A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control
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A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control
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Author : Olga Valeryevna Kartuzova
language : en
Publisher:
Release Date : 2012
A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control written by Olga Valeryevna Kartuzova and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control
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Author : Olga Valeryevna Kartuzova
language : en
Publisher:
Release Date : 2012
A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control written by Olga Valeryevna Kartuzova and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Effects Of Pulsing On Film Cooling Of Gas Turbine Airfoils
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Author : Sarah Marie Coulthard
language : en
Publisher:
Release Date : 2005
Effects Of Pulsing On Film Cooling Of Gas Turbine Airfoils written by Sarah Marie Coulthard and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Gas-turbines categories.
The objective of this project was to determine the effects of pulsed film cooling on turbine blades. High combustor temperatures, resulting in elevated turbine inlet temperatures, produce high engine efficiency. At current operating temperatures, the turbine inlet temperature is above the melting point of the turbine blades. Thus cooling the blades in the first stages after the combustor is essential. Current methods for film cooling utilize a continuous stream of bleed air from the compressor. This air is routed into a cavity inside each blade and bled out of holes onto the blade surface, creating a film of cool air. Pulsed film cooling may reduce the amount of bleed air used, thus increasing the efficiency of the engine by allowing more air to flow through the combustor, while providing equivalent protection for the blades. In this study, a section of a turbine blade was modeled using a plate with a row of five film cooling holes. Coolant air was pulsed via solenoid valves from a plenum, while a wind tunnel provided a mainstream flow. Temperature and velocity fields were measured over the blade surface with varying blowing rates of the coolant and frequencies of pulsing. The film cooling effectiveness, a measure of how well the coolant protects the blade surface, was calculated based on the measured temperatures. The results were compared to baseline cases with continuous blowing and no blowing. The overall best case was continuous film cooling with the jet velocity one fourth of the mainstream velocity. However, results showed that pulsed film cooling has the potential to provide an equivalent or greater film cooling effectiveness for higher jet velocities. The case of pulsed jets with a jet velocity equal to the mainstream velocity, pulsing frequency of 20 Hertz, and 75% duty cycle showed an increased film cooling effectiveness and decreased heat transfer compared to the continuous blowing case. This study suggests that pulsed film cooling has the potential to adequately protect gas turbine blades with additional research, ultimately allowing for an increased efficiency in a gas turbine engine.
Experimental And Computational Studies Of Film Cooling With Compound Angle Injection
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Author :
language : en
Publisher:
Release Date : 1995
Experimental And Computational Studies Of Film Cooling With Compound Angle Injection written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.
The thermal efficiency of gas turbine systems depends largely on the turbine inlet temperature. Recent decades have seen a steady rise in the inlet temperature and a resulting reduction in fuel consumption. At the same time, it has been necessary to employ intensive cooling of the hot components. Among various cooling methods, film cooling has become a standard method for cooling of the turbine airfoils and combustion chamber walls. The University of Minnesota program is a combined experimental and computational study of various film-cooling configurations. Whereas a large number of parameters influence film cooling processes, this research focuses on compound angle injection through a single row and through two rows of holes. Later work will investigate the values of contoured hole designs. An appreciation of the advantages of compound angle injection has risen recently with the demand for more effective cooling and with improved understanding of the flow; this project should continue to further this understanding. Approaches being applied include: (1) a new measurement system that extends the mass/heat transfer analogy to obtain both local film cooling and local mass (heat) transfer results in a single system, (2) direct measurement of three-dimensional turbulent transport in a highly-disturbed flow, (3) the use of compound angle and shaped holes to optimize film cooling performance, and (4) an exploration of anisotropy corrections to turbulence modeling of film cooling jets.
Fluid Mechanics And Heat Transfer Research Related To High Temperature Gas Turbines
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Author :
language : en
Publisher:
Release Date : 1995
Fluid Mechanics And Heat Transfer Research Related To High Temperature Gas Turbines written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.
The objective of the research was to enhance the understanding of airfoil passage transport processes and film cooling by conducting a coordinated experimental and computational study of flow behavior and airfoil and end-wall surface heat transfer as influenced by turbulence and more coherent structures in the passage flow, streamline curvature, and other effects. Computation is used to evaluate and develop film cooling schemes, as well as to extend by analysis the experience base beyond the experimental cases investigated. The outcome of the research will be improved physical understanding and computational models of these processes, both of which are of direct utility to the engine designers in the aircraft industry. The research project finds a number of innovative features. They include: (a) detailed local heat (mass) transfer measurements on turbine blade surfaces, (b) investigation of the mass transfer and turbulent characteristics in curved channel flows, (c) determination of local film cooling effectiveness in endwall film cooling and total-coverage discrete hole wall cooling, (d) evaluation of a fence for endwall flow control, and (e) accurate numerical modeling in film cooling.
