The Experts below are selected from a list of 1614 Experts worldwide ranked by ideXlab platform
Hee Koo Moon - One of the best experts on this subject based on the ideXlab platform.
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heat transfer measurement near endwall region of first stage gas turbine Nozzle having platform misalignment at combustor turbine interface
International Communications in Heat and Mass Transfer, 2016Co-Authors: Heeyoon Chung, Chang Woo Hong, Seon Ho Kim, Hyung Hee Cho, Hee Koo MoonAbstract:Abstract The effect of a misalignment between Vane endwall and combustor exit in a gas turbine was investigated using a Computational Fluid Dynamics (CFD) simulation and experimental measurements. The misaligned endwall platform was simulated as a backward facing step in this study. The CFD simulation predicted two legs of the vortex, referred to as a step-induced vortex, created by the step flowing through Nozzle passage. Heat transfer measurements demonstrated the effect of the step-induced vortex on the endwall and the Vane surface indicated by locally increased heat transfer coefficients which corresponded to the locus of the vortex, as also predicted by the simulation. Although a boundary layer transition occurred early, the locally increased heat transfer persisted to the Vane trailing edge. In summary, a misaligned endwall platform causes negative effects on the gas turbine with respect to the thermal design. A vortex was generated by the step, which caused a higher thermal load on the Nozzle Vane surfaces, especially near the endwall.
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the effects of Vane showerhead injection angle and film compound angle on Nozzle endwall cooling phantom cooling
Journal of Turbomachinery-transactions of The Asme, 2014Co-Authors: Luzeng Zhang, Juan Yin, Hee Koo MoonAbstract:The effects of airfoil showerhead injection angle and film cooling hole compound angle on Nozzle endwall cooling (second order film cooling effects, also called “phantom cooling”) was experimentally investigated in a scaled linear cascade. The test cascade was built based on a typical industrial gas turbine Nozzle Vane. Endwall surface phantom cooling film effectiveness measurements were made using a computerized pressure sensitive paint (PSP) technique. Nitrogen gas was used to simulate cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness can be obtained by the mass transfer analogy. Two separate Nozzle test models were fabricated, which have the same number and size of film cooling holes but different configurations. One had a showerhead angle of 45° and no compound angles on the pressure and suction side film holes. The other had a 30° showerhead angle and 30° compound angles on the pressure and suction side film cooling holes. Nitrogen gas (cooling air) was fed through Nozzle Vanes, and measurements were conducted on the endwall surface between the two airfoils where no direct film cooling was applied. Six cooling mass flow ratios (MFRs, blowing ratios) were studied, and local (phantom) film effectiveness distributions were measured. Film effectiveness distributions were pitchwise averaged for comparison. Phantom cooling on the endwall by the suction side film injections was found to be insignificant, but the pressure side airfoil film injections noticeably helped the endwall cooling (phantom cooling) and was a strong function of the MFR. It was concluded that reducing the showerhead angle and introducing a compound angle on the pressure side injections would enhance the endwall surface phantom cooling, particularly for a higher MFR.Copyright © 2014 by Solar Turbines Incorporated
Alberto Lunaramirez - One of the best experts on this subject based on the ideXlab platform.
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analysis of conjugate heat transfer of a gas turbine first stage Nozzle
Applied Thermal Engineering, 2006Co-Authors: Zdzislaw Mazur, Alejandro Hernandezrossette, Rafael Garciaillescas, Alberto LunaramirezAbstract:Abstract Steady-state analysis of heat transfer in a base-load power generation gas turbine was conducted by thermal conjugation inside and outside of the first stage Nozzle, which consists of thermal convection and conduction by coupling of fluid flow and solid body. A computer CFD code, Star CD V 3.150A, was used to solve the problem. The principal issues of the work were concerned with the three-dimensional behavior of the temperature distribution of the Nozzle Vane, which is influenced by the inlet gas flow conditions, internal cooling conditions and film cooling conditions. The numerical results of the effects of cooling flow rate and temperature on heat transfer rates in the Nozzle are also presented. The paper focuses on the estimation of the temperature distribution on the Nozzle Vane by prediction of the thermal environment around the Nozzle Vane and heat conduction in the Nozzle which is necessary to carry out the Nozzle thermal load analysis and finally life assessment. Also, the evaluation of service induced degradation of cobalt base alloy FSX-414 of the Nozzle, after 24,000 h of operation at high temperature is presented. The assessment includes the precipitation of the Nozzle carbides and grain type and size characterization. The predictions were used to estimate stress and creep strain, which are demanded to evaluate the damage of the Nozzle during steady-state operation conditions.
