Date of Graduation
Statler College of Engineering and Mineral Resources
Mechanical and Aerospace Engineering
John M. Kuhlman.
Improvements have been made to an existing 2-component Point Doppler Velocimetry (PDV) system to improve instrument accuracy and repeatability and to reduce mean velocity offset. Most importantly, the original iodine cells have been replaced by vapor-limited iodine cells that are not influenced by room temperature variations. PDV is a non-intrusive laser based flow measurement technique with capabilities that are similar to hot wire anemometry, but without inserting a probe into the flow. The insertion of a probe into a flow can affect the flow, resulting in inaccurate measurements.;PDV measurements for 1 inch diameter standard, swirling, and annular jets have been made at a nominal exit velocity of 60 m/s, corresponding to a Reynolds number of 100,000. Measurements of radial profiles of mean and RMS velocities were taken for each jet from the jet exit to X/D=12 at nine different X locations. Also, centerline velocity profiles were taken from the jet exit to X/D=12. Comparisons between hot wire anemometry and PDV measurements have been made for standard and swirling jets, and PDV data repeatability has been judged by multiple runs for each jet.;Hot wire anemometry measurements in the swirling jet appear to be inaccurate for X/D ≤ 4 due to the inability of the hot wire anemometer to accurately measure two-dimensional flow velocities. The PDV and hot wire comparisons for the standard jet have good correlation for the mean velocity; however, the RMS velocities do not agree. PDV measurements of the axial and circumferential mean velocities exhibited an uncertainty and repeatability of 2 m/s. This error, for the axial mean velocity, was of the same order as was produced by using a different calibration from the same day. PDV RMS velocities exhibited a repeatability of 0.5--1.0 m/s, and generally are about one half as large as the hot wire anemometer RMS velocities.
Collins, Patrick Michael, "Point Doppler velocimetry measurements in circular jets" (2000). Graduate Theses, Dissertations, and Problem Reports. 1015.