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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
471

Mechanical Stresses on Nasal Mucosa Using Nose-On-Chip Model

Brooks, Zachary Edward January 2019 (has links)
No description available.
472

Ungdomsromanens liv : En komparativ undersökning av tilltal i fyra samtida ungdomsromaner

Eriksson, Evelina January 2023 (has links)
Denna uppsats har i syfte att analysera tilltalen i fyra samtida ungdomsromaner: Grim (2021) av Sara Bergmark Elfgren, Fula tjejer (2020) av Johanna Lindbäck, Lisa Bjärbo och Sara Ohlsson, Bergtagen (2020) av Camilla Sten och A Good Girl’s Guide to Murder (2019) av Holly Jackson. Metoden och den huvudsakliga teorin är baserade på Barbara Walls The Narrative Voice: The Dilemma of Children’s Fiction från 1991 och hennes användning av narratologiska koncept om berättarperspektiv för att avgöra om en bok är skriven för barn. Analysen visar hur de fyra romanerna använder olika och unika sätt att tilltala de implicita unga läsarna. Den implicita författaren syns ibland via berättarens röst, beroende på vilket berättarperspektiv romanerna har. I slutändan är det dock svårt att försöka definiera ungdomslitteraturgenren på samma sätt som Wall definierar barnlitteratur. Jag menar att man skulle behöva överväga ungdomslitteraturens unika förutsättningar samt dess läsare för att försöka definiera genren ännu tydligare. / This thesis aims to analyse the narrative address of four contemporary novels for young adults: Grim (2021) by Sara Bergmark Elfgren, Fula tjejer (2020) by Johanna Lindbäck, Lisa Bjärbo och Sara Ohlsson, Bergtagen (2020) by Camilla Sten, and A Good Girl’s Guide to Murder (2019) by Holly Jackson. The method and main theory are based on Barbara Wall’s The Narrator’s Voice: The Dilemma of Children’s Fiction from 1991 and her use of narratological concepts of narrative perspective to determine if a book is written for children. The analysis shows how the four novels use unique and different approaches to address their implied young readers. The implied author can sometimes be shown through the narrator’s voice, depending on which narrative perspective the novels have. In the end, however, it is difficult to try to define the genre of young adult fiction in the same way that Wall defines the genre of children’s fiction. I argue that one would need to consider the unique conditions of young adult literature and its readers to try to define the genre even clearer.
473

Structure of 2-D and 3-D Turbulent Boundary Layers with Sparsely Distributed Roughness Elements

