Oleksandr Ivchenko

The object of research is the shape of the blade of a vertical-axis installation. The problem solved in this work is to find the optimal shape of the blade for a wind power installation for operation at low wind speeds or in areas where its flow is limited. In the course of the work, the interaction between each blade option and the wind flow depending on the shape of the blade was considered. With the help of a reduced model of the wind turbine, a flat blade, a blade with a «pocket», and a blade with a «pocket» and a slit were tested. The test results prove the effectiveness of the designed and manufactured blade with a «pocket» and a slit. This was confirmed by the study results, according to which, during the experiment, the number of revolutions of a wind turbine with blades made with a «pocket» and a slit was the largest. In comparison with flat-shaped blades, the increase was 20 %, and, in comparison with blades with a «pocket», the increase was 10 %. In order to compare wind turbines that have flat-shaped blades and blades with a «pocket» and a slit, experimental studies and calculations of the power factor Ср were carried out. A flat-blade wind wheel has Ср1=24; a blade with a «pocket» – Ср2=52.9; a blade that has a «pocket» and a slit – Cp3=58.7. Therefore, one can assume that the power generated by the wind wheel with the above blades is also the largest, Р3=98 W, compared to two other shapes of blades: flat, P1=32.3 W; with a «pocket», Р2=88.2 W. It would increase during the test time from zero speed to reaching a constant rotational speed. The studies confirm that the wind wheel, which has blades with a «pocket» and a slit, has the highest speed of rotation over the entire period of time when measurements were performed

This paper considers the possibility of using liquid-vapor ejectors in condensing units of steam turbines. This unit is designed for pumping out a steam-air mixture from a steam turbine condenser, in which the process occurs at a pressure lower than atmospheric. In the traditional scheme, this is provided by a two-stage steam-jet ejector unit. The proposed scheme involves the use of a single-stage liquid-vapor ejector and its possible pre-vacuum mode of operation in conjunction with a liquid-ring vacuum pump. A working process of the liquid-vapor ejector does not require the supply of working steam from the outside since its generation occurs in the active nozzle of the liquid-vapor ejector. A description of the traditional scheme and the proposed options is given, which are different both in the scheme solution and in the operating parameters. The object of this study is a liquid-vapor ejector, which is used in the condensing system of a steam turbine. Thermodynamic calculation of the proposed circuit solutions was carried out. As a result, the necessary mode parameters of the schemes were determined. To assess the feasibility of using a liquid-vapor ejector in the condensation systems of steam turbines, an exergy analysis was performed. The proposed scheme makes it possible to increase efficiency by 2.3 times, and when used with a liquid-ring vacuum pump – by 2.44 times. To assess the economic efficiency of the modernization of the condensing system, thermoeconomic analysis was performed. The use of the proposed scheme makes it possible to reduce the cost of generating boiler steam and reduce the cost of the resulting product of the steam turbine unit by about 51 %. The estimated cost of a unit of the amount of boiler steam consumed per ton of product and the unit cost of steam were established.