional vane swirler and a rotating element which interrupts the swirling flow. Such unsteady interruption enhances the turbulence and mixing characteristics of the swirling flow. The novel concept is assessed by performing four numerical simulations at four different angular velocities for the rotating element which are 0, 240, 480, and 960 rpm. A trend of increasing turbulence kinetic energy with the rotating element angular velocity was observed.
Parviz Moin - One of the best experts on this subject based on the ideXlab platform.
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large eddy simulation of realistic Gas Turbine Combustors
AIAA Journal, 2006Co-Authors: Parviz Moin, Sourabh V. ApteAbstract:Large-eddy simulation is a promising technique for accurate prediction of reacting multiphase flows in practical Gas-Turbine combustion chambers involving complex physical phenomena of turbulent mixing and combustion dynamics. Development of advanced models for liquid fuel atomization, droplet evaporation, droplet deformation and drag, and turbulent combustion is discussed specifically for Gas-Turbine applications. The nondissipative, yet robust numerical scheme for arbitrary shaped unstructured grids developed by Mahesh et al. (Mahesh, K., Constantinescu, G., and Moin, P., "A New Time-Accurate Finite-Volume Fractional-Step Algorithm for Prediction of Turbulent Flows on Unstructured Hybrid Meshes," Journal of Computational Physics, Vol. 197, No. 1, 2004, pp. 215-240) is modified to account for density variations due to chemical reactions. A systematic validation and verification study of the individual spray models and the numerical scheme is performed in canonical and complex combustor geometries. Finally, a multiscale, multi physics, turbulent reacting flow simulation in a real Gas-Turbine combustor is performed to assess the predictive capability of the solver.
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A New Paradigm for Simulation of Turbulent Combustion in Realistic Gas Turbine Combustors Using LES
Volume 2: Turbo Expo 2003, 2003Co-Authors: George Constantinescu, Krishnan Mahesh, Sourabh V. Apte, Gianluca Iaccarino, Frank Ham, Parviz MoinAbstract:This paper presents a new paradigm for numerical simulation of turbulent combustion in realistic Gas Turbine Combustors. Advanced CFD methods using Large Eddy Simulation (LES) turbulence models are central to this paradigm in fluid dynamics where engineers can apply the full predictive abilities of numerical simulations to the design of realistic Gas Turbine Combustors. The use of LES models is motivated by their demonstrated superiority over RANS to predict turbulent mixing. The subgrid scale models incorporated in LES are based on the dynamic approach where the model coefficients are computed rather than prescribed by the user. This has provided unparalleled robustness to modern turbulent flow computations using LES. A new numerical algorithm was derived that is discretely energy conserving on hybrid unstructured grids, thus allowing numerical simulations at high Reynolds numbers corresponding to operating conditions without using artificial numerical dissipation. This paper deals specifically with the simulation of the Gas phase flow through realistic Gas Turbine Combustors and the implementation of combustion and spray models that are needed to predict and control the combustion phenomena in these geometries. Results from several simulations and comparison with experimental data are used to validate this approach. In particular, a complete simulation of the unsteady flow field in a realistic combustor geometry is carried out. Some preliminary results for reacting flow simulations in Gas Turbine Combustors are also discussed. We discuss several challenges related to large-scale simulations of the flow in realistic Combustors, including methods to further accelerate the algorithm’s convergence (e.g., use of multigrid techniques), improvement of the parallel performance of the flow solver for two-phase flow simulations (e.g., use of dynamic load balancing that accounts for the additional CPU time spent in the spray module when particles are present in the cells).Copyright © 2003 by ASME