George, Jacob 15 July 2005 (has links)
The present study deals with the effects of sparsely distributed three-dimensional elements on two-dimensional (2-D) and three-dimensional (3-D) turbulent boundary layers (TBL) such as those that occur on submarines, ship hulls, etc. This study was achieved in three parts: Part 1 dealt with the cylinders when placed individually in the turbulent boundary layers, thereby considering the effect of a single perturbation on the TBL; Part 2 considered the effects when the same individual elements were placed in a sparse and regular distribution, thus studying the response of the flow to a sequence of perturbations; and in Part 3, the distributions were subjected to 3-D turbulent boundary layers, thus examining the effects of streamwise and spanwise pressure gradients on the same perturbed flows as considered in Part 2. The 3-D turbulent boundary layers were generated by an idealized wing-body junction flow. Detailed 3-velocity-component Laser-Doppler Velocimetry (LDV) and other measurements were carried out to understand and describe the rough-wall flow structure. The measurements include mean velocities, turbulence quantities (Reynolds stresses and triple products), skin friction, surface pressure and oil flow visualizations in 2-D and 3-D rough-wall flows for Reynolds numbers, based on momentum thickness, greater than 7000. Very uniform circular cylindrical roughness elements of 0.38mm, 0.76mm and 1.52mm height (k) were used in square and diagonal patterns, yielding six different roughness geometries of rough-wall surface. For the 2-D rough-wall flows, the roughness Reynolds numbers, based on the element height (k) and the friction velocity, range from 26 to 131. Results for the 2-D rough-wall flows reveal that the velocity-defect law is similar for both smooth and rough surfaces, and the semi-logarithmic velocity-distribution curve is shifted by an amount depending on the height of the roughness element, showing that this amount is a function of roughness Reynolds number and the wall geometry. For the 3-D flows, the data show that the surface pressure gradient is not strongly influenced by the roughness elements. In general, for both 2-D and 3-D rough-wall TBL, the differences between the two roughness patterns (straight and diagonal), as regards the mean velocities and the Reynolds stresses, are limited to about 3 roughness element heights from the wall. The study on single elements revealed that the separated shear layers emanating from the top of the elements form a pair of counter rotating vortices that dominate the downstream flow structure. These vortices, termed as the roughness top vortex structure (RTVS), in conjunction with mean flow, forced over and around the elements, are responsible for the production of large Reynolds stresses in the neighborhood of the element height aft of the elements. When these elements are placed in a distribution, the effects of RTVS are not apparent. The roughness elements create a large region of back flow behind them which is continuously replenished by faster moving fluid flowing through the gaps in the rough-wall. The fluid in the back flow region moves upward as low speed ejections where it collides with the inrushing high speed flow, thus, leading to a strong mixing of shear layers. This is responsible for the generation of large levels of turbulent kinetic energy (TKE) in the vicinity of the element height which is transported, primarily, by turbulent diffusion. As regards the 3-D rough-wall TBL, the effect of flow three-dimensionality is seen in the large skewing of the distributions of mean velocities, Reynolds stresses and TKE, aft of the elements. In general, the regions of large TKE production-rates seem to propagate in the direction of the local velocity vector at the element height. The data-sets also enable the extraction of the turbulent flow structure to better describe the flow physics of these rough-wall turbulent boundary layers. / Ph. D.
474

The Design and Development of Lightweight Composite Wall, Roof, and Floor Panels for Rigid Wall Shelter

Artman, Jeremy J 05 1900 (has links)
This thesis presents a research effort aimed at developing a stronger, lighter, and more economic shelter using rigid wall panels. Reported herein is insulation research, wall and roof panel design and testing, floor section modeling and strength calculations, and cost and weight calculations. Beginning stages focus on developing solid wall and roof panels using cold-formed steel corrugated sheathing and members, as well as polyurethane spray foam for insulation. This research includes calculating uniform load density, to determine the overall strength of the panel. The next stage focuses on the flexural strength of the wall and roof panels, as well as finalizing the floor design for the shelter. This includes determining maximum flexural strength required to meet the standards set by the project goal. Direct strength method determined the correct thickness of members to use based on the dimension selected for the design. All Phases incorporated different connection methods, with varied stud spacing, to determine the safest design for the new shelters. Previous research has shown that cold-formed steel corrugated sheathing performs better than thicker flat sheathing of various construction materials, with screw and spot weld connections. Full scale shear wall tests on this type of shear wall system have been conducted, and it was found that the corrugated sheathing had rigid board behavior before it failed in shear buckling in sheathing and sometimes simultaneously in screw connection failures. Another aspect of the research is on the insulation of the wall panels. Research was conducted on many different insulation options for the mobile facilities. Specifically, insulation made of lightweight material, is non-combustible, added rigidity to the structure, and has high thermal properties. Closed cell polyurethane spray foam was selected for full-scale testing in this research. Closed cell polyurethane adds extra rigidity, is lighter than common honeycomb insulation, and has a higher R-value. Several polyurethane foam companies were studied for this research, and promising products were identified. The research focuses on the impacts of the polyurethane foam to the structural performance of the wall panels. Both shear and 4-point bending tests were completed to investigate the strength and behavior of the cold-formed steel framed wall panels with polyurethane foam insulation. Comparing the cost and weight of the current shelter, and the new design is reported herein. The material studies, specimen details, and test results are reported in this thesis.
475

