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 43 for “"propulsive efficiency"”.
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Propulsive efficiency of a flexible hull underwater vehicle
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1996.
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Noise And Propulsive Efficiency Interactions For Rotors And Propellers At Constant Thrust
… particulate emissions while also having enough propulsive efficiency to complete the mission. This thesis aims to study the relationship between noise and propulsive efficiency as related to any aircraft equipped with an electric motor and a variable pitch rotor/propeller. The combination of the …
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Form, function and flow in the plankton : jet propulsion and filtration by pelagic tunicates
… performance variables including thrust, drag and propulsive efficiency. All species investigated swam via vortex ring propulsion. Though Weelia cylindrica was the fastest swimmer, Pegea confoederata was the most efficient, producing the highest weight-specific thrust and wholecycle propulsive …
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Numerical Assessment of the Performance of Jet-Wing Distributed Propulsion on Blended-Wing-Body Aircraft
… suggested by Kuchemann as a way to improve propulsive efficiency. In addition, one can envision a jet-wing with deflected jets replacing flaps and slats and the associated noise. The purpose of this study was to assess the performance benefits of jet-wing distributed propulsion. The …
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The Multidisciplinary Design Optimization of a Distributed Propulsion Blended-Wing-Body Aircraft
… important effect modeled is the impact on the propulsive efficiency. There has been conjecture that there will be an increase in propulsive efficiency when there is blowing out of the trailing edge of a wing. A mathematical formulation was derived to explain this. The formulation showed that …
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Form, function and flow in the plankton : jet propulsion and filtration by pelagic tunicates
… performance variables including thrust, drag and propulsive efficiency. All species investigated swam via vortex ring propulsion. Though Weelia cylindrica was the fastest swimmer, Pegea confoederata was the most efficient, producing the highest weight-specific thrust and whole-cycle propulsive …
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Propulsion By Sinusoidal Locomotion: A Motion Inspired By Caenorhabditis Elegans
… the motion, we have derived the closed forms of propulsive force, lift and other generalized forces applying on the wing. We also calculated the power required to perform the motion, the power lost due to the shed vortices and the propulsive efficiency. These forces and powers are given as …
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Autonomous Underwater Vehicle (AUV) Propulsion System Analysis and Optimization
… that have specific mission scenarios is the propulsive efficiency. The propulsive efficiency affects the amount of power storage required to achieve a specific mission. As the efficiency increases the volume of energy being stored decreases. The decrease in volume allows for a smaller …
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Unsteady Aerodynamic/Hydrodynamic Analysis of Bio-inspired Flapping Elements at Low Reynolds Number
… the role of fish-tail flexibility on thrust and propulsive efficiency. Flexible tails enhance thrust production in comparison to a rigid ones of the same size and under the same operating conditions. Further analysis indicates that varying the tail's aspect ratio has a more significant effect on …
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Unsteady Aerodynamic and Aeroelastic Analysis of Flapping Flight
… At these low Reynolds numbers, the aerodynamic efficiency of conventional fixed airfoils significantly deteriorates. On the other hand, flapping flight employed by birds and insects whose flight regime coincides with that of micro air vehicles offers a viable alternate solution. For the analysis …
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Constant Velocity Combustion Scramjet Analysis
… ratio, thrust specific fuel consumption, thermal efficiency, propulsive efficiency, overall efficiency and thrust flux. The objective of the work is to determine the desirable performance terms of the ideal scramjet, by varying three different candidate fuels and three different candidate …
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An Experimental Characterization of Tip Leakage Flows and Corresponding Effects on Multistage Compressor Performance
… on overall pressure rise capability, isentropic efficiency, and stall margin. With modern engine designs trending toward decreased core sizes to increase propulsive efficiency (by increasing bypass ratio) or additional compression stages to increase thermal efficiency by increasing the overall …
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Improving Seaglider Efficiency: An Analysis of Wing Shapes, Hull Morphologies, and Propulsion Methods
… Can a conventional propulsion system match the efficiency of an underwater glider buoyancy engine? A first-principles, energy-based approach to glider operations was derived and verified using real world data. The energy usage for buoyancy driven propulsion was then compared to conventional …
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Numerical Studies of Jet-Wing Distributed Propulsion and a Simplified Noise Metric Method
… engine. Kuchemann suggested a way to improve the propulsive efficiency by changing the normal configuration of engine and aircraft. This concept is the jet-wing distributed propulsion idea, which redistributes the thrust across the span of the wings. Distributed propulsion is accomplished by using …
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Resistance and wake prediction for early stage ship design
… for use in an optimization program, having total propulsive efficiency as an objective function. There exist design tools to predict the total resistance and propeller wake, but none that provide adequate computational times for the preliminary design stage. The tool developed uses a potential …
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Parametric Scramjet Analysis
… ratio, thrust-specific fuel consumption, thermal efficiency, propulsive efficiency, overall efficiency, and thrust flux. The information presented in this work has not been done by others in the scientific literature. This work yields simple algebraic equations for scramjet performance which are …
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A comparison study of biologically inspired propulsion systems for an autonomous underwater vehicle
… and one contributing factor to this is the efficiency of the propulsion system, which is usually based on marine propellers. As fish are highly efficient swimmers greater propulsive efficiency may be possible by mimicking their fish tail propulsion system. The main concept behind this work …
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Design and cavitation performance of contra-rotating propellers
Improvement of the propulsive efficiency of ships has always been one of the main objectives for naval architects and marine engineers. Contra-Rotating propellers (CRP) are propulsor configurations offering higher efficiency compared to conventional single propellers by recovering the rotational …
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Analysis and experiments for contra-rotating propeller
… on fuel economy and the improvement of the propulsive efficiency. OPENPROP is an open source propeller design and analysis code that has been in development at MIT since 2007. This thesis adds another feature to the project with the off design analysis of a contra-rotating propeller set. …
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Use of an asymmetric propeller for unmanned underwater vehicles
… The first was a possible improvement in propulsive efficiency. For UUVs meant to operate for long periods without recharging, any increase in propeller efficiency can result in more time on station. The second object was to allow for an alternate method of steering the UUV. By controlling …
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