EBookClubs

Read Books & Download eBooks Full Online

EBookClubs

Read Books & Download eBooks Full Online

Book Film Cooling with Forward and Backward Injection for Cylindrical and Fan shaped Holes Using PSP Measurement Technique

Download or read book Film Cooling with Forward and Backward Injection for Cylindrical and Fan shaped Holes Using PSP Measurement Technique written by Andrew F. Chen and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A systematic study was performed to investigate the combined effects of hole geometry, blowing ratio, density ratio and free-stream turbulence intensity on flat plate film cooling with forward and backward injection. Detailed film cooling effectiveness distributions were obtained using the steady state pressure sensitive paint (PSP) technique. Four common film-hole geometries with forward injection were used in this study: simple angled cylindrical holes and fan-shaped holes, and compound angled (ß= 45°) cylindrical holes and fan-shaped holes. Additional four film-hole geometries with backward injection were tested by reversing the injection direction from forward to backward to the mainstream. There are seven holes in a row on each plate and each hole is 4 mm in diameter. The blowing ratio effect is studied at 10 different blowing ratios ranging from M = 0.3 to M = 2.0. The coolant to main stream density ratio (DR) effect is studied by using foreign gases with DR = 1 (N2), 1.5 (CO2), and 2 (15% SF6 + 85% Ar). The free stream turbulence intensity effect is tested at 0.5% and 6%. The results of the parametric effects to the film cooling effectiveness with forward injection agreed with open literatures. In general, the results show the film cooling effectiveness with backward injection is greatly reduced for shaped holes as compared with the forward injection. However, significant improvements can be seen in simple angled cylindrical hole at higher blowing ratios. Backward injection also shows improvements at near film-hole regions for compound angled cylindrical holes at higher blowing ratios. Comparison was made between the experimental data and empirical correlation for simple angled fan-shaped holes. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151849

Book Shaped Hole Effects on Film Cooling Effectiveness and a Comparison of Multiple Effectiveness Measurement Techniques

Download or read book Shaped Hole Effects on Film Cooling Effectiveness and a Comparison of Multiple Effectiveness Measurement Techniques written by Trent Alan Varvel and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This experimental study consists of two parts. For the first part, the film cooling effectiveness for a single row of seven cylindrical holes with a compound angle is measured on a flat surface using five different measurement techniques: steady-state liquid crystal thermography, transient liquid crystal thermography, pressure sensitive paint (PSP), thermocouples, and infrared thermography. A comparison of the film cooling effectiveness from each of the measurement techniques is presented. All methods show a good comparison, especially for the higher blowing ratios. The PSP technique shows the most accurate measurements and has more advantages for measuring film cooling effectiveness. Also, the effect of blowing ratio on the film cooling effectiveness is investigated for each of the measurement techniques. The second part of the study investigates the effect of hole geometries on the film cooling effectiveness using pressure sensitive paint. Nitrogen is injected as the coolant air so that the oxygen concentration levels can be obtained for the test surface. The film effectiveness is then obtained by the mass transfer analogy. Five total hole geometries are tested: fan-shaped laidback with a compound angle, fan-shaped laidback with a simple angle, a conical configuration with a compound angle, a conical configuration with a simple angle, and the reference geometry (cylindrical holes) used in part one. The effect of blowing ratio on film cooling effectiveness is presented for each hole geometry. The spanwise averaged effectiveness for each geometry is also presented to compare the geometry effect on film cooling effectiveness. The geometry of the holes has little effect on the effectiveness at low blowing ratios. The laterally expanded holes show improved effectiveness at higher blowing ratios. All experiments are performed in a low speed wind tunnel with a mainstream velocity of 34 m/s. The coolant air is injected through the coolant holes at four different coolant-to-mainstream velocity ratios: 0.3, 0.6, 1.2, and 1.8.

Book Gas Turbine Heat Transfer and Cooling Technology Second Edition

Download or read book Gas Turbine Heat Transfer and Cooling Technology Second Edition written by Je-Chin Han and published by CRC Press. This book was released on 2012-11-27 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Book Flow Visualization of Discrete hole Film Cooling with Spanwise Injection Over a Cylinder

Download or read book Flow Visualization of Discrete hole Film Cooling with Spanwise Injection Over a Cylinder written by Louis M. Russell and published by . This book was released on 1979 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Influence of Gap Leakage on the Film Effectiveness and Heat Transfer Around Discrete Injection Holes

