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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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    <item>
      <title>SOURCE LEVEL MODEL FOR PROPELLER BLADE RATE RADIATION FOR THE WORLD'S MERCHANT FLEET</title>
      <link>https://trid.trb.org/View/166054</link>
      <description><![CDATA[A model is developed for the acoustic source strength of blade rate line energy produced by single-screw merchant vessels.  These source strengths are based on observed cavitation time histories on merchant vessels and on limitations imposed by considerations of propeller design procedures and ship vibration criteria.  Relationships are given for the expected value of the blade rate source strength for ships of different lengths.  These relationships are based on a small sample of merchant ship characteristics and are exercised for the estimated population of ships at sea.  This calculation yields a statistical description of the distribution of source level and frequency of propeller blade rate acoustic energy for the fleet of single-screw merchant vessels.]]></description>
      <pubDate>Thu, 12 Mar 1981 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/166054</guid>
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    <item>
      <title>HOW HIGHLY SKEWED PROPELLERS REDUCE NOISE AND VIBRATION</title>
      <link>https://trid.trb.org/View/166078</link>
      <description><![CDATA[With controllable-pitch propellers in mind, the Author first explains how a highly-skewed propeller can lengthen the duration of suction-side cavitation as compared with a conventional propeller and so reduce the rate of variation of cavitation with time, resulting in a reduction of vibration.  The dynamic forces absorbed through the propeller shaft will also be reduced.  Although the Author's firm (Hjelset Motorfabrikk A/S, Norway) has not carried out full-scale meaurements, it was found that, where a comparison between a conventional and a highly-skewed propeller has been possible, a reduction of about 50% in propeller-induced vibration has been obtained with the highly-skewed blades.  The article includes some comparisons (for a conventional four-bladed c.p. propeller) of pressure impulses, at blade frequency and twice blade frequency, between the values calculated by a statistical method developed from full-scale measurements, the values calculated by lifting-surface theory, and the values measured in sea trials.  While it is not possible to recommend a general maximum for pressure impulses, it can be stated that 600 to 700 kp/m square (single amplitude at blade frequency) should not be exceeded in a single-screw ship.  Spindle torque in a highly-skewed propeller can be kept at the same level as that of a conventional propeller through a balanced blade design.  The primary application of the highly-skewed propeller is for passenger ships, where comfort requirements are high; it is also useful for favourable pressure-impulse and dynamic bearing-force characteristics can be utilised to save fuel.  Where maximum vibration level is specified, the highly-skewed propeller can fulfil this requirement with a larger diameter and a low shaft- speed and so give improved propulsive efficiency.]]></description>
      <pubDate>Thu, 12 Mar 1981 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/166078</guid>
    </item>
    <item>
      <title>EARLY DESIGN-STAGE APPROACH TO REDUCING HULL SURFACE FORCES DUE TO PROPELLER CAVITATION</title>
      <link>https://trid.trb.org/View/157363</link>
      <description><![CDATA[The approach for the selection of parameters at a very early design stage to reduce hull surface excitation forces induced by blade cavitation has been based on regression anlaysis of data from model wake field measurements and full-scale investigations.  Recommendations on the selection of after-body lines to reduce the "wake peak" are given for both slender V-shaped and full-form ships.  Criteria for acceptable pressure fluctuations on the hull are presented which should give satisfactory local vibration levels in the afterbody structure as well as global vibration levels in the accommodation area.  Further, more specific guidelines are presented on how to select main propeller parameters and clearances to give the best basis for future investigations.  How to use the developed methods in a complete design procedure is proposed.]]></description>
      <pubDate>Wed, 18 Feb 1981 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/157363</guid>
    </item>
    <item>
      <title>ASPECTS OF THE DESIGN AND APPLICATION OF OFF-LOADED TIP PROPELLERS</title>
      <link>https://trid.trb.org/View/149770</link>
      <description><![CDATA[Since the presentation of an earlier paper in which a description was given of a new design method that enables the propeller designer to select a radial load distribution and blade-section characteristics corresponding to minimum cavitation, and hence to reduced amplitudes of full surface pressure fluctuations, the model experiments discussed in that paper have been completed.  Also, the results of the first full-scale application (a retrofit on a large gas-carrier) have become available, and the design method has been further developed.  In the present paper, which includes a brief description of the design method, the Authors (of, respectively, the University of Newcastle upon Tyne and SMM Propellers Ltd) use the results of the model tests (for the propeller of a single-screw container-ship) to demonstrate the effects of different degrees of tip off-loading on propeller geometry and on pressure amplitudes and propulsive performance.  The design of the retrofit propeller for the gas carrier (the first of a series of four Norwegian-built 125,000-cu m LNG carriers) is described, together with the full-scale pressure measurements and their comparison with theoretical predictions.  This first full-scale application has shown that the new design method can make a significant improvement in vibration, particularly in relation to blade-rate impulse level. Further development is in hand, with the immediate objective of shortening the design time.  From this work, it can be concluded that tip unloading results in significant reductions in pressure impulses, in particular the component at blade frequency.  In most cases, partial unloading will be adequate and the resulting loss in propulsion performance should be acceptable.  Further experiments are necessary to determine the degree of correlation between model predictions and full-scale performance.  Order from BSRA as No. 52,514.]]></description>
