Hydraulic units of the third stage of the Dniester PSPP

Purpose

Development of highly efficient hydraulic units for the Dniester PSPP

Tasks

• development of impellers for radial axial pump turbines for hydraulic units No. 5-7 of the Dniester PSPP;
• manufacturing and conducting power tests of impeller models;
• determination of energy and pulsation characteristics in a wide range of turbine and pumping modes.

Description

The design work for the flow part of hydroelectric units 5-7 at Dnistrovska PSPP set the task of expanding the range of operation in turbine mode to between 40-100% of the rated capacity. Hydropower units 1-4, which are currently in operation at the plant, have never operated even at 70% of their capacity. The problem can be solved, first of all, by designing a new impeller, since all the components – the spiral chamber with the stator, the suction pipe, the impeller chamber – had to remain unchanged in accordance with the task. One of the most promising areas is the design of impellers with significantly larger blades.
The Pidgorny Institute of Mechanical Engineering of the National Academy of Sciences of Ukraine has developed a method for spatial profiling of impeller blades of radial-axis pump turbines using circular piles. In such profiling, the design cross-sections of the blade remain unchanged, only their relative position in the circular direction changes. In order to expand the range of operation in turbine mode, reduce the level of pulsations in the flow part and increase efficiency, two modifications of the Dniester PSPP impeller were designed: RK5217M – with a 35º shift of the bushing cross-section towards the rotor rotation compared to the original version (RK5217) and RK5217M2 – with a 55º shift of the bushing cross-section in the opposite direction. For a preliminary assessment of the performance of the flow parts with the new impellers, numerical studies of viscous incompressible fluid were carried out using the IPMFlow software (developed by the Institute of Mechanical Engineering Problems of the National Academy of Sciences of Ukraine). The calculations determined the influence of the spatial shape of the blades on the flow structure and energy characteristics. To confirm the calculated results, models of impellers with a diameter of D1 = 350 mm were made of the original version, which was implemented at units 1-4 of the Dniester PSPP, and two modified versions. The blades were manufactured using a 3D printer from PLA plastic, which significantly reduced the time and cost of the work. Energy tests of the three wheel variants were carried out at the hydrodynamic test bench of the Institute’s laboratory EKS-30, which has the status of a national treasure. Energy and pulsation characteristics were obtained in a wide range of turbine and pumping modes. It was confirmed that the maximum efficiency of the RK5217M2 in the flow part is 0.6-0.7% higher than that of units 1-4 of the Dniester PSPP. In generating mode at rated head, the efficiency of the new flow part is 1.0-1.5% higher than the original version in almost the entire operating range. The level of pressure fluctuations in the suction pipe was reduced by 20-25% compared to the original version.

Fields of prospective use

Power machine engineering

Potential stakeholders

PJSC “Ukrhydroelektro”, JSC “Ukrainian Power Machines”

Budget

Required: needs to be clarified

Inquired: 0M ₴

Workplace creation potential: needs to be clarified

Possible sources of funding

International community, budget funds, funds of interested enterprises (PJSC “Ukrhydroelectro” , JSC “Energetic Machines”)

Website

www.ipmach.kharkov.ua