Documents disponibles écrits par cet auteur

Air flow modulation for refined control of the combustion dynamics using a novel actuator / Fabrice Giuliani in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 2 (Février 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 2 (Février 2012) . - 08 p. Titre : Air flow modulation for refined control of the combustion dynamics using a novel actuator Type de document : texte imprimé Auteurs : Fabrice Giuliani, Auteur ; Andreas Lang, Auteur ; Klaus Johannes Gradl, Auteur ; Peter Siebenhofer, Auteur ; Johannes Fritzer, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Actuators  Combustion  Electric  motors  Gas  turbines  Turbomachinery  Turbulence  Virtual  instrumentation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A specific actuator able to modulate the air feed of a gas a burner at a given frequency and amplitude is presented. The Combustion Department at the Institute for Thermal Turbomachinery and Machine Dynamics at the Graz University of Technology has experience on the study of combustion instabilities in gas turbines using a flow excitor. The stability of an industrial burner is tested at elevated pressure and temperature conditions in the frame of the NEWAC project. For practical matters of operation among which the possibility to induce progressively a perturbation when the flame conditions are all set, the need was expressed to design, construct and validate a flexible actuator able to set an air flow modulation at a given frequency and at a desired amplitude level, with the possibility during operation to let these two factors vary in a given range independently from each other. This device should operate within the 0–1 kHz range and 0%–20% amplitude range at steady-state, during transients, or follow a specific time sequence. It should be robust and sustain elevated pressures. The objective is to bring a perturbation in the flow to which the combustor will respond, or not. For elevated levels of pulsation, it can simulate the presence of vortex-driven combustion instabilities. It can also act as a real-time actuator able to respond in frequency and in phase to actively damp a “natural” combustion instability. Other issues are a better and quicker mixing due to the enhanced turbulence level, and pushing forward the blow out limits at lean conditions with controlled injection dynamics. The basic construction is the one of a siren, with an elevated pressure side where the air is throttled, and a low pressure outlet where the resulting sonic jet is sheared by a rotating wheel. A mechanism allows to let vary the surface of interaction between the wheel and the jet. Two electromotors driven by Labview set both frequency and amplitude levels. This contribution describes the actuator's principles, design, operation range and the results of the characterization campaign. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000002 [...] [article] Air flow modulation for refined control of the combustion dynamics using a novel actuator [texte imprimé] / Fabrice Giuliani, Auteur ; Andreas Lang, Auteur ; Klaus Johannes Gradl, Auteur ; Peter Siebenhofer, Auteur ; Johannes Fritzer, Auteur . - 2012 . - 08 p. Génie mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 2 (Février 2012) . - 08 p. Mots-clés : Actuators  Combustion  Electric  motors  Gas  turbines  Turbomachinery  Turbulence  Virtual  instrumentation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A specific actuator able to modulate the air feed of a gas a burner at a given frequency and amplitude is presented. The Combustion Department at the Institute for Thermal Turbomachinery and Machine Dynamics at the Graz University of Technology has experience on the study of combustion instabilities in gas turbines using a flow excitor. The stability of an industrial burner is tested at elevated pressure and temperature conditions in the frame of the NEWAC project. For practical matters of operation among which the possibility to induce progressively a perturbation when the flame conditions are all set, the need was expressed to design, construct and validate a flexible actuator able to set an air flow modulation at a given frequency and at a desired amplitude level, with the possibility during operation to let these two factors vary in a given range independently from each other. This device should operate within the 0–1 kHz range and 0%–20% amplitude range at steady-state, during transients, or follow a specific time sequence. It should be robust and sustain elevated pressures. The objective is to bring a perturbation in the flow to which the combustor will respond, or not. For elevated levels of pulsation, it can simulate the presence of vortex-driven combustion instabilities. It can also act as a real-time actuator able to respond in frequency and in phase to actively damp a “natural” combustion instability. Other issues are a better and quicker mixing due to the enhanced turbulence level, and pushing forward the blow out limits at lean conditions with controlled injection dynamics. The basic construction is the one of a siren, with an elevated pressure side where the air is throttled, and a low pressure outlet where the resulting sonic jet is sheared by a rotating wheel. A mechanism allows to let vary the surface of interaction between the wheel and the jet. Two electromotors driven by Labview set both frequency and amplitude levels. This contribution describes the actuator's principles, design, operation range and the results of the characterization campaign. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000002 [...]