Download or read book Influence of Gap Leakage on the Film Effectiveness and Heat Transfer Around Discrete Injection Holes written by Yue Cheng Hsing and published by . This book was released on 1997 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research has been performed to investigate the heat transfer characteristics of cooling film over a misaligned leaking gap, using a thermographic phosphor fluorescence imaging technique. Such a flow pattern is usually seen on the component-to-component interface of inlet guide vanes in a gas turbine system. This problem can be classified as a four-temperature problem. The present study defines a true driving potential of the convective heat transfer of a four-temperature system. Experiments are performed systematically to investigate problems of traditional film cooling, the gap leakage together with a misaligned interface effect, and finally, a combined four-temperature system. The result of current film cooling studies reveals a comparable agreement with that found in open literature using conventional measurement techniques. The same conclusion is obtained for a gap leakage study at an aligned interface circumstance. Another finding of the gap leakage study is that the cooling performance in a backward-facing step is the best among all misaligned interface situations. For a four-temperature situation, the flowfield changes significantly in the presence of a leaking gap downstream of film-cooling jets or vise versa. The cooling performance of each coolant injection is either enhanced or degraded, depending on the ratio of the blow strength the first coolant film to that of the second. The misaligned interface effect lessens when the ratio is smaller than one. In contrast to the gap leakage results, the forward-facing step situation presents the best film effectiveness distribution. Generally, the cooling performance is decreased when film-cooling jets re revealed upstream of a gap leakage. The effect is opposite when a leaking gap is located upstream.

Book Stagnation Region Gas Film Cooling Spanwise Angled Coolant Injection

Download or read book Stagnation Region Gas Film Cooling Spanwise Angled Coolant Injection written by David W. Luckey and published by . This book was released on 1976 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: This experimental investigation involved the study of gas film cooling from a single row of spanwise angled holes using the stagnation region of a cylinder in cross flow to model the leading edge of a turbine vane. The objective was to obtain data for the local convective heat transfer rates to a highly cooled, curved surface exposed to a turbulent hot mainstream flow and a secondary, film coolant flow. Since the leading edge of the first stage, inlet turbine vane experiences some of the most severe thermal loads found in the turbine engine, effective film cooling is most important in this area. Film cooling of the leading edge area was modeled by making heat transfer measurements on the front stagnation region of a cylinder in cross flow. Experiments were conducted in a rectangular duct using a film cooled cylindrical test surface normal to a two-dimensional freestream flow. A gas turbine combustor provided heated air flow to simulate a Reynolds number typical of a high pressure, high temperature turbine vane. Internal convection cooling of the cylinder allowed a gas-to-wall temperature ratio of 2.1 to be achieved while using a moderate freestream gas temperature (1000R; 555K. The film coolant was chilled to obtain a coolant-to-freestream density ratio of 2.2, representative of the gas turbine environment. The cylindrical test surface was instrumented with miniature heat flux gages, and wall thermocouples to determine the influence of the film coolant blowing ratio and the injection hole geometry on the film cooling performance.

Book Evaluation of Film Cooling Superposition Method on the Suction Side of a Blade Model

Download or read book Evaluation of Film Cooling Superposition Method on the Suction Side of a Blade Model written by Christopher Yoon and published by . This book was released on 2018 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Film cooling is often used for turbine airfoil cooling, and there are numerous studies of the performance of a single row of holes. Typically, blades and vanes in gas turbine engines have multiple rows of holes that interact. Consequently, there is a need to develop techniques to predict film cooling performance with multiple rows of holes. One of the method is to superposition single row cooling effectiveness to predict combined effectiveness. Although there have been many studies of superposition techniques with multiple rows of cylindrical holes, there have been very few in which shaped holes were used with a typical turbine airfoil model. In this study, film effectiveness was measured on the suction side of a turbine blade model using two rows of 7-7-7 shaped holes, with pitch to diameter ratio of 6, and the two rows were more than 40 diameters apart. Measurements were made with each row operating independently, which provided the experimental data for superposition predictions. These predictions were evaluated with effectiveness measurements with both rows operational. For these combined row tests, two different upstream blowing ratios and a wide range of downstream blowing ratios were selected. The superposition predictions were reasonably accurate when the upstream blowing ratio was high with a corresponding smaller film effectiveness downstream (due to jet separation). However, when the upstream coolant holes were operated at optimum blowing ratio with maximum film effectiveness downstream, the superposition analysis predicted film effectiveness levels slightly lower than actual levels. These results indicate that there was an interaction between jets that resulted in higher film effectiveness than what the superposition method had predicted

Book A Detailed Analysis of Film cooling Physics Part II Compound angle Injection with Cylindrical Holes

Download or read book A Detailed Analysis of Film cooling Physics Part II Compound angle Injection with Cylindrical Holes written by Kevin T. McGovern and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the International Gas Turbine & Aeroengine Congress & Exhibition, Orlando, FL, Jun 2 - Jun 5, 1997.

