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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.
71

An evaluation of combined air-cooling and water-cooling for non-permeable clothing

Wang, I-Chung January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
72

Physics based modeling of axial compressor stall

Zaki, Mina Adel 28 August 2009 (has links)
Axial compressors are used in a wide variety of aerodynamic applications and are one of the most important components in aero-engines. The operability of compressors is however limited at low-mass flow rates by fluid dynamic instabilities such as stall and surge. These instabilities can lead to engine failure and loss of engine power which can compromise the aircraft safety and reliability. Therefore, a better understanding of how stall occurs and the causes behind its inception is extremely important. In the vicinity of the stall line, the flow field is inherently unsteady due to the interactions between adjacent rows of blades, formation of separation cells, and the viscous effects including shock-boundary layer interaction. Accurate modeling of these phenomena requires a proper set of stable and accurate boundary conditions at the rotorstator interface that conserve mass, momentum and energy, while eliminating false reflections. As a part of this effort, an existing 3D Navier-Stokes analysis for modeling single stage compressors has been modified to model multi-stage axial compressors and turbines. Several rotor-stator interface boundary conditions have been implemented. These have been evaluated for the first stage (a stator and a rotor) of the two stage fuel turbine on the space shuttle main engine (SSME). Their effectiveness in conserving global properties such as mass, momentum, and energy across the interface, while yielding good performance predictions has been evaluated. While all the methods gave satisfactory results, a characteristic based approach and an unsteady sliding mesh approach are found to work best. Accurate modeling of the formation of stall cells requires the use of advanced turbulence models. As a part of this effort, a new advanced turbulence model called Hybrid RANS/KES (HRKES) has been developed and implemented. This model solves Menter's k--SST model near walls and switches to a Kinetic Eddy Simulation (KES) model away from walls. The KES model solves directly for local turbulent kinetic energy and local turbulent length scales, alleviating the grid spacing dependency of the length scales found in other Detached Eddy Simulation (DES) and Hybrid RANS/LES (HRLES) models. Within the HRKES model, combinations of two different blending functions have been evaluated for blending the near wall model to the KES model. The use of realizability constraints to bound the KES model parameters has also been studied for several internal and external flows. The current methodology is used in the prediction of the performance map for the NASA Stage 35 compressor configuration as a representative of a modern compressor stage. The present approach is found to satisfactory predict the onset of stall. It is found that the rotor blade tip leakage vortex and its interaction with the shock wave is mainly the reason behind the stall inception in this compressor stage.
73

Some compressed air tests at high altitude

Robson, Thomas Cueller. January 1930 (has links) (PDF)
Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1930. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed November 30, 2009) Includes bibliographical references (p. 26).
74

Efficiency and performance measurements of a PDC Inc. single stage diaphragm hydrogen compressor /

Allen, Andrea Leticia. January 1900 (has links)
Thesis (M.S.)--Humboldt State University, 2009. / Includes bibliographical references (leaves 71-72). Also available via Humboldt Digital Scholar.
75

Examination of flow around second-generation controlled diffusion compressor blades in cascade at stall /

Fitzgerald, Kevin D. January 2004 (has links) (PDF)
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, June 2004. / Thesis advisor(s): Garth V. Hobson. Includes bibliographical references (p. 63). Also available online.
76

Active identification and control of aerodynamic instabilities in axial and centrifugal compressors

Krichene, Assaad 12 1900 (has links)
No description available.
77

Identification of sound transmission paths within a hermetic reciprocating refrigeration compressor via multiple-input/single-output modeling /

Craun, Matthew Ashby, January 1994 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 119-121). Also available via the Internet.
78

Study of a novel R718 turbocompression cycle

Kharazi, Amir Ahmadzadeh January 2006 (has links)
Thesis (Ph. D.)--Michigan State University. Dept. of Mechanical Engineering, 2006. / Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographic references (p. 84-89). Also issued in print.
79

Structural design of composite rotor blades with consideration of manufacturability, durability, and manufacturing uncertainties

Li, Leihong. January 2008 (has links)
Thesis (Ph.D.)--Aerospace Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Hodges, Dewey H.; Committee Member: Bauchau, Olivier A.; Committee Member: Johnson, Ellis; Committee Member: Makeev, Andrew; Committee Member: Volovoi, Vitali V.
80

Impact of leading-edge orientation and shape on performance of a compressor blade /

Powell, Jonathan D. January 2005 (has links) (PDF)
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): Knox T. Millsaps. Includes bibliographical references (p. 73-74). Also available online.

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