The Experts below are selected from a list of 9273 Experts worldwide ranked by ideXlab platform
Spyridon A Kinnas - One of the best experts on this subject based on the ideXlab platform.
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Cavitating Propeller Analysis including the effects of wake alignment
Journal of Ship Research, 1999Co-Authors: Spyridon A Kinnas, Sangwoo PyoAbstract:Various wake alignment techniques which have been developed in the past for the Analysis of non-cavitating Propellers in uniform inflows are reviewed and some of them are extended in the case of cavitating flows subject to inclined inflows. The effect of the inclined trailing wake geometry on the predicted cavities and blade forces is found to be significant. Predicted open flow characteristics and unsteady forces acting on the blades of an inclined shaft Propeller are compared with those predicted by other methods, as well as with those measured in experiments.
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A design method for high-speed propulsor blades
Journal of Fluids Engineering-transactions of The Asme, 1998Co-Authors: Paul E. Griffin, Spyridon A KinnasAbstract:This study uses a nonlinear optimization method coupled with a vortex lattice cavitating Propeller Analysis method to design efficient Propeller blades. Different constraints are imposed to improve Propeller design. Several advancements in the method are shown, including the option for quadratic skew, user specified skew distribution, and a constraint limiting the minimum pressure in wetted regions of the blade. Results for a series of fully wetted runs demonstrate the effectiveness of the constraint on minimum pressure in preventing the onset of bubble or mid-chord cavitation. A comparison ofa design in uniform inflow with a design in non-axisymmetric inflow indicates that a Propeller designed by the present method in non-axisymmetric inflow has more favorable cavitating flow characteristics than a Propeller design assuming uniform inflow. Results are also shown for a series of runs utilizing the cavity constraints. These results indicate that the present method can be used to improve on Propeller designs by imposing constraints on the cavity area and cavity volume velocity harmonics, as well as by using a quadratic skew distribution
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Experimental Validation of a Ducted Propeller Analysis Method
Journal of Fluids Engineering-Transactions of the ASME, 1992Co-Authors: M. J. Hughes, Spyridon A Kinnas, Justin E KerwinAbstract:A ducted Propeller model was tested in the MIT water tunnel. A hub\napparatus was designed which allowed for the duct and Propeller forces\nto be measured separately. The forces on the duct and Propeller were\nmeasured over a range of advance coefficients. Velocities were measured\nupstream and downstream from the duct using a Laser Doppler Velocimetry\nsystem. Using these velocities the experimental values for the spanwise\ndistribution of circulation on the Propeller blades were then calculated.\nThe experimental results were compared to the results from a Propeller\nlifting surface/duct and hub surface panel Analysis code over the\nsame range of advance coefficients showing very good agreement for\nthe duct and Propeller forces and the circulation in the region of\nattached flow.
Leo Veldhuis - One of the best experts on this subject based on the ideXlab platform.
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Analysis and Design of a Small-ScaleWingtip-Mounted Pusher Propeller
2019Co-Authors: T.c.a. Stokkermans, Bas Nootebos, Leo VeldhuisAbstract:The wingtip-mounted pusher Propeller, which experiences a performance benefit from the interaction with the wingtip flowfield, is an interesting concept for distributed propulsion. This paper examines a Propeller design framework and provides verification with RANS CFD simulations by analyzing the wing of a 9-passenger commuter airplane with a wingtip-mounted Propeller in pusher configuration. In the taken approach, a wingtip flowfield is extracted from a CFD simulation, circumferentially averaged and provided to a lower order Propeller Analysis and optimisation routine. Possible propulsive efficiency gains for the Propeller due to installation are significant, up to 16% increase at low thrust levels, decreasing to approximately 7:5% at the highest thrust level, for a range of thrust from 5% up to 100% of the wing drag. These gains are found to be independent of Propeller radius for thrust levels larger than 30% of the wing drag. Effctively, the Propeller geometry is optimized for the required thrust and to a lesser degree for the non-uniformity in the flowfield. Propeller blade optimization and installation result in higher profile eciency in the blade root sections and a more inboard thrust distribution.
