Semi-actuator disk theory for compressor choke flutter

A mathematical anaysis predict the unsteady aerodynamic utilizing semi actuator theory environment for a cascade of airfoils harmonically oscillating in choked flow was developed. A normal shock is located in the blade passage, its position depending on the time dependent geometry, and pressure perturbations of the system. In addition to shock dynamics, the model includes the effect of compressibility, interblade phase lag, and an unsteady flow field upstream and downstream of the cascade. Calculated unsteady aerodynamics were compared with isolated airfoil wind tunnel data, and choke flutter onset boundaries were compared with data from testing of an F100 high pressure compressor stage

Cooling Duct Analysis for Transpiration/Film Cooled Liquid Propellant Rocket Engines

The development of a low cost space transportation system requires that the propulsion system be reusable, have long life, with good performance and use low cost propellants. Improved performance can be achieved by operating the engine at higher pressure and temperature levels than previous designs. Increasing the chamber pressure and temperature, however, will increase wall heating rates. This necessitates the need for active cooling methods such as film cooling or transpiration cooling. But active cooling can reduce the net thrust of the engine and add considerably to the design complexity. Recently, a metal drawing process has been patented where it is possible to fabricate plates with very small holes with high uniformity with a closely specified porosity. Such a metal plate could be used for an inexpensive transpiration/film cooled liner to meet the demands of advanced reusable rocket engines, if coolant mass flow rates could be controlled to satisfy wall cooling requirements and performance. The present study investigates the possibility of controlling the coolant mass flow rate through the porous material by simple non-active fluid dynamic means. The coolant will be supplied to the porous material by series of constant geometry slots machined on the exterior of the engine

Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers

For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters

Analysis of Lean Premixed/Prevaporized Combustion with KIVA-2

Requirements to reduce the emissions of pollutants from gas turbines used in aircraft propulsion and ground based power generation have led to consideration of lean premixed/prevaporized (LPP) combustion concept. This paper describes some of the LPP flame tube analyses performed at the NASA Research Center with KIVA-2, a well-known multi-dimensional CFD code for problems including sprays, turbulence, and combustion. Modifications to KIVA-2's boundary condition and chemistry treatments have been made to meet the needs of the present study. The study itself focuses on two key aspects of the LPP concept, low emissions and flame stability (including flashback and lean blowoff

An adapted heat transfer model for engines with tumble motion

In the last years, a growing interest about increasing the engine efficiency has led to the development of new engine technologies. The accurate determination of the heat transfer across the combustion chamber walls is highly relevant to perform a valid thermal balance while evaluating the potential of new engine concepts. Several works dealing with heat transfer correlations that consider the swirl motion are found in the literature; however, there is a lack of works dealing with heat transfer correlations which take into account the effect of the tumble movement. In this work, a new heat transfer model accounting for the tumble motion is presented. A two stroke HSDI Diesel engine with high tumble and no swirl is used to perform the theoretical study, the model development and its final calibration. Initially, a theoretical analysis of the gas movement phenomena is carried out based on CFD results and then, a model is developed and calibrated based on a skip-fire testing technique. Finally, a sensitivity study focused on evaluating the model robustness is performed. The results confirm an average RMSE reduction of 70% with respect to the Woschni model, being this consistent improvement qualitatively evidenced in the instantaneous heat transfer evolutionThe support of the Spanish Ministry of Economy and Competitiveness (TRA2013-41348-R) is greatly acknowledged.Olmeda González, PC.; Martín Díaz, J.; Novella Rosa, R.; Carreño, R. (2015). An adapted heat transfer model for engines with tumble motion. Applied Energy. 158:190-202. https://doi.org/10.1016/j.apenergy.2015.08.051S19020215

Analysis of turbulence and surface growth models on the estimation of soot level in ethylene non-premixed flames

