Parameters that Affect Shaped Hole Film Ooling Performance and the Effect of Density Ratio on Heat Transfer Coefficient Augmentation PDF Download
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Author: Emily June Boyd Publisher: ISBN: Category : Languages : en Pages : 492
Book Description
Film cooling is used in gas turbine engines to cool turbine components. Cooler air is bled from the compressor, routed internally through turbine vanes and blades, and exits through discrete holes, creating a film of coolant on the parts' surfaces. Cooling the turbine components protects them from thermal damage and allows the engine to operate at higher combustion temperatures, which increases the engine efficiency. Shaped film cooling holes with diffuser exits have the advantage that they decelerate the coolant flow, enabling the coolant jets to remain attached to the surface at higher coolant flow rates. Furthermore, the expanded exits of the coolant holes provide a wider coolant distribution over the surface. The first part of this dissertation provides data for a new laidback, fan-shaped hole geometry designed at Pennsylvania State University's Experimental and Computational Convection Laboratory. The shaped hole geometry was tested on flat plate facilities at the University of Texas at Austin and Pennsylvania State University. The objective of testing at two laboratories was to verify the adiabatic effectiveness performance of the shaped hole, with the intent of the data being a standard of comparison for future experimental and computational shaped hole studies. At first, measurements of adiabatic effectiveness did not match between the labs, and it was later found that shaped holes are extremely sensitive to machining, the material they are machined into, and coolant entrance effects. In addition, the adiabatic effectiveness was found to scale with velocity ratio for multiple density ratios and mainstream turbulence intensities. The second part of this dissertation measures heat transfer coefficient augmentation (hf/h0) at density ratios (DR) of 1.0, 1.2, and 1.5 using a uniform heat flux plate and the same shaped hole geometry. In the past, heat transfer coefficient augmentation was generally measured at DR = 1.0 under the assumption that hf/h0 was independent of density ratio. This dissertation is the first study to directly measure the wall and adiabatic wall temperature to calculate heat transfer coefficient augmentation at DR > 1.0. The results showed that the heat transfer coefficient augmentation was low while the jets were attached to the surface and increased when the jets started to separate. At DR = 1.0, hf/h0 was higher for a given blowing ratio than at DR = 1.2 and DR = 1.5. However, when velocity ratios are matched, better correspondence was found at the different density ratios. Surface contours of hf/h0 showed that the heat transfer was initially increased along the centerline of the jet, but was reduced along the centerline at distances farther downstream. The decrease along the centerline may be due to counter-rotating vortices sweeping warm air next to the heat flux plate toward the center of the jet, where they sweep upward and thicken the thermal boundary layer. This warming of the core of the coolant jet over the heated surface was confirmed with thermal field measurements.
Author: Emily June Boyd Publisher: ISBN: Category : Languages : en Pages : 492
Book Description
Film cooling is used in gas turbine engines to cool turbine components. Cooler air is bled from the compressor, routed internally through turbine vanes and blades, and exits through discrete holes, creating a film of coolant on the parts' surfaces. Cooling the turbine components protects them from thermal damage and allows the engine to operate at higher combustion temperatures, which increases the engine efficiency. Shaped film cooling holes with diffuser exits have the advantage that they decelerate the coolant flow, enabling the coolant jets to remain attached to the surface at higher coolant flow rates. Furthermore, the expanded exits of the coolant holes provide a wider coolant distribution over the surface. The first part of this dissertation provides data for a new laidback, fan-shaped hole geometry designed at Pennsylvania State University's Experimental and Computational Convection Laboratory. The shaped hole geometry was tested on flat plate facilities at the University of Texas at Austin and Pennsylvania State University. The objective of testing at two laboratories was to verify the adiabatic effectiveness performance of the shaped hole, with the intent of the data being a standard of comparison for future experimental and computational shaped hole studies. At first, measurements of adiabatic effectiveness did not match between the labs, and it was later found that shaped holes are extremely sensitive to machining, the material they are machined into, and coolant entrance effects. In addition, the adiabatic effectiveness was found to scale with velocity ratio for multiple density ratios and mainstream turbulence intensities. The second part of this dissertation measures heat transfer coefficient augmentation (hf/h0) at density ratios (DR) of 1.0, 1.2, and 1.5 using a uniform heat flux plate and the same shaped hole geometry. In the past, heat transfer coefficient augmentation was generally measured at DR = 1.0 under the assumption that hf/h0 was independent of density ratio. This dissertation is the first study to directly measure the wall and adiabatic wall temperature to calculate heat transfer coefficient augmentation at DR > 1.0. The results showed that the heat transfer coefficient augmentation was low while the jets were attached to the surface and increased when the jets started to separate. At DR = 1.0, hf/h0 was higher for a given blowing ratio than at DR = 1.2 and DR = 1.5. However, when velocity ratios are matched, better correspondence was found at the different density ratios. Surface contours of hf/h0 showed that the heat transfer was initially increased along the centerline of the jet, but was reduced along the centerline at distances farther downstream. The decrease along the centerline may be due to counter-rotating vortices sweeping warm air next to the heat flux plate toward the center of the jet, where they sweep upward and thicken the thermal boundary layer. This warming of the core of the coolant jet over the heated surface was confirmed with thermal field measurements.
