| 1. |
- Giuliani, Fabrice, et al.
(författare)
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EFFECTS OF A CONTROLLED PHASE-SHIFT ON THE OUTLET CONDITIONS OF A SET OF PULSE DETONATORS
- 2009
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Ingår i: PROCEEDINGS XIX International Symposium on Air Breathing Engines.
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Konferensbidrag (refereegranskat)abstract
- A study on innovative combustion system for future aeroengine core concepts is done in the frame ofthe NEWAC project. A part of the high pressure core is replaced by a pulse detonation combustor. The ambition is to achieve a technical leap in TSFC reduction. In order toprovide technical assessments on both the feasibility and the performance of such a concept, specific tools were developed at TU Graz and Chalmers and are herebypresented and validated. The approach consists in a simultaneous averaged approach at system level,combined to a real-time simulation of the flow intermittency and its possible impact on the ambient. Theeffect of a phase-shift on the operation of neighbour tubescomposing a PDC is analysed into details.
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| 2. |
- Giuliani, Fabrice, et al.
(författare)
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PULSE DETONATION AS AN OPTION FOR FUTURE INNOVATIVE GAS TURBINE COMBUSTION TECHNOLOGIES: A CONCEPT ASSESSMENT
- 2010
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Ingår i: 27TH INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES Proceedings.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A study on innovative combustion system for future aeroengine core concepts is done in the frame of the NEWAC project (EU FP6, AIP5-CT-2006-030876). A part of the high pressure core is replaced by a pulse detonation combustor. The ambition is to achieve a technical leap in TSFC reduction, or alternatively a lighter engine. In order to provide technical assessments on both the feasibility and performance of such a concept, specific tools were developed at TU Graz, Austria and Chalmers University, Sweden. The study emphasises the impact of flow intermittency on the direct environment of the pulse detonation combustor, and on the performance of a hybrid turbofan. A literature survey establishes the state of the art on pulse detonation technologies. Numerical tools for CFD calculation and performance analysis are presented. A concept assessment with a TSFC reduction by 5% in comparison to a conventional cycle is derived.1 General IntroductionThe need for more efficient and environment friendly engines is tending towards new methods of combustion. Although new injections systems currently in development, like LPP (Lean Premixed Prevaporised), RQL (Rich burn Quick quench Lean burn) and LDI (Lean Direct Injection), are promising a reduction in pollutant emission there is also the trend to look for innovative combustion methods to lower in addition fuel consumption. One premising way to reduce thrust specific fuel consumption (TSFC) is to use pulse detonation [6].A study on innovative combustion system for future aeroengine core concepts is done in the frame of the NEWAC project. A part of the high pressure core of a conventional aeroengine is replaced by a pulse detonation combustor. A medium-range two-spool turbofan is taken as a baseline for a back-to-back comparison.Pulse detonation (PD) is attractive because of its potential for higher thermal efficiency.
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| 3. |
- Grönstedt, Tomas, 1970, et al.
(författare)
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First and Second Law Analysis of Future Aircraft Engines
- 2013
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Ingår i: ASME Turbo Expo, 2013. - 9780791855133 ; 2:GT2013-95516
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Konferensbidrag (refereegranskat)abstract
- An optimal baseline turbofan cycle designed for a performance level expected to be available around year 2050 is established. Detailed performance data are given in take-off, top of climb and cruise to support the analysis. Losses are analyzed based on a combined use of the first and second law of thermodynamics, to establish a basis for discussion on future radical engine concepts and to quantify loss levels of very high performance engines. In the light of the performance of the future baseline engine, three radical cycles designed to reduce the observed major loss sources are introduced. The combined use of a first and second law analysis of an open rotor engine, an intercooled recuperated engine and an engine working with a pulse detonation combustion core is presented. In the past, virtually no attention has been paid to the systematic quantification of the irreversibility rates of such radical concepts. Previous research on this topichas concentrated on the analysis of the turbojet and the turbofan engine. In the framework developed, the irreversibility rates are quantified through the calculation of the exergy destruction per unit time. A striking strength of the analysis is that it establishes a common currency for comparing losses originating from very different physical sources of irreversibility. This substantially reduces the complexity of analyzing and comparing losses in aero engines. In particular, the analysis sheds new light on how the intercooled recuperated engine establishes its performance benefits.
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| 4. |
- Grönstedt, Tomas, 1970, et al.
(författare)
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First and Second Law Analysis of Future Aircraft Engines
- 2014
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Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 136:3
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Tidskriftsartikel (refereegranskat)abstract
- An optimal baseline turbofan cycle designed for a performance level expected to be available around year 2050 is established. Detailed performance data are given in take-off, top of climb, and cruise to support the analysis. The losses are analyzed, based on a combined use of the first and second law of thermodynamics, in order to establish a basis for a discussion on future radical engine concepts and to quantify loss levels of very high performance engines. In light of the performance of the future baseline engine, three radical cycles designed to reduce the observed major loss sources are introduced. The combined use of a first and second law analysis of an open rotor engine, an intercooled recuperated engine, and an engine working with a pulse detonation combustion core is presented. In the past, virtually no attention has been paid to the systematic quantification of the irreversibility rates of such radical concepts. Previous research on this topic has concentrated on the analysis of the turbojet and the turbofan engine. In the developed framework, the irreversibility rates are quantified through the calculation of the exergy destruction per unit time. A striking strength of the analysis is that it establishes a common currency for comparing losses originating from very different physical sources of irreversibility. This substantially reduces the complexity of analyzing and comparing losses in aero engines. In particular, the analysis sheds new light on how the intercooled recuperated engine establishes its performance benefits.
