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Investigation of cooling effectiveness of gas turbine inlet fogging location relative to the silencer / Jobaidur R. Khan 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) . - 09 p. Titre : Investigation of cooling effectiveness of gas turbine inlet fogging location relative to the silencer Type de document : texte imprimé Auteurs : Jobaidur R. Khan, Auteur ; Ting Wang, Auteur ; Mustapha Chaker, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Compressors  Computational  fluid  dynamics  Cooling  Gas  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The output and efficiency of gas turbines are reduced significantly during the summer, especially in areas where the daytime temperature reaches as high as 50°C. Gas turbine inlet fogging and overspray has been considered a simple and cost-effective method to increase the power output. One of the most important issues related to inlet fogging is to determine the most effective location of the fogging device by determining (a) how many water droplets actually evaporate effectively to cool down the inlet air instead of colliding on the wall or coalescing and draining out (i.e., fogging efficiency), and (b) quantifying the amount of nonevaporated droplets that may reach the compressor bellmouth to ascertain the erosion risk for compressor airfoils if wet compression is to be avoided. When the silencer is installed, there is an additional consideration for placing the fogging device upstream or downstream of the silencer baffles. Placing arbitrarily the device upstream of the silencer can cause the silencer to intercept water droplets on the silencer baffles and lose cooling effectiveness. This paper employs computational fluid dynamics (CFD) to investigate the water droplet transport and cooling effectiveness with different spray locations such as before and after the silencer baffles. Analysis on the droplet history (trajectory and size) is employed to interpret the mechanism of droplet dynamics under influence of acceleration, diffusion, and body forces when the flow passes through the baffles and duct bent. The results show that, for the configuration of the investigated duct, installing the fogging system upstream of the silencer is about 3 percentage points better in evaporation effectiveness than placing it downstream of the silencer, irrespective of whether the silencer consists of a single row of baffles or two rows of staggered baffles. The evaporation effectiveness of the staggered silencer is about 0.8 percentage points higher than the single silencer. The pressure drop of the staggered silencer is 6.5% higher than the single silencer. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000002 [...] [article] Investigation of cooling effectiveness of gas turbine inlet fogging location relative to the silencer [texte imprimé] / Jobaidur R. Khan, Auteur ; Ting Wang, Auteur ; Mustapha Chaker, Auteur . - 2012 . - 09 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) . - 09 p. Mots-clés : Compressors  Computational  fluid  dynamics  Cooling  Gas  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The output and efficiency of gas turbines are reduced significantly during the summer, especially in areas where the daytime temperature reaches as high as 50°C. Gas turbine inlet fogging and overspray has been considered a simple and cost-effective method to increase the power output. One of the most important issues related to inlet fogging is to determine the most effective location of the fogging device by determining (a) how many water droplets actually evaporate effectively to cool down the inlet air instead of colliding on the wall or coalescing and draining out (i.e., fogging efficiency), and (b) quantifying the amount of nonevaporated droplets that may reach the compressor bellmouth to ascertain the erosion risk for compressor airfoils if wet compression is to be avoided. When the silencer is installed, there is an additional consideration for placing the fogging device upstream or downstream of the silencer baffles. Placing arbitrarily the device upstream of the silencer can cause the silencer to intercept water droplets on the silencer baffles and lose cooling effectiveness. This paper employs computational fluid dynamics (CFD) to investigate the water droplet transport and cooling effectiveness with different spray locations such as before and after the silencer baffles. Analysis on the droplet history (trajectory and size) is employed to interpret the mechanism of droplet dynamics under influence of acceleration, diffusion, and body forces when the flow passes through the baffles and duct bent. The results show that, for the configuration of the investigated duct, installing the fogging system upstream of the silencer is about 3 percentage points better in evaporation effectiveness than placing it downstream of the silencer, irrespective of whether the silencer consists of a single row of baffles or two rows of staggered baffles. The evaporation effectiveness of the staggered silencer is about 0.8 percentage points higher than the single silencer. The pressure drop of the staggered silencer is 6.5% higher than the single silencer. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000002 [...]

Three-dimensional modeling for wet compression in a single stage compressor including liquid particle erosion analysis / Jobaidur R. Khan in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 1 (Janvier 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 1 (Janvier 2011) . - 13 p. Titre : Three-dimensional modeling for wet compression in a single stage compressor including liquid particle erosion analysis Type de document : texte imprimé Auteurs : Jobaidur R. Khan, Auteur ; Ting Wang, Auteur Année de publication : 2012 Article en page(s) : 13 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Acceleration  Compressible  flow  Compressors  Computational  fluid  dynamics  Cooling  Drops  Gas  turbines  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Gas turbine inlet fog/overspray cooling is considered as a simple and effective method to increase power output. To help understand the water mist transport in the compressor flow passage, this study conducts a 3D computational simulation of wet compression in a single rotor-stator compressor stage using the commercial code FLUENT. A sliding mesh scheme is used to simulate the stator-rotor interaction in a rotating frame. Eulerian–Lagrangian method is used to calculate the continuous phase and track the discrete (droplet) phase. Models to simulate droplet breakup and coalescence are incorporated to take into consideration the effect of local acceleration and deceleration on water droplet dynamics. Analysis on the droplet history (trajectory and size) with stochastic tracking is employed to interpret the mechanism of droplet dynamics under the influence of local turbulence, acceleration, diffusion, and body forces. A liquid-droplet erosion model is included. The sensitivity of the turbulence models on the results is conducted by employing six different turbulence models and four different time constants. The result shows that the local thermal equilibrium is not always achieved due to short residence time and high value of latent heat of water. Local pressure gradients in both the rotor and stator flow passages drive up the droplet slip velocity during compression. The erosion model predicts that the most eroded area occurs in the leading edge and one spot of the trailing edge of the rotor suction side. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Three-dimensional modeling for wet compression in a single stage compressor including liquid particle erosion analysis [texte imprimé] / Jobaidur R. Khan, Auteur ; Ting Wang, Auteur . - 2012 . - 13 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 1 (Janvier 2011) . - 13 p. Mots-clés : Acceleration  Compressible  flow  Compressors  Computational  fluid  dynamics  Cooling  Drops  Gas  turbines  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Gas turbine inlet fog/overspray cooling is considered as a simple and effective method to increase power output. To help understand the water mist transport in the compressor flow passage, this study conducts a 3D computational simulation of wet compression in a single rotor-stator compressor stage using the commercial code FLUENT. A sliding mesh scheme is used to simulate the stator-rotor interaction in a rotating frame. Eulerian–Lagrangian method is used to calculate the continuous phase and track the discrete (droplet) phase. Models to simulate droplet breakup and coalescence are incorporated to take into consideration the effect of local acceleration and deceleration on water droplet dynamics. Analysis on the droplet history (trajectory and size) with stochastic tracking is employed to interpret the mechanism of droplet dynamics under the influence of local turbulence, acceleration, diffusion, and body forces. A liquid-droplet erosion model is included. The sensitivity of the turbulence models on the results is conducted by employing six different turbulence models and four different time constants. The result shows that the local thermal equilibrium is not always achieved due to short residence time and high value of latent heat of water. Local pressure gradients in both the rotor and stator flow passages drive up the droplet slip velocity during compression. The erosion model predicts that the most eroded area occurs in the leading edge and one spot of the trailing edge of the rotor suction side. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]