Improved Connections for Blast-Resistant Curtain Walls

Nasseralshariati, Ehsan 01 September 2023 (has links)
Curtain walls provide exterior façade to modern buildings. When subjected to blast shock waves, curtain walls may suffer significant damage, potentially causing serious injuries and casualties to building occupants. Protective films, laminated glass and strengthening of mullions and transoms are used to protect curtain wall components against blast loads. Limited research is available on blast protection of curtain wall components. On the other hand, connections of curtain wall mullions with the supporting substrate, as well as mullion-transom connections form potentially vulnerable locations under blast loads. Research on these connections is lacking in the literature. Therefore, a comprehensive research project has been undertaken in this thesis to address the behavior, analysis, and design of curtain wall connections, both between the mullions and supporting concrete slabs/beams and the mullions and transoms. The research project consists of three phases: i) Experimental research using the University of Ottawa Shock Tube as blast simulator, ii) Numerical investigation based on three-dimensional finite element method (FEM) using LS-DYNA, and iii) Non-linear dynamic analysis of curtain wall systems based on a single-degree-of-freedom (SDOF) to develop a connection design procedure. The experimental phase consisted of tests of three full-size curtain walls mounted on steel HSS sections of the Shock Tube to investigate mullion-to-transom connections and nine single mullions connected to concrete beams to investigate mullion-to-concrete substrate connection. The single mullions either represented floor-to-floor mullions or continuous mullions over the supporting slab. They were connected to concrete beams (representing floor slabs) by means of brackets, which provided high degree of rotational restraints and full translational restraints or connected through damping materials (springs or HRD rubber pads), which allowed translational movements as they dampened the effects of the shock wave. The numerical investigation involved FEM analysis and modeling of all the test specimens. The first step involved the validation of numerical models against test data. The analysis was then extended to conduct a parametric investigation to cover cases that have not been covered in the experiments. This resulted in the investigation of six different design parameters used in connection design. The numerical outcomes illustrated the importance of blast effects on connection design parameters, support reactions, curtain wall response, force and stress distributions on curtain wall components. The information gathered through experimental and numerical research on connection performance led to the formulation of a connection design procedure. Single-degree-of-freedom (SDOF) dynamic analysis technique was adopted to curtain wall analysis as a tool to compute connection design forces. Both the Uniform Facilities Criteria (UFC) charted solution (manual calculations) and two computer software developed at the University of Ottawa (RC-Blast and CW-Blast) were used to conduct SDOF analysis to validate the procedure against experimental and numerical results before they were recommended as design tools. Finally, the details of connection design are provided for different types of connections.
476

A State of the Art Review of Special Plate Shear Walls

Just, Paul J., III 28 June 2016 (has links)
No description available.
477

Developing Prefabricated, Light-weight CLT Exterior Wall Panels for Mid-rise Buildings

