The problem of polyphase currents At the 13th IAHR Congress

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<ul><li><p>THE IAHR NATIONAL COMMITTEE OF THE SOVIET UNION </p><p>THE PROBLEM OF POLYPHASE CURRENTS </p><p>AT THE 13th IAHR CONGRESS* </p><p>M. V. Pechenkin </p><p>The lath IAHR Congress which took place at Kyoto. Japan, examined in the Technical Session B the problem of the flow of polyphase liquids. Thirty-nine papers from 16 countries were presented on this subject; Japan pre- sented ten papers, the US eight, the USSR five, Venezuela and India two each, Australia, England, Norway, Romania, Turkey, the German Federal Republic, Czechoslovakia, Switzerland, Sweden, and Yugoslavia one each; two papers were presented jointly by two countries: one by Turkey and the US and one by Czechoslovakia and Canada. </p><p>Two-phase close conduit currents with a solid dispersion phase are examined in the papers 13-15, 13-16, B-2I, and 13-29. The papers 13-15 by N. A. Silin, V. M. Karasik, Yu. K. Vitoshkin, and V. F. Ocheretko (USSPO, and 13-16 by M. V. Pechenkin (USSP0 present the results of experimental investigations of the turbulent characteristics of a cur- rent carrying suspended solids at high concentrations. The experiments carried out using an optical method have established for the first t ime the influence of large concentrations of suspended particles on the pulsation character- istics of the simultaneous flow of liquid and particles. Paper 13-21 by Y. Awaya and T. Kusuda (Japan) examines the problem of the turbulence spectrum produced by the movement of small pa~cles in a vertical cylindrical tube. The concentration measurements are obtained by a photoelectric method, and the velocity measurements by means of a thermoanemometer. Paper 13-23 by K. Subramanya (India) presents the results of investigations on the theological properties of sand-water suspensions by means of a capillary viscosimeter. It was established that the critical con- centration at which a sharp change in the characteristics of the suspension takes place is 0.3 to 0.85, a result which is in close agreement with those obtained by other investigations, particularly with those carried out in the USSR. </p><p>The most numerous group of papers was that dedicated to open-channel flow of two-phase currents with a solid dispersed phase, which included 15 papers: B-10, 13-11, 13-12, B-14, 13-17, B-19, B-22, 13-24, B-25, 13-26, B-32, 13-33, B-34, 13-38, and B-Ex3. Papers B-11, B-19, 13-24, B-33, and B-34 introduce the reader to the methodological laboratory investigations of two-phase currents, uncovering some aspects of the physical processes of the suspension and mass transfer of solid particles. In paper B-11, H. Jobson (USA) demonstrates that the mass transfer coefficient of the solid phase is close to the transfer coefficient of the momentum. For large particles the coefficient is some- what smaller but increases with the increase of depth. The basis of the paper B-19 by Y. Tsuchiya of lapan is the analytical examination of the saltation of suspended particles. The theoretical conclusions are supported by experi- ments carried out with the help of a motion picture camera. Very closely related to this work and to some extent its further development is the investigation described in paper B-34 by K. Yano and A. Daiodo (Japan) where the dis- crepancy between the distribution of the longitudinal velocities of the current with suspensions and the logarithmic distribution law is explained on the basis of the rotational movement of the particles. However, the authors of these papers do not take into account the role of the mechanical friction of the particles which play a not lesser role in the movement of sediment, and in the case of high concentrations a decisive one. In paper 13-38 by A. Zagustin and K. Z agustin (Venezuela) it is stated that the velocity profile of a two-phase current can be allegedly represented by a logarith- mic profile similar to that of sediment-free water, the difference between the two respective equations which relate the tangential stresses with the velocity gradient consisting only in Karman's constant, which is considered, however, an in- variant for the whole current. It should be noted that the conclusions obtained are valid only for currents with low concentration of suspended sediment, as is indicated, for example, in paper 13-34. The most complete checking of the validity of the logarithmic distribution law of the velocities in a current carrying suspended sediment was done in the work of Bagnold (England) and of the Soviet researchers (M. V. Pechenldn, V. F. Ocheretko, and Yu. N. Kriv- enko), who carried out experiments with a very large range of bed load concentrations. </p><p>"See Gidrotekhnicheskoe Suoitel'stvo, No. 12 (1969). </p><p>Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 2, pp. 44-47, February, 1971. </p><p>172 </p></li><li><p>THE PROBLEM OF POLYPHASE CURRENTS AT THE 13th IAHR CONGRESS 173 </p><p>Papers B-10, B-17, and B-38 am dedicated to the field investigations of flow in rivers. Paper B-10 by D. Bonnard