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1
Collins, Alan, and Jen Snowball. "The effectiveness and impacts of subsidies to film industries." South African Cultural Observatory (SACO), 2016. http://hdl.handle.net/10962/68511.
Повний текст джерелаАнотація:
Publisher versionConference paper presented at the South African Cultural Observatory, First National Conference: Counting Culture, The Cultural and Creative Industries in National and International Context, 16-17 May 2016, The Boardwalk International Convention Centre, Nelson Mandela Bay.
2
Varvel, Trent Alan. "Shaped hole effects on film cooling effectiveness and a comparison of multiple effectiveness measurement techniques." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1524.
Повний текст джерелаАнотація:
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.
3
Marsh, Jan H. "Development of an experimental setup for the study of film pulsation effects on film cooling effectiveness." Honors in the Major Thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1111.
Повний текст джерелаАнотація:
This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Engineering and Computer Science
Aerospace Engineering
4
Gao, Zhihong. "Experimental investigation of film cooling effectiveness on gas turbine blades." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1557.
Повний текст джерела
5
Li, Ke. "Experimental Study of Heat Transfer Coefficient and Film Cooling Effectiveness." Thesis, KTH, Energiteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-249061.
Повний текст джерелаАнотація:
This thesis investigates the possibility to evaluate the film cooling thermal performance on flat plate using Thermochromic Liquid Crystal. After an introduction of the basic concept and background of gas turbine blades film cooling and Thermochromic Liquid Crystal, a thorough explanation of four methods is presented. Dimensional or similarity analysis is implemented to build relationship between real engine and laboratory model. Also, the Reynolds number and Blowing ratio are the fundamental of test object design and TLC selection. This study illustrated the layout of the test rig and corresponding setups, and the following part explains the data collection system and image processing MATLAB script which is vital for the success of data extraction. The least square method is applied to figure time-series optimal solution in solver. All the experiments are conducted at near room temperature as opposed to the extremely high gas turbine exhausted gas, including two calibration test and one heat transfer experiment. The heat transfer coefficient and film cooling effectiveness are the target objective through the entire project. By comparison with a similar experiment in a literature, the outcomes partially validated the film cooling performance under the pre-set flow and thermal condition and the Liquid Crystal thermography technique is proved to be a trustworthy method to mapping heat transfer surface.Denna avhandling undersöker möjligheten att utvärdera filmkylningens termiska prestanda på plan platta med användning av Termokromisk Flytande Kristall (TLC). Efter en introduktion av grundkonceptet och bakgrunden till gasturbinbladens filmkylning och termokromisk flytande kristall presenteras en grundlig förklaring av fyra metoder. Dimensionell eller likhetsanalys implementeras för att bygga upp förhållandet mellan verklig motor och laboratoriemodell. Reynoldstalet och blåsningsförhållandet (blowing ratio) är också grunden för testobjektdesign och TLC-val. Denna studie illustrerade provriggens layout och tillhörande inställningar. I följande del förklaras datainsamlingssystemet och bildbehandling, MATLABTM-skriptet som är avgörande för framgång med datautvärdering. Den minsta kvadratiska metoden tillämpas för att hitta tidsseriens optimala lösning i lösaren. Alla experiment utförs vid nära rumstemperatur i motsats till den höga temperature på gasturbingasen, inklusive två kalibreringstest och ett värmeöverföringsexperiment. Värmeöverföringskoefficienten och filmkylningseffektiviteten är målmålet genom hela projektet. Resultaten validerade partiellt filmkylningens prestanda under det förinställda flödet och det termiska tillståndet. Liquid Crystal-termografitekniken har visat sig vara en pålitlig metod för att kartlägga värmeöverföringsytan jämfört med ett liknande experiment i den öppna litteraturen.
6
Aghasi, Paul P. "Dependence of Film Cooling Effectiveness on 3D Printed Cooling Holes." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1458893416.
Повний текст джерела
7
Rodriguez, Sylvette. "EFFECT OF PRESSURE GRADIENT AND WAKE ON ENDWALL FILM COOLING EFFECTIVENESS." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2940.
Повний текст джерелаАнотація:
Endwall film cooling is a necessity in modern gas turbines for safe and reliable operation. Performance of endwall film cooling is strongly influenced by the hot gas flow field, among other factors. For example, aerodynamic design determines secondary flow vortices such as passage vortices and corner vortices in the endwall region. Moreover blockage presented by the leading edge of the airfoil subjects the incoming flow to a stagnating pressure gradient leading to roll-up of the approaching boundary layer and horseshoe vortices. In addition, for a number of heavy frame power generation gas turbines that use cannular combustors, the hot and turbulent gases exiting from the combustor are delivered to the first stage vane through transition ducts. Wakes induced by walls separating adjacent transition ducts located upstream of first row vanes also influence the entering main gas flow field. Furthermore, as hot gas enters vane passages, it accelerates around the vane airfoils. This flow acceleration causes significant streamline curvature and impacts lateral spreading endwall coolant films. Thus endwall flow field, especially those in utility gas turbines with cannular combustors, is quite complicated in the presence of vortices, wakes and strong favorable pressure gradient with resulting flow acceleration. These flow features can seriously impact film cooling performance and make difficult the prediction of film cooling in endwall. This study investigates endwall film cooling under the influence of pressure gradient effects due to stagnation region of an axisymmetric airfoil and in mainstream favorable pressure gradient. It also investigates the impact of wake on endwall film cooling near the stagnation region of an airfoil. The investigation consists of experimental testing and numerical simulation. Endwall film cooling effectiveness is investigated near the stagnation region on an airfoil by placing an axisymmetric airfoil downstream of a single row of inclined cylindrical holes. The holes are inclined at 35° with a length-to-diameter ratio of 7.5 and pitch-to-diameter ratio of 3. The ratio of leading edge radius to hole diameter and the ratio of maximum airfoil thickness to hole diameter are 6 and 20 respectively. The distance of the leading edge of the airfoil is varied along the streamwise direction to simulate the different film cooling rows preceding the leading edge of the airfoil. Wake effects are induced by placing a rectangular plate upstream of the injection point where the ratio of plate thickness to hole diameter is 6.4, and its distance is also varied to investigate the impact of strong and mild wake on endwall film cooling effectiveness. Blowing ratio ranged from 0.5 to 1.5. Film cooling effectiveness is also investigated under the presence of mainstream pressure gradient with converging main flow streamlines. The streamwise pressure distribution is attained by placing side inserts into the mainstream. The results are presented for five holes of staggered inclined cylindrical holes. The inclination angle is 30° and the tests were conducted at two Reynolds number, 5000 and 8000. Numerical analysis is employed to aid the understanding of the mainstream and coolant flow interaction. The solution of the computational domain is performed using FLUENT software package from Fluent, Inc. The use of second order schemes were used in this study to provide the highest accuracy available. This study employed the Realizable κ-ε model with enhance wall treatment for all its cases. Endwall temperature distribution is measured using Temperature Sensitive Paint (TSP) technique and film cooling effectiveness is calculated from the measurements and compared against numerical predictions. Results show that the characteristics of average film effectiveness near the stagnation region do not change drastically. However, as the blowing ratio is increased jet to jet interaction is enhanced due to higher jet spreading resulting in higher jet coverage. In the presence of wake, mixing of the jet with the mainstream is enhanced particularly for low M. The velocity deficit created by the wake forms a pair of vortices offset from the wake centerline. These vortices lift the jet off the wall promoting the interaction of the jet with the mainstream resulting in a lower effectiveness. The jet interaction with the mainstream causes the jet to lose its cooling capabilities more rapidly which leads to a more sudden decay in film effectiveness. When film is discharged into accelerating main flow with converging streamlines, row-to-row coolant flow rate is not uniform leading to varying blowing ratios and cooling performance. Jet to jet interaction is reduced and jet lift off is observed for rows with high blowing ratio resulting in lower effectiveness.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering PhD
8
Ahn, Jaeyong. "Film cooling effectiveness measurements on rotating and non-rotating turbine components." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4664.
