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Author: James R. Winka Publisher: ISBN: Category : Languages : en Pages : 246
Book Description
A series of experiments were carried out to measure the effects of convex surface curvature on film cooling. In the first series of experiments cooling holes were positioned along the vane such that their non-dimensional curvature parameter, 2r/d, was matched. Single row of holes with the same diameter were placed at high and moderate curvature position along a turbine vane resulting in 2r/d = 28 and 40, accordingly. A third row of holes was installed on the vane at the same location as the moderate curvature row with a larger hole diameter, resulting in 2r/d = 28, matching the high curvature row. Adiabatic temperature measurements were then carried out for blowing ratios of M = 0.30 to 1.60 tested at a density ratio of DR = 1.20. The results indicated that there was some scaling of performance present with matching 2r/d, but there was not an exact matching of performance. The second series of experiments focused on the effects of a changing surface curvature downstream of injection. Two row of holes were positioned along the vane surface such that the local radius of curvature and hole diameters were equivalent, with one row positioned upstream of the maximum curvature point and the other downstream of the maximum curvature point. Adiabatic temperature measurements were carried out for blowing ratios of M = 0.30 to 1.60 and tested at a density ratio of DR = 1.20. The results show that the change in curvature downstream plays a significant role in the performance of film cooling and that the local surface curvature is insufficient in capturing its effects. Additional experiments were carried out to measure the effects of the approaching boundary layer influence on film cooling as well as the effect of injection angle at a weakly convex surface.
Author: James R. Winka Publisher: ISBN: Category : Languages : en Pages : 246
Book Description
A series of experiments were carried out to measure the effects of convex surface curvature on film cooling. In the first series of experiments cooling holes were positioned along the vane such that their non-dimensional curvature parameter, 2r/d, was matched. Single row of holes with the same diameter were placed at high and moderate curvature position along a turbine vane resulting in 2r/d = 28 and 40, accordingly. A third row of holes was installed on the vane at the same location as the moderate curvature row with a larger hole diameter, resulting in 2r/d = 28, matching the high curvature row. Adiabatic temperature measurements were then carried out for blowing ratios of M = 0.30 to 1.60 tested at a density ratio of DR = 1.20. The results indicated that there was some scaling of performance present with matching 2r/d, but there was not an exact matching of performance. The second series of experiments focused on the effects of a changing surface curvature downstream of injection. Two row of holes were positioned along the vane surface such that the local radius of curvature and hole diameters were equivalent, with one row positioned upstream of the maximum curvature point and the other downstream of the maximum curvature point. Adiabatic temperature measurements were carried out for blowing ratios of M = 0.30 to 1.60 and tested at a density ratio of DR = 1.20. The results show that the change in curvature downstream plays a significant role in the performance of film cooling and that the local surface curvature is insufficient in capturing its effects. Additional experiments were carried out to measure the effects of the approaching boundary layer influence on film cooling as well as the effect of injection angle at a weakly convex surface.
Author: Owen Michael O'Neal Publisher: ISBN: Category : Languages : en Pages : 206
Book Description
This study was focused on measurements of adiabatic effectiveness on a scaled turbine vane which made use of a contoured endwall to match engine conditions. The vane model featured a full coverage film-cooling configuration with five rows of cylindrical holes in the showerhead and ten rows of laidback fanshaped holes distributed on the pressure and suction sides. The vane model was tested across a wide range of blowing ratios in several different coolant configurations including: individual rows on the pressure and suction side, full coverage tests with and without showerhead cooling, and full coverage tests at low and high mainstream turbulence levels. Comparisons between these configurations were made in order to assess the effects of local curvature, showerhead cooling, and mainstream turbulence levels. Single row tests measured in areas of high convex curvature tended to have an improved performance relative to flat plate predictions, while the opposite was true for rows in areas of concave curvature. Overall, showerhead cooling did not provide any significant improvements in effectiveness far downstream on both the pressure and suction side. Increasing mainstream turbulence levels tended to diminish the film cooling effectiveness. The negative effect of higher mainstream turbulence was most significant at low blowing ratios, but became negligible at higher flow rates.