Soot prediction in a combustion system has become a subject of attention, as many factors influence its accuracy. An accurate temperature prediction will likely yield better soot predictions, since the inception, growth and destruction of the soot are affected by the temperature. This paper reported the study on the influences of turbulence closure and surface growth models on the prediction of soot levels in turbulent flames. The results demonstrated that a substantial distinction was observed in terms of temperature predictions derived using the k-ε and the Reynolds stress models, for the two ethylene flames studied here amongst the four types of surface growth rate model investigated, the assumption of the soot surface growth rate proportional to the particle number density, but independent on the surface area of soot particles, ƒ(As) = ρNs , yields in closest agreement with the radial data. Without any adjustment to the constants in the surface growth term, other approaches where the surface growth directly proportional to the surface area and square root of surface area, ƒ(As) = As and ƒ(As) = √As, result in an under- prediction of soot volume fraction. These results suggest that predictions of soot volume fraction are sensitive to the modelling of surface growth

Ten educational slide-narrative programs on orchids

The present creative project was undertaken to prepare educational programs on orchids. The author has worked with orchids for a period of ten years during which time he has developed expertise in the taxonomy, culturing, photography and collection of this family of plants.The creative project involved the selection of 385 35 mm slides from the author's collection, and the development of narrative which illustrates basic information about the Orchidaceae. The programs were developed for audiences possessing at least a modest botanical background. Two specific groups expected to use the programs are botany students at Ball State University and members of the American Orchid Society.The material on orchids was divided into ten topics: (1) Definition of an Orchid, (2) Diversity of Orchids; (3) Pollination of Orchids, (4) Hybridization of Orchids; (5) Propagation of Orchids; (6) Culture of Orchids; (7) Culture and Problems of Orchids; (8) Species of Orchids; (9) Buying and Showing of Orchids; (10) Orchid Collecting in Paraguay. Complete sets of 35 mm slides to accompany the narrative for each program have been placed on file in the Department of Biology at Ball State University.Ball State UniversityMuncie, IN 47306Thesis (M.S.)"Complete sets of 35 mm slides to accompany the narrative ... have been placed on file in the Department of Biology at Ball State University.

Pinklined Planning and the Need to Plan for Women

159 pagesTraditional forms of land use pinkline communities, constrain mobility, limit employment opportunities, reinforce outdated family structures as the norm, and provide inadequate support systems for women (Fainstein & Servon, 2005). Yet, little has been done in practice to address these concerns, and gender issues are still largely marginalized to the periphery of planning (Leavitt, 2003). However, aging-related work in planning has gained momentum in recent years (Warner et al., 2016), and there are similarities between the needs of an aging population and the needs of women around housing, transportation, and services.This dissertation has three goals. Theoretically, this dissertation brings together multiple lines of literature to create a theory of pinklining, the division of space, and exclusion of women and women's needs from mainstream planning. Empirically, this project operationalizes feminist criticisms of traditional zoning regulations, transportation planning, and public participation processes by creating and analyzing the 2014 Women and Aging survey. Practically, this project identifies potential planning interventions that can address the needs of women. This dissertation uses four regression models to test for gender responsive planning in a sample of U.S. communities. Two models evaluate the broad factors contributing to a community engaging in either gender responsive land use or gender responsive transportation planning. Two additional models disaggregate aging from gender to determine which factors are the strongest drivers of gender responsive planning. Data for this dissertation is primarily from the 2014 Women and Aging survey, an online survey conducted in collaboration with the American Planning Association's Planning and Women Division. Results from the regression models reveal that traditional land use regulations are relatively stuck in place and unable to address issues of gender adequately at the time of the survey. The models also demonstrate that there is potential for gender issues to move forward in discussion and resolution with transportation planning. Furthermore, leveraging aging work is an important tool to continue the conversation about gender issues in land use and transportation planning. With planners already advancing the aging population's needs, they should also advocate planning for women to create more equitable, inclusive, and livable communities for all

A double-blind study to evaluate the prophylactic use of naproxen sodium and diflunisal in controlling endodontic posttreatment pain : a thesis submitted in partial fulfillment ... Master of Science in Endodontics ... / Susan L. Micklow.

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