      <pubDate>Thu, 26 Jun 1980 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/149770</guid>
    </item>
    <item>
      <title>TURBINE BLADING EXCITATION AND VIBRATION</title>
      <link>https://trid.trb.org/View/72297</link>
      <description><![CDATA[This is a review of the literature on blade excitation forces, vibration of turbine blades with large and small aspect ratios, disc blade interaction, and experimental methods of vibration measurement, including the use of a laser doppler instrument.  These subjects are briefly discussed with extensive references to published literature.]]></description>
      <pubDate>Wed, 12 Apr 1978 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/72297</guid>
    </item>
    <item>
      <title>THEORY FOR THE VIBRATORY FORCES ON A FLAT PLATE ARISING FROM INTERMITTENT PROPELLER BLADE CAVITATION</title>
      <link>https://trid.trb.org/View/52983</link>
      <description><![CDATA[An analysis was made which shows that the dominant cavity-induced force on a flat bottomed, shallow draft ship is expressible in a very simple form when the cavity volume as a function of blade position is known.  The increased loading on conventionally configured propellers has led to the frequent occurrence of intermittent propeller blade cavitation in the region between + or - 60 degree about the 12 o'clock position on tankers as well as on high-speed container ships.  Measurements of hull pressures on models in variable pressure facilities, as well as on ships, have shown these cavity-induced pressures to be large not only at blade frequencies, but also at higher harmonics.  The effects are particularly large at twice and three times blade frequency.]]></description>
      <pubDate>Wed, 22 Jun 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/52983</guid>
    </item>
    <item>
      <title>PROPELLER-EXCITED VIBRATION WITH PARTICULAR REFERENCE TO FULL-SCALE MEASUREMENTS</title>
      <link>https://trid.trb.org/View/47130</link>
      <description><![CDATA[The paper presents work for a comprehensive set of full- scale measurements of ship vibration responses.  Service data have been presented in terms of blade passage frequency and its harmonics.  For the former a summary of data from 25 trials has been given in the form of a presentation of the mean vertical vibration at the stern gland against a power-geometry factor.  In addition, data are given which relate the mean vibration levels at a standard  measuring position at the wheelhouse top to the stern gland responses. It is suggested that such information can be used as a basis for comparison and prediction of mean vibration levels for new ship designs.  The responses for the higher harmonics have been presented in a way which helps to define those characteristics which are associated with the more severe cases of propeller-excited vibration.]]></description>
      <pubDate>Tue, 26 Oct 1976 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/47130</guid>
    </item>
    <item>
      <title>PROPELLER HYDRODYNAMICS AND SHAFT DYNAMICS</title>
      <link>https://trid.trb.org/View/30670</link>
      <description><![CDATA[With increased dimensions and installed power, heavier shaft systems are applied in modern ships.  The consequence is a shift of the resonance of the shafting system to lower frequencies.  At the same time the number of blades of the propeller are necessarily increased in order to absorb the higher power and to meet the requirement of restricted draft.  Consequently, the blade frequency (blade number multiple of number of shaft revolutions per second), which is the most important excitation frequency, does not show a strong reduction.  In many cases even an increase will be bound.  The difference between excitation and resonance frequency is diminished, so that the propeller operation at service speed is close to or on the resonance of the shafting vibrations.  For the transverse vibrations this is more relevant than for the longitudinal vibrations and this paper is restricted to the transverse, lateral or whirling vibrations.]]></description>
      <pubDate>Wed, 04 Feb 1976 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/30670</guid>
    </item>
    <item>
      <title>TECHNIQUES FOR ESTIMATING VIBRATORY FORCES GENERATED BY PROPELLERS</title>
      <link>https://trid.trb.org/View/28598</link>
      <description><![CDATA[This Bulletin is a condensation of available practical information on the various aspects of ship propeller forces and propeller-induced hull forces arising from the spatially non-uniform flows to which almost all ship propellers are subjected.  The work embraces brief physical descriptions of the manner in which blade frequency pressures are generated by propellers; the attending induced pressures on nearby structures to produce hull forces; the forces on the propeller itself and the blade- bending moment and a distillation of experimental results from model tests and full-scale measurements which reveal the dominant effects of certain parameters as currently exhibited.]]></description>
      <pubDate>Wed, 05 Nov 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/28598</guid>
    </item>
    <item>
      <title>STEADY AND TIME-DEPENDENT PROPELLER BLADE LOADING AND STRESS ANALYSIS</title>
      <link>https://trid.trb.org/View/38112</link>
