Author: John J. Nelka
Publisher:
ISBN:
Category : Cavitation
Languages : en
Pages : 84
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Results are given showing the experimental effect of propeller-blade warp on open-water performance, cavitation performance, unsteady field-point pressures, and unsteady propeller loading for a series of warped propellers. Blade warp is defined as the angular displacement at the midchord point of the blade section from the blade reference line in the plane of rotation. Open-water results indicate that at the design thrust-loading coefficient and shaft horsepower the warped propellers are as much as 4.5 percent less than the design rpm. Cavitation results show a widening of the cavitation-free bucket with increasing warp; however, there is some crossover in the inception of back cavitation and tip-vortex cavitation. Field-point pressures and the unsteady propeller forces and moments have been found to decrease with increasing warp to reductions previously achieved with blade skew. (Author).
Author: Robert J. Boswell
Publisher:
ISBN:
Category : Propellers
Languages : en
Pages : 196
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Experimental results are presented on the spindle torque and open-water performance of two skewed controllable-pitch propellers. Both propellers have radial distributions of skew specified so that the section midchord is forward of the spindle axis at the inner radii and aft of the spindle axis at the outer radii. One propeller has no rake and the other has substantial forward rake. The experiments were conducted at steady conditions in uniform flow in a towing basin over a range of positive and negative pitch ratios and a range of positive and negative advance coefficients so that the complete maneuvering envelope of the ship was simulated in a quasi-steady manner. The experimental open-water performance was correlated with calculated values based on a least-squares fit to previous systematic experimental data.
Author:
Publisher:
ISBN:
Category : Weights and measures
Languages : en
Pages : 838
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 970
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Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: Pauline H. Gurewitz
Publisher:
ISBN:
Category : Fluid mechanics
Languages : en
Pages : 364
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Author: Robert J. Boswell
Publisher:
ISBN:
Category : Propellers
Languages : en
Pages : 52
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Author:
Publisher:
ISBN:
Category : Hydraulic engineering
Languages : en
Pages : 708
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Author: Robert J. Boswell
Publisher:
ISBN:
Category : Propellers
Languages : en
Pages : 82
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Static strains were measured in a systematic series of five marine propeller blades. The propeller blades have projected skew angle at the blade tip equal to zero, 36 degrees and 72 degrees without rake, and 36 and 72 degrees with sufficient forward rake to place the locus of the section midchord in the propeller plane. This combination of skew and rake is called warp. The primary experiments were conducted with the blades under uniform loading applied with air pressure using specially constructed chambers. Limited supplemental experiments were conducted using concentrated loads. The experimental results under uniform loading were correlated with modified beam theory. Both the experimental results and the modified beam theory indicate that for all the skewed and warped propeller blades evaluated, the largest value of the maximum principal stress is no greater than 1.20 times the maximum prinicipal stress on the unskewed propeller.
Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 628
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Author:
Publisher:
ISBN:
Category : Propellers
Languages : en
Pages : 532
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