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| 5. |
- Irannezhad, Mohammad, 1978
(författare)
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A Numerical Study of Reacting Flows Using Finite Rate Chemistry
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fossil fuels will remain the main source of energy for mankind in theforeseeable future. Heat released in combustion of fossil fuels is alwaysaccompanied by emission of undesired pollutants. Environmental concernshave led to stringent emission rules for combustion industry speciallyfor reducing the amount of NOx production. Lean premixed combustionhas increasingly gained interest in recent years as an approachtoward reduced NOx emissions by reducing the operating temperature.However, lean blow off limit and the tendency of the dynamic flame tobecome unstable present technical challenges. The low swirl burnerconcept is a rather new and promising design to stabilize lean premixedflames close to their flammability limit. Large Eddy Simulationtogether with a finite rate chemistry combustion model have been usedhere for numerical studies of a laboratory low swirl stabilized flame.The importance of the inlet boundary condition is investigated and anoptimized approach is suggested. The flame stabilization mechanismis discussed and it is shown that the choice of the inlet boundary conditioncan significantly affect this mechanism.Air transport is becoming more common and aviation contributionto anthropogenic CO2 production will soon become prominent. Turbomachineryefficiency in modern aircraft engines is close to perfectionand innovative core designs are needed for significant efficiency improvements.Unsteady phenomena in the working cycle of a conceptualPulse Detonation Engine is studied here using URANS and a finite ratechemistry combustion model. The limitations imposed by the unsteadyflow at compressor side are compared for two alternative engine configurations
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| 6. |
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| 7. |
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| 8. |
- Irannezhad, Mohammad, 1978, et al.
(författare)
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Large Eddy Simulation of premixed flames with multi-step global reaction mechanisms
- 2011
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 318:SECTION 9, s. Art. no. 092006-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Large Eddy Simulation is a powerful tool to simulate the unsteady lean premixedflames and to predict combustion instabilities. However the resolution of an LES grid is typicallylarger than the thickness of practical flames. In artificially thickened flame concept the mixing inthe flame region is enhanced by explicitly increasing heat and mass diffusivity while decreasingthe average reaction rates. The resulted flame is resolvable and propagates with the correct speedbut the flame response to small turbulent structures is decreased which should be compensated.A novel flame thickening technique is applied here to implement a multi-step global reactionmechanism in an LES solver. This method exploits the intrinsic numerical diffusion of theupwind biased discretization schemes to implicitly enhance mixing in the flame region hencethickening the flame to sizes resolvable on an LES grid. Unlike the previous thickening methodthis technique does not increase the diffusion in the plane tangent to the flame front hencereduces the loss of the flame surface. Simulation of a lean premixed low swirl methane-air flamereveals that this new method tends to keep some of those small flame structures which aresmeared out by the previous flame thickening methods.
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| 9. |
- Irannezhad, Mohammad, 1978
(författare)
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Large Eddy Simulation of Swirling Reacting Flows
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The combustion of fossil fuels remains a key technology as these fuels are the main source of energy in the foreseeable future. Heat released in combustion is often accompanied by emission of undesired soot, CO and NOx pollutants. Environmental concerns have led to stringent emission rules for combustion industry specially for reducing the amount of NOx emissions. This ever increasing demand for clean combustion has led to high interests in lean premixed combustion in recent years as an approach toward reduced NOx emissions by reducing the operating temperature. However, lean blow off limit and the tendency of the dynamic flame to become unstable present technical challenges. Low swirl burner is a rather new and promising design to stabilize lean premixed flames close to their flammability limit. Low swirl burner prototypes have been built at different sizes but the underlying physical processes which govern the operating conditions are not yet well understood.This thesis aims to employ and develop the existing numerical tools to simulate the flow in an experimental low swirl burner. A computational domain including the major components of the burner is adapted to the geometry and Large eddy simulation along with a novel flame capturing combustion model are used to solve the governing equations. The results are then validated against the available experimental data.The inflow boundary condition is investigated and an inlet profile is found which gives the correct boundary conditions. The exact stabilization mechanism of the flame in these burners is not yet understood and is discussed within the scope of the thesis.
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| 10. |
- Irannezhad, Mohammad, 1978, et al.
(författare)
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LIMITATIONS ON TUBE FILLING IN A PULSED DETONATION ENGINE
- 2011
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Ingår i: 20th ISABE Conference Proceedings.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Computational fluid dynamics is usedto study the limitations of fillingthe tubes in a Pulsed DetonationEngine. Direct replacement of thecombustor in a conventional enginewith the tubes can severely limit theoperational conditions. Analternative method for integrating thetubes in the engine is suggested andis shown to give a wide range ofworking conditions.
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