Повний текст джерелаАнотація:
Detailed film cooling effectiveness distributions were measured on the stationary
blade tip and on the leading edge region of a rotating blade using a Pressure Sensitive
Paint technique. Air and nitrogen gas were used as the film cooling gases and the
oxygen concentration distribution for each case was measured. The film cooling
effectiveness information was obtained from the difference of the oxygen concentration
between air and nitrogen gas cases by applying the mass transfer analogy. In the case of
the stationary blade tip, plane tip and squealer tip blades were used while the film
cooling holes were located (a) along the camber line on the tip or (b) along the span of
the pressure side. The average blowing ratio of the cooling gas was controlled to be 0.5,
1.0, and 2.0. Tests were conducted in a five-bladed linear cascade with a blow down
facility. The free stream Reynolds number, based on the axial chord length and the exit
velocity, was 1,100,000 and the inlet and the exit Mach number were 0.25 and 0.59,
respectively. Turbulence intensity level at the cascade inlet was 9.7%. All
measurements were made at three different tip gap clearances of 1%, 1.5%, and 2.5% of
blade span. Results show that the locations of the film cooling holes and the presence
of squealer have significant effects on surface static pressure and film-cooling effectiveness. Same technique was applied to the rotating turbine blade leading edge
region. Tests were conducted on the first stage rotor of a 3-stage axial turbine. The
Reynolds number based on the axial chord length and the exit velocity was 200,000 and
the total to exit pressure ratio was 1.12 for the first rotor. The effects of the rotational
speed and the blowing ratio were studied. The rotational speed was controlled to be
2400, 2550, and 3000 rpm and the blowing ratio was 0.5, 1.0, and 2.0. Two different
film cooling hole geometries were used; 2-row and 3-row film cooling holes. Results
show that the rotational speed changes the directions of the coolant flows. Blowing
ratio also changes the distributions of the coolant flows. The results of this study will
be helpful in understanding the physical phenomena regarding the film injection and
designing more efficient turbine blades.
9
Zuniga, Humberto. "STUDY OF FILM COOLING EFFECTIVENESS: CONICAL, TRENCHED AND ASYMMETRICAL SHAPED HOLES." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2239.
Повний текст джерелаАнотація:
Film cooling is a technique whereby air from the compressor stage of a gas turbine engine is diverted for cooling purposes to parts, such as the turbine stage, that operate at very high temperatures. Cooling arrangements include impingement jets, finned, ribbed and turbulated channels, and rows of film cooling holes, all of which over the years have become progressively more complex. This costly, but necessary complexity is a result of the industry's push to run engines at increasingly higher turbine inlet temperatures. Higher temperatures mean higher efficiency, but they also mean that the turbine first stage operates hundreds of degrees Kelvin above the melting point of the metal core of the vanes and blades. Existing cooling technology and materials make it possible to protect these parts and allow them to function for extended periods of time--but this comes at a price: the compressed air that is used for cooling represents a considerable penalty in overall turbine efficiency. The aim of current cooling research is threefold: to improve the protection of components from extreme fluxes in order to extend the life of the parts; to increase the inlet turbine operating temperature; and to reduce the amount of air that is diverted from the compressor for cooling. Current film cooling schemes consist of forcing air through carefully machined holes on a part and ejecting it at an angle with the intent of cooling that part by blanketing the surface downstream of the point of ejection. The last major development in the field has been the use of expanded hole exits, which reduce coolant momentum and allow for greater surface coverage. Researchers and designers are continuously looking for novel geometries and arrangements that would increase the level of protection or maintain it while using less coolant.
It was found that the performance of fan-shaped holes inside trenches is actually diminished by the presence of the trench. It is obvious, since the fan diffuses the flow, reducing the momentum of the coolant; the addition of the trench further slows the flow down. This, in turn, leads to the quicker ingestion of the main flow by the jets resulting in lower effectiveness. The next part of the study consisted of systematically increasing the depth of the trench for the fan-shaped holes. The purpose of this was to quantify the effect of the trench on the film cooling effectiveness. It was found that the presence of the trench significantly reduces the film effectiveness, especially for the deeper cases. At the higher blowing ratios, the overall performance of the fans collapses to the same value signifying insensitivity to the blowing ratio. A recent study suggests that having a compound angle could reduce the protective effect of the film due to the elevated interaction between the non-co-flowing coolant jet and the mainstream. Although it has been suggested that a non-symmetric lateral diffusion could mitigate the ill effects of having a compound angle, little has been understood on the effect this non-symmetry has on film cooling effectiveness. The last part of this study investigates the effect of non-symmetric lateral diffusion on film cooling effectiveness by systematically varying one side of a fan-shaped hole. For this part of the study, one of the lateral angles of diffusion of a fan-shaped hole was changed from 5° to 13°, while the other side was kept at 7°. It was found that a lower angle of diffusion hurts performance, while a larger diffusion angle improves it. However, the more significant result was that the jet seemed to be slightly turning. This dissertation investigates such novel methods which one day may include combinations of cylindrical and fan-shaped holes embedded inside trenches, conical holes, or even rows of asymmetric fan-shaped holes. The review of current literature reveals that very few investigations have been done on film cooling effectiveness for uniformly diffusing conical holes. They have been treated as a sort of side novelty since industrial partners often say they are hard to manufacture. To extend our understanding of effectiveness of conical holes, the present study investigates the effect of increasing diffusion angle, as well as the effect of adding a cylindrical entrance length to a conical hole. The measurements were made in the form of film cooling effectiveness and the technique used was temperature sensitive paint. Eight different conical geometries were tested in the form of coupons with rows of holes. The geometry of the holes changed from pure cylindrical holes, a 0° cylindrical baseline, to an 8° pure cone. The coupons were tested in a closed loop wind tunnel at blowing ratios varying from 0.5 to 1.5, and the coolant employed was nitrogen gas. Results indicate that the larger conical holes do, in fact offer appropriate protection and that the holes with the higher expansion angles perform similar to fan-shaped baseline holes, even at the higher blower ratios. The study was also extended to two other plates in which the conical hole was preceded by a cylindrical entry length. The performance of the conical holes improves as a result of the entry length and this is seen at the higher blowing ratios in the form of a delay in the onset of jet detachment. The results of this study show that conical expanding holes are a viable geometry and that their manufacturing can be made easier with a cylindrical entry length, at the same time improving the performance of these holes.
This suggests that the jets actually have two regions: one region with reduced momentum, ideal for protecting a large area downstream of the point of injection; and another region with more integrity which could withstand more aggressive main flow conditions. A further study should be conducted for this geometry at compound angles with the main flow to test this theory. The studies conducted show that the temperature sensitive paint technique can be used to study the performance of film cooling holes for various geometries. The studies also show the film cooling performance of novel geometries and explain why, in some cases, such new arrangements are desirable, and in others, how they can hurt performance. The studies also point in the direction of further investigations in order to advance cooling technology to more effective applications and reduced coolant consumption, the main goal of applied turbine cooling research.