Barigozzi Giovanna - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of the aerodynamic and thermal behaviour of the film at the leading edge of a cooled Nozzle Vane cascade
EuroTurbo (European Turbomachinery Society), 2019Co-Authors: Casarsa Luca, Pagnacco Fabio, Abdeh Hamed, Barigozzi GiovannaAbstract:This paper presents the results of an experimental investigation of the aerodynamic behavior of coolant ejection at the leading edge of a Nozzle Vane cascade. Highly spatially resolved Particle Image Velocimetry (PIV) data were acquired on mid span blade-to-blade planes and along the span wise direction to capture the 3D mixing process. Complementary Pressure Sensitive Paints (PSP) data are used to support the aerodynamic analysis. Tests were performed at a fixed cascade operating condition (Ma2is = 0.2 and Tu1 = 1.6%) varying the coolant to main stream blowing ratio (BR) from 2.0 up to 4.0. Flow filed data clearly show a shift in stagnation and a strong jet to jet as well as jet to mainstream interaction for all tested BR, supporting the unsteady and highly anisotropic nature of the phenomenon
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Experimental investigation of the interaction between showerhead coolant jets and main flow
'Elsevier BV', 2019Co-Authors: Barigozzi Giovanna, Casarsa Luca, Pagnacco Fabio, Rouina SamanehAbstract:This paper presents the results of an experimental investigation into the thermal and aerodynamic behavior of coolant ejection at the leading edge of a highly loaded Nozzle Vane cascade. The leading-edge cooling scheme features four rows of cylindrical holes in a staggered configuration (showerhead). Pressure Sensitive Paints (PSP) technique was used to get the adiabatic film cooling effectiveness distribution, while Particle Image Velocimetry (PIV) and flow visualizations were used to investigate the mixing process taking place between coolant and main flow. PSP tests were conducted by using N2 (Density Ratio DR=1.0) as coolant at variable blowing ratio (BR=2.0 – 4.0). Further tests were run by using CO2 (DR=1.5) at matching BR and momentum flux ratio (I) in order to investigate the effects of density ratio. The BR = 3.0 injection case was selected for the PIV investigation. Thermal and flow field data consistently show a shift in the position of stagnation line towards the suction side. Jet liftoff close to stagnation and a strong jet to jet as well as jet to mainstream interaction were also observed, resulting in a complex 3D flow characterized by high turbulence levels with a high degree of anisotropy. No coherent structures were detected, supporting the random nature of mixing process
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Experimental investigation of the interaction between showerhead coolant jets and main flow
2019Co-Authors: Barigozzi Giovanna, Casarsa Luca, Pagnacco Fabio, Rouina SamanehAbstract:This paper presents the results of an experimental investigation into the thermal and aerodynamic behavior of coolant ejection at the leading edge of a highly loaded Nozzle Vane cascade. The leading-edge cooling scheme features four rows of cylindrical holes in a staggered configuration (showerhead). Pressure Sensitive Paints (PSP) technique was used to get the adiabatic film cooling effectiveness distribution, while Particle Image Velocimetry (PIV) and flow visualizations were used to investigate the mixing process taking place between coolant and main flow. Tests were run at low speed (Ma 2is = 0.2) and low inlet turbulence intensity (Tu 1 = 1.6%). PSP tests were conducted by using N 2 (Density Ratio DR = 1.0) as coolant at variable blowing ratio (BR = 2.0–4.0). Further tests were run by using CO 2 (DR = 1.5) at matching BR and momentum flux ratio (I) in order to investigate the effects of density ratio. The BR = 3.0 injection case was selected for the PIV investigation. Thermal and flow field data consistently show a shift in the position of stagnation line towards the suction side. Jet liftoff close to stagnation and a strong jet to jet as well as jet to mainstream interaction were also observed, resulting in a complex 3D flow characterized by high turbulence levels, with velocity fluctuations as high as 30% of the approaching velocity and with a high degree of anisotropy. No coherent structures were detected, supporting the random nature of mixing process
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Assessment of binary PSP technique for film cooling effectiveness measurement on Nozzle Vane cascade with cutback trailing edge
2018Co-Authors: Barigozzi Giovanna, Abdeh Hamed, Mucignat Claudio, Scandella Davide, Dolci GiorgioAbstract:The present paper shows the results of an experimental investigation aiming to assess advantages and disadvantages of binary Pressure Sensitive Paints (PSP) technique for the measurement of film cooling effectiveness distribution. For this purpose, two test cases pertaining to gas turbine high pressure Nozzle Vane cooling systems have been used: a classical flat plate model with coolant injection through a single large scale shaped hole and a high loaded Nozzle Vane cascade with a pressure side cooling system that features two rows of cylindrical holes followed by a pressure side cutback with film cooling slots. Both models have been extensively tested: in particular, film cooling effectiveness data measured by means of well established thermal measurement techniques (Infrared thermocamera for the flat plate and wide banded Thermocromic Liquid Crystals for the Vane cascade) are available from the literature. Pressure Sensitive Paints technique was able to provide high quality data all over the investigated test cases and operating conditions. Moreover, the binary version allows to fully eliminate any spurious temperature influence, thus making this technique well suited for the analysis of complex flows and geometries
