Abstract
Problem Statement (Relevance): Today, centrifugal turbines are quite commonly used in all business areas. Because of the high power consumption of turbomachinery, it is extremely important to properly operate such machines and choose the most efficient operating modes, as well as the machines offering most energy efficiency. The analysis of the design of existing turbines shows that they still have their shortcomings, which can hardly be acceptable in today’s production environments. Such shortcomings include a narrow range of efficient operation, reduced energy efficiency when running in off-design modes and a low hydraulic efficiency. These shortcomings are largely due to the design of the machines, since they have components that are subject to high hydraulic losses. The available methods are not capable to provide any major increase in energy efficiency for the existing makes of a multi-stage centrifugal turbine. It can only be possible to expand the efficiency spectrum of a turbine if an alternative scheme is developed for the fluid flowing from one stage to another, without the use of transfer channels. One of the alternatives includes a centrifugal turbine with coaxial impellers. Objectives: The objective of this research is to determine how the operating conditions can impact the pressure generated by a turbine. Methods Applied: A mathematical analysis and an experimental study conducted in the laboratory environment. Originality: The originality of this research is in the proposed design of a centrifugal turbine, i.e. the coaxial arrangement of the impellers when the fluid flows directly from one stage to the next one, without transfer channels or intermediate guides. Findings: With the help of the mathematical analysis and the experimental study conducted, the authors were able to obtain a clear picture of how the energy exchange takes place between the impeller vanes and the fluid flow. Practical Relevance: Due to optimum operating conditions identified for the centrifugal turbine with coaxial impellers, the machine can be operated with a high degree of energy efficiency.
Keywords
Radial turbine, coaxial arrangement, head and rate, energy exchange, operating mode.
1. Lobanov I.E. Mathematical modeling of intensified heat transfer taking place in the turbulent flow travelling through longitudinally washed bundles of pipes with transverse annular grooves based on a compound three-layer model of a turbulent boundary layer. Vestnik Magnitogorskogo gosudarstvennogo tekhnicheskogo universiteta im.G.I. Nosova. [Vestnik of Nosov Magnitogorsk State Technical University]. 2016, no. 1, pp. 109–115. (In Russ.)
2. Zharkovskiy A.A. Matemeticheskoe modelirovanie rabochikh protsessov v tsentrobezhnykh nasosakh nizkoy i sredney bystrokhodnosti dlya resheniya zadach avtomatizirovannogo proektirovaniya: dis. … d-ra tekhn. nauk [Mathematical modeling of the processes taking place in low and medium speed centrifugal pumps for solving computer-aided design problems. Doctoral dissertation]. Saint Petersburg, 2003, 568 p.
3. Galerkin Yu.B., Rekstin A.F., Soldatova K.V. et al. Radial and mixed flow impellers of centrifugal compressors: Advantages, disadvantages, application. Kompressornaya tekhnika i pnevmatika [Compressor engineering and pneumatics]. 2015, no. 7, pp. 23–32. (In Russ.)
4. Podbolotov S.V., Kolga A.D. Multi-stage centrifugal pump. Aktual'nyye problemy povysheniya effektivnosti i bezopasnosti ekspluatatsii gorno-shakhtnogo i neftepromyslovogo oborudovaniya: materialy II Mezhdunarodnoy. nauch.-prak. konf. Gornaya elektromekhanika [Current problems of enhancing the efficiency and safety of mine machinery and oil-field equipment: Proceedings of the II International Conference. Mining Electromechanics]. Perm: Publishing House of Perm National Research Polytechnic University, 2015, vol. 1, pp.57–62. (In Russ.)
5. Zhumakhov I.M. Nasosy, ventilyatory i kompressory [Pumps, fans and compressors]. Moscow: Ugletekhizhdat, 1958, 619 p. (In Russ.)
6. Lomakin A.A. Tsentrobezhnyye i osevye nasosy [Centrifugal and axial pumps]. Leningrad: Mashinostroenie, 1966, 365 p. (In Russ.)
7. Kovalevskaya V.I., Babak G.A., Pak V.V. Shakhtnyye tsentrobezhnyye ventilyatory [Centrifugal mine fans]. Moscow: Nedra, 1976, 320 p. (In Russ.)
8. Englar R. J. Overview of circulation control pneumatic aerodynamics. In: Applications of circulation control technology. Progress in astronautics and aeronautics. Vol. 214, AIAA, 2006, pp. 23–68.
9. Makarov V.N., Gorbunov S.A., Kornilova T.A. The perspective task of increasing the efficiency of booster fans. Izv. vuzov. Gornyy zhurnal [Proceedings of the Russian universities. Mining Journal]. 2013, no. 6, pp. 124–129. (In Russ.)
10. Podbolotov S.V., Kolga A.D. Hydraulic losses in turbines. Dobycha, obrabotka i primeneniye prirodnogo kamnya: sb. nauch. tr. [Extraction, processing and application of natural stone: Research papers]. Magnitogorsk: Publishing House of Nosov Magnitogorsk State Technical University, 2016, pp. 134–138. (In Russ.)