Author: Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The adiabatic film cooling effectiveness on convex and concave curved surfaces (as a model for suction and pressure side film cooling of gas turbine blades) with two staggered rows of injection holes are investigated by using a mass transfer technique. Additionally measurements on a flat plate are made for comparison. Two different radii of curvature (R/D = plus or minus 60, plus or minus 120) and two streamwise distances of the rows (12D and 24D) with film cooling holes inclined at 40 degrees are considered. The blowing rates are varied in a wide range from 0.25 to 2.0 and the main stream Reynolds numbers (Re(sub D)) between 10000 and 50000. At low and moderate blowing rates the effectiveness is enhanced on convex and reduced on concave curved surfaces compared to results obtained on the flat surface. At high blowing rates the effectiveness is not greatly influenced by surface curvature. The effect of curvature was found to be negligible between the two rows and reduced downstream of the second row compared to results described in the literature for single row injection.
Author: Jacob Damian Moore Publisher: ISBN: Category : Languages : en Pages : 324
Book Description
Surface curvature has been shown to have significant effects on the film cooling performance of round holes, but the present literature includes very few studies dedicated to curvature’s effects on shaped hole geometries despite their prevalence in turbine blade and vane designs. Experiments were performed on two rows of holes placed on the suction side of a scaled-up gas turbine blade model in a low-Mach-number linear cascade wind tunnel. The test facility was set up to match a high-Mach-number pressure distribution without modifying the blade’s geometry or including contoured end walls to accelerate the flow. By adjusting the positions of the movable walls in the tunnel test section, the suction side pressure distribution could be matched to the design distribution. One row was placed in a region of high convex surface curvature; the other, in a region of low convex curvature. Other geometric and flow parameters near the rows were matched in the design of the experiment, including hole geometry and spacing. The hole geometry was a standard 7-7-7 shaped hole. In addition, local freestream conditions for the rows were measured and set to match as closely as possible. Comparison of the adiabatic effectiveness results from the two rows revealed trends similar to those seen in previous literature for round holes. The high curvature row outperformed the low curvature row at lower coolant injection rates, having wider jets and higher centerline effectiveness. But as the injection rate was increased, the low curvature row surpassed the high curvature row in effectiveness. The driver behind this behavior was the surface-normal pressure gradient that arose from the convex surface curvature. As flow traveled around the surface, centripetal acceleration produced a pressure gradient directed towards the surface, effectively pushing jets toward the blade wall. However, at higher blowing ratios, the jets’ high momenta overcame the effects of this pressure gradient. At these injection rates, the high curvature row’s jets’ trajectories did not follow the surface as it curved away. The high surface curvature exacerbated the adverse effects of jet separation on film cooling performance.
Author: Thomas Earl Dyson Publisher: ISBN: Category : Languages : en Pages : 576
Book Description
This study focused on the improvement of film cooling for gas turbine vanes using both computational and experimental techniques. The experimental component used a matched Biot number model to measure scaled surface temperature (overall effectiveness) distributions representative of engine conditions for two new configurations. One configuration consisted of a single row of holes on the pressure surface while the other used numerous film cooling holes over the entire vane including a showerhead. Both configurations used internal impingement cooling representative of a 1st vane. Adiabatic effectiveness was also measured. No previous studies had shown the effect of injection on the mean and fluctuating velocity profiles for the suction surface, so measurements were made at two locations immediately upstream of film cooling holes from the fully cooled cooling configuration. Different blowing conditions were evaluated. Computational tools are increasingly important in the design of advanced gas turbine engines and validation of these tools is required prior to integration into the design process. Two film cooling configurations were simulated and compared to past experimental work. Data from matched Biot number experiments was used to validate the overall effectiveness from conjugate simulations in addition to adiabatic effectiveness. A simulation of a single row of cooling holes on the suction side also gave additional insight into the interaction of film cooling jets with the thermal boundary layer. A showerhead configuration was also simulated. The final portion of this study sought to evaluate the performance of six RANS models (standard, realizable, and renormalization group k-[epsilon]; standard k-[omega]; k-[omega] SST; and Transition SST) with respect to the prediction of thermal boundary layers. The turbulent Prandtl number was varied to test a simple method for improvement of the thermal boundary layer predictions.