Author: Joshua Brian Anderson Publisher: ISBN: Category : Languages : en Pages : 572
Book Description
Film cooling is widely used in gas turbine engines to manage temperatures within the hot section of the engine. In this work, several investigations are described, all of which studied how fundamental hydrodynamic and thermal parameters influence the performance of film cooling. The first investigation studied the impact of freestream turbulence, boundary layer thickness, Reynolds number, and Mach number on film cooling performance, using axial shaped film cooling holes. The second study considered a similar set of parameters, and investigated their impact on compound-angle oriented film cooling holes. Both of these studies utilized measurements of adiabatic effectiveness and heat transfer coefficient augmentation. In general, the parameters had effects which were dependent on the coolant flow rate and density ratio. The final study considered methods to reduce the experimental uncertainty which arises from conduction and radiation errors in thermal measurements. A careful evaluation of the thermal boundary layer was used to validate these corrections
Author: Shane Haydt Publisher: ISBN: Category : Languages : en Pages :
Book Description
Gas turbines are used around the world to provide thrust for airplanes and to generate electricity. Designers and operators are constantly chasing higher thermal efficiency, and even an incremental increase is considered an achievement. Higher thermal efficiency begets higher turbine inlet temperatures, and the parts that are exposed to these temperatures require sophisticated cooling technologies. One such cooling method is shaped film cooling, which ejects low momentum coolant with the goal of it staying attached to the wall, spreading laterally, and providing a lower driving temperature for convection.In some film cooling manufacturing processes, the meter and diffuser are created in separate steps with separate machines, and an offset can occur in that process. A study was designed to quantify the change in adiabatic effectiveness for five offset directions: fore, fore-left, left, aft-left, and aft. All offset directions caused a detriment to film cooling performance, except for the fore offset, which improved adiabatic effectiveness relative to a no offset case. CFD helped show that the fore offset created a separation in the region of the film cooling metering section where jetting occurs, which decreased the high momentum and made the cooling jet more likely to remain attached to the surface. This study resulted in a patent.A large range of area ratios and blowing ratios were examined in a study designed to isolate the effect of area ratio by lengthening the diffuser of a shaped hole. Very high area ratios were generated that resulted in significant cooling potential. It was shown that at each area ratio there is an optimal blowing ratio beyond which the effectiveness will decrease or plateau. This was reduced to an optimal effective blowing ratio, M/AR, which was shown through CFD to be the condition when the coolant jet core has similar velocity magnitude to the mainstream flow. This results in a weak shear layer and a weak counter-rotating vortex pair.In an axially oriented hole, the mainstream flows over the top of a cooling jet and around the sides, in equal measure, creating a symmetric flowfield. In a compound angled shaped hole, the mainstream flows primarily around the leeward side, creating a strong shear layer and an asymmetric streamwise vortex. Compound angled shaped holes are used commonly in gas turbines, but there has been no work examining the adiabatic effectiveness and heat transfer coefficient augmentation at a range of compound angles, and there are no flowfield measurements. A comprehensive study of the flowfield, cooling effectiveness, and heat transfer coefficient were obtained for compound angled shaped holes for compound angles ranging from 0-60 in 15 increments. It is shown that asymmetry and vorticity magnitude increase with increasing compound angle and increasing blowing ratio. Holes with high compound angles can maintain jet attachment at high blowing ratios because the streamwise component of blowing ratio is reduced, which leads to high effectiveness. The most important contribution of this work was showing that the streamwise vortex increases heat transfer coefficient in a region adjacent to the jet, where very little coolant coverage exists. For this reason, compound angled shaped holes can cause local regions of increased heat flux relative to an uncooled surface, which may be an issue for some designs if not properly accounted for. Heat transfer coefficient augmentation increases as compound angle and blowing ratio increase. Designs that promote jet interaction, such as holes with a smaller pitchwise spacing or holes with significant lateral motion, cover the entire endwall in coolant and lessen the negative effects of high heat transfer coefficient augmentation.