Sharifniay Dizboni, Houri 10 June 2024 (has links)
The building construction industry has seen the emergence of Cross Laminated Timber (CLT) as a renewable replacement for structural application of steel, concrete, and masonry. However, CLT has not been researched extensively as a nonstructural component of the building envelope/facade. In the presented research, the application of CLT is introduced in the form of lightweight CLT (CLT-L) panels and presents a framework to evaluate the opportunities and application of CLT-L panels as an alternative construction method for non-load-bearing exterior wall systems. Since exterior walls as part of the enclosure system have a significant role in energy consumption and human comfort level, the research evaluates application opportunities of the CLT panels for US climates, by conducting a life cycle environmental analysis, and a thermal evaluation of CLT-L systems for Phoenix, Arizona, and Minneapolis, Minnesota. The life cycle analysis was conducted to assess the environmental impact of a typical CLT wall system as compared to three conventional panelized wall systems. The results of the analysis have shown that CLT wall systems exhibit the lowest cumulative life cycle environmental impact indicators, including acidification potential, fossil fuel consumption, global warming potential, and human health particulate when compared to other wall systems. These results suggest that CLT wall systems could be a viable alternative to conventional panelized exterior wall systems from an environmental impact perspective. In the next step, a parametric study was conducted to determine the optimal configuration of a CLT-L wall system for enhanced thermal performance. This was achieved through dynamic thermal simulations by employing the conduction transfer algorithm and analyzing various thicknesses and locations of the thermal insulation layer. Through analysis of the annual thermal transmission load and decrement factor, the optimum insulation thicknesses for CLT wall systems in two climate regions were determined. The results showed that the exterior insulation location yields better thermal efficiency. The results of this phase were employed in the development of the CLT wall system model and conduction of a comparative parametric study on the thermal mass behavior of CLT and CMU wall systems via finite difference algorithm. One significant outcome of the simulation data analysis was the heat transfer dynamics within the CLT and CMU wall system when exterior insulation is applied. The analysis revealed that in the presence of exterior insulation, the CLT layer continues to be the primary contributor to the reduced thermal transmission of the wall. However, in the CMU mass wall configuration, the insulation layer assumes a dominant role in the reduced thermal transmission of the wall. The findings of this research present CLT as a potential environmentally efficient envelope alternative for framed buildings and provide insights into the thermal performance of CLT wall systems, which can lead to the opening of a new market for CLT panel application in the U.S. / Doctor of Philosophy / The construction industry has witnessed a notable shift with the advent of Cross Laminated Timber (CLT), presenting itself as a renewable substitute for conventional materials like steel, concrete, and masonry in structural applications. However, the potential of CLT as a building component, particularly as a component of building exteriors wall, remains relatively underexplored. This research endeavors to fill this gap by introducing lightweight CLT (CLT-L) panels, which are three-layer CLT panels, and exploring their viability as an alternative construction method for non-load-bearing exterior wall systems. Non-load bearing exterior wall panels do not carry any structural support for the building. Recognizing the significant influence of exterior walls on both energy consumption and human comfort levels, the study assesses the applicability of CLT panels across diverse climates in the United States including states Minnesota and Arizona which show exterior temperature swings. The investigation began by conducting a comprehensive life cycle environmental analysis, comparing the environmental impact of a typical CLT wall system with three conventional panelized wall systems. Results revealed that CLT wall systems exhibit the lowest cumulative life cycle environmental impact indicators suggesting their potential as a sustainable alternative. The environmental indicators included acidification potential, fossil fuel consumption, global warming potential, and human health particulates. Subsequently, a parametric study delved into optimizing the thermal performance of CLT-L wall systems through dynamic thermal simulations. The dynamic simulation considered the exterior temperature changes during the day. By varying insulation thicknesses and locations, the study identifies optimal configurations for different climate regions. Notably, the analysis underscores the efficacy of exterior insulation placement in enhancing thermal efficiency. Furthermore, the study investigated the thermal mass behavior of CLT compared to concrete block (CMU) wall systems under different scenarios. Findings revealed that while CLT retains its significance as a primary contributor to thermal mass, particularly with exterior insulation, CMU configurations see a shift in thermal mass dynamics towards the insulation layer. These findings collectively underscored the potential of CLT as an environmentally efficient envelope alternative for framed buildings, shedding light on its thermal performance and paving the way for broader adoption in the US construction industry.
478

Machine learning assisted convective wall heat transfer models for fire modeling along vertical walls, ceilings and floors

