Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 31 for “"Rotor Tip"”.
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Design, Analysis, Optimization and Control of Rotor Tip Flows
… over the past decades, the turbine tip design presents numerous challenges to the engine manufacturers, and remains the primary factor defining the machine durability for the periodic removal of the turbine components during overhaul. Due to the hot gases coming from the upstream …
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HIGH-SPEED ROTOR TIP CLEARANCE MEASUREMENTS IN A TRANSONIC COMPRESSOR
… dependent on the size of the region between the rotor blade’s tips and the surrounding casing, the tip clearance, which dynamically changes with rising rotor speed due to rotor blade radial growth from centrifugal loading. Too large a tip clearance introduces disruptive air flow that will lower …
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Effects of rotor tip blade loading variation on compressor stage performance
… in loss generation associated with altering the rotor tip loading of an embedded compressor stage is assessed. Steady and unsteady three-dimensional computations, complemented by control volume analyses, for varying rotor tip loading distributions provided results for determining if aft-loading …
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Effects of rotor tip clearance on an embedded compressor stage performance
Compressor efficiency variation with rotor tip gap is assessed using numerical simulations on an embedded stage representative of that in a large industrial gas turbine with Reynolds number being approximately 2 x 106 to 7 x 106. The results reveal three distinct behaviors of efficiency variation …
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Effects of upstream unsteady flow conditions on rotor tip leakage flow
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001.
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The Effects of Shrouded Rotor Tip Leakage Flow on the Downstream Stator Aerodynamics in Turbines
… (stators) followed by a row of rotating blades (rotors). This arrangement necessitates radial clearance gaps above the tips of the rotor blades and below the hub end of the stator blades. Therefore, a fraction of the gas does not pass through the blade rows, but instead leaks through the tip and …
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Heat Transfer and Flow Characteristics on the Rotor Tip and Endwall Platform Regions in a Transonic Turbine Cascade
… of the turbine extremity regions i.e. the blade tip and endwall regions. The heat transfer and secondary flow characteristics were analyzed for different engine relevant configurations and exit Mach/Reynolds number conditions. The experiments were conducted in a linear blowdown cascade at …
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Tip clearance effects on multistage axial compressor performance and flow structure for small core application
… effect of increasing multistage axial compressor rotor blade tip clearance on embedded stage performance and flow structure for clearance-to-span ratios ranging from 1.4% to 5.6% using steady and unsteady three-dimensional viscous flow multistage computations. Embedded stage efficiency displays …
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An Experimental Characterization of Tip Leakage Flows and Corresponding Effects on Multistage Compressor Performance
The effect of rotor tip clearances in turbomachinery applications has been a primary research interest for nearly 80 years. Over that time, studies have shown increased tip clearance in axial flow compressors typically has a detrimental effect on overall pressure rise capability, isentropic …
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An experimental study on the effects of blade row interactions on aerodynamic loss mechanisms in a multistage compressor
… vane clocking of the embedded stage, while the rotors have different blade counts producing amplitude modulation of the unsteady interactions. ^ A detailed investigation of corrected conditions is presented to establish repeatable, compressor performance year-round in a facility utilizing …
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Investigating the Rotary Mechanism of ATP Synthase Using Molecular Dynamics Simulations
… The γ C-terminal helix constitutes of the rotor tip that is seated in an apical bearing formed by the α3β3 head. It remains uncertain to what extent the γ conformation during rotation differs from that seen in rigid crystal structures. Existing models assume that the entire γ subunit …
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Three-dimensional separations in compressors
… is inherent in compressor blade passages and tip clearance dominated 3D flow in the rotor tip region, has limited the success of 3D blade design. This dissertation is therefore aimed at contributing to compressor design process by exploring the formation of 3D separations. Detailed …
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An output-based adaptive and high-order method for a rotor in hover
… are presented and applied to an isolated rotor in hover. A simplex cut-cell mesh generation technique is used to support robust and autonomous creation of higher-order meshes. The calculations are performed using a parallel implementation of the DG discretization and the results are …
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Tip clearance flows in axial compressors: stall inception and stability enhancement
The flow in the rotor tip clearance gap in an axial compressor influences the loss levels and the stall onset point. The role of tip clearance flows in the stall inception process is still debated, though. The aim of this thesis is to improve the fundamental understanding of the tip clearance flow …
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A Computational Study of Axial Compressor Rotor Casing Treatments and Stator Land Seals
… in terms of surge margin and efficiency, rotor casing treatments and stator land seals.ADPAC and Fluent CFD solvers were used in the analysis of circumferential groove casing treatments and two types of stator seals, one typical of a front stage stator and one typical of a rear stage …
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The correlation of randomness with high tip losses in an axial flow fan stage
… the source of high losses located near the rotor tip. A technique for quantifying randomness of an unsteady flow is developed, and the randomness of the surveyed flow is shown to correlate with the losses. A new method of ensemble averaging instantaneous data is presented which produces an …
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Rotordynamic assessment for a permanent magnet synchronous motor
High speed and high rotor tip-speed, in particular, combined with high magnetic and electrical loading, are key enablers for obtaining high specific power in electric machines. The rotor described in this thesis pushes the tip speed to about 80% of the speed of sound. An outer rotor design with a …
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Experimental investigation of an aspirated fan stage
… a throughflow adiabatic efficiency of 89% at a rotor tip speed of 750 ft/s. Aspiration equal to 0.5% of the inlet flow was applied to the blade surface of both the rotor and stator. Aspiration was also used on the endwall boundary layers. Detailed flowfield measurements are made behind the rotor …
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Turbulence and Sound Generated by a Rotor Operating Near a Wall
… measurements have been carried out on a rotor operating in a planar turbulent boundary layer near a wall for a variety of thrust conditions and yaw angles with respect to the inflow. At the highest thrust condition a strong flow reversal in the wall-rotor tip gap was observed. Average …
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An Improved Prescribed Wake Analysis for Wind Turbine Rotors
The trajectories of the tip vortices of a model wind turbine rotor are quantitatively tracked for twenty-seven separate test conditions. Three pitch angles are used (-8°, -3° and 3°). Three tip speed ratios are examined (2, 5 and 10). Finally, data for rotors with one, two and three …
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