Author: Budugur Lakshminarayana Publisher: John Wiley & Sons ISBN: 9780471855460 Category : Technology & Engineering Languages : en Pages : 846
Book Description
Over the past three decades, information in the aerospace and mechanical engineering fields in general and turbomachinery in particular has grown at an exponential rate. Fluid Dynamics and Heat Transfer of Turbomachinery is the first book, in one complete volume, to bring together the modern approaches and advances in the field, providing the most up-to-date, unified treatment available on basic principles, physical aspects of the aerothermal field, analysis, performance, theory, and computation of turbomachinery flow and heat transfer. Presenting a unified approach to turbomachinery fluid dynamics and aerothermodynamics, the book concentrates on the fluid dynamic aspects of flows and thermodynamic considerations rather than on those related to materials, structure, or mechanical aspects. It covers the latest material and all types of turbomachinery used in modern-day aircraft, automotive, marine, spacecraft, power, and industrial applications; and there is an entire chapter devoted to modern approaches on computation of turbomachinery flow. An additional chapter on turbine cooling and heat transfer is unique for a turbomachinery book. The author has undertaken a systematic approach, through more than three hundred illustrations, in developing the knowledge base. He uses analysis and data correlation in his discussion of most recent developments in this area, drawn from over nine hundred references and from research projects carried out by various organizations in the United States and abroad. This book is extremely useful for anyone involved in the analysis, design, and testing of turbomachinery. For students, it can be used as a two-semester course of senior undergraduate or graduate study: the first semester dealing with the basic principles and analysis of turbomachinery, the second exploring three-dimensional viscid flows, computation, and heat transfer. Many sections are quite general and applicable to other areas in fluid dynamics and heat transfer. The book can also be used as a self-study guide to those who want to acquire this knowledge. The ordered, meticulous, and unified approach of Fluid Dynamics and Heat Transfer of Turbomachinery should make the specialization of turbomachinery in aerospace and mechanical engineering much more accessible to students and professionals alike, in universities, industry, and government. Turbomachinery theory, performance, and analysis made accessible with a new, unified approach For the first time in nearly three decades, here is a completely up-to-date and unified approach to turbomachinery fluid dynamics and aerothermodynamics. Combining the latest advances, methods, and approaches in the field, Fluid Dynamics and Heat Transfer of Turbomachinery features: The most comprehensive and complete coverage of the fluid dynamics and aerothermodynamics of turbomachinery to date A spotlight on the fluid dynamic aspects of flows and the thermodynamic considerations for turbomachinery (rather than the structural or material aspects) A detailed, step-by-step presentation of the analytical and computational models involved, which allows the reader to easily construct a flowchart from which to operate Critical reviews of all the existing analytical and numerical models, highlighting the advantages and drawbacks of each Comprehensive coverage of turbine cooling and heat transfer, a unique feature for a book on turbomachinery An appendix of basic computation techniques, numerous tables, and listings of common terminology, abbreviations, and nomenclature Broad in scope, yet concise, and drawing on the author's teaching experience and research projects for government and industry, Fluid Dynamics and Heat Transfer of Turbomachinery explains and simplifies an increasingly complex field. It is an invaluable resource for undergraduate and graduate students in aerospace and mechanical engineering specializing in turbomachinery, for research and design engineers, and for all professionals who are—or wish to be—at the cutting edge of this technology.
