Ph. D.

This thesis is an experimental and numerical full-coverage film cooling study. The objective of this work is the quantification of local heat transfer augmentation and adiabatic film cooling effectiveness for two full-coverage film cooling geometries. Experimental data was acquired with a scientific grade CCD camera, where images are taken over the heat transfer surface, which is painted with a temperature sensitive paint. The CFD component of this study served to evaluate how well the v2-f turbulence model predicted film cooling effectiveness throughout the array, as compared with experimental data. The two staggered arrays tested are different from one another through a compound angle shift after 12 rows of holes. The compound angle shifts from ?=-45° to ?=+45° at row 13. Each geometry had 22 rows of cylindrical film cooling holes with identical axial and lateral spacing (X/D=P/D=23). Levels of laterally averaged film cooling effectiveness for the superior geometry approach 0.20, where the compound angle shift causes a decrease in film cooling effectiveness. Levels of heat transfer augmentation maintain values of nearly h/h0=1.2. There is no effect of compound angle shift on heat transfer augmentation observed. The CFD results are used to investigate the detrimental effect of the compound angle shift, while the SST k-? turbulence model shows to provide the best agreement with experimental results.

This report describes the development and application of a validated Computational Fluid Dynamics (CFD) modelling approach for internal cooling passages in rotating turbomachinery. A CFD Modelling approach and accompanying assumptions are tuned and validated against academically available experimental results for various serpentine passages. Criteria of the CFD modelling approach selected for investigation into advanced internal cooling flows include accuracy, robustness, industry familiarity, and computational cost. Experimental data from NASA HOST (HOt Section Technology), Texas A&M, and University of Manchester tests are compared to RANS CFD results generated using Fluent v14.5 in order to benchmark a CFD modelling approach. Capability of various turbulence models in the representation of cooling physics is evaluated against experimental data. Model sensitivity to boundary conditions and mesh density is also evaluated. The development of a validated computational model of internal turbine cooling channels with bounded error allows for the identification of particular shortcomings of heat transfer correlations and provides a baseline for future CFD based exploration of internal turbine cooling concepts.

This thesis describes the modifications made to the Cal Poly Thermal Science Laboratory’s steam turbine experiment. While the use of superheating or reheating is commonly used to increase efficiency in a Rankine cycle the methods prove unfeasible in a small scale project. For this reason, a mathematical model and proof of concept design using hydrostatic head generated by elevation and venturi ejection for use by the condenser is developed along with the equations needed to predict the changes to the system. These equations were used to create software to predict efficiency as well as lay down the foundation for future improvements of the system.

This work discusses the modification and analysis of the Blue Thermal Vacuum Chamber (TVAC) located at the Space Environments Lab at California Polytechnic State University, San Luis Obispo. The modified design has a cylindrical test section and can accommodate 6U Cubesats or larger for educational or research purposes. The sizing process for the modified shroud cooling system and modular heating plates is discussed. The modified cooling system uses existing nitrogen plumbing into the chamber and control systems with a new copper shroud. The modified heating system uses modular heater plates, which utilize the existing three heater strips. The modified system includes high emissivity coatings for improved heat transfer performance, lower thermal mass materials to minimize thermal mass and liquid nitrogen consumption, and modular components for flexibility in operation. Analysis presented shows correlation between experimental results and a steady state thermal model using SolidWorks and SolidWorks Flow Simulation. The results demonstrate a maximum absolute difference in modeled vs experimental temperatures at measured locations of 11C in all cases, and 3C for test article temperatures only. Chamber performance is compared and characterized through a series of thermal vacuum tests and demonstrates capability exceeding ISO 19683 requirements for all thermal vacuum chamber testing categories except tolerance, with a tested temperature range of -145C at the shroud to 95C at the heater plates, >10 cycles between -15C and 55C, dwells in excess of 3 hours, ramp rates of 1-2C/min, and chamber pressures under

A method of performing local transient heat flux measurements in an uncooled axisymmetric hybrid rocket nozzle is presented. Surface temperatures are collected at various axial locations during short duration tests and post processed using finite difference techniques to determine local transient heat fluxes and film coefficients. Comparisons are made between the collected data and the complete Bartz model. Although strong agreement is observed in certain sections of the nozzle, ideal steady state conditions are not observed to entirely validate the Bartz model for hybrid rocket nozzles. An experimental error analysis indicates the experimental heat fluxes are accurate within ±5.2% and supports the accuracy of the results.

