Research work has been carried out to determine the power-efficient regime of operation of an electric-pulse setup for breaking and crushing natural stones. The optimal energy and geometrical parameters of the method (dependence of the degree of breakdown of materials on the voltage and the electrode spacing in the switching unit) have been established. The proposed method makes it possible to effectively perform drilling in vertical wells for installing heat exchangers of thermal pumps.

We report on the results of experiments on determining the head resistance and lift force for a rotating cylinder with a porous surface in the air flow velocity range 5–13 m/s (Re = 40000–105000) at a constant rotation number of the cylinder about its own axis. We also give the results of measurement of the head resistance and the lift force for a single rotating cylinder in the range of cylinder revolution numbers 400–1400 rpm at a constant air flow velocity. It is shown that the drag coefficient and the lift coefficient depend on the Reynolds number and on the number of revolutions of the cylinder. The dependence of the coefficients of aerodynamic characteristics on the degree of porosity of the rotating cylinder surface is established.

The object of the study is coal sludge and coal fines of the Shubarkol deposit and the Kuznetsk coal basin (Republic of Kazakhstan) for the production of coal-water fuel, which allows replacing liquid and gaseous expensive products. The resulting fuel (after treatment of coal seams and burial) from industrial waste should not harm the environment, which requires certain economic investments. For crushing coal and coal sludge in the crushing and grinding unit, an electrohydroimpulse device for fine grinding of materials was used, consisting of a control unit with a protection system, a pulse capacitor and a high-voltage generator (capacitor bank capacity 0.75 µF, pulse discharge voltage 15–30 kV, length of the interelectrode distance 7–10 mm). After grinding, fine coal particles rise to the surface of the water, and impurities settle at the bottom of the device, which allows enriching the product (flotation). Surface structures and coal fraction sizes were obtained using a Tescan Mira 3 scanning electron microscope. The main characteristics of coal-water fuel during vortex combustion were: the diameter of the fraction 0–250 microns – 63–74 %, process water – 36–24 %, special additive – 1–2 %. Coal-water fuel is similar to liquid fuel, and when transferring heat-generating plants to combustion of suspension, no significant changes in the design of boilers (units) are required. This makes it easy to mechanize and automate the processes of receiving, feeding and burning fuel, and the vortex combustion technology at a temperature of 950–1,050 °C guarantees fuel efficiency of more than 97 %. The given optimal parameters of electrohydroimpulse technology when introduced into production will allow not only grinding, but also enriching the coal product

We have reported the results of experiments on determining the drag coefficient and the thrust coefficient of a two-bladed wind-powered engine based on the Magnus effect with rotating rough cylinders in the range of air flow velocity of 4–10 m/s (Re = 26800–90000) for a constant rotation number of a cylindrical blade about its own axis. The results show that an increase in the Reynolds number reduces the drag coefficient and the thrust coefficient. The extent of the influence of the relative roughness on the aerodynamic characteristics of the two-bladed wind-powered engine has been experimentally established.

The authors of the work numerically studied the aerodynamic coefficients of the sail blade, during which the patterns of three-dimensional flow around airflow and the pressure distribution field were obtained. The triangular sail blade is used as the power element of wind turbines. The sail blade modeling was based on the Reynolds-averaged Navier–Stokes equations (RANS) using the ANSYS FLUENT computer program. A flow pattern is obtained, which gives a physical explanation of the nature of the airflow around the sail blade and the pressure distribution field. Comparative analyses of theory and experiment are given. In the range of Reynolds numbers from 0.5 × 10⁴ to 2.5 × 10⁴, the change in the drag force coefficient is from 1.04 to 0.54, and the difference in the lift force coefficient is from 0.52 to 0.33.