Trench cooling consists of having film cooling holes embedded inside a gap, commonly called a trench. The walls of this gap are commonly vertical with respect to the direction of the main flow and are directly in the path of the coolant. The coolant hits the downstream trench wall which forces it to spread laterally, resulting in more even film coverage downstream than that of regular holes flush with the surface. Recent literature has focused on the effect that trenching has on cylindrical cooling holes only. While the results indicate that trenches are an exciting, promising new geometry derived from the refurbishing process of thermal barrier ceramic coatings, not all the parameters affecting film cooling have been investigated relating to trenched holes. For example, nothing has been said about how far apart holes inside the trench will need to be placed for them to stop interacting. Nothing has been said about shaped holes inside a trench, either. This dissertation explores the extent to which trenching is useful by expanding the PI/D from 4 to 12 for rows of round and fan holes. In addition the effect that trenching has on fan-shaped holes is studied by systematically increasing the trench depth. Values of local, laterally-averaged and spatially-averaged film cooling effectiveness are reported. It is found that placing the cylinders inside the trench and doubling the distance between the holes provides better performance than the cylindrical, non-trenched baseline, especially at the higher blowing ratios, M [greater than] 1.0. At these higher coolant flow rates, the regular cylindrical jets show detachment, while those in the trench do not. They, in fact perform very well. The importance of this finding implies that the number of holes, and coolant, can be cut in half while still improving performance over regular holes. The trenched cylindrical holes did not, however, perform like the fan shaped holes.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering PhD
10
Chen, Amber Marie. "Developing and Studying the Effectiveness of EFR Annotations for Chinese Language Learners." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/2299.
Повний текст джерелаАнотація:
This project is intended to take the film To Live, directed by Zhang Yimou, and apply the Electronic Film Review (EFR) approach to it in a Chinese as a Foreign Language (CFL) setting. The Electronic Film Review project, developed by Alan K. Melby, is aimed at providing a superior language learning experience for Americans learning Chinese. Using feature films as a teaching tool has been found to stimulate and motivate students to achieve higher language levels, but in order for optimal learning to occur the material must be challenging yet accessible to the student. Most feature films, by themselves, are too advanced for the average language learner. The EFR approach provides annotations designed specifically for the feature film with the language learner in mind. These annotations can include access to vocabulary helps, grammar and cultural notes in order to bridge the gap between the learner and the film. It does not alter the film itself. This approach has been used with ESL students (English annotations), French language learners, and with Korean ESL learners (Korean annotations), but has not been developed for students learning Chinese. The purpose of this project is not only to apply the technology of the Electronic Film Review program to a Chinese film for the purpose of aiding Chinese language learners, but also to critique whether or not the tool is effective in helping students to gain better listening comprehensions skills and therefore ultimately better language skills. Previous studies have not shown clear results on this issue. This thesis will briefly review what the EFR project is and how it has been used with other films and languages as well as the findings up to this point. Then it will look at the effects of annotations on several aspects of listening comprehension as well as student preferences and reactions. It will then evaluate the results collectively to determine whether students watching the film without the help of EFR annotations show differing levels of listening comprehension achievement when compared with those using the EFR tools. Suggestions will be made for further improvements.
11
Hinse, Mathieu. "Investigation of Transpiration Cooling Film Protection for Gas Turbine Engine Combustion Liner Application." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42425.
Повний текст джерелаАнотація:
Transpiration cooling as potential replacement of multi-hole effusion cooling for gas turbine engines combustion liner application is investigated by comparing their cooling film effectiveness based on the mass transfer analogy (CFEM). Pressure sensitive paint was used to measure CFEM over PM surfaces which was found to be on average 40% higher than multi-hole effusion cooling. High porosity PM with low resistance to flow movement were found to offer uneven distribution of exiting coolant, with large amounts leaving the trailing edge, leading to lopsided CFEM. Design of anisotropic PM based on PM properties (porosity, permeability, and inertia coefficient) were investigated using numerical models to obtain more uniform CFEM. Heat transfer analysis of different PM showed that anisotropic samples offered better thermal protection over isotropic PM for the same porosity. Comparison between cooling film effectiveness obtained from temperatures CFET against CFEM revealed large differences in the predicted protection. This is attributed to the assumptions made to apply CFEM, nonetheless, CFEM remains a good proxy to study and improve transpiration cooling. A method for creating a CAD model of designed PM is proposed based on critical characteristics of transpiration cooling for future use in 3D printing manufacturing.
12
Wheeler, Daniel Aaron. "The effectiveness of the Dove Evolution film as a one-shot media literacy treatment." Orlando, Fla. : University of Central Florida, 2009. http://purl.fcla.edu/fcla/etd/CFE0002650.
Повний текст джерела
13
Collins, Alan, Alessio Ishizaka, and Jeanette D. Snowball. "Film production incentives, employment transformation and domestic expenditure in South Africa: visualizing subsidy effectiveness." Taylor & Francis Group, 2016. http://hdl.handle.net/10962/67456.
Повний текст джерелаАнотація:
Publisher versionIn 2004 the South African Department of Trade and Industry (DTI) introduced a Film and Television Production Rebate Programme. In order to qualify for the rebate, certain criteria have to be met including success in job creation and skills development within the industry, alongside a particular focus on the percentage of ‘historically disadvantaged individuals’ employed. This study sets out the issues associated with evaluating success in meeting these various criteria and is, to the best of our knowledge, the first study to apply multi-criteria visualization techniques to inform the evaluation of public subsidy effectiveness. The ‘PROMETHEE’ method is applied and apart from presenting project performance in a visually intuitive manner, the approach helps to clarify patterns of relative success, show where policy objectives are competing, and to identify project exemplars for more efficiently guiding future public support in the sector.
14
Couch, Eric L. "Measurements of Cooling Effectiveness Along the Tip of a Turbine Blade." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/76815.
Повний текст джерелаАнотація:
In a gas turbine engine, turbine blades are exposed to temperatures above their melting point. Film-cooling and internal cooling techniques can prolong blade life and allow for higher engine temperatures. This study examines a novel cooling technique called a microcircuit, which combines internal convection and pressure side injection on a turbine blade tip. Holes on the tip called dirt purge holes expel dirt from the blade, so other holes are not clogged. Wind tunnel tests are used to observe how effectively dirt purge and microcircuit designs cool the tip. Tip gap size and blowing ratio are varied for different tip cooling configurations.
Results show that the dirt purge holes provide significant film cooling on the leading edge with a small tip gap. Coolant injected from these holes impacts the shroud and floods the tip gap reducing tip leakage flow.
With the addition of a microcircuit, coolant is delivered to a larger area of the tip. In all cases, cooling levels are higher for a small tip gap than a large tip gap. Increased blowing ratio does not have a dramatic effect on microcircuit film-cooling at the midchord but does improve internal cooling from the microcircuit. While the combined dirt purge holes and microcircuit cool the leading edge and midchord areas, there remains a small portion of the trailing edge that is not cooled. Also, results suggest that blowing from the microcircuit diminishes the tip leakage vortex. Overall, the microcircuit appears to be a feasible method for prolonging blade life.Master of Science
15
Smith, Dwight E. "An Investigation of Heat Transfer Coefficient and Film Cooling Effectiveness in a Transonic Turbine Cascade." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/43913.
