Flow visualization around cylinders in a channel flow using Particle Image Velocimetry

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.The objective of the undertaken study was to apply state-of the-art Particle Image Velocimetry to measure full field turbulent flow around cylinders, starting with one cylinder and eventually to a quad cylinder arrangement. Particle Image Velocimetry as used herein is identical to the techniques in use in Texas A&M University's Pulsed Laser Velocimetry Laboratory where the test facilities include a flow bench, a ND-YAG pulsed laser, and data acquistion equipment, consisting of a CCD camera and attendant PC's programmed to control the laser and camera, and to acquire and store the digitized data. The data can then be retrieved for analysis. The data was analyzed using an existing algorithm, the Cross Correlation Code. Full-field, fluid two-dimensional velocity around, about, and past the test specimens was obtained with the digital camera which captured the images of light reflected from seeds flowing within the fluid within a given time exposure time of 53.8 ms. The viewing field area (approximately 5 cm by 5 cm) was illuminated by two light sheets impinging on the test specimens from opposing sides at angles less than 90' from the horizontal. The impinging angles were selected to create the least amount of shading by the test specimen and the incident target on the test specimen was common to both light sheets so that they would superimpose on the target, thus reinforcing the illumination intensity. The two light sheets were created by splitting the pulsing beam into two beams, and then each beam directed with, and to, mirrors which were part of an optical train consisting of three cylindrical lenses which converted the beam into a light sheet 0.5 to 1.0mm thick and 5 cm wide. The test conditions had a range of from 0.043 to 0.0579 m/s for the average velocity of the fluid and a range of Reynolds number of 7142 to 8140. Given these test conditions, vector plots representing the flow fieldwere generated for one test run on each of the these specimens. The velocity component of the plotted vectors was derived from a scale within the plots. Thus, two-dimensional velocities could be read anywhere within the plots. A mix of quantitative and qualitative data was obtained for the one, two, three, and quad cylinder arrangement test specimens