published_or_final_version / Civil Engineering / Master / Master of Philosophy

No description available.

Particle Image Velocimetry (PIV) is now emerging as a powerful tool for the investigation of unsteady fluid mechanics. At the same time, the study and optimisation of in-cylinder flow processes in automotive Internal Combustion (IC) engines is of increasing importance in the design of improved combustion systems with lower emissions and favourable power and efficiency characteristics. This thesis describes the development and application of PIV as a routine diagnostic tool for the investigation of in-cylinder flows in a production geometry single cylinder research engine exhibiting "barrel swirl" or "tumbling" in-cylinder fluid motion. The work has involved the design and installation of a complete PIV engine facility, based around a four-valve, four-stroke Rover research engine equipped with piston crown optical access and a glass cylinder liner. Novel techniques for the on-line monitoring of important experimental parameters have been developed which permit the reliable acquisition of high spatial resolution PIV data from both horizontal and vertical measurement planes within the engine cylinder. A novel optical correction technique has been developed to control the severe particle image degradation which was experienced when imaging vertical planes within the glass cylinder. A simple means for selection of an appropriate corrective lens for this application is described, together with an experimental evaluation of the lens performance. A representative set of PIV images and data from both horizontal and vertical planes are then presented. These have been selected from a comprehensive set of flow mapping experiments in the motored engine. The data are discussed with reference to the work of others in engines of similar geometry and have shed new light on the detailed processes involved in the formation and breakdown of barrel swirl. Initial PIV measurements ahead of a flame under part load, skip fired conditions have also been made in the engine. This has demonstrated the possibility of investigating incylinder flow behaviour under conditions approaching those in a fully firing, production geometry optical engine. Finally, limitations in the PIV technique employed in this work and methods of overcoming them are described and the prospects for further work are discussed.

Thesis (Ph. D.)--West Virginia University, 2005 / Title from document title page. Document formatted into pages; contains ix, 183 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 178-183).

Thesis (M. Phil.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 170-171).

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 72-74). Also available on the World Wide Web.

abstract: Modern day gas turbine designers face the problem of hot mainstream gas ingestion into rotor-stator disk cavities. To counter this ingestion, seals are installed on the rotor and stator disk rims and purge air, bled off from the compressor, is injected into the cavities. It is desirable to reduce the supply of purge air as this decreases the net power output as well as efficiency of the gas turbine. Since the purge air influences the disk cavity flow field and effectively the amount of ingestion, the aim of this work was to study the cavity velocity field experimentally using Particle Image Velocimetry (PIV). Experiments were carried out in a model single-stage axial flow turbine set-up that featured blades as well as vanes, with purge air supplied at the hub of the rotor-stator disk cavity. Along with the rotor and stator rim seals, an inner labyrinth seal was provided which split the disk cavity into a rim cavity and an inner cavity. First, static gage pressure distribution was measured to ensure that nominally steady flow conditions had been achieved. The PIV experiments were then performed to map the velocity field on the radial-tangential plane within the rim cavity at four axial locations. Instantaneous velocity maps obtained by PIV were analyzed sector-by-sector to understand the rim cavity flow field. It was observed that the tangential velocity dominated the cavity flow at low purge air flow rate, its dominance decreasing with increase in the purge air flow rate. Radially inboard of the rim cavity, negative radial velocity near the stator surface and positive radial velocity near the rotor surface indicated the presence of a recirculation region in the cavity whose radial extent increased with increase in the purge air flow rate. Qualitative flow streamline patterns are plotted within the rim cavity for different experimental conditions by combining the PIV map information with ingestion measurements within the cavity as reported in Thiagarajan (2013). / Dissertation/Thesis / M.S. Mechanical Engineering 2013

Flow visualization techniques have recently been applied for the investigation of various cryogenic flows of liquid helium. Particle image velocimetry and particle tracking velocimetry techniques, proven in the past as very fruitful in many scientific and industrial areas of research, are being used for the analysis of cryogenic flows. The Joint Low Temperature Laboratory at the Charles University in Prague is the first in Europe to employ flow visualization techniques to investigate liquid helium flows. The approach had to be optimized due to a number of technical and fundamental dificulties, i.e., the optical access to the helium bath and choice of suitable tracer particles. Water experiments at room temperature were performed to prove that the experimental apparatus is well-suited for the low-temperature experiments performed as the main part of the work. The latter focused on thermal counter flow. The results from both, room-temperature experiments and low-temperature experiments are discussed and positively compared with well-known theoretical results.

No description available.

An investigation of mixed convection in a rectangular enclosure is presented in which the velocity fields in the enclosure are determined using Particle Image Velocimetry (PIV). Basically, this technique records optical images of flow tracers within a flow field, and determines the velocity field by measuring the displacement of the flow tracers during short time intervals. The components which comprise the PIV system and its operation are described in detail to familiarize the reader with this relatively new technique. The main objective of this investigation is to determine the accuracy and applicability of the PIV technique as a velocity measurement tool. This is accomplished by comparing present experimental velocity results to those obtained by Nurnberg [2] using Laser Doppler Anemometry (LDA). LDA has been proven to be an accurate velocity measurement tool and provides data for evaluating PIV results. A second objective of this research is to use the PIV results to verify a numerical code written by Nurnberg [2] which predicts the velocity fields in the rectangular enclosure. However, the comparison of experimental results of the two measurement techniques revealed that the PIV results were too inaccurate to perform this function. The large amount of error present in this PIV system prompted the recommendation of an improved, more accurate system. Although this improved system is very expensive - approximately $40,000 - it will provide velocity measurements with an accuracy close to that of LDA, at half the cost of an LDA system and with far less time for data acquisition and analysis. / Thesis / Master of Engineering (ME)