Film Cooling In A Pulsating Wall Jet
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Author :
language : en
Publisher:
Release Date : 2000
Film Cooling In A Pulsating Wall Jet written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.
Turbulent wall jets have many important engineering applications. Much effort has been spent to investigate the plane turbulent wall jet without external stream (Launder and Rodi 1981,1983, Katz et al 1992, Wygnanski et al 1992) and with a relatively slow external stream (Zhou and Wygnanski 1993, Zhou et al 1996). However, many engineering applications seem to be described better by a wall jet embedded in a uniform stream of comparable velocity (the weak wall jet), for example, the cooling turbine blades and the flows over a wing equipped with a slotted flap (Fig. 1) represents such flows. The recently developed technique for separation control by periodic blowing/suction on the flap also belongs to category (Fig. 2). Thus, it is important to provide a better understanding of the development of these flows. For example: the possibility of flow similarity, normalization of the mean velocity fields, scaling laws for the governing parameters, as well as the various responses to external excitations. This report represents but a single facet of the general effort endeavoring to use the wall jet for boundary layer control, film cooling and the exertion of force on a body through the use of what is commonly known as the Coanda Effect.
Parametric Study Of Turbine Blade Internal Cooling And Film Cooling
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Author : Akhilesh P. Rallabandi
language : en
Publisher:
Release Date : 2010
Parametric Study Of Turbine Blade Internal Cooling And Film Cooling written by Akhilesh P. Rallabandi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
Gas turbine engines are extensively used in the aviation and power generation industries. They are used as topping cycles in combined cycle power plants, or as stand alone power generation units. Gains in thermodynamic efficiency can be realized by increasing the turbine inlet temperatures. Since modern turbine inlet temperatures exceed the melting point of the constituent superalloys, it is necessary to provide an aggressive cooling system. Relatively cool air, ducted from the compressor of the engine is used to remove heat from the hot turbine blade. This air flows through passages in the hollow blade (internal cooling), and is also ejected onto the surface of the blade to form an insulating film (film cooling). Modern land-based gas turbine engines use high Reynolds number internal flow to cool their internal passages. The first part of this study focuses on experiments pertaining to passages with Reynolds numbers of up to 400,000. Common turbulator designs (45degree parallel sharp-edged and round-edged) ribs are studied. Older correlations are found to require corrections in order to be valid in the high Reynolds number parameter space. The effect of rotation on heat transfer in a typical three-pass serpentine channel is studied using a computational model with near-wall refinement. Results from this computational study indicate that the hub experiences abnormally high heat transfer under rotation. An experimental study is conducted at Buoyancy numbers similar to an actual engine on a wedge shaped model trailing edge, roughened with pin-fins and equipped with slot ejection. Results show an asymmetery between the leading and trailing surfaces due to rotation - a difference which is subdued due to the provision of pin-fins. Film cooling effectiveness is measured by the PSP mass transfer analogy technique in two different configurations: a flat plate and a typical high pressure turbine blade. Parameters studied include a step immediately upstream of a row of holes; the Strouhal number (quantifying rotor-stator interaction) and coolant to mainstream density ratio. Results show a deterioration in film cooling effectiveness with on increasing the Strouhal number. Using a coolant with a higher density results in higher film cooling effectiveness.
Conjugate Heat Transfer Effects On Gas Turbine Film Cooling
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Author : William Robb Stewart
language : en
Publisher:
Release Date : 2014
Conjugate Heat Transfer Effects On Gas Turbine Film Cooling written by William Robb Stewart and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
The efficiency of natural gas turbines is directly linked to the turbine inlet temperature, or the combustor exit temperature. Further increasing the turbine inlet temperature damages the turbine components and limits their durability. Advances in turbine vane cooling schemes protect the turbine components. This thesis studies the conjugate effects of internal cooling, film cooling and thermal barrier coatings (TBC) on turbine vane metal temperatures. Two-dimensional thermal profiles were experimentally measured downstream of a single row of film cooling holes on both an adiabatic and a matched Biot number model turbine vane. The measurements were taken as a comparison to computational simulations of the same model and flow conditions. To improve computational models of the evolution of a film cooling jet as it propagates downstream, the thermal field above the vane, not just the footprint on the vane surface must be analyzed. This study expands these data to include 2-D thermal fields above the vane at 0, 5 and 10 hole diameters downstream of the film cooling holes. In each case the computational jets remained colder than the experimental jets because they did not disperse into the mainstream as quickly. Finally, in comparing results above adiabatic and matched Biot number models, these thermal field measurements allow for an accurate analysis of whether or not the adiabatic wall temperature was a reasonable estimate of the driving temperature for heat transfer. In some cases the adiabatic wall temperature did give a good indication of the driving temperature for heat transfer while in other cases it did not. Previous tests simulating the effects of TBC on an internally and film cooled model turbine vane showed that the insulating effects of TBC dominate over variations in film cooling geometry and blowing ratio. In this study overall and external effectiveness were measured using a matched Biot number model vane simulating a TBC of thickness 0.6d, where d is the film cooing hole diameter. This new model was a 35% reduction in thermal resistance from previous tests. Overall effectiveness measurements were taken for an internal cooling only configuration, as well as for three rows of showerhead holes with a single row of holes on the pressure side of the vane. This pressure side row of holes was tested both as round holes and as round holes embedded in a realistic trench with a depth of 0.6 hole diameters. Even in the case of this thinner TBC, the insulating effects dominate over film cooling. In addition, using measurements of the convective heat transfer coefficient above the vane surface, and the thermal conductivities of the vane wall and simulated TBC material, a prediction technique of the overall effectiveness with TBC was evaluated.
