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The flow through a compressor cascade with tip leakage has been studied experimentally. The cascade of GE rotor B section blades had an inlet angle of 65.1º, a stagger angle of 56.9º, and a solidity of 1.08. The final turning angle of the cascade was 11.8º. This compressor configuration was representative of the core compressor of an aircraft engine. The cascade was operated with a tip gap of 1.65%, and operated at a Reynolds number based on the chord length (0.254 m) of 388,000. Measurements were made at 8 axial locations to reveal the structure of the flow as it evolved through the cascade. Measurements were also made to reveal the effects of grid generated turbulence on this flow. The data set is unique in that not only does it give a comparison of elevated free stream turbulence effects, but also documents the developing flow through the blade row of a compressor cascade with tip leakage. Measurements were made at a total of 8 locations 0.8, 0.23 axial chords upstream and 0, 0.27, 0.48, 0.77, 0.98, and 1.26 axial chords downstream of the leading edge of the blade row for both inflow turbulence cases. The measurements revealed the formation and development of the tip leakage vortex within the passage. The tip leakage vortex becomes apparent at approximately X/ca= 0.27 and dominated much of the endwall flow. The tip leakage vortex is characterized by high streamwise velocity deficits, high vorticity and high turbulence kinetic energy levels. The result showed that between 0.77 and 0.98 axial chords downstream of the leading edge, the vortex structure and behavior changes. The effects of grid generated turbulence were also documented. The results revealed significant effects on the flow field. The results showed a 4% decrease in the blade loading and a 20% reduction in the vorticity levels within tip leakage vortex. There was also a shift in the vortex path, showing a shift close to the suction side with grid generated turbulence, indicating the strength of the vortex was decreased. Circulation calculations showed this reduction, and also indicated that the tip leakage vortex increased in size by about 30%. The results revealed that overall, the turbulence kinetic energy levels in the tip leakage vortex were increased, with the most drastic change occurring at X/ca= 0.77. / Ph. D.

A detailed study of the feasibility of anchoring fiber reinforced plastic wires for civil engineering applications is presented. An experimental investigation using tensile testing machines is performed, testing anchorages of 1, 7 and 19 wires. Conventional strain gage and acoustic emission measurement techniques are used. The tests are essential in determining the failure load and failure mode. However, the experimental data alone do not provide enough information about the behavior of the anchorage to be used exclusively in the design process. The results are used to modify the design of the anchorage system. It is shown that for a successful anchorage system the choice of material for the load transfer medium is crucial. A solution is presented to overcome the high stress concentration at the load entry area of the wire into the anchor. A finite element analysis of the anchors for 1 and for 19 wires is used to assess the stress and strain fields inside the anchor, to validate the analytical model, and to determine locations of possible high stress concentrations. Three-dimensional and one-dimensional models, that utilize axisymmetry, are evaluated. The results of the numerical analysis are used to demonstrate the improvement as a result of a change in material choice or design of the anchor. It is shown that the modification of the load transfer medium results in a decrease of 30 % of the average stress level. In the analytical investigation, several common models are introduced that describe the fiber pullout behavior. Based on a recent treatment by C. H. Hsueh, a model is developed that describes the anchorage of a wire in a conical shaped socket using orthotropic materials. This model includes boundary conditions that are similar to the ones observed in the experiments. A parametric study is performed to obtain information on the ideal geometry of the anchor system. The results and predictions of the applied techniques, i. e. analytical description, finite element method and experimental investigation, are compared and contrasted. Based on the analytical, numerical and experimental results, recommendations for improving the design of the anchor system are made. Subsequently, a modified anchor system is proposed that utilizes the properties of a load transfer medium that has a variable stiffness. The inclusion of a pure resin collar and supporting wires is suggested. For a successful completion of this project, ideas are proposed and suggestions made for future work. / Ph. D.

An analysis is presented for hot wire/film anemometer measurement of mean velocities and turbulent stresses in a three dimensional flow field with a predominant flow direction. The experimental data can be taken with an automated traverse under the control of a digital data acquisition system which has been modified for this particular application. / Master of Science

Model fan blades designed to implement the wake management technique of trailing-edge blowing were tested in a linear cascade configuration. Measurements were made on two sets of blowing blades installed in the Virginia Tech low-speed linear cascade wind tunnel. The simple blowing blades were identical to the baseline GE Rotor B blades, aside from a slight difference in trailing-edge thickness, a set of internal flow passages, and a blowing slot just upstream of the trailing-edge on the suction side of the blade. The Kuethe vane blades were also slightly thicker at the trailing-edge, and had a set of nine evenly spaced vortex generators upstream of the blowing slot on the suction side. The cascade tunnel accommodates eight blades with adjustable tip-gap heights, although only the center four blades were replaced by blowing blades in this study. The tunnel has an inlet angle of 65.1â a, a stagger angle of 56.9â a and a flow turning angle of 11.8â a. The tip-gap was set to 0.004125c and the freestream velocity of 24.7m/s led to a Reynolds number based on the chord of 385,000. Blowing slot uniformity measurements made with a single hot-wire immediately behind the trailing-edge revealed that the blowing becomes more spanwise uniform as blowing rate is increased. The same occurs with the Kuethe vane blades, despite a spanwise serrated pattern that appears as a result of the upstream vortex generators. Cross-sections made perpendicular to the blade span gave preliminary evidence that the simple blowing wake deficit increases from the passive suction case at a blowing rate of 1.4% and becomes overblown by 2.6%. The Kuethe vane wake deficit does not increase at low blowing rates. Both sets of blowing blades indicated a slight angling of the wake towards the pressure side with blowing. Pitot-static full cross-sections of the simple blowing blades at x/ca = 0.839 and 1.877 verified the increase in wake depth and width at 1.4% as compared to the passive suction and non-blowing baseline cases, and the wake overblowing that occurs as blowing rate is increased to approximately 2.6%. The Kuethe vane blades only achieve partial wake cancellation at the maximum tested rate of 2.6% for these measurements. The results of the baseline study of Geiger (2005) are used for comparison with the mid-span velocity profiles made at four downstream locations. The velocity profiles clearly confirm the results of the normal-to-span and full cross-sections, while also revealing a decrease from the baseline of at least 25% in most of the maximum Reynolds normal stresses and turbulent kinetic energies at all rates between 1.4% and 2.7% for both sets of blowing blades. Spectral measurements of the simple blowing blades show clear reductions of the energy in the wake for all blowing rates over the majority of the range of normalized frequencies, while the Kuethe vane blades show reductions at all rates and all frequencies. By performing Fourier decompositions, the tone noise benefits over the non-blowing baseline blades are directly comparable in decibels. The optimum blowing rate for the simple blowing blades is clearly 2.5%, since this rate shows the most potential tone noise reduction. The Kuethe vane blades suggest decreases in tone noise over all of the tested blowing rates. / Master of Science

Modern FPGAs contain routing resources easily exceeding millions of wires. While mainstream design flows and place-and-route tools make very good use of these routing resources, they do so at the cost of very significant processing time. A well established alternative scheme is to modify or generate configuration bitstreams directly, resulting in more dynamic designs and shorter processing times. This thesis introduces a complete set of alternate wire databases for Xilinx Virtex, Virtex-E, and Virtex-II FPGAs, suitable for standalone use or as an addition to the JBits API. The databases can be used to route or trace through any device in these families, and can generate the necessary bitstream configurations with the help of JBits or an independent bitstream interface. / Master of Science