Vol 55, No 1-2 (2019)

The problem of ensuring gas dynamic and strength parameters in impellers of low-power gas turbine engines is discussed. The most loaded points of high-speed turbines are determined. The influence of gas forces on stress distribution in the impeller vis-à-vis centrifugal forces and thermal impacts is analyzed. Several design modifications that permit stress reduction in turbine impeller are proposed. Computational investigation and analysis of strength of various blade joints with turbine impeller disk are conducted. The turbine engine impeller design that is most effective in terms of strength and gas dynamic parameters is selected by comparing the obtained data.

The metal content of tube bundles of rigid-type shell-and-tube heat exchangers is analyzed in terms of their design options and used materials. Outer tube diameters, tube material, wall thickness, pressure in the tubes, and inner diameter of the exchanger are considered as the influencing factors. Use of tube bundles consisting of strong tubes is proposed for reducing metal content of tube bundles. High-strength low-alloy steel tubes are recommended for medium and high pressures in the tubes. In the case of low pressure in the tubes, the difference in metal content of carbon steel and high-strength low-alloy steel tube bundles is negligible.

Results of a study of the thermal and dynamic characteristics of three types of six-row checkerboard bundles in a transverse flow in the interval of Reynolds number Re = (3−18) × 10³ are presented. The experimental data are generalized by similarity equations. The heat-exchange coefficients of each transverse row of the bundle are measured and features that arise in the variation of heat exchange by row of the bundle are identified. The mean value of the thermal contact resistance in the range of variation of the temperature of the contact surfaces 79−95°С is found to be equal to 2.13·10^{− 4} m²·K/W. On the basis of results of the study it is shown that the use of an equilateral configuration of tubes in bundles should be rejected and replaced by an isosceles configuration with steps S₁ = 68−69 mm and S₂ = 55.4 mm, a configuration that is advantageous in terms of energy and on the basis of a cost-benefit analysis.

The possibility of detecting oil films on a water surface using passive radar, i.e., microwave radiometers, is considered. Current and prospective microwave radiometric systems that function in different ranges of wavelengths are described. The main technical characteristics of existing radiometric systems are presented. It is shown that the method of microwave radiometry may be used to detect oil films on a water surface.

Based on mathematical modeling of wastewater treatment by adsorption of petroleum products, it is shown that the sorption material “SM-5” based on carbonate sludge can be used as an accessible and effective adsorption filter loading material at wastewater treatment plants of JSC “Nizhnekamskneftekhim”. The results of mathematical modeling prove the expediency of replacing activated carbon (“Sorber” brand) with the developed sorbent “SM-5” without making structural changes to the devices of the pilot plant to minimize the anthropogenic impact of wastewater of JSC “Nizhnekamskneftekhim” on the river Kama.

The investigations demonstrated that the mass–size characteristics of heaters can be improved considerably by raising the temperature of the intermediate heat carrier (for water as the heat carrier, this can be achieved by raising the pressure relative to the atmospheric pressure in the casing of combustion oil emulsion heaters). Equations are derived to determine the optimum temperature of the intermediate heat carrier, i.e., the temperature of the heat carrier corresponding to the minimum metal content of the heater, when water and high-boiling liquids are used as the intermediated heat carrier. Quantitative estimates of the obtained positive effect in heater operation with optimum temperature of the intermediate heat carrier are given.

A proximate method of determining the optimal diameters of an adsorber and the optimal height of the stationary layer of an adsorbent for the short-cycle adsorption (PSA) process is proposed. The notion of the length of the mass-transfer zone and its scaling with a change in the conditions under which the adsorption process is realized serves as thebasis of the calculation. A single experiment on a laboratory-scale or pilot plant issufficient for solving the problem. The optimal relationship between the height and diameter of the adsorbent layer as a function of the construction of the adsorber is in the range 1.65–2.0. A sample calculation of the parameters of an adsorber is performed.

The method of fractionation of fine particles of a certain size is substantiated by theoretical and experimental data obtained by analysis of the sedimentation of a finely ground powdered material suspended in a liquid in a centrifuge. The adequacy of the theoretical and experimental results is confirmed using the example of the technology of selecting finely ground particles of a particular size from diamond powder in a liquid separator.

The influence of the packing material and porosity in a lower stage of a regenerative heat exchanger on the operating efficiency of a GM cryocooler has been studied. Experiments were used to quantify the decrease in cooling capacity when replacing lead by tin. It is found that reduction in the porosity of the material leads to a decrease in cooling capacity of the cryocooler.

Hydrodynamic forces in gap seals of centrifugal pumps play a leading role in stabilizing the vibration activity of pump rotors. Non-contact seals of the flow part can perform the functions of internal support-sealing units of a centrifugal pump. The impeller self-aligns in symmetrical gap seals under the action of hydrodynamic forces and moments. According to the method proposed by the author for calculating the elements of the flow-through part of a centrifugal pump with gap supports-seals, a pump with a self-adjusting impeller was created. The modernized pump was subjected to lengthy hydraulic testing on a test bench.

Methodology allowing to calculate and analyze the current density, current output, working area of the membranes, the throughput capacity of the plant, the voltage expended on the electrodialysis process, the number of sections in the electrodialysis unit and a number of other parameters, important for separating industrial solutions and waste water of chemical industries, is proposed in this paper. It is estimated that the calculated process parameters correspond to the data obtained during laboratory studies within ±10 %.

New technology and equipment developed from the results of research work are created for producing bimetallic wire. A feature of the new technology is production of bimetallic wire by passing a steel core through molten metal. This method of obtaining bimetallic wire is called “freezing” in publications, since the external appearance of the wire obtained is similar to a form crystallized metal. Results are provided for comprehensive studies, and recommendations are aimed at increasing the level of adhesion between a coating and a core by application a thin underlayer of non-ferrous metal (copper, brass, tin, etc.) to the core surface. Use of a rotating metal brush is proposed for coating formation, i.e., a flexible tool cladding (FTC) method.

An estimate is made of the ultimate condition of main gas pipelines after long-term operation in the North by determining the impact strength of samples from the pipe material (in various conditions), and correlation of the values obtained with the speed of sound in materials.