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This study is an investigation of two specific effects on turbine blade film cooling. The effect of coolant to mainstream density ratio and upstream steps was studied. The studies were conducted on two flat plates with 4mm cylindrical film cooling holes, one with simple angle and the other with compound angle, in a low-speed suction type wind tunnel. Density effect was studied at ratios of 0.93 and 1.47 by using air and CO2 as coolant. An IR camera was used to record the temperature on the plate and T-type thermocouples were used to record the coolant and mainstream temperatures. During the study the nature of the conduction effect from the heated coolant was studied and found to be most prevalent along the plate surface not through the plate from the plenum. A methodology was presented by which conduction error free results were obtained. The results showed an increased effectiveness at higher density ratios, particularly near the holes and for the simple angle plate. Upstream step effect was studied using pressure sensitive paint and a coupled strobe light and camera. Steps of 0.5, 1 and 1.5mm were placed at the upstream edge of the holes. The steps were found to increase effectiveness significantly more than previous studies have shown when placing the step slightly upstream of the holes.

CO2 injection has been used to improve oil recovery for several decades. In recent years, CO2 injection has become even more attractive because of a dual effect; injection in the subsurface 1) allows reduction of CO2 concentration in the atmosphere to reduce global warming, and 2) improves the oil recovery. In this study, the density effect from CO2 dissolution in modeling of CO2 injection is examined. A method to model the increase in oil density with CO2 dissolution using the Peng-Robinson equation of state and the Pedersen viscosity correlation is presented. This method is applied to model the observed increase in oil density with CO2 dissolution in a West Texas crude oil. Compositional simulation of CO2 injection was performed in a 2D vertical cross section and a 3D reservoir with the density effect. The results show that the density increase from CO2 dissolution may have a drastic effect on CO2 flow path and recovery performance. One main conclusion from this work is that there is a need to have accurate density data for CO2/oil mixtures at different CO2 concentrations to ensure successful CO2 injection projects. While CO2 enhanced oil recovery (EOR) is part of the solution, saline aquifers have the largest potential for CO2 sequestration. A literature review of the CO2 sequestration in saline aquifers is performed. The dominant trapping mechanisms and transport processes and the methods used to model them are discussed in detail. The Aruma aquifer, a shallow saline aquifer in southwest Qatar is used as a case study for CO2 sequestration. A compositional simulation model is prepared for the Aruma aquifer using the available log data and flow test data. It was found that the grid size is a key parameter in modeling CO2 sequestration accurately. It affects the propagation of the CO2 plume and amount of CO2 dissolved in brine.