Author: Je-Chin Han Publisher: CRC Press ISBN: 1439855684 Category : Science Languages : en Pages : 892
Book Description
A comprehensive reference for engineers and researchers, Gas Turbine Heat Transfer and Cooling Technology, Second Edition has been completely revised and updated to reflect advances in the field made during the past ten years. The second edition retains the format that made the first edition so popular and adds new information mainly based on selected published papers in the open literature. See What’s New in the Second Edition: State-of-the-art cooling technologies such as advanced turbine blade film cooling and internal cooling Modern experimental methods for gas turbine heat transfer and cooling research Advanced computational models for gas turbine heat transfer and cooling performance predictions Suggestions for future research in this critical technology The book discusses the need for turbine cooling, gas turbine heat-transfer problems, and cooling methodology and covers turbine rotor and stator heat-transfer issues, including endwall and blade tip regions under engine conditions, as well as under simulated engine conditions. It then examines turbine rotor and stator blade film cooling and discusses the unsteady high free-stream turbulence effect on simulated cascade airfoils. From here, the book explores impingement cooling, rib-turbulent cooling, pin-fin cooling, and compound and new cooling techniques. It also highlights the effect of rotation on rotor coolant passage heat transfer. Coverage of experimental methods includes heat-transfer and mass-transfer techniques, liquid crystal thermography, optical techniques, as well as flow and thermal measurement techniques. The book concludes with discussions of governing equations and turbulence models and their applications for predicting turbine blade heat transfer and film cooling, and turbine blade internal cooling.
Author: Bengt Sundén Publisher: Witpress ISBN: Category : Medical Languages : en Pages : 544
Book Description
This title presents and reflects current active research on various heat transfer topics and related phenomena in gas turbine systems. It begins with a general introduction to gas turbine heat transfer, before moving on to specific areas.
Author: Ellen Katherine Wilkes Publisher: ISBN: Category : Languages : en Pages : 168
Book Description
There is limited information in the literature on the behavior of shaped film cooling holes fed by crossflow and even less information on the effect of crossflow parameters on film cooling performance. Here, two scaled film cooling models were used to independently vary the crossflow Reynolds numbers in the range of 36,000 to 57,000 and the crossflow velocity ratio from 0.36 to 0.64. Careful attention was paid to controlling physical parameters between comparisons to isolate the effects of internal velocity ratio or Reynolds number on the performance of shaped holes. In the process of controlling the physical parameters of the system, a novel correction for coolant to mainstream density ratio was proposed. The results of this study showed that channel velocity ratio had a larger effect on the film cooling performance of shaped holes than channel Reynolds number. When the mass flux of fluid through the film cooling holes was at the highest and lowest value, increasing the channel velocity ratio decreased the film cooling effectiveness. At a middle mass flux, the outcome was opposite such that an increase in channel velocity ratio resulted in increased effectiveness.
Author: Publisher: ISBN: Category : Languages : en Pages : 25
Book Description
Physics of film cooling for shaped, inclined slot-jets with realistic slot-length-to-width ratios is studied for a range of blowing ratio and density ratio parameters typical of gas turbine operations. Effect of inlet and exit shaping of the slot-jet on both flow and thermal field is isolated, and the dominant mechanisms responsible for differences in these items are documented. A computation method was used to study 4 configurations. Field results and surface phenomena are presented. Both adiabatic film effectiveness and heat transfer coefficient are vital in assessing film cooling performance. Performance of two popular turbulence models were studied to evaluate ability to handle highly elliptic jet/crossflow interaction type processes. The simulations were consistent.
Author: Heike Jagode Publisher: Springer Nature ISBN: 303090539X Category : Computers Languages : en Pages : 515
Book Description
This book constitutes the refereed post-conference proceedings of 9 workshops held at the 35th International ISC High Performance 2021 Conference, in Frankfurt, Germany, in June-July 2021: Second International Workshop on the Application of Machine Learning Techniques to Computational Fluid Dynamics and Solid Mechanics Simulations and Analysis; HPC-IODC: HPC I/O in the Data Center Workshop; Compiler-assisted Correctness Checking and Performance Optimization for HPC; Machine Learning on HPC Systems;4th International Workshop on Interoperability of Supercomputing and Cloud Technologies;2nd International Workshop on Monitoring and Operational Data Analytics;16th Workshop on Virtualization in High-Performance Cloud Computing; Deep Learning on Supercomputers; 5th International Workshop on In Situ Visualization. The 35 papers included in this volume were carefully reviewed and selected. They cover all aspects of research, development, and application of large-scale, high performance experimental and commercial systems. Topics include high-performance computing (HPC), computer architecture and hardware, programming models, system software, performance analysis and modeling, compiler analysis and optimization techniques, software sustainability, scientific applications, deep learning.
Author: Emily June Boyd
Author: Emily June Boyd
Author: Joshua Brian Anderson
Author: Shane Haydt
Author: Je-Chin Han
Author: 
Author: Bengt Sundén
Author: Lei Luo
Author: Ellen Katherine Wilkes
Author: 
Author: Heike Jagode