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Aero-Thermal Performance of a Nozzle Vane Cascade with a Generic Non Uniform Inlet Flow Condition - Part I: Influence of Non Uniformity Location
2016Co-Authors: Perdichizzi, Antonio Giovanni, Barigozzi Giovanna, Abdeh H., Henze M., Krueckels J.Abstract:In this paper, the modifications induced by the presence of an inlet flow non uniformity on the aerodynamic performance of a Nozzle Vane cascade are experimentally assessed. Tests were carried out in a six Vane linear cascade whose profile is typical of a first stage Nozzle guide Vane of a modern heavy duty GT. An obstruction was located in the wind tunnel inlet section to produce a non uniform flow upstream of the leading edge plane. The cascade was tested in an atmospheric wind tunnel at an inlet Mach number Ma1 = 0.12, with a high turbulence intensity (Tu1 = 9%) and variable obstruction tangential and axial positions, as well as tangential extension. The presented results show that an inlet flow non uniformity influences the stagnation point position when it faces the Vane leading edge from the suction side. A relevant increase of both 2D and secondary losses are observed when the non uniformity is aligned to the Vane leading edge. When it is instead located in between the passage it does not affect the stagnation point location, in the meanwhile allowing a reduction in the secondary loss
Zdzislaw Mazur - One of the best experts on this subject based on the ideXlab platform.
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analysis of conjugate heat transfer of a gas turbine first stage Nozzle
Applied Thermal Engineering, 2006Co-Authors: Zdzislaw Mazur, Alejandro Hernandezrossette, Rafael Garciaillescas, Alberto LunaramirezAbstract:Abstract Steady-state analysis of heat transfer in a base-load power generation gas turbine was conducted by thermal conjugation inside and outside of the first stage Nozzle, which consists of thermal convection and conduction by coupling of fluid flow and solid body. A computer CFD code, Star CD V 3.150A, was used to solve the problem. The principal issues of the work were concerned with the three-dimensional behavior of the temperature distribution of the Nozzle Vane, which is influenced by the inlet gas flow conditions, internal cooling conditions and film cooling conditions. The numerical results of the effects of cooling flow rate and temperature on heat transfer rates in the Nozzle are also presented. The paper focuses on the estimation of the temperature distribution on the Nozzle Vane by prediction of the thermal environment around the Nozzle Vane and heat conduction in the Nozzle which is necessary to carry out the Nozzle thermal load analysis and finally life assessment. Also, the evaluation of service induced degradation of cobalt base alloy FSX-414 of the Nozzle, after 24,000 h of operation at high temperature is presented. The assessment includes the precipitation of the Nozzle carbides and grain type and size characterization. The predictions were used to estimate stress and creep strain, which are demanded to evaluate the damage of the Nozzle during steady-state operation conditions.
Heeyoon Chung - One of the best experts on this subject based on the ideXlab platform.
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heat transfer measurement near endwall region of first stage gas turbine Nozzle having platform misalignment at combustor turbine interface
International Communications in Heat and Mass Transfer, 2016Co-Authors: Heeyoon Chung, Chang Woo Hong, Seon Ho Kim, Hyung Hee Cho, Hee Koo MoonAbstract:Abstract The effect of a misalignment between Vane endwall and combustor exit in a gas turbine was investigated using a Computational Fluid Dynamics (CFD) simulation and experimental measurements. The misaligned endwall platform was simulated as a backward facing step in this study. The CFD simulation predicted two legs of the vortex, referred to as a step-induced vortex, created by the step flowing through Nozzle passage. Heat transfer measurements demonstrated the effect of the step-induced vortex on the endwall and the Vane surface indicated by locally increased heat transfer coefficients which corresponded to the locus of the vortex, as also predicted by the simulation. Although a boundary layer transition occurred early, the locally increased heat transfer persisted to the Vane trailing edge. In summary, a misaligned endwall platform causes negative effects on the gas turbine with respect to the thermal design. A vortex was generated by the step, which caused a higher thermal load on the Nozzle Vane surfaces, especially near the endwall.