Validation of an infrared extinction method for fuel vapor concentration measurements towards the systematic comparison between alternative and conventional fuels for aviation / Johannes Fritzer in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 1 (Janvier 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 1 (Janvier 2012) . - 08 p. Titre : Validation of an infrared extinction method for fuel vapor concentration measurements towards the systematic comparison between alternative and conventional fuels for aviation Type de document : texte imprimé Auteurs : Johannes Fritzer, Auteur ; Fabrice Giuliani, Auteur ; Strzelecki, Alain, Auteur ; Virginel Bodoc, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Avionics  Chemical  variables  measurement  Climate  mitigation  Combustion  Fossil  fuels  Infrared  detectors  Iterative  methods  Measurement  by  laser  beam  Mie  scattering  Optimisation  Sprays  Transportation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Due to increasing oil prices and the obvious influence of the combustion of fossil fuel-derivatives on climate change on the one hand and the steady growth of transportation needs on the other, it is necessary to develop alternatives to oil for aviation. For this purpose a specific research program on the investigation of adequate alternative fuels for aviation has been founded by the European Commission's Framework Program. The project Alfa Bird (Alternative Fuels and Bio-fuels in Aircraft Development) focuses on an identification of possible alternative fuels to kerosene, the investigation of the adequacy of the selected ones, an evaluation of the environmental and economic impact of them, and finally the creation of a future perspective for the industrial use of the “best” alternative. The main part of the investigation activities at TU Graz, in cooperation with ONERA Centre de Toulouse and Fauga-Mauzac on these specific topics consists of the analysis of the evaporation of the previously chosen fuel types in comparison to fully synthetic jet fuel. Therefore qualitative measurements to obtain vapor concentration gradients will be done using the infrared extinction (IRE) measurement method. Based on a simplified Beer–Bouguer–Lambert law the integral vapor concentrations can be obtained. The main hypothesis is that if the line-of-sight extinction due to Mie-scattering is similar for both infrared and visible wavelengths because of the presence of the spray, only infrared light will be absorbed by the fuel vapor, being transparent to visible light. This contribution focuses on the validation of the infrared measurement technique on a well characterized spray. The tests are performed under controlled boundary conditions. Therefore an existing IRE test arrangement at ONERA Toulouse using an ultrasonic atomizer injecting n-octane at atmospheric conditions has been analyzed. Error sources related to misalignments in the hardware have been considered and an iterative alignment method of the laser beams followed by a beam diameter and diffraction analysis have been performed. Optimizing the setup to obtain a stable operation point has been successful. Improved experimental results at this operation point were compared with existing simulation results for the evaporation of the ultrasonic atomizer used. The achieved data has shown good accordance to the existing simulation results. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000001 [...] [article] Validation of an infrared extinction method for fuel vapor concentration measurements towards the systematic comparison between alternative and conventional fuels for aviation [texte imprimé] / Johannes Fritzer, Auteur ; Fabrice Giuliani, Auteur ; Strzelecki, Alain, Auteur ; Virginel Bodoc, Auteur . - 2012 . - 08 p. Génie mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 1 (Janvier 2012) . - 08 p. Mots-clés : Avionics  Chemical  variables  measurement  Climate  mitigation  Combustion  Fossil  fuels  Infrared  detectors  Iterative  methods  Measurement  by  laser  beam  Mie  scattering  Optimisation  Sprays  Transportation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Due to increasing oil prices and the obvious influence of the combustion of fossil fuel-derivatives on climate change on the one hand and the steady growth of transportation needs on the other, it is necessary to develop alternatives to oil for aviation. For this purpose a specific research program on the investigation of adequate alternative fuels for aviation has been founded by the European Commission's Framework Program. The project Alfa Bird (Alternative Fuels and Bio-fuels in Aircraft Development) focuses on an identification of possible alternative fuels to kerosene, the investigation of the adequacy of the selected ones, an evaluation of the environmental and economic impact of them, and finally the creation of a future perspective for the industrial use of the “best” alternative. The main part of the investigation activities at TU Graz, in cooperation with ONERA Centre de Toulouse and Fauga-Mauzac on these specific topics consists of the analysis of the evaporation of the previously chosen fuel types in comparison to fully synthetic jet fuel. Therefore qualitative measurements to obtain vapor concentration gradients will be done using the infrared extinction (IRE) measurement method. Based on a simplified Beer–Bouguer–Lambert law the integral vapor concentrations can be obtained. The main hypothesis is that if the line-of-sight extinction due to Mie-scattering is similar for both infrared and visible wavelengths because of the presence of the spray, only infrared light will be absorbed by the fuel vapor, being transparent to visible light. This contribution focuses on the validation of the infrared measurement technique on a well characterized spray. The tests are performed under controlled boundary conditions. Therefore an existing IRE test arrangement at ONERA Toulouse using an ultrasonic atomizer injecting n-octane at atmospheric conditions has been analyzed. Error sources related to misalignments in the hardware have been considered and an iterative alignment method of the laser beams followed by a beam diameter and diffraction analysis have been performed. Optimizing the setup to obtain a stable operation point has been successful. Improved experimental results at this operation point were compared with existing simulation results for the evaporation of the ultrasonic atomizer used. The achieved data has shown good accordance to the existing simulation results. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000001 [...]