Author: David Richard Robertson Publisher: ISBN: Category : Languages : en Pages : 372
Book Description
This study investigates the effect that surface roughness has on the adiabatic effectiveness performance of the first row of suction side cooling holes on a turbine inlet guide vane. The effects of roughness placement (roughness upstream, downstream, or combined up and downstream of the row of film cooling holes) are investigated. Additionally, for each roughness placement, the effect of mainstream turbulence level and showerhead coolant will be quantified. To gain insight into the state of the boundary layer just upstream of the row of film cooling holes, a hot-wire anemometer will be used to measure the velocity and turbulence profiles that exist under various conditions. It was found that roughness degrades the adiabatic effectiveness performance of low blowing ratios and enhances the adiabatic effectiveness performance of high blowing ratios. Roughness also shifts the optimum blowing ratio, toward higher coolant flow rates. Roughness thickens the boundary layer and increases its turbulence intensity
Author: David Alan Kistenmacher Publisher: ISBN: Category : Languages : en Pages : 364
Book Description
In the United States, natural gas turbine generators account for approximately 7% of the total primary energy consumed. A one percent increase in gas turbine efficiency could result in savings of approximately 30 million dollars for operators and, subsequently, electricity end-users. The efficiency of a gas turbine engine is tied directly to the temperature at which the products of combustion enter the first stage, high-pressure turbine. The maximum operating temperature of the turbine components' materials is the major limiting factor in increasing the turbine inlet temperature. In fact, current turbine inlet temperatures regularly exceed the melting temperature of the turbine vanes through advanced vane cooling techniques. These cooling techniques include vane surface film cooling, internal vane cooling, and the addition of a thermal barrier coating (TBC) to the exterior of the turbine vane. Typically, the performance of vane cooling techniques is evaluated using the adiabatic film effectiveness. However, the adiabatic film effectiveness, by definition, does not consider conjugate heat transfer effects. In order to evaluate the performance of internal vane cooling and a TBC it is necessary to consider conjugate heat transfer effects. The goal of this study was to provide insight into the conjugate heat transfer behavior of actual turbine vanes and various vane cooling techniques through experimental and analytical modeling in the pursuit of higher turbine inlet temperatures resulting in higher overall turbine efficiencies. The primary focus of this study was to experimentally characterize the combined effects of a TBC and film cooling. Vane model experiments were performed using a 10x scaled first stage inlet guide vane model that was designed using the Matched Biot Method to properly scale both the geometrical and thermal properties of an actual turbine vane. Two different TBC thicknesses were evaluated in this study. Along with the TBCs, six different film cooling configurations were evaluated which included pressure side round holes with a showerhead, round holes only, craters, a novel trench design called the modified trench, an ideal trench, and a realistic trench that takes manufacturing abilities into account. These film cooling geometries were created within the TBC layer. Each of the vane configurations was evaluated by monitoring a variety of temperatures, including the temperature of the exterior vane wall and the exterior surface of the TBC. This study found that the presence of a TBC decreased the sensitivity of the thermal barrier coating and vane wall interface temperature to changes in film coolant flow rates and changes in film cooling geometry. Therefore, research into improved film cooling geometries may not be valuable when a TBC is incorporated. This study also developed an analytical model which was used to predict the performance of the TBCs as a design tool. The analytical prediction model provided reasonable agreement with experimental data when using baseline data from an experiment with another TBC. However, the analytical prediction model performed poorly when predicting a TBC's performance using baseline data collected from an experiment without a TBC.
Author: James R. Winka
Author: James R. Winka
Author: Owen Michael O'Neal
Author: 
Author: Jacob Damian Moore
Author: זאב גאויתז
Author: Thomas Earl Dyson
Author: Budugur Lakshminarayana
Author: David Richard Robertson
Author: David Alan Kistenmacher
Author: James D. Heidmann