Повний текст джерелаАнотація:
This study is an investigation of the film cooling effectiveness and heat transfer coefficient of a two-dimensional turbine rotor blade in a linear transonic cascade. Experiments were performed in Virginia Tech's Transonic Cascade Wind Tunnel with an exit Mach number 0f 1.2 and an exit Reynolds numbers of 5x106 to simulate real engine flow conditions. The freestream and coolant flows were maintained at a total temperature ratio of 2(+,-)0.4 and a total pressure ratio of 1.04. The freestream turbulence was approximately 1%. There are six rows of staggered, discrete cooling holes on and near the leading edge of the blade in a showerhead configuration. Cooled air was used as the coolant. Experiments were performed with and without film cooling on the surface of the blade. The heat transfer coefficient was found to increase with the addition of film cooling an average of 14% overall and to a maximum of 26% at the first gauge location. The average film cooling effectiveness along the chord-wise direction of the blade is 25%. Trends were found in both the uncooled and the film-cooled experiments that suggest either a transition from a laminar to a turbulent film regime or the existence of three-dimensionality in the flow-field over the gauges.Master of Science
16
Guy, Ashley Ray. "Effect of Blowing Ratio on the Nusselt Number and Film Cooling Effectiveness Distributions of a Showerhead Film Cooled Blade in a Transonic Cascade." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/43764.
Повний текст джерелаАнотація:
This paper investigates the effect of blowing ratio on the film cooling performance of a showerhead film cooled first stage turbine blade. The blade was instrumented with double-sided thin film heat flux gages to experimentally characterize the Nusselt number and film cooling effectiveness distributions over the surface of the blade. The blade was arranged in a two-dimensional, linear cascade within a transonic, blowdown type wind tunnel. The wind tunnel freestream conditions were varied over two exit Mach numbers, Me=0.78 and Me=1.01, with an inlet freestream turbulence intensity of 12% , with an integral length scale normalized by blade chord of 0.26 generated by a passive, mesh turbulence grid. The coolant conditions were varied by changing the ratio of coolant to freestream mass flux, blowing ratio, over three values, BR=0.60, 1.0, and 1.5 while keeping a density ratio of 1.7.
Experimental results show that ingestion of freestream flow into the showerhead cooling plenum can occur below a blowing ratio of 0.6. Film cooling increases Nusselt number over the uncooled case and increasing the blowing ratio also increases Nusselt number. At a blowing ratio of 1.5 and Me=1.01 a large drop in effectiveness just downstream of injection on both the pressure and suction surfaces is evidence of jet liftoff. The blowing ratio of 1.0 was found to have superior heat load reduction over the blade surface at both freestream conditions tested. The blowing ratio of 1.0 reduced the heat load by as much as 39% and 32% at Me=0.78 and 1.01, respectively.Master of Science
17
Hoffs, Alexander. "Experimental investigations of heat transfer and film cooling effectiveness using the transient liquid crystal technique /." Lausanne : EPFL, 1996. http://library.epfl.ch/theses/?nr=1510.
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Nadalina, Jafabadi Hossein. "Investigation of Film Cooling Strategies CFD versus Experiments -Potential for Using Reduced Models." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-61263.
Повний текст джерелаАнотація:
The ability and efficiency of today’s gas turbine engines are highly dependent on development of cooling technologies, among which film cooling is one of the most important. Investigations have been conducted towards discovering different aspects of film cooling, utilizing both experiments and performing CFD simulations. Although, investigation by using CFD analysis is less expensive in general, the results obtained from CFD calculations should be validated by means of experimental results. In addition to validation, in cases like simulating a turbine vane, performing CFD simulations can be time consuming. Therefore, it is essential to find approaches that can reduce the computational cost while results are validated by experiments. This study has shown the potential for reduced models to be utilized for investigation of different aspects of film cooling by means of CFD at low turn-around time. This has been accomplished by first carrying out CFD simulations and experiments for an engine-like setting for a full vane. Then the computational domain is reduced in two steps where all results are compared with experiments including aerodynamic validation, heat transfer coefficient and film effectiveness. While the aerodynamic results are in close agreement with experiments, the heat transfer coefficient and film effectiveness results have also shown similarities within the expected range. Thus this study has shown that this approach can be very useful for e.g. early vane and film cooling design.
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Hatchett, John Henry. "An Investigation of Effectiveness of Normal and Angled Slot Film Cooling in a Transonic Wind Tunnel." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/31324.
Повний текст джерелаАнотація:
An experimental and numerical investigation was conducted to determine the film cooling effectiveness of a normal slot and angled slot under realistic engine Mach number conditions. Freestream Mach numbers of 0.65 and 1.3 were tested. For the normal slot, hot gas ingestion into the slot was observed at low blowing ratios (M < 0.25). At high blowing ratios (M > 0.6) the cooling film was observed to â lift offâ from the surface.
For the 30o angled slot, the data was found to collapse using the blowing ratio as a scaling parameter (x/Ms). Results from the current experiment were compared with the subsonic data published to confirm this test procedure. For the angled slot, at the supersonic freestream Mach number, the current experiment shows that at the same x/Ms, the film cooling effectiveness increases by as much as 25% as compared to the subsonic case.
The results of the experiment also show that at the same x/Ms, the film cooling effectiveness of the angled slot is considerably higher than that of the normal slot, at both subsonic and supersonic Mach numbers. The flow physics for the slot tests considered here are also described with computational fluid dynamic (CFD) simulations in the subsonic and supersonic regimes.Master of Science
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Elder, Erin N. "Internal Heat Transfer and External Effectiveness Measurements for a Novel Turbine Blade Cooling Design." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/77004.
Повний текст джерелаАнотація:
Efficiency and power output of gas turbines improve with an increase in turbine inlet temperatures, and blade designers continually seek out new methods of increasing these temperatures. Increases in turbine inlet temperatures are achieved by utilizing a combination of internal convective cooling and external film-cooling. This study will evaluate several novel cooling schemes for turbine airfoils, called microcircuits. Microcircuits are placed inside the turbine blade wall, and the features turbulate the air and increase heat transfer surface area, thereby augmenting convective cooling. The coolant flow then exits internal cooling passages to the external side of the blade. Here the coolant forms a protective layer along the external surface of the blade to protect the blade from the heated mainstream flow.
In the current study, a low-speed large-scale wind tunnel facility was developed to measure internal heat transfer coefficients and external adiabatic effectiveness, using thermal liquid crystallography and infrared thermography. This test facility is unique in that it can be used to test the effects of internal cooling features on external film cooling. Results show that the highest augmentations in internal heat transfer were seen at the lowest Reynolds numbers. Internal features affected the shapes of external film-cooling contours, but the magnitudes of the spanwise averaged values did not change significantly with changes in internal geometry.Master of Science
21
Zuniga, Humberto. "Study of Discharge Coefficient and Trends in Film Cooling Effectiveness of Conical Holes with Increasing Diffusion Angles." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3578.
Повний текст джерелаАнотація:
Previous studies indicate that increasing the diffusion angle in conical film-cooling holes leads to an improvement in their film cooling effectiveness. Discharge coefficient and film cooling effectiveness measurements are conducted to characterize this behavior. Part of the focus of this investigation is to find out how this trend develops and attempt to ascertain the optimum cone angle, if possible. Six test plates, each with one row of eight conical-shaped cooling holes of equal diffusion angles of 0, 1, 2, 3, 6, or 8 [degrees], with respect to the hole axis are used in this study. The ratios of the hole exit areas to the inlet areas range from 1 to 2.85. Coolant injection angle for all holes is at 35 degrees to the horizontal, in the direction of the main flow. Coefficients of discharge of all holes are reported under flow conditions. Temperature sensitive paint, TSP, is the technique used to find the temperature distribution downstream of the cooling holes and determine the laterally averaged film-cooling effectiveness. Data are obtained for blowing ratios ranging from 0.5 to 1.5, at a constant density ratio of 1.26. Results and trends are compared with established literature, which also recommends that a cylindrical entry length for diffused holes should be at least 4 diameters long. The effect that an added entry length has on the 3-degree conical plate's cooling effectiveness is also explored. Data are compared to baseline cylindrical holes, as well as to fan-shaped film holes found in open literature. Results indicate that the conical holes with larger diffusion angles provide strikingly even film protection and outperform fan shaped and cylindrical holes under certain conditions over extended downstream distances. Also, the addition of a cylindrical entry length to a conical hole, by providing a manageable metering diameter, should ease their usage while providing the full benefits of the conical geometry which may one day lead to numerous industrial applications.M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
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Kullberg, James C. "An experimental and numerical study of secondary flows and film cooling effectiveness in a transonic cascade." Honors in the Major Thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/454.