      <description><![CDATA[The unsteady lifting surface theory has been utilized in evaluating the blade loading distribution at all shaft frequencies and the corresponding hydrodynamic forces and moments at multiples of blade frequency (thrust, torque, bearing forces and bending moments) taking into account as realistically as possible the geometry of the propeller and the inflow field.  Stresses are determined by means of beam theory and the finite element technique, although the latter should be considered as a first attempt.]]></description>
      <pubDate>Tue, 30 Sep 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/38112</guid>
    </item>
    <item>
      <title>EVALUATION OF A FINITE DIFFERENCE HELICOIDAL SHELL ANALYSIS BY COMPARISON WITH TEST RESULTS FOR A MARINE PROPELLER</title>
      <link>https://trid.trb.org/View/38115</link>
      <description><![CDATA[The ability to predict the blade natural frequencies and the stresses under operating conditions is a necessary requirement of the blade design process.  This requires an accurate definition of the steady and cyclic pressure loads over the blade surface.  It also requires an appropriate structural model and analytic procedure for solving the structural response of the blade.  This paper presents the results achieved by application of a finite difference helicoidal shell analysis computer program to a supercavitating marine propeller blade.  The natural frequencies, mode shapes, steady stress and cyclic stress are evaluated, and the results are compared to measured values.  Comparison with test results is made using both analytically derived and measured pressure distributions. Correlation of measured and calculated "in air" natural frequencies and mode shapes is quite good particularly for the higher modes.  The calculated stresses agree well when compared to calculations based upon measured pressures.]]></description>
      <pubDate>Tue, 30 Sep 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/38115</guid>
    </item>
    <item>
      <title>INDUCED FIELD-POINT PRESSURES OF A DUCTED PROPELLER SYSTEM</title>
      <link>https://trid.trb.org/View/23358</link>
      <description><![CDATA[Total fluctuating pressures were measured on the internal surface of a 0-degree angle-of-attack duct of a ducted propeller system (Kort nozzle type).  The effects of blade loading in uniform flow and propeller blade cavitation in nonuniform flow on the harmonics of the blade-frequency propeller-induced pressure were determined. Also determined were the blade-frequency pressure-induced duct forces. Experimental results indicate that the blade-frequency pressures increase for an increase in blade loading with the second and third blade-frequency pressure being significant with respect to the blade-frequency pressure.  Fluctuating blade-frequency vertical forces determined by integrating the pressure results from nonuniform inflow noncavitating conditions were approximately 1-percent of the mean thrust. In the experiments conducted at a given loading, cavitation on the propeller blades tended to increase the blade-frequency pressure downstream of the propeller by as much as a factor of three.]]></description>
      <pubDate>Mon, 19 May 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/23358</guid>
    </item>
    <item>
      <title>TUNNEL HULL CAVITATION AND PROPELLER INDUCED PRESSURE INVESTIGATION</title>
      <link>https://trid.trb.org/View/23373</link>
      <description><![CDATA[Cavitation performance of two propellers at different hull clearance-to-diameter ratios in a tunnel hull model are presented, as well as the propeller-induced pressures measured in the tunnel wall. Cavitation performance of the two propellers in uniform flow is also included. The propellers operating in the tunnel hull were found to be more efficient than in uniform flow. Predominate features of the induced pressure measurements were the blade-frequency harmonics. There was no evidence of flow separation on the tunnel hull model at simulated ship speeds of 45 knots.]]></description>
      <pubDate>Mon, 19 May 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/23373</guid>
    </item>
    <item>
      <title>PROPELLER BLADE CAVITATION AS A SOURCE OF VIBRATIONS--FULL SCALE EXPERIENCES</title>
      <link>https://trid.trb.org/View/26824</link>
      <description><![CDATA[Equipment and methods for observation of propeller cavitation on board different types of ships in various loading conditions and water are described.  Recorded pressure impulses on the hull induced by the propeller are presented.  In this paper necessary equipment and methods developed for observations and characterizing one of the most important sources of vibrations on board ships are presented.  Development of equipment and investigations on board the ships have been carried out in close cooperation with the AKER GROUP and the SHIP RESEARCH INSTITUTE OF NORWAY.  Full scale investigations applying the equipment will continue for the next 2 years, so as to obtain more sufficient data as basis for correlations of model cavitation tests and theoretical methods of approach.]]></description>
      <pubDate>Thu, 01 May 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/26824</guid>
    </item>
    <item>
      <title>HULL RESONNANCE NO EXPLANATION FOR EXCESSIVE VIBRATION</title>
      <link>https://trid.trb.org/View/19381</link>
      <description><![CDATA[A new approach of marine vibration problems is given, showing that for modern, high powered ships excessive hull vibrations at service r.p.m. cannot be explained by hull resonances.  The fundamental cause is the increased power. Therefore the solution of present-day vibration problems must be found in reducing the excitation forces, strongly dominated by propeller cavitation and propeller shaft resonances.  Calculation of hull vibrations is nowadays only required to know the final response level, in order to detect unpleasant or dangerous vibrations, and no longer to know the higher node hull resonances in order to avoid their excitation at service speed.]]></description>
      <pubDate>Mon, 15 Jul 1974 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/19381</guid>
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