An investigation of tip leakage flow and its effects on loss production was performed on a large-scale linear turbine cascade having a tip gap measuring 2.1% of the blade height. The Reynolds number based on axial chord and cascade exit velocity was 4.5x10⁵. The experimental work began with a visualization study of the flow in and around the tip gap. The actual flow measurements consisted of two phases, the tip gap exit plane measurements for determination of the losses incurred within the tip gap, and the downstream measurements for determination of the overall cascade losses. The downstream measurements made 140% of an axial chord downstream of the blade leading edges show the development of the leakage flow and its associated losses. Numerical analyses of the data were used to evaluate various flow properties at both the tip gap exit plane and the downstream measurement plane. Using the measured downstream flow, a mixing analysis was performed to estimate the maximum loss of the cascade. Models of the flow were developed to explain and quantify the various factors contributing to the cascade's overall loss. At a particular downstream location, the additional loss due to tip leakage was found to be the sum of the measured loss at the tip gap exit plane and the amount of tip gap secondary kinetic energy which had been dissipated by that downstream location. / M.S.

In this paper, an analysis of the internal water-cooling of a gas turbine was carried out. The density differences due to heating of the water in the blade and drum, combined with the very large force field associated with the centrifugal force caused by the rotation of water, sets up strong convection currents, which resulted in a very efficient heat transfer. Using the Havier-Stoke's and the continuity equations, applying Prandtl’s analogy between heat transfer and fluid friction and von Karman's - Nikuradse’s universal velocity distribution equation, the coefficient of heat transfer was derived and the maximum gas effective temperature predicted. For the conditions used in this investigation the following enumerated results can be stated: 1) The computed coefficient of heat transfer between cooling passage wall and water is 3850 Btu/(hr)(sq ft) (°F). 2) The rate of coolant flow is 11.35 lb/sec. 3) The effective gas temperature is 2510°F, assuming no radial heat flow alone the metal parts. 4) The average blade temperature is 600°F. 5) The blade has one cooling passage 4" long and .25" in diameter, and one equivalent in half to it in the cooling effect. / Master of Science

This thesis documents the experimental research conducted on a transonic turbine cascade. The cascade was a two-dimensional model of a jet-engine turbine with an, approximately, 1.2 design, exit Mach number, and was tested in a blow-down type wind-tunnel. The primary goal of the research was to examine the effect of trailing edge thickness on aerodynamic losses. The original cascade was tested and, then, the blades were cut-back at the trailing edge to make the trailing edge thicker. The ratios of the trailing edge thickness to axial chord length for the two cascades were 1.27 and 2.00 percent; therefore, the ratio of the two trailing edge thicknesses was 1.57. To simulate the blade cooling method that involves trailing edge coolant ejection, and to examine the effect of that on aerodynamic losses, CO₂ was ejected from slots near the trailing edge in the direction of the flow. Two different blowing rates were used, in addition to tests without CO₂. A coefficient, L̅, was used to quantify aerodynamic losses, and this was the mass-averaged total pressure drop, normalized by dividing with the total pressure upstream of the cascade. The traversing, downstream total pressure probe was stationed at one of three different locations, in order to investigate the loss development downstream of the cascade. The two cascades were tested for an exit Mach number ranging from 0.60 to 1.36. The research suggested that the main influence of the trailing edge thickness on losses is through affecting the strength of the trailing edge shock system, since L̅ was almost the same for the two cascades in the subsonic Mach number region. The losses mainly differed (larger for the cut-back cascade) in the Mach number region of 1.0 to 1.2. In this region, the difference in loss maximized, showing a loss for the cut-back cascade 20 to 30 percent more than the original cascade. The CO₂ was found to have no significant effect for high Mach numbers; for low Mach numbers, the high blowing rate slightly decreased the loss. Finally, the loss, nearly, stopped to increase after one axial chord length downstream of the cascade. / Master of Science

The increasing exploitation of marine renewable energy resources will create novel and unprecedented levels of anthropogenic activities in many coastal locations across the UK. In particular, locations with extensive and exploitable tidal stream energy resources will see large and dense arrays of installations, driven by the aggregated and limited distribution of this resource. Whilst the number of installations exploiting tidal stream energy resources is increasing, the environment impacts of installations remain unknown. This uncertainty is linked to our poor knowledge of the ecological function and importance of the high-energy environments, characterised with mean current speeds exceeding 2 ms-1, which are required for commercially viable installations. This thesis aims to increase our understanding of deep-diving seabirds' (Alcidae, Phalacrocoridae) use of high-energy environments, helping provide the information needed to estimate whether, which and when species could interact with installations. Chapters 3, 5 and 6 highlight the influence of predictable physical conditions (hydrodynamics, seabed features) on the foraging distributions of deep-diving seabirds across several spatial and temporal scales, indicating that the probable times and locations of foraging events within these habitats can be predicted. Chapter 4 directly tackles the estimation of spatial overlap between the foraging distributions of deep-diving seabirds and the locations of tidal stream turbines within a high-energy environment, evaluating and implementing methods to assess potential impacts at local and regional levels. Collectively, this thesis provides rare and novel studies into deep-diving seabirds' use of high-energy environments outside North America, and the only studies within these habitats that have collected quantitative and concurrent measurements of physical conditions and the foraging distributions of seabirds at fine spatial and temporal scales. In doing so, this thesis provides the empirical evidence needed to start identifying potential impacts from tidal stream energy extraction with more precision and confidence. By revealing the influence of predictable physical conditions on foraging events over several spatial and temporal scales, and also quantifying differences in habitat and microhabitat selection amongst deep-diving seabird species, this thesis also provides a unique contribution to our knowledge of the processes driving the foraging distributions of seabirds within coastal environments.

published_or_final_version / Mechanical Engineering / Master / Master of Science in Engineering

No description available.

No description available.

No description available.

No description available.

No description available.