Повний текст джерелаАнотація:
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.; 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 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.B.S.M.E.
Bachelors
Engineering and Computer Science
Mechanical Engineering
23
Mehlman, Bruno Philippe. "Experimental slot film cooling effectiveness measurements for varying injection angles in accelerating and non-accelerating flows." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13971.
Повний текст джерела
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La, Rosa Rivero Renzo Josue. "Effects on Heat Transfer Coefficient and Adiabatic Effectiveness in Combined Backside and Film Cooling with Short-Hole Geometry." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/97010.
Повний текст джерелаАнотація:
Heat transfer experiments were done on a flat plate to study the effect of internal counter-flow backside cooling on adiabatic film cooling effectiveness and heat transfer coefficient. In addition, the effects of density ratio (DR), blowing ratio (BR), diagonal length over diameter (L/D) ratio, and Reynolds number were studied using this new configuration. The results are compared to a conventional plenum fed case. Data were collected up to X/D =23 where X=0 at the holes, an S/D = 1.65 and L/D=1,2. Testing was done at low L/D ratios since short holes are normally found in double wall cooling applications in turbine components. A DR of 2 was used in order to simulate engine-like conditions and this was compared to a DR of 0.92 since relevant research is done at similar low DR. The BR range of 0.5 to 1.5 was chosen to simulate turbine conditions as well. In addition, previous research shows that peak effectiveness is found within this range. Infrared (IR) thermography was used to capture temperature contours on the surface of interest and the images were calibrated using a thermocouple and data analyzed through MATLAB software. A heated secondary fluid was used as 'coolant' in the present study. A steady state heat transfer model was used to perform the data reduction procedure. Results show that backside cooling configuration has a higher adiabatic film cooling effectiveness when compared to plenum fed configurations at the same conditions. In addition, the trend for effectiveness with varying BR is reversed when compared with traditional plenum fed cases. Yarn flow visualization tests show that flow exiting the holes in the backside cooling configuration is significantly different when compared to flow exiting the plenum fed holes. We hypothesize that backside cooling configuration has flow exiting the holes in various directions, including laterally, and behaving similar to slot film cooling, explaining the differences in trends. Increasing DR at constant BR shows an increase in adiabatic effectiveness and HTC in both backside cooling and plenum fed configurations due to the decreased momentum of the coolant, making film attachment to the surface more probable. The effects of L/D ratio in this study were negligible since both ratios used were small. This shows that the coolant flow is still underdeveloped at both L/D ratios. The study also showed that increasing turbulence through increasing Reynolds number decreased adiabatic effectiveness.MS
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Saland, Ariel E. "#SaveChuck: The Effectiveness of Fan Campaigns to Save Television Shows." Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/scripps_theses/262.
Повний текст джерелаАнотація:
I explore the effectiveness of fan campaigns to save television shows through the lens of audience participation and fandom studies. Beginning with a background of active audience reception theory and the evolution of fan studies, I identify what elements are necessary for a successful fan campaign. The most important factors of a successful campaign are numbers and adherence to the television economy. Using case studies, I trace the development of fan campaigns from the 1960s to the present and analyze the effectiveness of various tactics used. I also explore how the Internet, particularly social media, has changed both the perception of fans and the effectiveness of fan campaigns.
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Peravali, Anil. "PRELIMINARY STUDY ON THE IMPACT OF IMPINGEMENT ON THE EFFECTIVENESS OF FILM COOLING IN THE PRESENCE OF GAS PATH PRESSURE GRADIEN." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4224.
Повний текст джерелаАнотація:
Impingement is the most commonly used method of cooling in the hot stages of gas turbines. This is often combined with film cooling to further increase the cooling performance. The mainstream flow where in the coolant films discharge often has large stream wise pressure variations. All existing studies on coupled film and impingement cooling concentrated on the effect of the film depletion on the impingement heat transfer. This study investigates the impact of impingement on film cooling, where the jets impinging on a flat plate are depleted through arrays of film cooling holes in the presence of pressure gradient in the main gas path. The main characteristic of the test setup is that there is an impingement wall on the backside of the film effusion wall. The fluid used for both impingement flow and main flow is air. The impingement flow is heated as opposed to the usual practice of heating mainflow, and the array of film holes are configured under the impingement jet hole arrays such that there is no direct impingement on the film holes. The static pressure variations and Mach number (0.01 to 0.3) in the mainstream underneath the flat plate are controlled by inserts with varying flow area. The detailed temperature distribution on the film-covered surface is measured using the Temperature Sensitive Paint (TSP) technique, and film cooling effectiveness is calculated from the measurements. Results are presented for averaged impingement jet Reynolds numbers of 5000 and 8000. The effect of impingement on film effectiveness is studied by comparing the results from the two cases: one where film flow is directly supplied from a plenum and the other where the post- impingement flow is depleted through film effusion holes. The results are presented for cylindrical film cooling holes which are inclined at angles of 20 deg and 30 deg with respect to the target plate surface. The variation of the effectiveness of the film hole arrays along the mainstream are studied in detail. It is observed that the impingement through jet effects the pressure distribution on the target plate with film holes, which in turn affects the blowing rates of each row. The change in the blowing ratios because of a different pressure distribution on the impingement side of the target plate causes the effectiveness to change. From the results it is observed that the farther rows of impingement are affected by the pressure distribution underneath the film holes and have more flow through the film cooling rows, this increases the inlet flow of the films which increase the blowing ratios and in turn decreases the effectiveness of the film cooling holes. The pressure distribution and the change of effectiveness are studied in detail.M.S.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
27
MIRANDA, Marco. "Heat Transfer coefficient and film cooling effectiveness measurement in flat plate and cutback trailing edge vane cascade." Doctoral thesis, Università degli studi di Bergamo, 2014. http://hdl.handle.net/10446/30626.
Повний текст джерелаАнотація:
This thesis presents a dissertation about an experimental method, and a subsequent numerical data post processing, having as goal the heat transfer coefficient and adiabatic effectiveness measurement in gas turbine film cooling problems.
The present work has been developed starting from an aerodynamic characterization of a linear nozzle vane cascade, cooled at the trailing edge by a cutback geometry, mounted in a suction-type wind tunnel at University of Bergamo turbomachinery laboratory. In second instance the thermodynamic problem was studied. After a bibliographic analysis, an optimization method based on transient technique has been implemented to process the experimental data, in order to obtain film cooling effectiveness and convective heat transfer coefficients.
The second part of the thesis regards a simpler kind of problem. Indeed, in order to test the optimization method, a new series of test were performed, on a flat plate wind tunnel, allowing to develop and verify new experimental techniques (Pressure Sensitive Paints) and new procedures.
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MIRANDA, Marco. "Heat Transfer coefficient and film cooling effectiveness measurement in flat plate and cutback trailing edge vane cascade." Doctoral thesis, Università degli studi di Bergamo, 2014. http://hdl.handle.net/10446/222110.