Jie Tao (18859882) 24 June 2024 (has links)
<p dir="ltr">Fires cause significant casualties and property damage. As critical component of indoor and building fires, fires along a surface (vertical or horizontal) contribute significantly to fire spreading and resulted damage. Accurately predicting the interactions between a wall surface and fire is crucial to minimizing losses. Computational methods, such as large-eddy simulations (LES), can result in errors in fire modeling along a surface due to various model and numerical errors among which the error in the convective wall heat transfer models is an important source. The convective heat transfer model error grows when the grid resolution near a thermal boundary layer along a wall surface decreases. Traditional wall-function based heat transfer models, mostly developed for forced convection heat transfer problems, tend to fail in the buoyancy-driven fire wall heat transfer. It is imperative to develop accurate and efficient convective wall heat transfer models for fire modeling.</p><p dir="ltr">In this study, machine learning is employed as an alternative to traditional physics-based modeling approach for wall heat transfer in fire modeling. A significant advantage of machine learning over physics-based modeling is that machine learning does not require thorough knowledge of fire wall heat transfer which is generally hard to acquire due to the complexity of the problem. A machine-learning assisted convective wall heat transfer model, aiming to enhance wall fire predictions, is developed in this work. The objective is to improve predictions of convective heat flux to a wall in under-resolved LES of wall fires. An amplification factor ($\beta$) is introduced to compensate the under-prediction of temperature gradients normal to a wall surface in coarse grid simulations. Machine learning is then employed to assist the construction of models for $\beta$ with the training data obtained directly from fine-resolution LES. Extensive studies are conducted to identify suitable machine learning architecture, input features, training data generation strategies, training procedure, and testing and validation approaches.</p><p dir="ltr">A vertical wall fire test case is considered first to develop a baseline machine learning model. The focus is on identifying suitable input features and training strategies for machine learning of convective wall fire heat transfer. A four-parameter (input) machine learning model for $\beta$ is constructed. Both \textit{a priori} and \textit{a posteriori} testing are developed in the vertical wall fire case to provide preliminary model performance assessment. The fully tested model is also examined in an intermediate-scale parallel-wall fire spreading case that was not seen in the model training to assess the applicability of the developed machine learning model. In general, excellent model performance is observed in the vertical wall fire case.</p><p dir="ltr">The established machine learning approach for the vertical wall case is then extended to horizontal surfaces like floor fires and ceiling fires to expand the training scope of the machine learning model. The unique challenges in these new fire scenarios are investigated separately to identify the need of additional input features and training strategies. It is found that a fifth input parameter, in addition to the four parameters identified in the vertical wall, is generally needed in order to correctly identify different fire scenarios. Data augmentation techniques are also found to be a useful technique to handle data sparsity during model training. Different machine learning architectures like random forest and deep neural network are also compared.</p><p dir="ltr">The above studies are finally integrated into a unified machine learning model suitable for both vertical and horizontal surfaces. Extensive testing shows that the unified model reproduces the model performance of the separately trained models. The work is significant in demonstrating the feasibility of using machine learning approaches to enhance fire simulations. The developed machine learning modeling techniques improve predictions in various fire scenarios by using relatively coarse grid to maintain low computational cost, a critical consideration when simulation approaches are employed in real fire simulations.</p>
479

