Documents disponibles écrits par cet auteur

Characterization of forced flame response of swirl-stabilized turbulent lean-premixed flames in a gas turbine combustor / Kyu Tae Kim in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 08 p. Titre : Characterization of forced flame response of swirl-stabilized turbulent lean-premixed flames in a gas turbine combustor Type de document : texte imprimé Auteurs : Kyu Tae Kim, Auteur ; Jong Guen Lee, Auteur ; Hyung Ju Lee, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Chemiluminescence  Combustion  Flames  Gas  turbines  Heat  transfer  Swirling  flow  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Flame transfer function measurements of turbulent premixed flames are made in a model lean-premixed, swirl-stabilized, gas turbine combustor. OH*, CH*, and CO2* chemiluminescence emissions are measured to determine heat release oscillation from a whole flame, and the two-microphone technique is used to measure inlet velocity fluctuation. 2D CH* chemiluminescence imaging is used to characterize the flame shape: the flame length (LCH* max) and flame angle (alpha). Using H2-natural gas composite fuels, XH2=0.00–0.60, a very short flame is obtained and hydrogen enrichment of natural gas is found to have a significant impact on the flame structure and flame attachment points. For a pure natural gas flame, the flames exhibit a “V” structure, whereas H2-enriched natural gas flames have an “M” structure. Results show that the gain of M flames is much smaller than that of V flames. Similar to results of analytic and experimental investigations on the flame transfer function of laminar premixed flames, it shows that the dynamics of a turbulent premixed flame is governed by three relevant parameters: the Strouhal number (St=LCH* max/Lconv), the flame length (LCH* max), and the flame angle (alpha). Two flames with the same flame shape exhibit very similar forced responses, regardless of their inlet flow conditions. This is significant because the forced flame response of a highly turbulent, practical gas turbine combustor can be quantitatively generalized using the nondimensional parameters, which collapse all relevant input conditions into the flame shape and the Strouhal number. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Characterization of forced flame response of swirl-stabilized turbulent lean-premixed flames in a gas turbine combustor [texte imprimé] / Kyu Tae Kim, Auteur ; Jong Guen Lee, Auteur ; Hyung Ju Lee, Auteur . - 2010 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 08 p. Mots-clés : Chemiluminescence  Combustion  Flames  Gas  turbines  Heat  transfer  Swirling  flow  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Flame transfer function measurements of turbulent premixed flames are made in a model lean-premixed, swirl-stabilized, gas turbine combustor. OH*, CH*, and CO2* chemiluminescence emissions are measured to determine heat release oscillation from a whole flame, and the two-microphone technique is used to measure inlet velocity fluctuation. 2D CH* chemiluminescence imaging is used to characterize the flame shape: the flame length (LCH* max) and flame angle (alpha). Using H2-natural gas composite fuels, XH2=0.00–0.60, a very short flame is obtained and hydrogen enrichment of natural gas is found to have a significant impact on the flame structure and flame attachment points. For a pure natural gas flame, the flames exhibit a “V” structure, whereas H2-enriched natural gas flames have an “M” structure. Results show that the gain of M flames is much smaller than that of V flames. Similar to results of analytic and experimental investigations on the flame transfer function of laminar premixed flames, it shows that the dynamics of a turbulent premixed flame is governed by three relevant parameters: the Strouhal number (St=LCH* max/Lconv), the flame length (LCH* max), and the flame angle (alpha). Two flames with the same flame shape exhibit very similar forced responses, regardless of their inlet flow conditions. This is significant because the forced flame response of a highly turbulent, practical gas turbine combustor can be quantitatively generalized using the nondimensional parameters, which collapse all relevant input conditions into the flame shape and the Strouhal number. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Effect of flame structure on the flame transfer function in a premixed gas turbine combustor / Daesik Kim in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Titre : Effect of flame structure on the flame transfer function in a premixed gas turbine combustor Type de document : texte imprimé Auteurs : Daesik Kim, Auteur ; Jong Guen Lee, Auteur ; Bryan D. Quay, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Gas  turbines  Transfer  functions Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The flame transfer function in a premixed gas turbine combustor is experimentally determined. The fuel (natural gas) is premixed with air upstream of a choked inlet to the combustor. Therefore, the input to the flame transfer function is the imposed velocity fluctuations of the fuel/air mixture without equivalence ratio fluctuations. The inlet-velocity fluctuations are achieved by a variable-speed siren over the forcing frequency of 75–280 Hz and measured using a hot-wire anemometer at the inlet to the combustor. The output function (heat release) is determined using chemiluminescence measurement from the whole flame. Flame images are recorded to understand how the flame structure plays a role in the global heat release response of flame to the inlet-velocity perturbation. The results show that the gain and phase of the flame transfer function depend on flame structure as well as the frequency and magnitude of inlet-velocity modulation and can be generalized in terms of the relative length scale of flame to convection length scale of inlet-velocity perturbation, which is represented by a Strouhal number. Nonlinear flame response is characterized by a periodic vortex shedding from shear layer, and the nonlinearity occurs at lower magnitude of inlet-velocity fluctuation as the modulation frequency increases. However, for a given modulation frequency, the flame structure does not affect the magnitude of inlet-velocity fluctuation at which the nonlinear flame response starts to appear. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Effect of flame structure on the flame transfer function in a premixed gas turbine combustor [texte imprimé] / Daesik Kim, Auteur ; Jong Guen Lee, Auteur ; Bryan D. Quay, Auteur . - 2010 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Mots-clés : Combustion  Gas  turbines  Transfer  functions Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The flame transfer function in a premixed gas turbine combustor is experimentally determined. The fuel (natural gas) is premixed with air upstream of a choked inlet to the combustor. Therefore, the input to the flame transfer function is the imposed velocity fluctuations of the fuel/air mixture without equivalence ratio fluctuations. The inlet-velocity fluctuations are achieved by a variable-speed siren over the forcing frequency of 75–280 Hz and measured using a hot-wire anemometer at the inlet to the combustor. The output function (heat release) is determined using chemiluminescence measurement from the whole flame. Flame images are recorded to understand how the flame structure plays a role in the global heat release response of flame to the inlet-velocity perturbation. The results show that the gain and phase of the flame transfer function depend on flame structure as well as the frequency and magnitude of inlet-velocity modulation and can be generalized in terms of the relative length scale of flame to convection length scale of inlet-velocity perturbation, which is represented by a Strouhal number. Nonlinear flame response is characterized by a periodic vortex shedding from shear layer, and the nonlinearity occurs at lower magnitude of inlet-velocity fluctuation as the modulation frequency increases. However, for a given modulation frequency, the flame structure does not affect the magnitude of inlet-velocity fluctuation at which the nonlinear flame response starts to appear. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Experimental investigation of the nonlinear response of swirl-stabilized flames to equivalence ratio oscillations / Kyu Tae Kim in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 2 (Fevrier 2011) . - 08 p. Titre : Experimental investigation of the nonlinear response of swirl-stabilized flames to equivalence ratio oscillations Type de document : texte imprimé Auteurs : Kyu Tae Kim, Auteur ; Jong Guen Lee, Auteur ; Bryan D. Quay, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Flames  Fluid  oscillations  Gas  turbines  Swirling  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The nonlinear response of a swirl-stabilized flame to equivalence ratio oscillations was experimentally investigated in an atmospheric-pressure, high-temperature, lean-premixed model gas turbine combustor. To generate high-amplitude equivalence ratio oscillations, fuel was modulated using a siren-type modulating device. The mixture ratio oscillations at the inlet of the combustion chamber were measured by the infrared absorption technique, and the flame's response, i.e., the fluctuation in the flame's rate of heat release, was estimated by CH* chemiluminescence emission intensity. Phase-resolved CH* chemiluminescence images were taken to characterize the dynamic response of the flame. Results show that the amplitude and frequency dependence of the flame's response to equivalence ratio oscillations is qualitatively consistent with the flame's response to inlet velocity oscillations. The underlying physics of the nonlinear response of the flame to equivalence ratio oscillations, however, is associated with the intrinsically nonlinear dependence of the heat of reaction and burning velocity on the equivalence ratio. It was found that combustion cannot be sustained under conditions of high-amplitude equivalence ratio oscillations. Lean blowoff occurs when the normalized amplitude of the equivalence ratio oscillation exceeds a threshold value. The threshold value is dependent on the mean equivalence ratio and modulation frequency. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Experimental investigation of the nonlinear response of swirl-stabilized flames to equivalence ratio oscillations [texte imprimé] / Kyu Tae Kim, Auteur ; Jong Guen Lee, Auteur ; Bryan D. Quay, Auteur . - 2012 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 2 (Fevrier 2011) . - 08 p. Mots-clés : Flames  Fluid  oscillations  Gas  turbines  Swirling  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The nonlinear response of a swirl-stabilized flame to equivalence ratio oscillations was experimentally investigated in an atmospheric-pressure, high-temperature, lean-premixed model gas turbine combustor. To generate high-amplitude equivalence ratio oscillations, fuel was modulated using a siren-type modulating device. The mixture ratio oscillations at the inlet of the combustion chamber were measured by the infrared absorption technique, and the flame's response, i.e., the fluctuation in the flame's rate of heat release, was estimated by CH* chemiluminescence emission intensity. Phase-resolved CH* chemiluminescence images were taken to characterize the dynamic response of the flame. Results show that the amplitude and frequency dependence of the flame's response to equivalence ratio oscillations is qualitatively consistent with the flame's response to inlet velocity oscillations. The underlying physics of the nonlinear response of the flame to equivalence ratio oscillations, however, is associated with the intrinsically nonlinear dependence of the heat of reaction and burning velocity on the equivalence ratio. It was found that combustion cannot be sustained under conditions of high-amplitude equivalence ratio oscillations. Lean blowoff occurs when the normalized amplitude of the equivalence ratio oscillation exceeds a threshold value. The threshold value is dependent on the mean equivalence ratio and modulation frequency. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Flame response mechanisms due to velocity perturbations in a lean premixed gas turbine combustor / Brian Jones in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 2 (Fevrier 2011) . - 09 p. Titre : Flame response mechanisms due to velocity perturbations in a lean premixed gas turbine combustor Type de document : texte imprimé Auteurs : Brian Jones, Auteur ; Jong Guen Lee, Auteur ; Bryan D. Quay, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Flames  Flow  visualisation  Gas  turbines  Transfer  functions Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The response of turbulent premixed flames to inlet velocity fluctuations is studied experimentally in a lean premixed, swirl-stabilized, gas turbine combustor. Overall chemiluminescence intensity is used as a measure of the fluctuations in the flame's global heat release rate, and hot wire anemometry is used to measure the inlet velocity fluctuations. Tests are conducted over a range of mean inlet velocities, equivalence ratios, and velocity fluctuation frequencies, while the normalized inlet velocity fluctuation (V[prime]/Vmean) is fixed at 5% to ensure linear flame response over the employed modulation frequency range. The measurements are used to calculate a flame transfer function relating the velocity fluctuation to the heat release fluctuation as a function of the velocity fluctuation frequency. At low frequency, the gain of the flame transfer function increases with increasing frequency to a peak value greater than 1. As the frequency is further increased, the gain decreases to a minimum value, followed by a second smaller peak. The frequencies at which the gain is minimum and achieves its second peak are found to depend on the convection time scale and the flame's characteristic length scale. Phase-synchronized CH* chemiluminescence imaging is used to characterize the flame's response to inlet velocity fluctuations. The observed flame response can be explained in terms of the interaction of two flame perturbation mechanisms, one originating at flame-anchoring point and propagating along the flame front and the other from vorticity field generated in the outer shear layer in the annular mixing section. An analysis of the phase-synchronized flame images show that when both perturbations arrive at the flame at the same time (or phase), they constructively interfere, producing the second peak observed in the gain curves. When the perturbations arrive at the flame 180 degrees out-of-phase, they destructively interfere, producing the observed minimum in the gain curve. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Flame response mechanisms due to velocity perturbations in a lean premixed gas turbine combustor [texte imprimé] / Brian Jones, Auteur ; Jong Guen Lee, Auteur ; Bryan D. Quay, Auteur . - 2012 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 2 (Fevrier 2011) . - 09 p. Mots-clés : Combustion  Flames  Flow  visualisation  Gas  turbines  Transfer  functions Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The response of turbulent premixed flames to inlet velocity fluctuations is studied experimentally in a lean premixed, swirl-stabilized, gas turbine combustor. Overall chemiluminescence intensity is used as a measure of the fluctuations in the flame's global heat release rate, and hot wire anemometry is used to measure the inlet velocity fluctuations. Tests are conducted over a range of mean inlet velocities, equivalence ratios, and velocity fluctuation frequencies, while the normalized inlet velocity fluctuation (V[prime]/Vmean) is fixed at 5% to ensure linear flame response over the employed modulation frequency range. The measurements are used to calculate a flame transfer function relating the velocity fluctuation to the heat release fluctuation as a function of the velocity fluctuation frequency. At low frequency, the gain of the flame transfer function increases with increasing frequency to a peak value greater than 1. As the frequency is further increased, the gain decreases to a minimum value, followed by a second smaller peak. The frequencies at which the gain is minimum and achieves its second peak are found to depend on the convection time scale and the flame's characteristic length scale. Phase-synchronized CH* chemiluminescence imaging is used to characterize the flame's response to inlet velocity fluctuations. The observed flame response can be explained in terms of the interaction of two flame perturbation mechanisms, one originating at flame-anchoring point and propagating along the flame front and the other from vorticity field generated in the outer shear layer in the annular mixing section. An analysis of the phase-synchronized flame images show that when both perturbations arrive at the flame at the same time (or phase), they constructively interfere, producing the second peak observed in the gain curves. When the perturbations arrive at the flame 180 degrees out-of-phase, they destructively interfere, producing the observed minimum in the gain curve. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]