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AN EXPERIMENTAL AND NUMERICAL STUDY OF SECONDARY FLOWS AND FILM COOLING EFFECTIVENESS IN A TRANSONIC CASCADE
Title
AN EXPERIMENTAL AND NUMERICAL STUDY OF SECONDARY FLOWS AND FILM COOLING EFFECTIVENESS IN A TRANSONIC CASCADE.
Creator
Kullberg, James, Kapat, Jayanta, University of Central Florida
Abstract / Description
In the modern world, gas turbines are widely used in aircraft propulsion and electricity generation. These applications represent a massive use of energy worldwide, so even a very small increase in efficiency would have a significant beneficial economic and environmental impact. There are many ways to optimize the operation of a gas turbine, but a fundamental approach is to increase the turbine inlet temperature to increase the basic thermodynamic efficiency of the turbine. However, these...
Show moreIn the modern world, gas turbines are widely used in aircraft propulsion and electricity generation. These applications represent a massive use of energy worldwide, so even a very small increase in efficiency would have a significant beneficial economic and environmental impact. There are many ways to optimize the operation of a gas turbine, but a fundamental approach is to increase the turbine inlet temperature to increase the basic thermodynamic efficiency of the turbine. However, these temperatures are already well above the melting temperature of the components. A primary cooling methodology, called film cooling, creates a blanket of cool air over the surface and is an effective way to help protect these components from the hot mainstream gasses. This paper focuses on the effect of the film holes upstream of the first row of blades in the turbine because this is the section that experiences the highest thermal stresses. Many factors can determine the effectiveness of the film cooling, so a complete understanding can lead to effective results with the minimum flow rate of coolant air. Many studies have been published on the subject of film cooling, but because of the difficulty and expense of simulating turbine realistic conditions, many authors introduce vast simplifications such as low speed conditions or linear cascades. These simplifications do not adequately represent the behavior of a turbine and therefore their results are of limited use. This study attempts to eliminate many of those simplifications. The test rig used in this research is based on the NASA-GE E3 design, which stands for Energy Efficient Engine. It was introduced into the public domain to provide an advanced platform from which open-literature research could be performed. Experimental tests on a transonic annular rig are time-consuming and expensive, so it is desirable to use experimental results to validate a computational model which can then be used to extract much more information. The purpose of this work is to create a numerical model that can be used to simulate many different scenarios and then to apply these results to experimental data.
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Date Issued
2011
Identifier
CFH0003772, ucf:44728
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH0003772
INTERACTION BETWEEN SECONDARY FLOW AND FILM COOLING JETS OF A REALISTIC ANNULAR AIRFOIL CASCADE (HIGH MACH NUMBER)
Title
INTERACTION BETWEEN SECONDARY FLOW AND FILM COOLING JETS OF A REALISTIC ANNULAR AIRFOIL CASCADE (HIGH MACH NUMBER).
Creator
Nguyen, Cuong, Kapat, Jayanta, University of Central Florida
Abstract / Description
Film cooling is investigated on a flat plate both numerically and experimentally. Conical shaped film hole are investigated extensively and contribute to the current literature data, which is extremely rare in the open public domain. Both configuration of the cylindrical film holes, with and without a trench, are investigated in detail. Design of experiment technique was performed to find an optimum combination of both geometrical and fluid parameters to achieve the best film cooling...
Show moreFilm cooling is investigated on a flat plate both numerically and experimentally. Conical shaped film hole are investigated extensively and contribute to the current literature data, which is extremely rare in the open public domain. Both configuration of the cylindrical film holes, with and without a trench, are investigated in detail. Design of experiment technique was performed to find an optimum combination of both geometrical and fluid parameters to achieve the best film cooling performance. From this part of the study, it shows that film cooling performance can be enhanced up to 250% with the trenched film cooling versus non-trenched case provided the same amount of coolant. Since most of the relevant open literature is about film cooling on flat plate endwall cascade with linear extrusion airfoil, the purpose of the second part of this study is to examine the interaction of the secondary flow inside a 3D cascade and the injected film cooling jets. This is employed on the first stage of the aircraft gas turbine engine to protect the curvilinear (annular) endwall platform. The current study investigates the interaction between injected film jets and the secondary flow both experimentally and numerically at high Mach number (M=0.7). Validation shows good agreement between obtained data with the open literature. In general, it can be concluded that with an appropriate film coolant to mainstream blowing ratio, one can not only achieve the best film cooling effectiveness (FCE or η) on the downstream endwall but also maintain almost the same aerodynamic loss as in the un-cooled baseline case. Film performance acts nonlinearly with respect to blowing ratios as with film cooling on flat plate, in the other hand, with a right blowing ratio, film cooling performance is not affect much by secondary flow. In turn, film cooling jets do not increase pressure loss at the downstream wake area of the blades.
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Date Issued
2010
Identifier
CFE0003546, ucf:48944
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003546