<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=PHNlYXJjaD48cGFyYW1zPjxwYXJhbSBuYW1lPSJkYXRlaW4iIHZhbHVlPSJhbGwiIC8+PHBhcmFtIG5hbWU9InN1YmplY3Rsb2dpYyIgdmFsdWU9Im9yIiAvPjxwYXJhbSBuYW1lPSJ0ZXJtc2xvZ2ljIiB2YWx1ZT0ib3IiIC8+PHBhcmFtIG5hbWU9ImxvY2F0aW9uIiB2YWx1ZT0iMCIgLz48L3BhcmFtcz48ZmlsdGVycz48ZmlsdGVyIGZpZWxkPSJpbmRleHRlcm1zIiB2YWx1ZT0iJnF1b3Q7UG9seW1lciBlamVjdGlvbiBzeXN0ZW1zJnF1b3Q7IiBvcmlnaW5hbF92YWx1ZT0iJnF1b3Q7UG9seW1lciBlamVjdGlvbiBzeXN0ZW1zJnF1b3Q7IiAvPjwvZmlsdGVycz48cmFuZ2VzIC8+PHNvcnRzPjxzb3J0IGZpZWxkPSJwdWJsaXNoZWQiIG9yZGVyPSJkZXNjIiAvPjwvc29ydHM+PHBlcnNpc3RzPjxwZXJzaXN0IG5hbWU9InJhbmdldHlwZSIgdmFsdWU9InB1Ymxpc2hlZGRhdGUiIC8+PC9wZXJzaXN0cz48L3NlYXJjaD4=" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <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>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>APPARATUS FOR IMPROVING THE OVERALL EFFICIENCY OF A MARINE SCREW PROPELLER</title>
      <link>https://trid.trb.org/View/89293</link>
      <description><![CDATA[Elongate slots are formed near the leading edges of propeller blades and a supply of polyethylene oxide is ejected through the slots to form a continuous sheet of the polymer flowing on the suction side surface in the region where about 70% of the thrust loading is distributed. The polymer changes the propeller's pressure distribution and increases its lift factor and efficiency. When ejected at a proper flow rate, frictional drag also is reduced. The slots are shaped channels having a particular depth, width and directional orientation that assures the continuity of the flowing sheet. To achieve the benefits, polymer concentration is maintained at a level capable of providing a trailing edge concentration of about 2-20 ppm. (Author)]]></description>
      <pubDate>Wed, 17 Oct 1979 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/89293</guid>
    </item>
    <item>
      <title>A NOTE ON LIFT AND DRAG EFFECTS DUE TO POLYMER INJECTIONS FROM SEVERAL LOCATIONS ON A SYMMETRIC HYDROFOIL</title>
      <link>https://trid.trb.org/View/80794</link>
      <description><![CDATA[It is well known that the injection of dilute polymer solutions into the boundary layer on two-dimensional hydrofoils produces changes in both the drag and lift of the foils, with the changes being dependent on the polymer, its concentration , the injection technique, the location of the injection slit, and the rate of injection.  Previous tests have also shown that the observed drag reduction does not necessarily increase linearly with the rate of injection of the polymer.  Indeed, beyond a certain injection rate, further increases lead to little or no drag reduction and, in some cases, actually lead to a drag increase.  Thus, one question that is of considerable practical interest is the effect of multiple injections of a given amount of polymer from several chordwise locations as compared with that due to the injection from a single location.  The present study investigates the effects on lift and drag of a 20.16-cm (8 in.) chord NACA 63 sub 4-010 two dimensional hydrofoil due to multiple injections of 200-ppm Polyox WSR 301 solution from several chordwise locations.  The results indicate that, for a given flux of polymer injection, multiple injections from properly selected locations as compared with the injection from a single location result in a larger drag reduction without adversely affecting the foil lift.]]></description>
      <pubDate>Sat, 13 Jan 1979 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/80794</guid>
    </item>
    <item>
      <title>LIFT EFFECTS ASSOCIATED WITH DRAG-REDUCING POLYMER INJECTION ON TWO-DIMENSIONAL HYDROFOILS</title>
      <link>https://trid.trb.org/View/66595</link>
      <description><![CDATA[The effect of a boundary-layer injection of drag-reducing additive solutions on the lift and drag of a 10-cm chord, NACA 63A020 symmetrical two-dimensional hydrofoil was investigated for various freestream and injection velocities, foil incidences, and additive concentrations ranging from 50 to 400 ppm of POLYOX WSR 301.  The experimental results demonstrate that the lift of the hydrofoil can either increase or decrease depending upon whether the polymer injection is made on the suction or pressure side of the foil surface, respectively.  In both cases, however, the drag is reduced.  The net result of the injection of the drag-reducing agent is an augmentation of the lift-drag ratio.  The magnitude of this augmentation and its dependence on the freestream velocity, the injection velocity, the concentration of polymer, and the incidence of the foil are analyzed.]]></description>
