Download or read book Development of a Procedure to Measure Unsteady Propeller Forces written by William Campbell Pfister and published by . This book was released on 1971 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Determination of Unsteady Forces on Contrarotating Propellers in Uniform Flow written by Marlin L. Miller and published by . This book was released on 1976 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Propeller Forces Fundamental Hydrodynamics and Unconventional Propulsion written by Ralph D. Cooper and published by . This book was released on 1971 with total page 1700 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Development of Numerical Methods for the Computation of Unsteady Propeller Forces written by Oddvar Frydenlund and published by . This book was released on 1978 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design and Construction of a System for Measurement of Unsteady Propeller Forces written by Charles Oliver Horton and published by . This book was released on 1970 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Development of Numerical for the Computation of Unsteady Propeller Forces written by Oddvar Frydenlund and published by . This book was released on 1978 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Practical Methods for Predicting Periodic Propeller Loads written by Robert J. Boswell and published by . This book was released on 1983 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Optimization Method for the Reduction of Propeller Unsteady Forces written by Thomas S. Mauther and published by . This book was released on 1988 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on the work of Greenblatt (1978), an enhanced optimization technique for the reduction of propeller unsteady forces and the determination of skew distributions has been developed. The current method provides an efficient propeller design tool capable of determining a variety of cubic or quadratic skew distributions, subject to constraints, which minimize the unsteady forces produced by the various harmonic components of the input wake. The original skew optimization method was extended to include higher order harmonics, and the original force calculation method was replaced by an extended version of the method developed by Thompson (1976). Calculation of forces and skew distributions associated with a representative propeller show that acceptable reduction of unsteady forces can be obtained without having to place severe restrictions on the model constraints. The problem considered herein is the generation of propeller noise due to non-uniform inflow velocity fields. This has been still is an issue of research in the area of marine propellers, and it is felt that a recently developed method of calculating unsteady forces may also be applicable in the design and analysis of aircraft propellers. Angle-of-attack fluctuations result in unsteady blade loadings and the generation of propeller noise, and the noise sources are characterized by three types of unsteady force mechanisms: a) turbulence injection; b) vortex shedding; and c) blade-rate.
Download or read book Unsteady Propeller Loading Measurement Correlation With Theory and Parametric Study written by Robert J. Boswell and published by . This book was released on 1968 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Objectives of the present study are to measure the unsteady forces and moments on a series of marine propellers due to circumferentially nonuniform inflow; to correlate the measured unsteady thrust and torque with calculated values, based on various proposed theories; and to investigate variation of unsteady thrust and torque over a range of pertinent parameters, using the method determined from those described to be the best available for calculating unsteady loading. Experimental blade-frequency thrust and torque were compared with values calculated by the following techniques: quasi-steady, two-dimensional unsteady, combination quasi-steady two-dimensional unsteady, and three-dimensional unsteady. The three-dimensional unsteady theory yields the best correlation with experiment; however, the numerical techniques employed breakdown for narrow-bladed propellers and for propellers with blade overlap.
Download or read book NBS Special Publication written by and published by . This book was released on 1976 with total page 838 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Determination of Unsteady Forces on Contrarotating Propellers for Application to Torpedoes written by and published by . This book was released on 1981 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents results of measurements of unsteady forces and moments on 4x4 and 4x5 bladed sets of contrarotating propellers in uniform flow and in a 4-cycle wake for application to torpedo propeller design. The uniform flow measurements were made to check earlier results that had been in disagreement with the results from calculations based on propeller theory. The uniform flow results confirmed the earlier results in showing larger forces on the forward propeller which is contrary to the prediction of existing theory. The results of the experiments in the 4-cycle wake showed unsteady forces on the forward propeller due to the effect of the wake along with the interaction forces between the two propellers. No theoretical calculations are available for comparison with the wake results. The present procedure for conducting unsteady force and moment measurements on contrarotating propellers continues to be tedious and easily subject to error. Consequently, it is recommended that no further experiments be conducted using this procedure. It is recommended that for future experiments on contrarotating propellers the shafts be locked together mechanically and that a second dynamometer be used so that unsteady measurements can be made on both propellers simultaneously. (Author).
Download or read book Measurement Correlation with Theory and Parametric Investigation of Unsteady Propeller Forces and Moments written by Robert J. Boswell and published by . This book was released on with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Some Ship and Model Measurements of Unsteady Propeller Forces written by A. Silverleaf and published by . This book was released on 1966 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Propeller Induced Velocity Field by Means of Unsteady Lifting Surface Theory written by and published by . This book was released on 1972 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analysis based on lifting surface theory has been developed for evaluation of the vibratory velocity field induced by an operating marine propeller in both uniform and nonuniform inflow fields. The analysis demonstrates how in the case of nonuniform flow the velocity at any field point is made up of a large number of combinations of the frequency constituents of the loading function with those of the space function. A numerical procedure has been developed adaptable to a high-speed digital computer and the existing program, which evaluates the steady and unsteady propeller loadings, the resulting hydrodynamic forces and moments and the pressure field, has been extended to include evaluation of the velocity field as well. The program could become a versatile and useful tool for the ship researcher or designer.
Download or read book Hydraulic Research in the United States and Canada 1974 written by Pauline H. Gurewitz and published by . This book was released on 1976 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Unsteady and Mean Loads on a CP Propeller Blade on a Model of the FF 1088 for Simulated Modes of Operation written by Robert J. Boswell and published by . This book was released on 1976 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments are described in which the mean and unsteady loads were measured on a single blade of a model of the controllable-pitch propeller on the FF-1088. The experiments were conducted behind a model of the FF-1088 hull under steady ahead operation, hull pitching motions, simulated crash ahead maneuvers, and simulated crash astern maneuvers. The experimental techniques are outlined and the dynamometer and data analysis system described. The results show that the circumferential variation of all measured components of blade loading is primarily a once-per-revolution variation, with maximum and minimum values occurring near the angular positions in which the spindle axis is horizontal. For sinusoidal pitching of the model hull with amplitude of 2 deg and frequency of 0.8 Hz, the peak-to-peak circumferential variation of measured forces and moments increased by a minimum of 50 percent over the values without hull pitching. For simulated operation during a crash ahead or crash astern maneuver, the circumferential variation of measured forces and moments varied approximately as the product of ship speed and propeller rotational speed, and was a function of propeller pitch. At no time during the simulated crash ahead or crash astern maneuvers were the circumferential variations of loads as large as during steady ahead operation. For steady ahead operation, circumferential variation of loading determined from the model experiments agreed fairly well with full-scale data, but was substantially larger than the theoretically calculated values. (Author).
Download or read book Hydraulic Research in the United States and Canada written by United States. National Bureau of Standards and published by . This book was released on 1978 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:
