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I detta arbete har energisimuleringsprogrammet IDA ICE utvärderats genom att simuleringar gjorda i detta program jämförts med simuleringar gjorda i CFD-programmet ANSYS Fluent. Modeller i form av ett kvadratiskt kontorsrum med fönster ställdes upp för ett basfall i de båda programmen och parametern operativ temperatur jämfördes. För att se hur förändringar i modellerna påverkade resultatet ställdes ett antal nya fall upp där olika parametrar varierades. Variablerna som en i taget ändrades vid uppställningar av nya simuleringsfall var: rumshöjd, U-värde på fönstret, deplacerande istället för omblandande ventilation, radiator istället för golvvärme, tilluftstemperatur, mätpunktens placering samt hur till-och frånluftsdonen placerades. Resultatet av simuleringarna visade att den operativa temperaturen höll sig på en relativt konstant nivå för de olika fallen i IDA ICE, medan värdet på denna parameter varierade för de olika fallen vid CFD-simuleringarna. Slutsatsen som dras av detta är att IDA ICE är bra för generella beräkningar av operativ temperatur och termisk komfort, men att denna parameter inte bör användas vid optimering av systemet i IDA ICE eftersom programmet inte tar hänsyn till luftrörelser och hur don är placerade.

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.

Today's educators are in need of tests or rating systems that provide specific and valid feedback to parents, students and programs. This need includes the area of expressive fluent oral reading. One way to address this need is to provide a rating system based on theoretical models that explore how fluency develops. This study explores the dimensions, constructs, or aspects that make up fluency. It also explores whether there is a sequence or order in how fluent oral reading with expression develops and the theoretical reasons for that ordering. This study further addresses whether word recognition or accuracy confounds the ratings of other aspects of fluency. Such issues may affect the reading community's approach to the teaching of fluency in the schools. For, if there is a developmental ordering of constructs that make up fluency, or if it is found that accuracy (word recognition) is separate from fluency, knowledge of such an ordering and separation can influence paradigms of how we as educators view present approaches to the teaching of reading in the classroom, especially in how we build our students' fluent oral reading skills. The researcher developed a rating scale to measure fluent oral reading with expression. He found that there are two dimensions providing the most meaningful interpretation to expressive fluent oral reading: accuracy and fluency. The author provides the rationale and empirical evidence that there is a learning order of subordinate constructs belonging to the fluency dimension. This order, as determined by a many-facets Rasch analysis, is (a) phrasing, (b) smoothness, (c) rate, (d) expression, and (e) confidence. When accuracy is used in the same Rasch analysis, it was found to be easier than phrasing, showing that the method used to select texts easy enough for students was successful. Accuracy was used as a control dimension to assure that fluency constructs could be observed by avoiding confounding the observations of fluent oral reading with word knowledge problems. Each construct consists of at least two descriptors or indicators, totaling 14 indicators in all. Three indicators load together on accuracy, and ten load together on fluency. An indicator designed for fluency, Smoothness 2: No Repeats, also loads on accuracy when included in the factor analysis, but it was found not to be a good indicator of accuracy or fluency. This clarification of number of dimensions and ordering constitutes the beginnings of a domain theory of fluent oral reading with expression (FORE) which provides an empirical description of the developmental sequence of progressive attainments that the average learner achieves on the two primary dimensions.

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Scoops are important parts in an aircraft engine design, as they provide airflowto different equipment and subsystems. The optimization of such a component isessential in order to find a design that can perform properly within a range of flightconditions, with a minimum impair of main flow aerodynamic performances. Scoopdesign methods are generally based on previous experimental results and are usuallyconstrained by the limited space available. The studied configuration concerns theflush scoop located inside the secondary flow of turbofans which provides flow fora turbine cooling equipment. Depending on flight conditions and engine workingpoint, this scoop will experience various flow regimes, from low mass flow rates tochoke flows. Therefore, the study of several scooped mass flow rates is mandatoryto extract the scoop behaviour. The thesis concerns the preliminary step beforea 3D CFD optimization : a study of influence is run on the baseline geometry inorder to investigate the robustness of the solution computed using different methodsand to determine the parameters to be optimized. Firstly, the full post-processingmethodology is defined to properly evaluate the performance of a design (scoopefficiency, induced pressure losses). A second step consists in analysing the abilityof CFD solvers to capture the different flow behaviour. This point is addressed bycomparing solvers (Fluent, elsA, PowerFLOW), meshes (structured, unstructured)and turbulence models. The third step deals with the optimization strategy definitionto improve the scoop design and thus the engine fuel consumption.

