Vol 53, No 5-6 (2017)

The velocity of a fluid in the impeller of a centrifugal (radial-flow) turbine and the energy of the fluid flow which it absorbs are analyzed as a function of the angle of slope of the blade (which is assumed to be constant). The blades of the impeller absorb the kinetic energy of the flow, which is expended in rotation of the impeller and is determined by Euler’s equation. One-half the energy of the fluid is expended in rotation of the impeller and in varying the direction of the fluid, while the other half is expended in overcoming the action of centrifugal force, which reduces the rate of flow of the fluid through the impeller. The maximal flow rate of the fluid is achieved with an angle of slope of the blades of 45° while the maximal power transmitted by the fluid to rotate the turbine is attained at an angle of 60°.

Suspension separation process in a filtering centrifuge type of equipment with periodic and continuous sediment discharge as an aggregate of phenomena of solid sedimentation, sediment formation on rotor wall, and filtration of clarified liquid was studied. A quantitative analysis was made of the liquid system separation efficiency in terms of treatment time and throughput of specific centrifugal machines as a function of solid phase concentration in the suspension, dispersity of the treated product, and filtering principles of the rotor.

A procedure for camera laying out of holes in heat exchanger tubesheets where the holes are located at the vertices of equilateral triangles is described. The procedure can be used for heat exchangers of any diameter from 159 to 3000 mm and any heat exchanger tube diameter from 16 to 57 mm. An algorithm has been developed for determining the position of longitudinal baffles for realizing multipass performance of the tubes. It is proved that the angular coordinate of longitudinal baffles does not depend on absolute dimensions of the exchanger and is determined only by the scheme of fluid passage through the tubes in the apparatus. The schemes for realizing tubeside multipasses z = 2–10 are analyzed. A numerical example for z = 10, which indicates that the results are satisfactory for engineering practice, is given.

Possible transverse parametric vibrations of pipelines with compensating inserts are described and the basic relationships needed to calculate the amplitude of transverse vibrations are presented.

A procedural model for designing multiproduct chemical engineering systems is described. The model includes the following designing stages: determining types, number, and size of equipment at each stage of the production process, laying out equipment and pipelines in the production site, and designing individual equipment. The model is intended for creating intelligent systems for automated designing.

An electroultrafiltration apparatus with flat chambers and a method for calculating the number of devices required for efficient separation of solutions, heating power, amount of heat, and total energy required for electroultrafiltrational demineralization and concentration of a protein in industrial solutions from biodegradable plastics production were designed.

Questions related to the study of the transmitted pressure vibrations of fluid being injected into development and injection wells by means of a tubing string are considered. Mathematical models of a tubing string in pulse injection of fluid and in installation of the device for the purpose of damping hydraulic impacts are described. An expression by means of which the required parameters of effective damping of vibrations may be determined from the standpoint of maintaining the service life of the tubing string is obtained through transformations of the wave equations. A graphical dependence of the amplitude of the displacement on the ratio of the frequency of the vibrations of a tubing string is presented from calculations.

The flow passage of the centrifugal fan of a grinding-separating unit is optimized to reduce specific power consumption and improve flow rate and pressure characteristics using modern ANSYS CFX type of software with construction of working characteristics and levels of sound power and sound pressure. The sources of monople, dipole, and quadrupole noises of the blading section of the fan are identified. The possible ways of reducing broadband noise are determined.

The results of experimental studies of the effect of electrophysical processing of thermoplastic materials on their mechanical properties are discussed in the paper. The paper describes a new method of thermoplastics recycling.

A method is proposed for determining the fatigue limit of metallic material components based on measuring hardness, production residual stresses, surface roughness, and some other parameters. A dependence is given for fatigue limit on surface layer quality parameters. Application of the method is demonstrated on the example of steels 30KhGSNA, U8, titanium alloy VT3-1, and aluminum alloy D16 after different treatment.

A method is considered for preparing objects of the flange type made of steel of grades 09G2S and 10G2 by centrifugal electroslag casting (CESC). Results are given for chemical analysis and mechanical properties of objects prepared by different methods. The advantage of CESC technology is demonstrated making it possible to prepare cast blanks that with respect to production parameters and physicomechanical properties correspond to the GOST and TU for the given forms of steel having configuration and dimensions close to a finished object.

The possibility of using the fractal dimension as a criterion for assessing the sustainability of surface-roughness formation after electric-discharge machining (EDM) was justified scientifically. The nature of the changes in surface roughness after EDM of AK34 and VT20 alloys and the fractal dimension were studied experimentally as functions of the main process parameters (pulse rate and porosity). The fractal dimension and surface roughness after EDM were closely correlated, which allowed the roughness of the machined surface to be controlled in real time.

A technoeconomic analysis of transition from coal to water-coal-organic chemical slurry fuels (WCOSF) prepared from wastes of coal, petroleum, and used oil treatment was made with reference to a typical heat and electric power generating plant. The economic cost associated with transition to WCOSF and possible effects therefrom are evaluated. The studied fuel compositions are classified in terms of ignition and combustion properties, combustion heat, and cost. The specific parameters illustrating the expedience of WCOSF combustion in spite of the required structural and operational variations of heat and power generating blocks are determined.