No description available.

Thesis (Ph.D.) -- McMaster University, 1997. / Includes bibliographical references (p. 234-241). Also available via World Wide Web.

Thesis (Ph. D.)--Missouri University of Science and Technology, 2008. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed August 21, 2008) Includes bibliographical references.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (Ph. D.)--Institute of Paper Science and Technology, Georgia Institute of Technology, 2003.

Open channel raceway bioreactors are a low-cost system used to grow algae for biofuel production. Microalgae have many promises when it comes to renewable energy applications, but many economic hurdles must be overcome to achieve an economic fuel source that is competitive with petroleum-based fuels. One way to make algae more competitive is to improve vertical mixing in algae raceway bioreactors. Previous studies show that mixing may be increased by the addition of mechanisms such as airfoils. The circulation created helps move the algae from the bottom to top surface for necessary photosynthetic exchange. This improvement in light utilization allowed a certain study to achieve 2.2-2.4 times the amount of biomass relative to bioreactors without airfoils. This idea of increasing mixing in open channel raceways has been the focus of the Utah State University (USU) raceway hydraulics group. Computational Fluid Dynamics (CFD), Acoustic Doppler Velocimetry (ADV), and Particle Image Velocimetry (PIV) are all methods used at USU to computationally and experimentally quantify mixing in an open channel raceway. They have also been used to observe the effects of using delta wings (DW) in increasing vertical mixing in the raceway. These efforts showed great potential in the DW in increasing vertical mixing in the open channel bioreactor. However, this research begged the question, does the DW help increase algae growth? Three algae growth experiments comparing growth in a raceway with and without DW were completed. These experiments were successful, yielding an average 27.1% increase in the biomass. The DW appears to be a promising method of increasing algae biomass production. The next important step was to quantify vertical mixing and understand flow patterns due to two DWs side-by-side. Raceway channels are wider as they increase in size; and arrays of DWs will need to be installed to achieve quality mixing throughout the bioreactor. Quality mixing was attained for several paddle wheel (PW) speeds. Also, an optimal spacing between the DWs in an array was found to be the width of the DW. This optimal spacing allows for the best increase in vertical mixing along the width of the channel. Dimensional analysis was performed using experimental data to estimate vertical mixing index (VMI) results for data obtained by larger scale DW experiments. This rough analysis showed that the VMI may be estimated from small to large scale within 26.6% and 26.5% when equating Reynolds and Froude numbers, respectively. These results suggest that quality mixing would still be present at a larger DW scale.

No description available.

A rapidly scanning directionally sensitive three-velocity-component laser Doppler velocimeter (RSLDV) has been designed. It permits scans through three-dimensional flows to obtain space-time velocity information and almost "instantaneous" velocity profiles vital to understanding such flows. A flexible optical system allows for easy variation of the fringe spacing as well as the location and size of the measurement volume. Several optical techniques to maintain coincidence between the horizontal, U and W, and vertical, V, probe volumes were investigated. A lens, used like a prism, and two plane mirrors for the out of plane scanning laser beam maintains good coincidence between the probe volumes, while maintaining some flexibility. Moving fringe patterns in the horizontal and vertical planes are produced by two solid state Bragg cells. The Doppler frequency is independent of the position of the receiving optics, and only one photomultiplier tube (PMT) is needed to receive the signals for all three velocity components. A data acquisition, control and processing system has also been designed for use with the RSLDV. The PMT signal and location of the measurement volume are recorded simultaneously by two transient recorders. The system provides storage for up to 1.25 gigabytes (6 secs.) of LDV data, with permanent storage onto optical disk. A 20 MFLOP array processor provides for fast computation of velocity information. The Pisarenko harmonic decomposition (PHD) and fast Fourier transform (FFT) algorithms, with various interpolation techniques, were investigated for processing low signal-to-noise ratio signals for use with the RSLDV. The PHD algorithm was found to be unsuitable for use with processing RSLDV signals, however, the algorithm does provide superior frequency estimation for some frequency ratios at SNR levels above 30 dB, which are typical quality signals required for frequency counters. The FFT with zero-padding and log parabolic fit provides frequency estimates with RMS error below 1 % for signals with SNR above -5 dB. To obtain frequency estimates for signals with SNR below -5 dB, the FFT with zero-padding and parabolic lit must be used, signals with SNR down to -18 dB can be processed with this technique. / Master of Science / incomplete_metadata

A three-color, three-component Laser Doppler Anemometer (LOA) capable of making simultaneous measurements of three components of velocity is described, and the use of this LOA to measure three non-orthogonal velocity components in the rotor blade passage of a single-stage axial-flow compressor is reported. Measurements were made at four radial locations from 50% span out to the blade tip, and at seven different axial locations from -0.55 axial chord 1.40 axial chord. Measurements were made at only one throttle setting. The measured velocities are used to determine the flow in the orthogonal axial - tangential - radial, x - t - r, coordinate system of the compressor. Although the mean velocities and entire Reynolds stress tensor are obtained with this system, only the mean velocities are reported. Results are presented in the form of a series of vector plots showing: 1.) the primary flow as projected on the x - t plane and 2.) the secondary flow in the t - r plane. The LOA measurements are shown to agree with pitot probe measurements in the stationary frame and basic secondary flow theory. A detailed error analysis is presented, taking into account both measurement uncertainties and statistical biasing. An analysis is also made of particle lag in the rotating flow of the compressor blade passage. A discussion of the difficulties encountered in making three dimensional velocity measurements in turbomachinery blade passages is presented. Suggestions are made for improving the present system for this task. / Master of Science