Tethered polymer layers at solid-fluid interfaces are used widely in a variety of surface science applications. Although many of these applications require exposure to dynamic flow conditions, flow field penetration into densely grafted polymer brushes, is still a question open to debate despite the fact that it is a fundamental process crucial to mass transport through these polymer films. Although most theoretical work has indicated flow field penetration into polymer films, with varying predicted penetration depths predicted, the limited experimental attempts to investigate this phenomenon have resulted in inconsistent conclusions due to lack of a proper analytical method. To help resolve this controversy, in this Dissertation, a new spectroscopic method, FRET-TIRFM, based on a combination of Förster resonance energy transfer (FRET) and total internal reflectance fluorescence microscopy (TIRFM), is developed to provide the first direct, quantitative measurements on flow field penetration by measuring linear diffusion coefficients of small molecules through densely grafted, thin poly(N-isopropylacryl-amide) (pNIPAM) films. Decay curves from FRET of the acceptor with a donor covalently attached at the substrate surface were fit to a combined Taylor-Aris-Fickian diffusion model to obtain apparent linear diffusion coefficients of the acceptor molecules for different flow rates. These values can then be used to obtain quantitative estimates of flow field penetration depths. For a pNIPAM surface of 110 nm dry thickness, with a 0.6 chain/nm² grafting density, apparent diffusion coefficients ranging from 1.9-9.1 × 10-12 cm²/s were observed for flow rates ranging from 100 to 3000 μL/min. This increase in apparent diffusion coefficient with applied fluid flow rate is indicative of flow field penetration of the polymer film. The depth of penetration of the flow field is estimated to range from ~6% of the polymer film thickness to ~57% of the film thickness in going from 100 to 3000 μL/min flow rate of a good solvent. Factors other than flow rate that may impact flow field penetration were also investigated using this new FRET-TIRFM method. Solvent quality and polymer brush grafting density are the two most important parameters due to the fact that they influence changes in tethered polymer chain conformation. This work demonstrates that polymer films are most penetrable in a good solvent and least penetrable in a poor solvent under identical flow conditions. These findings are consistent with polymer chain conformational changes going from extended brushes to compact globules. For flow rates ranging from 100 to 3000 μL/min, flow field penetration depth ranges from ~6% of the film thickness to ~57% of film thickness for a good solvent compared to ~4% to ~19% for a poor solvent. Thus, by simply changing solvent quality from good to poor, flow field penetration decreases by about 38%. Grafting density has a less pronounced effect than solvent quality on penetration depth, probably due to the small range of grafting densities chosen for study. However, a roughly 10-20% difference in penetration depth was observed between high density (0.60 chain/nm²) and low density (0.27 chain/nm²) pNIPAM surfaces in the same solvent. Changes in grafting density have a less significant impact in a good solvent compared to a poor solvent. This is most likely caused by the fact that grafting density impacts polymer chain conformation mainly through polymer-polymer repulsion, which becomes less significant in a solvent that better solvates the polymer. For the two extreme cases studied here at flow rates ranging from 100 to 3000 μL/min, the penetration depth is estimated to range from ~4-19% of the original solvent-swollen film thickness for high density pNIPAM films in a poor solvent and from ~7-67% for low density films in a good solvent. One important assumption that underlies all of this work is that the dominant mass transport mechanism for small molecules in dense polymer brushes is diffusion. This assumption was further validated through the use of two different small molecule quenchers, RhB and 2-nitrobenzylalcohol. These molecules are significantly different in size, charge, and structure, and operate by different quenching mechanisms. Despite these differences, the results for flow field penetration are statistically the same for both. These observations validate the assumption of diffusive mass transport in these films.

Le développement actuel des moteurs doit répondre à une volonté de réduction de la consommation et à des normes de plus en plus sévères. Les moteurs Diesel, bien que performants, présentent des émissions trop importantes d'oxydes d'azote (NOx) et de particules de suies. Ces émissions polluantes proviennent essentiellement de l'existence de zones riches en carburant ne permettant pas une combustion optimale. La préparation du mélange air / carburant, fortement conditionné par l'entraînement d'air par le spray est donc essentielle. La Vélocimétrie par Images de Particules sur traceurs Fluorescents, associée à un traitement spécifique des champs de vitesses instantanés de la phase gazeuse externe sont utilisés afin d'obtenir des mesures en proche frontière du spray. Dans la zone quasi statique du spray, un effet important de la densité ambiante sur le taux de mélange est mis en évidence. D'autre part, la diminution du diamètre de trou d'injecteur améliore sensiblement le taux de mélange local. Pour compléter cette analyse, un gain du taux de mélange entre les deux injecteurs est calculé pour chaque densité ambiante. Pour les fortes densités, le gain issu de la réduction du diamètre de trou peut at! teindre une valeur importante (> 60%). La phase gazeuse latérale dans la zone instationnaire du spray est ensuite investiguée et la méthodologie de la F-PIV est transposée à cette zone. Un lien entre la longueur de pénétration du spray et des longueurs d'entraînement est défini. La densité ambiante n'a pas d'effet sur ces longueurs d'entraînement. La diminution du diamètre de trou engendre une augmentation du gaz entraîné à une distance plus courte du nez de l'injecteur. Cependant, cette étude montre que les deux sprays n'engendrent pas un entraînement de gaz similaire. / The actual development of the engine must reply to a will of fuel consumption reduction and to stricter norms concerning the pollutant emissions. Although the Diesel engines are competitive, the NOx and soot particle emissions mainly come from the existence of wealthy fuel zone preventing an optimal combustion. Therefore, the air / fuel mixing preparation, highly controlled by the air entrainment in spray, is essential. Particle Image Velocimetry on fluorescent tracers, associated with a specific processing of the instantaneous velocity fields have been applied to obtain measurements in the near vicinity of the spray edge. In the "quasi- teady" region of the spray, the important effect of the ambient density on the mixing rate has been pointed out. On the other hand, an orifice diameter decrease significantly improves the local air / fuel ratio. To complete this analyse, a gain in mixing rate between two different injectors has! been calculated for each gas density. For high densities, the gain due to a reduction of the hole diameter can reach important value (> 60%). Then, lateral gaseous phase in no stationary zone of spray is studying and F-PIV method is transposed to this zone. A link between the penetration length and entrainment lengths is defined. Ambient density has not effect on entrainment lengths. The hole diameter decrease generates entrained gas increase at shorter distance of injector nozzle. However, this study shows two sprays do not generated the same gas entrainment