      <pubDate>Wed, 16 Feb 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/66595</guid>
    </item>
    <item>
      <title>DIFFUSION OF A TANGENTIAL DRAG-REDUCING POLYMER INJECTION ON A FLAT PLATE AT HIGH REYNOLDS NUMBERS</title>
      <link>https://trid.trb.org/View/66597</link>
      <description><![CDATA[The diffusion of a thin tangential jet of an aqueous solution of drag-reducing polymer injected into the water- turbulent boundary layer of a flat plate at a freestream Reynolds number, 3.6 x 10 to the seventh power, and the accompanying drag reduction are investigated for a variety of initial concentrations and ratios of injection to freestream velocities.  The concentration distribution along the wall is found to be mainly represented by two regions.  In the first region the wall concentration is practically constant and equal to the injected one; in the second region the concentration varies approximately as the inverse of the distance from the injection slit.  The length of the first region is significantly increased by the polymer solution injection as compared with the pure solvent injection.  The drag-reduction effect associated with the polymer injection depends on the trailing-edge concentration achieved as a result of the diffusion process.]]></description>
      <pubDate>Wed, 16 Feb 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/66597</guid>
    </item>
    <item>
      <title>A STUDY OF THE DRAG CHARACTERISTICS AND POLYMER DIFFUSION IN THE BOUNDARY LAYER OF AN AXISYMMETRIC BODY</title>
      <link>https://trid.trb.org/View/43765</link>
      <description><![CDATA[Drag reduction by ejection of high molecular weight polymers on free-running bodies of revolution has been demonstrated repeatedly.  The quantities of polymer required have made the gains achieved marginal from a volume utilization tradeoff.  The ejection process is hypothesized to be the controlling factor.  Limited data obtained in pipe flow and flat plate flow experiments on ejection into developing boundary layers indicate a drastic reduction in polymer requirements for equivalent percent drag reductions. Extension to axisymmetric flow could result in significant achievable gains to volume utilization. This study examined these polymer ejection processes through measurement of wall and boundary layer concentration profiles and through a photographic study of the boundary layer.  Tests performed with fresh water ejection and solutions of the drag reducing polymer, Polyox WSR-301, lead to the hypothesis that optimal ejection for minimum polymer usage requires ejection into a laminar boundary layer prior to turbulent flow transition.  Analytical routines are developed which predict boundary layer parameters and polymer wall concentrations for this postulated optimal ejection process or the suboptimal case.  Limited verification of the model is made.  /Author/]]></description>
      <pubDate>Thu, 16 Sep 1976 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/43765</guid>
    </item>
    <item>
      <title>LIFT, DRAG, AND PRESSURE DISTRIBUTION EFFECTS ACCOMPANYING DRAG-REDUCING POLYMER INJECTION ON TWO- DIMENSIONAL HYDROFOIL</title>
      <link>https://trid.trb.org/View/42289</link>
      <description><![CDATA[Lift and drag forces and pressure distribution were measured for a 10 cm. chord, 20 percent relative thickness, NACA 63 sub 4-020, symmetrical, two-dimensional hydrofoil, with and without drag-reducing polymer injection. The 200 ppm solution of Polyox WSR 301 was introduced into the foil boundary layer with an injection velocity of 10 percent of the free stream velocity.  The injection slits were situated 10 and 30 percent of the chord length.  The pressure distribution data does not indicate any significant change of the separation point.  It demonstrates, however, that the polymer injection always results in a significant decrease of pressure in the region aft of the injection slit.  This decrease of the local pressure gives rise to a lift increase for injections made on the suction side of the foil surface and a lift decrease for injections made on the pressure side.  The data suggest an elongational viscoelastic effect and a tentative explanation is offered.]]></description>
      <pubDate>Thu, 22 Jul 1976 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/42289</guid>
    </item>
    <item>
      <title>EFFECT OF DRAG-REDUCING POLYMER INJECTION ON THE LIFT AND DRAG OF A TWO-DIMENSIONAL HYDROFOIL</title>
      <link>https://trid.trb.org/View/31264</link>
