Download or read book Design and Development of Experimental Techniques for the Measurement of Unsteady Pressure on Propeller Blades with Polyvinylidene Fluoride Film written by Christopher John Sullivan and published by . This book was released on 1996 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeroacoustic Measurements written by Thomas J. Mueller and published by Springer Science & Business Media. This book was released on 2013-11-27 with total page 327 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book describes recent developments in aeroacoustic measurements in wind tunnels and the interpretation of the resulting data. The reader will find the latest measurement techniques described along with examples of the results.
Download or read book Further Measurements of Model Propeller Pressure Distributions Using a Novel Technique written by Stuart D. Jessup and published by . This book was released on 1986 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Model propeller blade pressure distributions were measured using a novel technique. A single pressure gage was installed at a radial position to measure pressures at numerous chordwise locations through pressure taps and connecting channels. The technique resulted in accurate, detailed pressure distributions along two radial positions using two pressure gages. The major advantage of this technique is the ability to make measurements in the thin parts of the blade with high potential accuracy, and no disruption to the measuring surface, except for the orifice hole. The relatively along test time required to collect the data is the disadvantage. Keywords: Marine Propeller, Propeller Research Pressure Distribution, Model Experiments.
Download or read book The Aeronautical Journal written by and published by . This book was released on 1998 with total page 1158 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 Experimental Evaluation of a Series of Skewed Propellers with Forward Rake written by John J. Nelka and published by . This book was released on 1974 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1990 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Force Measurement Using Small Piezoelectric End Sensors written by Margalit Goldschmidt and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Most marine propellers operate in a nonuniform flow field. Understanding the unsteady lift generated on the propeller blades by these upstream wakes is important in order to reduce vibration and noise and therefore develop more efficient turbomachines. Currently, complex instrumentation involving unsteady dynamometry and pressure sensor arrays are utilized to characterize the unsteady pressures across propeller blades. New, simpler sensors have been designed to replace current instrumentation. These sensors take advantage of the oscillating nature of the unsteady lift, as at increasing inflow harmonics the rapidity of the unsteady lift fluctuations suggests that the lift nearly cancels out over the blade radius, and that the total unsteady force across a propeller blade can be found from parameters at the root and tip. These parameters were determined from an approximation provided by the Method of the Stationary Phase. Using this method, new sensors were designed and optimized to work universally. The newly designed sensors will be validated in a future experiment.
Download or read book Development of Experimental Inversion and Simulation Techniques to Study Propeller Blade Response to Inflow Distortion written by and published by . This book was released on 1995 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine propellers usually operate either in the non-uniform wake of a submarine or skewed flow under the stern of a surface ship. Therefore, the flow upstream of marine propeller blades is characterized by irregular patterns which are caused by various mean flow distortions due to the boundary layer growth on the hull of the ship, turbulent viscous wakes of upstream bodies (e.g., Hyun and Patel (1991)) or obstacles (e.g., Groves et al (1992)). Whether the inflow to the propeller is steady or unsteady, uniform or non-uniform, the flow over and downstream of the blades is unsteady. This unsteadiness can be due to a separation bubble near the leading edge of the blade, separated flow from the blade before the trailing edge, as well as tip and hub vortices. The unsteady flow over the blades produces unsteady hydrodynamic forces (i.e., excitations) which result in unwanted vibrations and noise. Inflow nonuniformities give rise to tonal and narrow band noise centered around the blade passing harmonics. Additional broad band signatures are superimposed due to turbulence-trailing edge interaction. Highly non-uniform and asymmetric inflows further exaggerate these effects. (MM).
Download or read book Measurements of Propeller Induced Unsteady Surface Force and Pressures written by and published by . This book was released on 1986 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of an experimental investigation carried out in the 24-inch water tunnel are presented for the cavitating propeller-induced surface pressures and a reference-area surface force measured on a flat plate boundary representation of a nearby ship hull. Newly designed apparatus for the measurement of surface force on an instrumented disc is described in detail. It involves special dynamometry that can be used in a reverse mode so that the force disc can be driven as a mechanical shaker. A model of a seven-bladed propeller was run in a screen-generated simulation of the steep axial wake velocity distribution for a single screw ship. Results are displayed for the longitudinal and transverse distribution of the first three blade rate harmonic components of the unsteady pressure amplitudes and the unsteady disc force amplitudes at the blade tip clearances of 0.26 (diameter) and 0.41D, over a range of cavitation numbers. The unsteady pressure pulse amplitudes obtained in this work compare reasonably will with measured values obtained previously in a large water tunnel experiment using a complete scale model of the ship hull. The experimentally inferred blade rate harmonic component of cavity volume velocity from the reciprocity measurement agrees approximately with the prediction by the PUF-3 propeller anlaysis scheme. Keywords: Pressure amplitude; Surface force; Propeller excavitation; Reciprocity experiment; Cavity volume velocity; PUF (propeller-induced unsteady forces).
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 Experimental Investigation of the Unsteady Forces Acting on a Reactangular Flat Plate Due to the Action of a Propeller written by August F. Lehman and published by . This book was released on 1968 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was undertaken in a water tunnel to determine the effect of propeller blade thickness, operating KT value, propeller tip-plate clearance and plate width on the forces, moments and pressure induced on a flat plate. The plate was oriented so as to be parallel with the rotational axis of the propeller. Propellers having three blades were tested, with one propeller design having blade thicknesses double that of the other but with both propellers having equal thrust - RPM performance. Plate widths were equal to 1 and 3 propeller radii, with the length of the plate constant at 6 propeller radii. The pressure was measured by a small flush mounted transducer located in the center of the plate surface and directly over the propeller. A comparison of certain theoretical predictions with the experimental force and pressure data resulted in generally good agreement. (Author).
Download or read book Static Stresses on Wide bladed Propellers written by Justin H. McCarthy and published by . This book was released on 1970 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Static stresses were obtained in laboratory experiments for a destroyer propeller, having aerofoil blade sections, and a super-cavitating propeller, having wedge-shaped blade sections, using specially constructed pressure chambers that allowed the blade faces to be loaded under air pressure. A new method for applying beam theory is presented that closely predicts the magnitude and distribution of radial stresses on the destroyer propeller blade. For the supercavitating propeller, neither the proposed beam-theory method nor a particular computerized-shell analysis can be considered entirely satisfactory for prediction of blade stresses. (Author).
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 Experimental Investigation of the Effect of Propeller Blade Pitch on Propeller produced Unsteady Bearing Forces and Moments written by D. T. Valentine and published by . This book was released on 1976 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Potential Flow Past a Propeller Blade Section written by Mohammad Ali Takallu and published by . This book was released on 1990 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