Повний текст джерелаАнотація:
This thesis presents a dissertation about an experimental method, and a subsequent numerical data post processing, having as goal the heat transfer coefficient and adiabatic effectiveness measurement in gas turbine film cooling problems. The present work has been developed starting from an aerodynamic characterization of a linear nozzle vane cascade, cooled at the trailing edge by a cutback geometry, mounted in a suction-type wind tunnel at University of Bergamo turbomachinery laboratory. In second instance the thermodynamic problem was studied. After a bibliographic analysis, an optimization method based on transient technique has been implemented to process the experimental data, in order to obtain film cooling effectiveness and convective heat transfer coefficients. The second part of the thesis regards a simpler kind of problem. Indeed, in order to test the optimization method, a new series of test were performed, on a flat plate wind tunnel, allowing to develop and verify new experimental techniques (Pressure Sensitive Paints) and new procedures.
29
LITZLER, JEFFREY W. "COMPUTATIONAL SIMULATION AND ANALYSIS OF FILM COOLING FOR THE LEADING-EDGE MODEL OF A TURBINE BLADE." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1179521120.
Повний текст джерела
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Prausa, Jeffrey Nathaniel. "Heat Transfer Coefficient and Adiabatic Effectiveness Measurements for an Internal Turbine Vane Cooling Feature." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/76790.
Повний текст джерелаАнотація:
Aircraft engine manufacturers strive for greater performance and efficiency by continually increasing the turbine inlet temperature. High turbine inlet temperatures significantly degrade the lifetime of components in the turbine. Modern gas turbines operate with turbine inlet temperatures well above the melting temperature of key turbine components. Without active cooling schemes, modern turbines would fail catastrophically. This study will evaluate a novel cooling scheme for turbine airfoils, called microcircuit cooling, in which small cooling channels are located extremely close to the surface of a turbine airfoil. Coolant bled from the compressor passes through the microcircuits and exits through film cooling slots. On further cooling benefit is that the microcircuit passages are filled with irregular pin fin features that serve to increase convective cooling through the channels.
Results from this study indicate a strong interaction between the internal microcircuit features and the external film-cooling from the slot exit. Asymmetric cooling patterns downstream of the slot resulted from the asymmetric pin fin design within the microcircuit. Adiabatic effectiveness levels were found to be optimum for the slot design at a blowing ratio of 0.37. The pin fin arrangement along with the impingement cooling at the microcircuit entrance increased the area-averaged heat transfer by a factor of three, relative to an obstructed channel, over a Reynolds range of 5,000 to 15,000.Master of Science
31
Bastarrachea, Gutiérrez Luis Javier. "Biodegradable poly(butylene adipate-co-terephtalate) film incorporated with nisin characterization, effectiveness against Listeria innocua, and nisin release kinetics /." Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Thesis/Spring2010/l_bastarrachea_031010.pdf.
Повний текст джерелаАнотація:
Thesis (M.S. in biological and agricultural engineering)--Washington State University, May 2010.Title from PDF title page (viewed on June 14, 2010). "Department of Biological Systems Engineering." Includes bibliographical references.
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Sedněvová, Šárka. "Efektivita product placementu v závislosti na známosti značky." Master's thesis, Vysoká škola ekonomická v Praze, 2012. http://www.nusl.cz/ntk/nusl-162693.
Повний текст джерелаАнотація:
Product placement as one of the modern tools of marketing communication has become very important. This is also the case of the Czech Republic, especially after recent legislative changes and related legalization of product placement. The thesis characterizes product placement, states its particular forms and methods of evaluating its effectiveness. The aim of the thesis is to determine the difference between product placement in a situation when in an audiovisual work is presented in the first case known brand, in the second case unknown brand and in the third case fictitious brand. This is examined by the executed experiment based on watching a video with three type situations and filling in a subsequent questionnaire survey. Analysis of the survey results reveals that product placement is the most effective when displaying known brand, using unknown brand is considerably less effective and that the effectiveness of fictitious brand is the lowest. On the basis of statistical hypothesis testing, it is confirmed that there is a statistically significant relation between brand knowledge and its effectiveness.
33
Mathebula, Norman. "A case study of the EIA for the Cape Town Film Studio : factors that undermine or underpin EIA effectiveness." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/4781.
Повний текст джерелаАнотація:
Includes abstract.Includes bibliographical references (leaves 93-100).
This case study is based in South Africaand in particular in the Western Cape province. The case study was reviewed for the purpose of evaluating its EIA effectiveness in which all the EIA stages from project design to follow up were revisited and analysed against criteria for effectiveness.
34
Al-Zurfi, Nabeel. "Large eddy simulation of cooling practices for improved film cooling performance of a gas turbine blade." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/large-eddy-simulation-of-cooling-practices-for-improved-film-cooling-performance-of-a-gas-turbine-blade(966b0252-4b0e-45de-9c1f-effe007261b0).html.
Повний текст джерелаАнотація:
The Large Eddy Simulation approach is employed to predict the flow physics and heat transfer characteristics of a film-cooling problem that is formed from the interaction of a coolant jet with a hot mainstream flow. The film-cooling technique is used to protect turbine blades from thermal failure, allowing the gas inlet temperature to be increased beyond the failure temperature of the turbine blade material in order to enhance the efficiency of gas turbine engines. A coolant fluid is injected into the hot mainstream through several rows of injection holes placed on the surface of a gas turbine blade in order to form a protective coolant film layer on the blade surface. However, due to the complex, unsteady and three-dimensional interactions between the coolant and the hot gases, it is difficult to achieve the desired cooling performance. Understanding of this complex flow and heat transfer process will be helpful in designing more efficiently cooled rotor blades. A comprehensive numerical investigation of a rotating film-cooling performance under different conditions is conducted in this thesis, including film-cooling on a flat surface and film-cooling on a rotating gas turbine blade. The flow-governing equations are discretised based on the finite-volumes method and then solved iteratively using the well-known SIMPLE and PISO algorithms. An in-house FORTRAN code has been developed to investigate the flat plate film-cooling configuration, while the gas turbine blade geometry has been simulated using the STAR-CCM+ CFD commercial code. The first goal of the present thesis is to investigate the physics of the flow and heat transfer, which occurs during film-cooling from a standard film hole configuration. Film-cooling performance is analysed by looking at the distribution of flow and thermal fields downstream of the film holes. The predicted mean velocity profiles and spanwise-averaged film-cooling effectiveness are compared with experimental data in order to validate the reliability of the LES technique. Comparison of adiabatic film-cooling effectiveness with experiments shows excellent agreement for the local and spanwise-averaged film-cooling effectiveness, confirming the correct prediction of the film-cooling behaviour. The film coverage and film-cooling effectiveness distributions are presented along with discussions of the influence of blowing ratio and rotation number. Overall, it was found that both rotation number and blowing ratio play significant roles in determining the film-cooling effectiveness distributions. The second goal is to investigate the impact of innovative anti-vortex holes on the film-cooling performance. The anti-vortex hole design counteracts the detrimental kidney vorticity associated with the main hole, allowing coolant to remain attached to the blade surface. Thus, the new design significantly improves the film-cooling performance compared to the standard hole arrangement, particularly at high blowing ratios. The anti-vortex hole technique is unique in that it requires only readily machinable round holes, unlike shaped film-cooling holes and other advanced concepts. The effects of blowing ratio and the positions of the anti-vortex side holes on the physics of the hot mainstream-coolant interaction in a film-cooled turbine blade are also investigated. The results also indicate that the side holes of the anti-vortex design promote the interaction between the vortical structures; therefore, the film coverage contours reveal an improvement in the lateral spreading of the coolant jet.
35
Blades, Rae. "A cost-effectiveness analysis of a silicone film-forming gel versus 10% glycerine in patients with head and neck cancer." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/198193/1/Rae_Blades_Thesis.pdf.
Повний текст джерелаАнотація:
Radiation dermatitis is one of the most common and difficult to manage side effects for patients with head and neck cancer undergoing radiotherapy. This thesis involved a trial based economic evaluation of a silicone gel (StrataXRT®) versus 10% Glycerine (Sorbolene) in the management of radiation dermatitis in patients with head and neck cancer. The study highlighted the importance of undertaking robust economic evaluations to inform health service managers' decision making about resource use. The use of silicone and other gels remains a promising area for future research.
36
Wigle, James Michael. "Heat transfer, adiabatic effectiveness and injectant distribution downstream of single and double rows of film-cooling holes with compound angles." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/27076.
Повний текст джерелаАнотація:
Approved for public release: Distribution is unlimitedExperimental results are presented which describe the development and structure of flow downstream of one row and downstream of two staggered rows of film-cooling holes with compound angle orientations. Results presented include distributions of iso-energetic Stanton number ratios, and adiabatic film-cooling effectiveness deduced from Stanton numbers using superposition. Also presented are plots showing the streamwise development of injectant distributions and streamwise development of mean velocity distributions. Spanwise averaged values of the adiabatic film-cooling effectiveness are highest for blowing ratio m=0.5 and decrease as blowing ratio increases for x/d less than 20. At farther downstream positions, spanwise averaged effectiveness values increase with blowing ratio, except for data obtained downstream of two rows of holes with a blowing ratio of 3.0 and data obtained downstream of two rows of holes with a blowing ratio of 3.0 and data obtained downstream of one row of holes with a blowing ratio of 4.0, where severe lift-off of injectant occurs. Spanwise averaged iso-energetic Stanton number ratios range between 1.0 and 1.4 and show little variation as x/d increases for each value of blowing ratio, however for each x/d, values increase with increasing blowing ratio.
37
Bishop, David Turner. "Heat transfer, adiabatic effectiveness and injectant distributions downstream of single and double rows of film-cooling holes with compound angles." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241095.
Повний текст джерелаАнотація:
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 1990.Thesis Advisor(s): Ligrani, Phillip M. ; Subramanian, Chelakara S. "September 1990." Description based on title screen viewed on December 16, 2009. DTIC Descriptor(s): Velocity, angles, injection, distribution, films, boundary layer, surfaces, holes(openings), power, mean, film cooling, pressure distribution, adiabatic conditions, downstream flow, heat transfer. DTIC Identifier(s): Film colling. Author(s) subject terms: Compound angel injection, embedded vortex, film-cooling, turbulent boundary layer. Includes bibliographical references (p. 134-135). Also available in print.
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Chua, Khim Heng. "Experimental characterisation of the coolant film generated by various gas turbine combustor liner geometries." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/12704.
Повний текст джерелаАнотація:
In modern, low emission, gas turbine combustion systems the amount of air available for cooling of the flame tube liner is limited. This has led to the development of more complex cooling systems such as cooling tiles i.e. a double skin system, as opposed to the use of more conventional cooling slots i.e. a single skin system. An isothennal experimental facility has been constructed which can incorporate 10 times full size single and double skin (cooling tile) test specimens. The specimens can be tested with or without effusion cooling and measurements have been made to characterise the flow through each cooling system along with the velocity field and cooling effectiveness distributions that subsequently develop along the length of each test section. The velocity field of the coolant film has been defined using pneumatic probes, hot-wire anemometry and PIV instrumentation, whilst gas tracing technique is used to indicate (i) the adiabatic film cooling effectiveness and (ii) mixing of the coolant film with the mainstream flow. Tests have been undertaken both with a datum low turbulence mainstream flow passing over the test section, along with various configurations in which large magnitudes and scales of turbulence were present in the mainstream flow. These high turbulence test cases simulate some of the flow conditions found within a gas turbine combustor. Results are presented relating to a variety of operating conditions for both types of cooling system. The nominal operating condition for the double skin system was at a coolant to mainstream blowing ratio of approximately 1.0. At this condition, mixing of the mainstream and coolant film was relatively small with low mainstream turbulence. However, at high mainstream turbulence levels there was rapid penetration of the mainstream flow into the coolant film. This break up of the coolant film leads to a significant reduction in the cooling effectiveness. In addition to the time-averaged characteristics, the time dependent behaviour of the .:coolantfilm was. also investigated. In particular, unsteadiness associated with large scale structures in the mainstream flow was observed within the coolant film and adjacent to the tile surface. Relative to a double skin system the single skin geometry requires a higher coolant flow rate that, along with other geometrical changes, results in typically higher coolant to mainstream velocity ratios. At low mainstream turbulence levels this difference in velocity between the coolant and mainstream promotes the generation of turbulence and mixing between the streams so leading to some reduction in cooling effectiveness. However, this higher momentum coolant fluid is more resistant to high mainstream turbulence levels and scales so that the coolant film break up is not as significant under these conditions as that observed for the double skin system. For all the configurations tested the use of effusion cooling helped restore the coolant film along the rear of the test section. For the same total coolant flow, the minimum value of cooling effectiveness observed along the test section was increased relative to the no effusion case. In addition the effectiveness of the effusion patch depends on the amount of coolant injected and the axial location of the patch. The overall experimental data suggested the importance of the initial cooling film conditions together with better understanding of the possible mechanisms that results in the rapid cooling film break-up, such as high turbulence mainstream flow and scales, and this will lead to a more effective cooling system design. This experimental data is also thought to be ideal for the validation of numerical predictions.
39
Natsui, Gregory. "Surface Measurements and Predictions of Full-Coverage Film Cooling." Master's thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5351.
Повний текст джерелаАнотація:
Full-coverage film cooling is investigated both experimentally and numerically. First,surface measurements local of adiabatic film cooling effectiveness and heat transfer augmentation for four different arrays are described. Reported next is a comparison between two very common turbulence models, Realizable k-epsilon and SST k-omega, and their ability to predict local film cooling effectiveness throughout a full-coverage array. The objective of the experimental study is the quantification of local heat transferaugmentation and adiabatic film cooling effectiveness for four surfaces cooled by large, both in hole count and in non-dimensional spacing, arrays of film cooling holes. The four arrays are of two different hole-to-hole spacings (P=D = X=D = 14.5; 19.8) and two different hole inclination angles (alpha = 30°; 45°), with cylindrical holes compounded relative to the flow(beta = 45°) and arranged in a staggered configuration. Arrays of up to 30 rows are tested so that the superposition effect of the coolant film can be studied. In addition, shortened arrays of up to 20 rows of coolant holes are also tested so that the decay of the coolant film following injection can be studied. Levels of laterally averaged effectiveness reach values as high as η = 0.5, and are not yet at the asymptotic limit even after 20 - 30 rows of injection for all cases studied. Levels of heat transfer augmentation asymptotically approach values of h=h0 ≈ 1.35 rather quickly, only after 10 rows. It is conjectured that the heat transfer augmentation levels off very quickly due to the boundary layer reaching an equilibrium in which the perturbation from additional film rows has reached a balance with the damping effect resulting from viscosity. The levels of laterally averaged adiabatic film cooling effectiveness far exceeding eta = 0.5 are much higher than expected.