      <description><![CDATA[The present paper describes an experimental investigation on the effects of injecting drag-reducing polymer solutions into the turbulent boundary layer of two NACA 63, two-dimensional, symmetrical, hydrofoils. The experiments were performed in a high-speed circulating channel with free stream velocities of up to 13 m/sec. The two foils used were 10 and 20 cm in chord, though both had a maximum thickness of 2 cm. The incidence of the foils varied between plus or minus 5 degrees with the ratios of the injection to free stream velocity of up to 0.2, and a concentration of poly(ethylene oxide), POLYOX WSR 301, of 200 ppm. The injection slits on both foils are situated one-tenth of a chord downstream of the leading edge. The gap of the injection slit was 0.0127 cm for the small foil and twice this value for the larger foil. (Modified author abstract)]]></description>
      <pubDate>Thu, 29 May 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/31264</guid>
    </item>
    <item>
      <title>DRAG-REDUCING POLYMER MOLECULAR WEIGHT EFFECTS ON TURBULENT DIFFUSION FOR UNIFORMLY DISTRIBUTED POLYMER INJECTION</title>
      <link>https://trid.trb.org/View/17482</link>
      <description><![CDATA[The effect of polymer molecular weight on turbulent diffusion and drag-reduction was investigated over a uniformly distributed polymer injection area. The purpose of the experiments, carried out in a porous wall pipe flow facility, was to determine optimum values of polymer molecular weight and injection mass flux for attaining maximum skin-friction reduction over a distributed injection area and to investigate associated turbulent diffusion characteristics. It was found for this type of polymer supply system, which provided polymer directly to the required wall shear stress region, that the optimum molecular weight was approximately an order of magnitude less than that normally used in skin-friction reduction applications with homogeneous solutions and localized injection. (Modified author abstract)]]></description>
      <pubDate>Wed, 06 Nov 1974 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/17482</guid>
    </item>
    <item>
      <title>DRAG REDUCTION BY EJECTING ADDITIVE SOLUTIONS INTO PURE-WATER BOUNDARY LAYER</title>
      <link>https://trid.trb.org/View/12109</link>
      <description><![CDATA[Drag reduction caused by ejecting additive solutions from a slot into a pure-water boundary layer on a flat plate has been systematically studied.  Results include drag measurements for a plane boundary, smooth and rough, with various openings of the slot and with various concentrations and discharges of the ejected additive solution. Conclusions have been drawn on the additive requirement in external flows and on the ejection technique for an optimum drag reduction.]]></description>
      <pubDate>Fri, 06 Apr 1973 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/12109</guid>
    </item>
    <item>
      <title>DRAG REDUCTION AND DIFFUSION ACCOMPANYING THIN SLIT INJECTIONS OF A DRAG REDUCING POLYMER ON A FLAT PLATE AT HIGH REYNOLDS NUMBERS</title>
      <link>https://trid.trb.org/View/7969</link>
      <description><![CDATA[The drag reduction and diffusion accompanying a thin tangential jet injection of an aqueous solution of drag reducing polymer, Polyox WSR 301, into the water turbulent boundary layer of a flat plate at a high free stream Reynolds number, 3.6 times 10 to the 7th power, was investigated for a variety of injected concentrations and ratios of injection to free stream velocities.  The wall concentration distribution was found to be mainly represented by two regions; the first region where the wall concentration is practically constant and equal to the injected one and the second region where the concentration varies approximately as the inverse of the distance from the injection slit.  It is shown that the increased wall length is directly related to the thickening of the viscous sublayer.  The wall concentration distribution is related to the drag reduction and a simple correlation between its values and the characteristics parameters of the external flow and the drag reducing injection can be established.]]></description>
      <pubDate>Fri, 02 Mar 1973 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/7969</guid>
    </item>
    <item>
      <title>POLYMER INJECTION FOR DRAG REDUCTION</title>
      <link>https://trid.trb.org/View/7970</link>
      <description><![CDATA[Viscous drag reduction caused by polymer injection into a developing turbulent boundary layer was investigated in a 12-inch I.D. hydraulically rough pipe.  Pressure drop measurements were made in the first 200 diameters of the pipe.  Velocity profile and concentration profile measurements were also  taken.  Drag reductions above 90 percent were realized in the inlet region for lower injection concentrations.  For a given polymer injection rate, drag reduction in the inlet region was found to decrease with increasing injection concentration.]]></description>
