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 120 for “"counter-rotating"”.
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Theoretical prediction of counter-rotating propeller noise
… been developed for the tone noise generated by a counter-rotation propeller. We start by deriving formulae for the harmonic components of the far acoustic field generated by the thickness and steady loading noise sources. Excellent agreement is shown between theory and measurements. Asymptotic …
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Aerodynamic design of an aspirated counter-rotating compressor
… blade aspiration in conjunction with rotor counter-rotation. Aspiration has been shown to make feasible significantly increased blade loading and counter-rotation provides a means of taking full advantage of this potential throughout a multistage compressor. The aspirated counter-rotating …
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Aerodynamic performance measurements in a counter-rotating aspirated compressor
… of the aerodynamic performances of a counter-rotating aspirated compressor. This compressor is implemented in a blow-down facility, which gives rigorous simulation of the characteristic aerodynamic parameters in which a compressor operates in steady state conditions. To measure the …
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Novel algorithms for fair bandwidth sharing on counter rotating rings
Rings are often preferred technology for networks as ring networks can virtually create fully connected mesh networks efficiently and they are also easy to manage. However, providing fair service to all the stations on the ring is not always easy to achieve. In order to capitalize on the advantages …
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Design of a multi-spool, high-speed, counter-rotating aspirated compressor
… blade and the rotational velocity of the blades. Counter-rotation provides for the largest change in swirl across a series of rotors, facilitating the largest pressure ratio. A three-stage, counter-rotating, compressor was designed to take advantage of these benefits. The tip speeds were kept as …
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Design and operation of a counter-rotating aspirated compressor blowdown test facility
A unique counter-rotating aspirated compressor was tested in a blowdown facility at the Gas Turbine Laboratory at MIT. The facility expanded on experience from previous blowdown turbine and blowdown compressor experiments. Advances in thermocouple and facility designs enabled efficiency estimates …
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Experimental and simulation study on the aerodynamic performance of a counter rotating vertical axis wind turbine
… performance predictions of a unique contra-rotating VAWT have been studied through experimental and computational approaches as it has yet to be applied to a VAWT. The main purpose of this study is to develop and investigate the practicality of employing the contra-rotating concept to a VAWT …
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Design and Numerical Evaluation of a Counter- Rotating Compressor in the Absence of Boundary Layer Control: Part II
<p>Exploration of counter-rotation is a logical step in the development of multistage axial compressors. The promise of substantial reduction in the number of stages and associated collateral benefits cannot be ignored. Despite improved performance, early studies were halted due to issues arising …
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Design and Numerical Evaluation of a Counter- Rotating Compressor in the Absence of Boundary Layer Control: Part I
… thesis was to design and evaluate a three stage counter-rotating compressor that employed well established design principles and technologies using a phased approach. The objective of the first phase was to generate the preliminary annulus shape and estimate the major parameters by modeling the …
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Using Single Propeller Performance Data to Predict Counter-Rotating Propeller Performance for a High Speed Autonomous Underwater Vehicle
The use of counter-rotating propellers is often desirable for aerospace and ocean engineering applications. Counter-rotating propellers offer higher peak efficiencies, better off-design performance, and roll control capabilities. But counter-rotating propeller matching is a difficult and complex …
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BOUNDARY LAYER ON FLAT PLATE WITH LEADING EDGE PATTERNS
THE DEVELOPMENT OF STREAMWISE COUNTER-ROTATING VORTICES IN THE BOUNDARY LAYER OF A FLAT PLATE HAS BEEN EXPERIMENTALLY INVESTIGATED BY MEANS OF SMOKE-WIRE FLOW VISUALIZATION AS WELL AS THE HOT-WIRE ANEMOMETRY. DIFFERENT LEADING EDGE PATTERNS SUCH AS TRIANGULAR, SINUSOIDAL AND NOTCHED PATTERNS WITH …
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Aerodynamics and multi-fidelity surrogate modelling of an inverted wing with vortex generators in ground effect
… vortex denerators in ground effect is presented. Counter-rotating and co-rotating rectangular-vane type vortex generators with different device heights are studied on the suction surface of the wing. The primary application of this study is a front wing of race cars. This study comprises three …
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An experimental investigation of interacting wing-tip vortex pairs
… angles of attack, generating pairs of co-rotating and counter rotating vortices. Meaningful hot wire measurements could be made because the vortices were found to be insensitive to probe interference and experienced very small wandering motions. The co-rotating pairs were observed to …
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Observation and Measurement of the Growth of the Primary Instabilities of the Richtmyer-Meshkov Instability and Observation of Secondary Instabilities
… initially cylindrical gas column; that is, the counter-rotating vortex pair and the central spike; and the observation of secondary instabilities within the primary instability. The formation of the instabilities is the result of a standing normal shock wave of air interacting with a cylindrical …
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Design of a spherical vehicle with flywheel momentum storage for high torque capabilities
… The addition of angular momentum storage via counter-rotating control moment gyroscopes is proposed in order to overcome significant limitations in the performance of earlier designs of spherical vehicles. Analysis and design of a fully functioning spherical vehicle incorporating such a …
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Application of the resonant rotating wave approximation to the theory of resonant scattering
… the context of a new approximation, the resonant rotating wave approximation (RRWA). The RRWA is similar to the standard R\-lA, except that non-resonant rotating terms, as well as all the counter-rotating terms, are neglected. The RRWA is derived, rigorously justified, and shown to yield results …
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Application of passive flow control to mitigate the thromboembolic potential of bileaflet mechanical heart valves: an in-vitro study
… leaflet. Two configurations were constructed: co-rotating VGs and counter-rotating VGs. Co-rotating VGs consist of single features 1mm tall and 2.8mm long spaced equally apart (5mm) at an angle of attack of 23 degrees. Counter-rotating VGs consist of mirrored feature pairs 1mm from each other with …
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Ram air turbine enhancement for auxiliary power unit replacement
… classical RAT design was improved by adding a counter-rotating system (counter-rotating RAT - CRRAT). The design of RAT blades was based on blade element momentum (BEM) theory. The performance of RAT and CRRAT was analyzed using FLUENT software. The adopted numerical scheme was the …
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