The heat transfer augmentation levels off quickly as opposed to the film effectiveness which continues to rise (although asymptotically) at large row numbers. This ensures that an increased row count represents coolant well spent. The numerical predictions are carried out in order to test the ability of the two most common turbulence models to properly predict full-coverage film cooling. The two models chosen, Realizable k-epsilon (RKE) and Shear Stress Transport k-omega (SSTKW), are both two-equation models coupled with Reynolds Averaged governing equations which makeseveral gross physical assumptions and require several empirical values. Hence, the models are not expected to provide perfect results. However, very good average values are seen tobe obtained through these simple models. Using RKE in order to model full-coverage film cooling will yield results with 30% less error than selecting SSTKW.M.S.A.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Aerospace Engineering; Thermofluid Aerodynamic Systems
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Rozati, Ali. "Large Eddy Simulation of Leading Edge Film Cooling: Flow Physics, Heat Transfer, and Syngas Ash Deposition." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/30127.
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The work presented in this dissertation is the first numerical investigation conducted to study leading edge film cooling with Large Eddy Simulation (LES). A cylindrical leading edge with a flat after-body represents the leading edge, where coolant is injected with a 30Ë compound angle. Three blowing ratios of 0.4, 0.8, and 1.2 are studied. Free-stream Reynolds number is 100,000 and coolant-to-mainstream density ratio is unity. At blowing ratio of 0.4, the effect of coolant inlet condition is investigated. Results show that the fully-turbulent coolant jet increases mixing with the mainstream in the outer shear layer but does not influence the flow dynamics in the turbulent boundary layer at the surface. As a result, the turbulent jet decreases adiabatic effectiveness but does not have a substantial effect on the heat transfer coefficient. At B.R.=0.4, three types of coherent structures are identified which consist of a primary entrainment vortex at the leeward aft-side of the coolant hole, vortex tubes at the windward side of the coolant hole, and hairpin vortices typical of turbulent boundary layers produced by the turbulent interaction of the coolant and mainstream downstream of injection. At B.R. = 0.8 and 1.2, coherent vortex tubes are no longer discernable, whereas the primary vortex structure gains in strength. In all cases, the bulk of the mixing occurs by entrainment which takes place at the leeward aft-side of the coolant jet. This region is characterized by a low pressure core and the primary entrainment vortex. Turbulent shear interaction between coolant jet and mainstream increases substantially with blowing ratio and contributes to the dilution of the coolant jet. As a result of the increased mixing in the shear layer and primary structure, adiabatic effectiveness decreases and heat transfer coefficient increases with increase in blowing ratio.
The dissertation also investigates the deposition and erosion of Syngas ash particles in the film cooled leading edge region. Three ash particle sizes of 1, 5, and 10 microns are investigated at all blowing ratios using Lagrangian dynamics. The 1 micron particles with momentum Stokes number St = 0.03 (based on approach velocity and cylinder diameter), show negligible deposition/erosion. The 10 micron particles, on the other hand with a high momentum Stokes number, St = 3, directly impinge and deposit on the surface, with blowing ratio having a minimal effect. The 5 micron particles with St=0.8, show the largest receptivity to coolant flow and blowing ratio. On a mass basis, 90% of deposited mass is from 10 micron particles, with 5 micron particles contributing the other 10%. Overall there is a slight decrease in deposited mass with increase in blowing ratio. About 0.03% of the total incoming particle energy can potentially be transferred as erosive energy to the surface and coolant hole, with contribution coming from only 5 micron particles at B.R.=0.4 and 0.8, and both 5 and 10 micron particles at B.R.=1.2.Ph. D.
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Polanka, Marcus Damian. "Detailed film cooling effectiveness and three component velocity field measurements on a first stage turbine vane subject to high freestream turbulence /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Ciriello, Salvatore. "Heat transfer, adiabatic effectiveness and injectant distributions downstream of single and double rows of film-cooling holes with simple and compound angles." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28257.
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Rocque, Ryan K. "A Study of the Effectiveness of Annotations in Improving the Listening Comprehension of Intermediate ESL Learners." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2370.pdf.
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Jackson, Stephen Mark. "Heat transfer, adiabatic effectiveness and injectant distributions downstream of single rows and two staggered rows of film-cooling holes with simple and compound angles." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28258.
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Blake, Sarah Anne. "Turbine blade platform film cooling with simulated stator-rotor purge flow with varied seal width and upstream wake with vortex." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1340.
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Chen, Xiaoyun Linda. "External organizational learning and firm performance." View the Table of Contents & Abstract, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38289015.
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Chen, Xiaoyun Linda, and 陳晓云. "External organizational learning and firm performance." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39311673.
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Thornblad, David Bengt. "The Effects of Firm Experience and Relational Resources on Firm Product Development Capabilities." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64302.
Повний текст джерелаАнотація:
Given that the focus of strategic management research is understanding the determinants of firm performance, and that product development capabilities have been shown to influence firm performance, the research question this dissertation attempts to answer is: what factors influence a firm's product development capabilities? Building on the resource based view and evolutionary theory, this dissertation proposes that firms leverage knowledge generating resources to modify or develop their routines. Firm level routines are theorized to influence the capabilities of the firm. This dissertation focuses on two firm-level product development capabilities: effectiveness and efficiency. Effectiveness refers to a firm's ability to develop desirable products and efficiency refers to the firm's ability to develop those products quickly.
The knowledge generating resources this dissertation examines is the firm's prior experience in product development and the firm's relational resources pertinent to product development. Specifically, this dissertation develops theory on four types of experience: market niche, component technology, platform technology, and general product development. Additionally, theory is developed regarding the effects of platform relational resources, as well as the breadth and depth of co-developers a firm utilizes in the development of their products.
Using the videogame development industry as the empirical context, few hypothesized relationships are statistically or substantively significant. Prior experience with component technologies lowered the effectiveness of a firm' product development capabilities, but were found to increase efficiency. In addition, older firms tended to create more desirable products
despite controlling for the four types of experience which may suggest that the age of the firm contributes something to the firm's ability to create desirable products beyond specific types of experience.
This dissertation makes contributions to the theory on how capabilities are developed and enhanced by introducing mechanisms regarding how firms can leverage knowledge generating resources to improve their capabilities. More specifically, this dissertation provides contributes to the product development literature as well as the literature on how experience and relational resources influence a firm's product development capabilities.Ph. D.
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McDermott, Margaret A. "An empirical investigation of core competence and firm performance." Click to access the dissertation via PQDT Click to view the dissertation via Digital dissertation consortium, 2003.
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Mesani, Anele. "How organisational behaviour is influenced in an acquired firm." Thesis, Nelson Mandela Metropolitan University, 2014. http://hdl.handle.net/10948/9925.
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In the current global market, companies are forming partnerships with other organisations with the aim of sustaining their competitive advantage. Most organisations participate in transactions such as mergers, acquisitions and joint ventures in order to maintain their competitive advantage (Sorge, 2002). South Africa forms part of the global market and is not immune towards the stipulated growth strategies. It is believed that South Africa has one of the highest unemployment rate internationally (Human Capital Mangement, 2005). There are various reasons that have contributed towards this perception; factors such as structural changes in the labour market have been highlighted as one of the factors that have contributed to the high unemployment rate (HCM, 2005). It is further said that when mergers and acquisitions occurs, structural changes are bound to occur (Greeve, 2008). Despite the constant merger activities that are occurring in various industries, research has shown that most mergers add no value or reduce shareholders value for the acquiring firm (Kusewitt, 2007). The primary objective of this research is to investigate how organisational behaviour is influenced in an acquired firm.There seems to be high level of uncertainity, trust and communication breakdown amoung employees of Kansai Plascon. This research will investigate whether this perception is related to the acquisition transaction that has occurred. The study will collect its primary data using a set of questionnaires that will be distributed to the employees of Kansai Plascon. The data will be analysed and interpreted.