Large-area forest assessment and monitoring using disparate lidar datasets

Gopalakrishnan, Ranjith 24 February 2017 (has links)
In the past 15 years, a large amount of public-domain lidar data has been collected over the Southeastern United States. Most of these acquisitions were undertaken by government agencies, primarily for non-forestry purposes. That is, they were collected mostly to aid in the creation of digital terrain models and to support hydrological and engineering assessments. Such data is not ideal for forestry purposes mainly due to the low pulse density per square meter, the high scan angles and low swath overlaps associated with these acquisitions. Nevertheless, the large area of coverage involved motivated this work. In this dissertation, I first look at how such lidar data (from non-forestry acquisitions) can be combined with National Forest Inventory tree height data to generate a large-area canopy height model. A simple linear regression model was developed using two lidar-based metrics as predictors: the 85th percentile of heights of canopy first returns and the coefficient of variation of the heights of canopy first returns. This model had good predictive ability over 76 disparate lidar projects, covering an area of approximately 297,000 square kilometers between them. Factors leading to the residual lack-of-fit of the model were also analyzed and quantified. For example, predictive ability was found to be better for softwood forests, forests with more homogeneous vegetation structure and for terrains with gentler slopes. Given that as much as 30% of the US is covered by public domain non-forestry lidar acquisitions, this is a first step for constructing a national wall-to-wall vertical vegetation structure map, which can then be used to ask important questions regarding forest inventories, carbon sequestration, wildlife habitat suitability and fire risk mitigation. Then, I examined whether such lidar data could be further used to predict understory shrub presence over disparate forest types. The predictability of classification model was low (accuracy = 62%, kappa = 0.23). Canopy occlusion factors and the heterogeneity of the understory layer were implicated as the main reasons for this poor performance. An analysis of the metrics chosen by the modeling framework highlighted the importance of non-understory metrics (metrics related to canopy openness and topographic aspect) in influencing shrub presence. As the proposed set of metrics were developed over a wide range of temperate forest types and topographic conditions of Southeastern US, it is expected that it will be useful for more localized future studies. Lastly, I explored the possibility of combining lidar-derived canopy height maps with Landsat-derived stand-age maps to predict plantation pine site index over large areas (site index is a measure of forest productivity). The model performance was assessed using a Monte Carlo technique (RMSE = 3.8 meters, relative RMSE = 19%). A sample site index map for large areas of Virginia and South Carolina was generated (map coverage area: 832 sq. km) and implications were discussed. Analysis of the resulting map revealed the following: (1) there is an increase in site index in most areas, compared to the 1970s, and (2) approximately 83% of the area surveyed had low levels of productivity (defined as site index < 22.0 meters for base age of 25 years). This work highlights the efficacy of combining lidar-based canopy height maps with other similar remote sensing based datasets to understand aspects of forest productivity over large areas, and to help make policy-relevant recommendations. / Ph. D. / Remote sensing, in the context of forestry and forest resource management, involves the acquisition of data over large forested areas by sensors situated at a distance. A good example is a high resolution satellite image over several hundred square kilometers allowing us to identify (say) patches of deforestation, reduced forest productivity, or species diversity. Lidar (which stands for Light Detection and Ranging) is a relatively new remote sensing technology in which the time it takes for a laser pulse to travel to a feature and return back to the sensor is used to measure how far away the feature is from the sensor. In forests, data from airborne laser scanners enable the measurement of both horizontal and vertical canopy structure (such as tree height and canopy cover). Data from airborne laser scanners have been collected over a large area of the US (roughly 30%). However, the sensors and acquisition parameters are optimized for the inexpensive collection of the data needed for topographic mapping, and not for forest measurement. Moreover, the lidar data were collected in disparate and dissimilar projects, making the production of maps over large areas technically challenging. A systematic study is required looking at whether lidar data from such dissimilar projects can be used together to generate robust forest parameter maps over large areas. This dissertation details such a study. Airborne laser scanner data collected for topographic mapping across many disparate projects can be used to estimate several important characteristics about forests. My conclusions are as follows: • Lidar data can be combined effectively with field measurement data to produce high quality, wall-towall tree height maps over a large area. • These lidar data can be used to map understory shrub presence, albeit with less accuracy, since fewer laser pulses penetrate the canopy. • Forest age, as estimated using multi temporal earth resource satellite data, can be combined with lidar-derived tree heights to estimate site index (a way to know how fast trees grow on a site) for pine plantations. Most sites in the study area (Eastern Virginia and Central South Carolina) are not particularly productive (site index <22 meters), but they are more productive on the whole than they were in the 1970s. Overall, the work outlined in this dissertation highlights the efficacy of using lidar data from disparate nonforestry projects along with other datasets to monitor useful forest parameters over large areas, and to help make policy-relevant recommendations.
480

Understanding and Exploiting Wind Tunnels with Porous Flexible Walls for Aerodynamic Measurement