Superhydrophobic (SH) surfaces are characterized by their extraordinary water repellent qualities. When water comes in contact with these surfaces, it beads up and rolls around. This phenomenon is due partially to surface chemistry which promotes weak adhesive forces between liquid and solid. However, micro- and nanoscale surface roughness also plays a crucial role by trapping air beneath the liquid, reducing liquid-solid contact. Many advantages of these surfaces have been identified, including drag reduction and self-cleaning properties, and the body of research regarding them has grown rapidly over the past few decades.This thesis is concerned with water droplets impinging superheated, superhydrophobic surfaces. In these scenarios, boiling is common in the droplet, producing vapor bubbles which burst through the droplet lamella and cause a spray of miniscule water particles known as thermal atomization. The work contained in this thesis uses an image processing technique to quantify trends in thermal atomization intensity during droplet impingement scenarios for a range of surface microstructure configurations, superheat temperatures, and Weber numbers.In one study, droplet impingement on a smooth hydrophobic and three post-patterned SH surfaces of similar solid fraction is considered. In general, as pitch (center-to-center distance between posts) increases, atomization intensity decreases. This is attributed to the enhanced ability for vapor escape beneath the droplet that is present for wider pitch surfaces. Atomization intensity increases with increasing Weber number for each of the surfaces considered. Additionally, the Leidenfrost point is found to increase with increasing Weber number and decreasing pitch.Next, thermal atomization on SH surfaces with two distinct microstructure configurations is considered: square posts (which allow vapor escape between structures) and square holes (which block vapor escape). Tests are done for each configuration with varying microstructure height, and structure spacing and solid fraction are held constant. Comparing the two configurations at each structure height and Weber number, the post-patterned surfaces suppress atomization for a large number of scenarios compared to the hole surfaces, supporting the theory that vapor escape through microstructures suppresses atomization. Microstructure height significantly affects trends in atomization intensity with surface temperature and Weber number. The LFP is seen to decrease with increasing height.

This thesis describes an experimental study of the air flow in ventilating ducts in the stators of electric motors and/or generators of conventional design. The objective was to facilitate prediction of local heat transfer coefficients in ventilating ducts. Various flow phenomena were observed and compared with theoretical predictions. While the theory usually used for similar cases was found o be inapplicable, a related theory was found that checked well with experimental results. A stall phenomenon was observed under certain identified conditions. Useful relationships for predicting the flow details were obtained. The relevance of the work is discussed and future work is proposed. / Thesis / Master of Engineering (MEngr)

Page iii was not included in the thesis. / Abstract Not Provided. / Thesis / Master of Engineering (MEngr)

Around the world, the energy over consumption issue has been one of the key socio-economic and political challenges, which has drastically worsened over the last few years. Over the years engineers and environmentalists have proposed several approaches to improve energy efficiency. One is to reduce energy demand by improving consumption habits and a second approach is to introduce the use of a "greener" concept by using biomaterials in a diverse and more efficient manner in engineering construction to create energy efficient environments. This work will investigate the effects of using "green" stabilized earth materials to provide and enhance thermal regulation for indoor environments. This effects can be compared to what skin does to regulate body temperature in humans, animals, and plants. On this effort the thermal behavior of several biomaterials will be analyzed using a computational tool in order to test the mechanical properties of biomaterials and also several geometry configurations to minimize the energy needed for heating and cooling an environment. In this research a localized radial basis function (LRBF) meshless method, developed by the Computational Mechanics Lab (CML) at the University of Central Florida, has been implemented to test several wall geometrical configuration using known biomaterials such as clay. The advantage of using the LRBF meshless method in this particular research is based in the accuracy of the numerical method and also because it decreases computation time regardless of model complexity geometry without the need of mesh generation. This research includes a complete description of the LRBF meshless method, as well as a quantification of cooling methods that have been used by past civilizations and recent construction standards but have not been validated on scientific basis. Results are presented which will demonstrate the effectiveness of using integrated sheets of biomaterials in engineering construction to increase energy efficiency in indoor environments.