Book A Detailed Analysis of Film cooling Physics Part I Streamwise Injection with Cylindrical Holes

Download or read book A Detailed Analysis of Film cooling Physics Part I Streamwise Injection with Cylindrical Holes written by Dibbon K. Walters and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the International Gas Turbine & Aeroengine Congress & Exhibition, Orlando, FL, Jun 2 - Jun 5, 1997.

Book A Detailed Investigation of the Fluid Dynamics and Heat Transfer Related to Injection from a Compound Angled Shaped Film Cooling Hole

Download or read book A Detailed Investigation of the Fluid Dynamics and Heat Transfer Related to Injection from a Compound Angled Shaped Film Cooling Hole written by Shane Haydt and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Book Evaluation of Additively Manufactured Internal Cooling Channels and Film Cooling Holes for Cooling Effectiveness

Download or read book Evaluation of Additively Manufactured Internal Cooling Channels and Film Cooling Holes for Cooling Effectiveness written by Emma Veley and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cooling of the high-pressure turbine in a gas turbine engine is essential for durability because the gas temperature entering the turbine exceeds the melting point of the hardware. Both internal and external cooling reduces the temperature of the blades and vanes. Using air that bypassed the combustor as coolant, the convective heat transfer from the hardware to this internal coolant is often augmented by ribs or a serpentine path. To cool the external surface, coolant passes through holes on the outer wall of airfoil. The coolant creates a protective film on the surface. The shape of the cooling hole influences the cooling effectiveness of this film cooling. Additive manufacturing facilitates rapid prototyping compared to traditional manufacturing methods, which can be exploited for designing and evaluating cooling schemes of gas turbine hardware. The work in this dissertation used additive manufacturing to investigate the cooling performance of several internal and external cooling schemes manufactured in at engine scale for the unique objective of determining the impacts of the internal cooling scheme on the external cooling. A variety of cooling hole shapes were investigated for this work: cylindrical hoes, meter-diffuser shaped holes, and novel optimized holes. Once additively manufactured, the as-built cooling hole surfaces were analyzed to determined their roughness and minimum cross-sectional areas. The arithmetic mean roughness of holes built at the optimal build orientation (perpendicular to the build plate) were on the order of 10 [mu]m; whereas those investigated at other build orientations had roughness values up to 75 [mu]m. For the holes built perpendicular to the substrate the minimum cross-sectional area was usually greater than the design intent but within 15%. The additive process also created an overbuilt lip on the leading edge (windward) side of the hole exit for these holes because of the thin wall thickness in the design. Using these cooling holes, the impact of rounding on meter-diffuser shaped holes and optimized holes on overall effectiveness was investigated. The rounding, which came in the form of inlet fillets on the meter-diffuser shaped holes, was found to decrease the required pressure ratio to obtain the same cooling effectiveness. The deviations from the design due to the additive process caused the novel cooling hole shapes designed through adjoint optimization to perform differently than anticipated. For example, the coolant jet from hole designed for co-flow did not bifurcate as the computational simulation showed. The cross-flow optimized hole outperformed the co-flow optimized hole for most of the tested blowing ratio when both holes were tested in a co-flow configuration. These results from the novel optimized holes proved the necessity of experimentally verifying new designs prior to incorporating into final cooling schemes. The effect of supply channel height, number of channels, ribs, and the cross-sectional shape of the supply channel was investigated to determine the impact of each on the overall effectiveness. Designs that had high overall effectiveness from only internal cooling had less augmentation in effectiveness from film cooling than designs with less effective internal cooling. For example, a ribbed channel typically had a lower film-cooling augmentation than the film-cooling augmentation for same supply channel without ribs. However, a highly effective feed channel can obtain a higher overall effectiveness without any film cooling than a poorly performing feed channel can obtain with film cooling. But the features that create a highly effective feed channel can also cause the cooling jet to lift-off the surface and mix with the hot gas path, which was seen with some rib and hole combinations and with the triangle -- vertex down supply channels. Therefore, the hole shape, the supply channel geometry, and the junction between the two all significantly contribute to a cooling scheme's performance and all three must be considered concurrently to create an optimal cooling design.