      <pubDate>Fri, 02 Mar 1973 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/7970</guid>
    </item>
    <item>
      <title>BOUNDARY LAYER ADDITIVES TO REDUCE SHIP RESISTANCE</title>
      <link>https://trid.trb.org/View/11913</link>
      <description><![CDATA[Pipes, flat plates and submerged bodies have been used to investigate the phenomenon whereby up to 50 percent reduction in frictional resistance can be achieved by using boundary layer additives in very dilute concentrations. Various theories have been advanced about the physical mechanism involved.  Among results obtained with ship models, AEW reduce the frictional resistance of a frigate form some 20-30 percent by continuously injecting polymer solution into the boundary layer to produce a nominal concentration of 10 wppm.  AEW and AML then carried out a full scale trial in a coastal minesweeper using equipment for continuously preparing solutions of polyox WSR301 and making provision for boundary layer sampling.  The fuel consumption of the CMS was reduced by up to 17 percent at 9 knots in spite of the Polyox being unevenly distributed in the boundary layer, but the result was grossly uneconomical in terms of current prices of Polyox and diesel oil.  Even when employing an injection technique of greatly increased efficiency in a large ship such as a supertanker or containership, there seems little prospect of utilizing boundary layer additives for profit until the cost of additive materials has been drastically reduced from present day levels.]]></description>
      <pubDate>Fri, 02 Mar 1973 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/11913</guid>
    </item>
    <item>
      <title>FLAT PLATE FRICTIONAL DRAG REDUCTION WITH POLYMER INJECTION</title>
      <link>https://trid.trb.org/View/5211</link>
      <description><![CDATA[A method is developed for prediction of frictional-drag reduction in high Reynolds number flows past smooth flat plates with polymer injection near the leading edge. Numerical results are given for water-Polyox WSR 301 solutions with either uniform concentration or injection.]]></description>
      <pubDate>Fri, 29 Sep 1972 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/5211</guid>
    </item>
    <item>
      <title>SUPPRESSED DIFFUSION OF DRAG-REDUCING POLYMER IN A TURBULENT BOUNDARY LAYER</title>
      <link>https://trid.trb.org/View/3983</link>
      <description><![CDATA[The concentration of drag-reducing polymer ejected from a thin wall slot into a developing turbulent boundary layer (external flow) was measured with a laser-phototransistor unit.  Experiments included tests of ejecting polymer solutions of various concentrations at various ejection rates.  The polymer solution was colored with dye and the additive concentration within the boundary layer was deduced from the dye concentration, which attenuated the laser light received by the phototransistor.  The results indicate a suppressed turbulent diffusion of polymer solution.]]></description>
      <pubDate>Fri, 21 Apr 1972 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/3983</guid>
    </item>
    <item>
      <title>DEVELOPMENT AND MODEL TESTS OF A SURFACE SHIP ADDITIVE SYSTEM</title>
      <link>https://trid.trb.org/View/1702</link>
      <description><![CDATA[A Froude scaled ship model 11.4 feet long and 1.4 feet girth was tested for drag while dilute polymer (FRA) water solutions were ejected around the hull.  A ram scoop-slot ejective arrangement in conjunction with a polymer mixing and feed system was developed and utilized successfully to affect the model's drag.  Four series of tests were conducted at various operating conditions including three ejection slot gap settings and two ejective slot locations. An actual drag reduction of about 12 percent of the total drag at top speed (20 ft/sec), was obtained.  Drag reduction of over 18 percent of the total drag or more than 55 percent in the frictional drag is conceivable at proper ejection conditions with two ejection stations.  This may be obtained when the ejected flow amounts only to about ten times the sublayer flow rate and contains a polymer concentration between 1000 and 1300 ppm.  Additional studies are recommended to enable the optimization of the polymer ejective system and assess its full potential.  (Author)]]></description>
      <pubDate>Fri, 27 Aug 1971 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1702</guid>
    </item>
  </channel>
</rss>