Analysis And Comparison Of Wall Cooling Schemes For Advanced Gas Turbine Applications
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Author : Raymond Strong Colladay
language : en
Publisher:
Release Date : 1972
Analysis And Comparison Of Wall Cooling Schemes For Advanced Gas Turbine Applications written by Raymond Strong Colladay and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1972 with Cooling categories.
The relative performance of (1) counterflow film cooling, (2) parallel-flow film cooling, (3) convection cooling, (4) adiabatic film cooling, (5) transpiration cooling, and (6) full-coverage film cooling was investigated for heat loading conditions expected in future gas turbine engines. Assumed in the analysis were hot-gas conditions of 2200 K (3500 F) recovery temperature, 5 to 40 atmospheres total pressure, and 0.6 gas Mach number and a cooling air supply temperature of 811 K (1000 F). The first three cooling methods involve film cooling from slots. Counterflow and parallel flow describe the direction of convection cooling air along the inside surface of the wall relative to the main gas flow direction. The importance of utilizing the heat sink available in the coolant for convection cooling prior to film injection is illustrated.
Effects Of Film Cooling On Turbine Blade Tip Flow Structures And Thermal Loading
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Author : Louis Edward Christensen
language : en
Publisher:
Release Date : 2022
Effects Of Film Cooling On Turbine Blade Tip Flow Structures And Thermal Loading written by Louis Edward Christensen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with Aerospace engineering categories.
Gas turbine engines are an essential technology in aviation and power generation. One of the challenges associated with increasing the efficiency of gas turbines is the thermal loading experienced by the engine components downstream of the combustors especially the high-pressure turbine blades. High temperatures and rotational velocities can cause blade failures in numerous ways such as creep or stress rupture. Technologies like film cooling are implemented in these components to lower the thermal loading and reduce the risk of failure. However, these introduce complexities into the flow which in turn increases the difficulty of predicting the performance of film cooled turbines. Accurately predicting the capabilities of these components is essential to prevent failure in gas turbine engines. Engineers use a combination of experiments and computational simulations to understand how these technologies perform and predict the operating conditions and lifespan of these components. A combined experimental and numerical program is performed on a single stage high-pressure turbine to increase understanding of film cooling in gas turbines and improve computational methods used to predict their performance. The turbine studied is a contemporary production model from Honeywell Aerospace with both cooled and uncooled turbine blades. The experimental work is performed at The Ohio State University Gas Turbine Laboratory Turbine Test Facility, a short duration facility operating at engine corrected conditions. The experiments capture heat flux, temperature, and pressure data across the entire blade, but this work will focus on the turbine blade tip data. Tip temperature data are captured using a high-speed infrared camera providing a unique data set unseen in the current literature. In addition to the experiments, transient conjugate heat transfer simulations of a single turbine passage are performed to recreate the experiments and give insight into the flow field in the tip region of the turbine blades. The experiments and simulations are conducted to provide a better understanding of the interactions of the film cooling and tip flows along with their relationship to the thermal loading on the turbine blade tip. Film cooling in the tip region adds complexity to the flow and a non-intuitive relationship exists between film cooling and thermal loading. Addition of cooling is not guaranteed to reduce the thermal loading on the blade tips. Cooling jets can displace hot gases protecting the blade, but they are also capable of shifting flow structures and trapping hot gases near the blade surface especially so in corners of the blade tips. These direct and indirect methods of altering the thermal loading open a new path to optimization where engineers consider how the coolant alters the flow in addition to forming a protective layer of cool gas. This can be done to more effectively use coolant not only in the blade tips but elsewhere on the turbine blades leading to higher engine efficiencies and more sustainable gas turbine engines.