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Mitigation of Pusher-Propeller Installation Effects by Pylon Trailing-Edge Blowing
Journal of Aircraft, 2017Co-Authors: Tomas Sinnige, Daniele Ragni, Georg Eitelberg, Leo VeldhuisAbstract:This paper presents an experimental assessment of the working principles of pylon trailing-edge blowing for the mitigation of the interaction between a pusher Propeller and its associated pylon. The experiments were performed at the Large Low-Speed Facility of the German–Dutch wind tunnels, using a powered Propeller model and an upstream pylon equipped with a trailing-edge blowing system. Inflow microphone measurements demonstrated the impact of pylon installation on the Propeller’s tonal noise emissions, with increases of up to 16 dB relative to the isolated Propeller. Analysis of the unsteady blade pressures showed that this installation effect was caused by the impulsive increase in blade loading during the pylon-wake passage. The efficacy of pylon trailing-edge blowing to reduce the momentum deficit in the pylon wake was confirmed by stereoscopic particle-image-velocimetry measurements between the pylon and the Propeller. Consequently, application of the pylon-blowing system alleviated the pylon-insta...
Jose Pascoa - One of the best experts on this subject based on the ideXlab platform.
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Validation of New Formulations for Propeller Analysis
Journal of Propulsion and Power, 2015Co-Authors: J. Morgado, M. Â. R. Silvestre, Jose PascoaAbstract:This paper reports the development of a new Propeller design and Analysis tool. JBLADE uses an improved version of blade element momentum that embeds a new model for the three-dimensional flow equilibrium. In addition, a new method for the prediction of the airfoil drag coefficient at a 90 deg angle of attack for a better poststall modeling is also presented. The software is developed as an open-source tool for the simulation of Propellers and has the capability to estimate the performance of a given Propeller geometry in design and offdesign operating conditions. The software allows the introduction of the blade geometry as an arbitrary number of sections. To validate the code, the Propellers from NACA Technical Report 530 by Gray (“Wind-Tunnel Tests of Two Hamilton Standard Propellers Embodying Clark Y and NACA 16-Series Blade Sections,” 1941) and NACA Technical Report 594 by Theodorsen et al. (“Characteristics of Six Propellers Including the High-Speed Range,” 1937) were simulated and the results were ...
Veldhuis L.l.m. - One of the best experts on this subject based on the ideXlab platform.
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Analysis and Design of a Small-ScaleWingtip-Mounted Pusher Propeller
'American Institute of Aeronautics and Astronautics (AIAA)', 2019Co-Authors: Stokkermans T.c.a., As Nootebos, Veldhuis L.l.m.Abstract:The wingtip-mounted pusher Propeller, which experiences a performance benefit from the interaction with the wingtip flowfield, is an interesting concept for distributed propulsion. This paper examines a Propeller design framework and provides verification with RANS CFD simulations by analyzing the wing of a 9-passenger commuter airplane with a wingtip-mounted Propeller in pusher configuration. In the taken approach, a wingtip flowfield is extracted from a CFD simulation, circumferentially averaged and provided to a lower order Propeller Analysis and optimisation routine. Possible propulsive efficiency gains for the Propeller due to installation are significant, up to 16% increase at low thrust levels, decreasing to approximately 7:5% at the highest thrust level, for a range of thrust from 5% up to 100% of the wing drag. These gains are found to be independent of Propeller radius for thrust levels larger than 30% of the wing drag. Effctively, the Propeller geometry is optimized for the required thrust and to a lesser degree for the non-uniformity in the flowfield. Propeller blade optimization and installation result in higher profile eciency in the blade root sections and a more inboard thrust distribution.Flight Performance and Propulsio
Baowei Song - One of the best experts on this subject based on the ideXlab platform.
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Convergence of different wake alignment methods in a panel code for steady-state flows
Journal of Marine Science and Technology, 2016Co-Authors: Youjiang Wang, Moustafa Abdel-maksoud, Baowei SongAbstract:Wake alignment models are always included in the modern panel codes for marine Propeller Analysis. The wake alignment algorithms influence directly the rate of convergence and the accuracy of calculations. In the present work, firstly, four different numerical methods to implement the wake alignment algorithms for the steady calculation are described. They perform quite differently in terms of convergence history and convergence rate. The comparison with the other methods shows that the direct application of the unsteady method leads to a much slower convergence rate. Secondly, high-order numerical methods including second-order and fourth-order Runge–Kutta methods are introduced into the wake alignment, which results in high-order wake alignment algorithms. The Analysis of the results shows that the high-order methods generate a different wake geometry from the low-order method. The thrust coefficient and torque coefficient have also been compared.