and J. Brnschin (Switzerland) makes recommendations on the organization of observations on sediment discharge based on field observations carried out in Switzerland. Paper B-l? by I. Egiazaroff (USSR) includes a wide range of problems regarding open channel and mud currents. The relationships between the average sediment con- centration of the river and the maximum river flow, the presence of clayey particles in the stream, and the grain size and mineralogic distribution of the suspended particles are shown. A wide experimental set of data illustrating the validity of the conclusions is given. In paper B-26, D. I. Grinvald (USSR) gives data on the structure of a two- phase turbulent current on the basis of field otmervations. The energy spectrum of such current is described, and the turbulence scales are computed from autocorrelation, structural, and spectral functions of the sediment concentration: on the basis of studies of the current structure of the Morava River, the authors of paper B-38 S. Bruk and V. Miloradov (Yugoslavia) check the validity of their conclusion that the coefficient of transport capacity introduced by M. A. Velikanov can be represented after some transformations as Richardson's number and be used as a dynamic similitude criterion of currents with suspended sediment. In paper B-12, K. Yano, Y. Tsuchiya, and M. Michiue (Iapan) exam- ine the problem of the movement of the bed load. Experiments with sand and gravel tracer particles indicated the possibility of utilizing stochastic models for describing the regular and the discontinuous movement of bed load. Paper B-22 by C. Posey (US) is dedicated to the problem of protecting a streambed against stream jets falling on it. A design of inverse filters capable of preventing soil particle entrainment is suggested on the basis of experimental investigations. In paper B-25, P. Bhattacharya, G. Glover, and I. Kennedy (US) describe an interesting instrument for the measurement of sediment concentration which is adequate for both laboratory and field observations. The instrument is designed on the basis of the photoelectric principle of measurement of suspension concentrations. </p><p>Two papers in this group, B-14 by M. Pa!c6n (Venezuela) and B-27 by I. S. Sheiuin (USSR), contain theoretical description of two-phase currents. Paper B-14 examines the model of an open-channel current carrying sediment. Attention is focused in this paper on the influence of the shape of the river bed on the sediment discharge. Paper B-27 solves the problem of the oscillations of an installation reflecting a sediment loaded stream with a density vary- ing with depth. In paper B-Ex3 S. Marcel (Romania) presents a method elaborated for the computation of grain frac- tion separation in hydraulic earthfills using for this purpose a digital computer. </p><p>The air entrainment in close conduit flow formed the subject of papers B-2, B-6, and B-8. Paper B-2 by K. Haindl (Czechoslovakia) examines the problem of the length of the ring jump developed in a pipe downstream of a butterfly valve. Paper 13-6 by A. Shima (Iapan) gives interesting data on the work of a centrifugal pump when a certain amount of air is supplied into the aspiration Hne. Three types of centrifugal pumps were investigated. The work contains interesting observation data. The theoretical examination of the behavior of a gas bubble in a non- Newtonian fluid is presented in paper B-8 by M. Murakami, H. Suehiro, T. lsaji, and J. Kajita (Iapan). The expres- sion giving the own frequency of a gas bubble in a Bingham Liquid was obtained for adiabatic conditions. </p><p>Open channel flow with air entrainment is examined in papers B-?, B-9, and B-36. T. Chandrasekhar demon- strates in paper B- 7, on the basis of experiments carried out at the Central Hydraulic Station of PoOh, that air en- trainment increases with the Froude Number. K. Tabnshi (Japan) described in paper B-9 the results of experiments determining the conjugation regime of a jet faiLing vertically into an open reservoir of limited volume. Air entrain- ment in the Liquid jet appeared to be influenced by the depth of the reservoir and the distance from the nozzle to the water surface in the reservoir. Paper B-36 by J. Killen and A. G. Anderson (US) investigates the interface between air and water in supercritieal flow. The measurements based on the determination of the electrical conductivity of the aerated flow indicated the distribution of the air entrained in the flow. </p><p>Paper B-18 by K. Rohan (Canada) and M. Zaidlik (Czechoslovakia) is devoted to the problem of emulsion flow. The paper describes a method supplied in the Scientific-Research Institute of Hydraulic of Bratislava for the design of gravity separators. The results of the initial investigations are presented. </p><p>Papers B-4 and B-5 by E. Bourodimns (US) are devoted to the problem of the flow of three-phase mixture of water, air, and sand. The paper examines the problem of hydrauLic losses and of the sedimentation and entrainment of bed load, and evaluates the possibility of the development of a