Brown, Kenneth Alexander 01 November 2016 (has links)
The aerodynamic behavior of wind tunnels with porous, flexible walls formed from tensioned Kevlar has been characterized and new measurement techniques in such wind tunnels explored. The objective is to bring the aerodynamic capabilities of so-called Kevlar-wall test sections in-line with those of traditional solid-wall test sections. The primary facility used for this purpose is the 1.85-m by 1.85-m Stability Wind Tunnel at Virginia Tech, and supporting data is provided by the 2-m by 2-m Low Speed Wind Tunnel at the Japanese Aerospace Exploration Agency, both of which employ Kevlar-wall test sections that can be replaced by solid-wall test sections. The behavior of Kevlar fabric, both aerodynamically and mechanically, is first investigated to provide a foundation for calculations involving wall interference correction and determination of the boundary conditions at the Kevlar wall. Building upon previous advancements in wall interference corrections for Kevlar-wall test sections, panel method codes are then employed to simulate the wind tunnel flow in the presence of porous, flexible Kevlar walls. An existing two-dimensional panel method is refined by examining the dependency of correction performance on key test section modeling assumptions, and a novel three-dimensional method is presented. Validation of the interference corrections, and thus validation of the Kevlar-wall aerodynamic performance, is accomplished by comparing aerodynamic coefficients between back-to-back tests of models carried out in the solid- and Kevlar-wall test sections. Analysis of the test results identified the existence of three new mechanisms by which Kevlar walls cause wall-interference. Additionally, novel measurements of the boundary conditions are made during the Kevlar-wall tests to characterize the flow at the boundary. Specifically, digital image correlation is used to measure the global deformation of the Kevlar walls under wind loading. Such data, when used in conjunction with knowledge of the pre-tension in the Kevlar wall and the material properties of the Kevlar, yields the pressure loading experienced by the wall. The pressure loading problem constitutes an inverse problem, and significant effort is made towards overcoming the ill-posedness of the problem to yield accurate wall pressure distributions, as well as lift measurements from the walls. Taken as a whole, this document offers a comprehensive view of the aerodynamic performance of Kevlar-wall test sections. / Ph. D. / Traditional wind tunnels, which measure the aerodynamic behavior of vehicles and components relevant to the aerospace industry, enclose some test object with solid walls and accelerate flow around the object. A new configuration has been developed which uses instead flexible, porous walls which are formed from tensioned Kevlar fabric. The original advantage of this configuration lies in its ability to produce high fidelity measurements of the acoustic signature of a model in a stream of air. This new configuration also has been emerging as tool for making the traditional measurements of aerodynamic behavior noted above. However, special considerations have to be made for the so-called Kevlar-wall test section because of the flexibility and porosity of the walls. This study focuses on understanding and exploiting Kevlar-wall wind tunnels with the hope to bring the aerodynamic measurement capabilities of Kevlar-wall test sections in-line with those of traditional solidwall test sections. The primary facility used for this purpose is the Stability Wind Tunnel at Virginia Tech, and supporting data is provided by the Low Speed Wind Tunnel at the Japanese Aerospace Exploration Agency, both of which employ Kevlar-wall test sections that can be replaced by solid-wall test sections. The behavior of Kevlar fabric, both aerodynamically and mechanically, is first investigated to provide a foundation for calculations of the effect of the Kevlar’s porosity and flexibility on the flow around a model in the test section. Building upon previous advancements in this area, computer simulations are then employed to predict the wind tunnel flow in the presence of porous, flexible Kevlar walls. An existing two-dimensional simulation is refined by examining the dependency of the simulation on key modeling assumptions, and a novel three-dimensional method is presented. Validation of the simulations’ effectiveness in providing accurate corrections for the Kevlar porosity and flexibility is accomplished by comparing measurements between back-to-back tests of models carried out in the solid- and Kevlar-wall test sections. Additionally, novel measurements of the deflection and pressure distributions over the Kevlar walls are made during the Kevlar-wall tests. Specifically, a three-dimensional camera imaging system is used to measure the deformation of the Kevlar walls under wind loading. Such data, when used in conjunction with knowledge of the pre-tension in the Kevlar wall, yields the pressure loading experienced by the wall. Taken as a whole, this document offers a comprehensive view of the aerodynamic performance of Kevlar-wall test sections.

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