The use of Computational Fluid Dynamics (CFD) tools throughout the engineering industry has become standard. Simulations are used during nearly all steps throughout the life cycle of products including design, production, and testing. Due to their wide range of use, industrial CFD codes are becoming more flexible and easier to use. These commercial codes require robustness, reliability, and efficiency. Consequently, linear eddy viscosity models (LEVM) are used to model turbulence for an increasing number of flow types. LEVM such as k-ε and k-ω provide modeling with little loss of computational efficiency and have proven to be robust. The LEVM that are most common in CFD tools, however, are not adequate for accurate prediction of complex flows. This includes flows with high streamline curvature, strong rotation and separation regions. Unfortunately, due to their ease of use in the commercial CFD tools, the models are used frequently for complex flows. Modifications have been made to LEVM such as k-ε in order to improve modeling, but generally, the modifications have only improved modeling of less complex flows. More advanced LEVM models have been developed using elliptic relaxation equations to help resolve these issues. The ν2-f model was developed to better capture flow physics for complex flows while being applicable to general flows. It is generally considered one of the most accurate LEVMs. It does, however, have issues with stability and robustness. Several improvements have been proposed. One of the most notable is its reformulation into the ζ-f model which offers several improvements while maintaining accurate flow prediction. The model improvement is still limited by being a LEVM. While models, such as differential Reynolds stress models, do exist which are able to capture relevant flow physics in complex flows, modeling difficulties make them impractical for use in a commercial CFD code. Algebraic Reynolds stress models have attempted to bridge this gap with varying levels of success. The models express the Reynolds stress tensor as a function of different higher level tensors. This is the same process used to derive non-linear eddy-viscosity models which add extra high-order terms to the Boussinesq approximation. According to Kassinos and Reynolds, however, this technique is fundamentally flawed. These models fail to capture all relevant information about the turbulence structure. The Reynolds stresses capture information regarding the turbulent componentiality, i.e. velocity components of turbulence. The dimensionality, which carries information regarding the direction of turbulent eddies, is not modeled, however. Kassinos and Reynolds constructed a structure-based model which attempts to capture turbulent componentiality and dimensionality by expressing the Reynolds stress tensor as a function of one-point turbulence structure tensors. Their original model introduced hypothetical turbulence eddies which could be averaged and then used to relate the eddy-axis transport equation to the proper structure tensors. The ideas behind this model were adapted into several different models including the R-D model and the Q-model. These formulations were able to accurately capture the flow physics for many complex flow types especially those with mean rotation. These resulting models, however, were overly complicated for application in commercial CFD codes. These structure-based models later resulted in the development of the algebraic structure based model (ASBM). The ASBM was developed in order to ensure computational efficiency while capturing relevant turbulence physics. The ASBM uses an algebraic model for the eddy statistics which is constructed from the local mean deformation and two turbulent scales. The original turbulent scales used were the turbulent kinetic energy and the large scale vorticity. Although the model was calibrated specifically for use with the turbulent kinetic energy and large scale vorticity transport equations, the algebraic model can be used in conjunction with any scalar transport equations as long as the field distribution of turbulent kinetic energy and turbulence time scale can be obtained. Based on its formulation, the ASBM, used in combination with any scalar transport equations, should be applicable to most commercial CFD codes. The objective of this work was to implement the ζ-f model and ASBM, coupled with k-ε and v2-f, in the commercial CFD solver FLUENT and validate its performance for canonical turbulent flows including a subsonic turbulent flat-plate, S3H4 2D hill, and backward-facing step. Each turbulent flow was evaluated using various turbulence models including Spalart-Allmaras, k-ε, k-ω, k-ω-SST, v2-f, ζ-f and two ASBM formulations and compared against experimental results. The ζ-f model produced improved results for both the flat plate and backward facing step as compared to all two-equation or less turbulence models and showed similar predictive capabilities to the v2-f model. It had difficulties predicting attached flow past the S3H4 2D hill just as the v2-f model. This, however, was expected due to its basis on the v2-f model. The model was also more stable than the v2-f model during calculation of the turbulent flat plate but showed no improvement in robustness for the more complex backward facing step. The semicoupled (linear eddy viscosity model based) v2-f-ASBM’s predictive capabilities were comparable to the two equation models for the turbulent flat plate case. It performed surprisingly well for the backward facing step and matched the experimental data within experimental uncertainty. The model did, however, have problems predicting the S3H4 2D hill just as the with the v2-f model.

Propulsive capabilities on a CubeSat are the next step in advancement in the Aerospace Industry. This is no longer a quest that is being sought by just university programs, but a challenge that is being taken on by all of the industry due to the low-cost missions that can be accomplished. At this time, all of the proposed micro-thruster systems still require some form of development or testing before being flight-ready. Stellar Exploration, Inc. is developing a monopropellant micropropulsion system designed specifically for CubeSat application. The addition of a thruster to a CubeSat would expand the possibilities of what CubeSat missions are capable of achieving. The development of these miniature systems comes with many challenges. One of the largest challenges that a hot thruster faces is the ability to complete burns for the specified mission without transferring excessive heat into the propulsion tank. Due to the close proximity of the thruster to the tank, thermal standoff options are necessary to help alleviate the heat going through the system, especially while in a thermally extreme environment. This thesis examines the heat transfer that occurs within a CubeSat with an operating hydrazine monopropellant thruster. Thermal analysis of the system revealed that having a solid stainless steel barrier between the thruster and tank led to increasing temperatures greater than 400K in the propellant tank while in an environment exposed to the sun. This creates a large amount of risk for the CubeSat and its mission. The use of a thermal insulating material or a hollow barrier for the standoff decreased the risk of using this system. This creates a standoff where the heat of the propellant reaction does not reach the propellant in the tank. Therefore, the maximum temperature that the tank reaches is equivalent to the temperature of the external environment while in extreme conditions. These results create the confidence that the thermal standoffs will function as intended to protect the spacecraft and its payload during flight.

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No description available.