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語言系統中，形音之間的映照關係為一持續受到探討的議題。本篇論文旨在利用眼動閱讀實驗以及口語理解─視覺典範深入探究閱聽中文形聲字時，音形映照之存在性及其時序歷程。 本文進行兩個眼動實驗。實驗一旨在探究視覺的閱讀歷程中，中文的音形映照於詞彙層次和次詞彙層次之歷程及影響。結果顯示，同音字密度效果未達顯著，但音形對應一致性效果於晚期眼動指標中顯著呈現。顯示出音形映照於視覺詞彙辨識的晚期產生影響，並證實語音表徵和字形表徵於視覺處理中是互為雙向影響之觀點，實驗一結果並支持音至形的反向連結映照於視覺模式中具有其重要性。實驗二主要使用口語理解─視覺典範，進一步探究並檢驗音形映照於口語詞彙辨識過程中之時序及歷程。結果顯示，音形對應一致性效果於早期眼動指標中顯著呈現，隨後同音字密度效果於晚期眼動指標中顯著呈現。此研究結果支持雙向交互激發模型(BIAM)之假設，顯示詞彙辨識機制中，存在字音和字形表徵之間的動態交互連結；並證實字形表徵於口語詞彙辨識過程中時序性的影響。 整體而論，本研究整合形音映照之概念所衍生出的形音一致性效果及同音字密度效果，就視、聽兩種模式之眼動實驗，檢視音形映照歷程，並進一步提供音形映照的實驗證據，探究其於中文語言系統的文字辨識歷程中之影響力與重要性。 / The present study aims to examine the states of phonological to orthographic (P-O) mappings when reading and listening Chinese phonograms. Two eye tracking experiments regarding to visual and auditory modalities were conducted to explore the intrinsic nature and the temporal dynamics of P-O mappings in Chinese word recognition. Experiment 1 manipulated homophone density and P-O consistency to investigate the involvement of P-O mappings at lexical and sublexical levels during the reading process. The result of Experiment 1 revealed that the P-O consistency effect was evident in second-pass eye movement indices of total viewing time (TVT) and rereading rate (RRR), demonstrating a late occurrence of P-O consistency effect at a the verification stage in reading. The occurrence of P-O consistency is in accordance with the view that the phonological information and orthographic representation are activated in a bidirectional flow, which implies that the mappings from phonology to orthography were guaranteed during the reading process. Experiment 2 utilizes visual world paradigm to explore the P-O mappings in auditory modality and further inspect the temporal dynamic in listening Chinese spoken characters. The result demonstrated that the P-O consistency effect emerged approximately 300 ms earlier than the homophone density effect, reflecting the early P-O consistency effect and the relatively late HD effect during the temporal stage of spoken word recognition. The result also supports the bidirectional activation of orthographic and phonological codes during word recognition, demonstrating the notion that the dynamic influences of orthography representation on spoken word recognition are ubiquitous at both sub-lexical and lexical levels.

農林水産研究情報センターで作成したPDFファイルを使用している。

農林水産研究情報センターで作成したPDFファイルを使用している。