gas or water plug. </p><p>E. Tesaker (Norway) gives in paper B-1 the results of investigations on current flow in a rectangular submerged flume of 10 m with variable slope, Data on velocity distribution and on the concentrations in the density current were obtained. The tangential stresses and apparent viscosity were determined. </p><p>The hydraulic resistance caused by the presence of a second phase in the current is examined in papem B-13, B-20, and B-37. V. Sayman (Turkey) suggests in paper B-13 a method for developing on models surfaces having a </p></li><li><p>174 M.V. PECHENKIN </p><p>hydraulic resistance equivalent to the resistance of a mobile bed. Paper 8-20 by E. Acaroglu (Turkey) and W. H. Craf (US) is dedicated to the problem of hydraulic resistance and roughness in open channels and pipes. An attempt is made to determine the supplementary resistance developed as a result of the formation of various bed forms. P. Franke (German Federal Republic) examines in paper B-37 the hydraulic resistance in pipes having a roughness similar to a granular one, and a roughness developed as a result of prolonged operation of pipes conveying water with an admix- ture of clay or other particles. It was shown that a ripple type of roughness develops at the wall of such pipes, and this causes an increased roughness which cannot be estimated in the same manner as the granular roughness. The in- crease of roughness depends to a lesser extent on the diameter of the grain and the quality of the water and to a larger extent on the texture of the roughness and its actual shape. </p><p>Streams with chemical stratification are examined inpapersB-28 and B-31. Paper B-28 by I. Wood (Australia) describes the application of methods for the computation of open-channel flow of layered fluids which enable one to determine the diffusion of salinity and heat. The validity of the theoretical conclusions was confirmed by tests in which the chemical stratification of the current was supplemented by a thermal one. Paper B-31 by H. Anwar contains the results of experimental observations on the dispersion of a stream tube of fresh water flowing into a saline solution. The distribution of concentrations was measured on the basis of the conductivity of the saline solu- tion. The measurements indicated that the distribution of the density is subjected to the Gauss distribution law and that its shape is close to that of a natural torch. </p><p>The problem of thermally stratified currents is analyzed in papers 13-30 and 13-32. Paper I3-30 by M. Hino and S. Onishi (Japan) gives the theoretical solution for a current flowing toward a point sink. It examines the critical conditions under which the development of a stagnant zone begins. The authors checked the validity of their con- clnsions by experiments in which the thermal stratification was replaced by a chemical one. In paper B-32 R. Eider and W. Wunderlich (US) present data on field observations organized by the Tennessee VaUey Authority at the water intake from two large reservoirs. Interesting results on the distribution of the velocity, density, and temperature in the diverted layer of water and in the reservoir were obtained. </p><p>Papers B-29 and B-35 are devoted to the general problems of the flow of stratified currents. In paper B-29 T. Hamada (Japan) investigates the general characteristics of a horizontal two-layer current in a control section. It was noted that a very important characteristic of the current are the coefficients of the internal and external friction. In paper B-95 Tin-Kan Hung (US) gives numerical methods for the solution of the Navier-Stokes equations using the method of finite differences. The method is applied to the investigation of the influence of the density stratification of a noncompressible viscous fluid in an unsteady circular current in a two-dimensional domain. There is no experi- mental check whatsoever of the results in these papers. </p><p>In conclusion it should be noted that the papers presented at the technical Session B were diverse from the viewpoint of the subject, extent, and scientific content. </p><p>From the first group of papers the following can be singled out: Paper B-15 and B-16 contain data on the in- ternal kinematic structures of close conduit flow of currents with high sediment concentrations. These papers enable one to evaluate on a new basis some aspects of the physical processes in two-phase currents which were not investi- gated up to now. The domain of practical applications is the computation of hydraulic pipeline transportation of gravel sand, slag, and ash, as well as of other dispersed materials. The results presented in paper B-21 have an es- sential significance for chemical processes in which the chemical reactions are obtained by means of a countercur- rent. The data obtained from paper B-23 expand our knowledge of the movement of finely dispersed, high-concen- trarion suspensions. </p><p>In the group of papers devoted to open-channel sediment currents, papers B-19 and...</p></li></ul>

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