The Influence of the Open Axial Clearance on the Gas Flow and Energy Losses in the Turbine Stage with a Shroud on Working Blades

Advanced aviation and power high-temperature gas turbine engines require high-load gas turbines, whose geometric parameters have to be optimized in order to improve the efficiency of the turbines, and reduce their size and weight. One of these parameters is the open axial clearance in the turbine flow passage. Traditionally, the choice of the axial clearance is associated with the equalization of the flow parameters in the gap between the grids due to the significant difference in pressure in the wake behind the outlet edges and the main flow, and the vibratory strength of the blades. To improve the efficiency of prospective engines in the 1960s and 1970s, V.V. Uvarov considered the possibility of burning fuel in the axial clearances of the flow passage of the turbine using a complex thermodynamic cycle. At present, interest in this issue has revived. This process requires establishing a relationship between the axial clearances and the zone of microflame combustion of the fuel. The influence of the increased open axial clearance on the efficiency of the shrouded stage of the gas turbine engine is studied. The turbine integral characteristics with variable rotational frequency of the turbine rotor and different values of the open axial clearance are determined. The analysis of the experiment results has shown that the efficiency of a turbine stage depends significantly on the open axial clearance when the boundary of the active jet falls under the impeller shroud, and shows a week dependence when the boundary of the jet falls directly into the open axial clearance.

References

[1] Inozemtsev A.A., Nihamkin M.A., Sandratskiy V.L. Osnovy konstruirovaniya aviatsionnyh dvigateley i energeticheskih ustanovok. T. 2. Kompressory. Kamery sgoraniya. Forsazhnye kamery. Turbiny. Vyhodnye ustroystva [Basics of designing aircraft engines and power plants. Vol. 2. Compressors. Combustion chamber. Afterburner. Turbines. Output device]. Moscow, Mashinostroenie publ., 2008. 368 p.

[2] Inozemtsev A.A., Sandratskiy V.L. Gazoturbinnye dvigateli [Turbine engine]. Moscow, Aviadvigatel’ publ., 2006. 1204 p.

[3] Muraeva M.A., Goryunov I.M., Haritonov V.F. Modelirovanie protsessa szhiganiya topliva v mezhlopatochnom kanale turbiny [Simulation of fuel combustion process in the inter-blade channel of the turbine]. Aviadvigateli 21 veka. Sb. dokl. [Aircraft engines of the 21 century. Collection of reports]. Moscow, 24–27 November 2015, Moscow, TSIAM im. P.I. Baranova publ., 2015, pp. 306–308.

[4] Rice M. Simulation of isothermal combustion in gas turbines. Thesis. Blacksburg, Virginia, Virginia Polytechnic Institute and State University, 2004. 108 p.

[5] Lattime S.B., Steinetz B.M. High-Pressure-Turbine Clearance Control Systems: Current Practices and Future Directions. Journal of Propulsion and Power, 2004, vol. 20, no. 2, pp. 302–311.

[6] Skibin V.A., Volkov S.A. Vybrosy vrednyh veshchestv ot aviatsionnyh dvigateley [Emissions of harmful substances from aircraft engines]. Aerokosmicheskiy kur’er [Aerospace courier]. 2003, no. 2, pp. 18–19.

[7] Varlamov G.B., Kamaev Yu.N., Poznyakov P.O., Yurashev D.N. Modernizatsiya gorelochnoy sistemy gazoturbinnogo dvigatelya DN80 s ispol’zovaniem trubchatoy tekhnologii [Modernization of the burner system of the gas turbine engine DN80 using tubular technology]. Vestnik NTU HPI: Novye resheniya v tekhnologiyah [NTU «KhPI» Bulletin: Series «New Solutions in Modern Technologies»]. 2012, no. 18, pp. 117–126.

[8] Tumanovskii A.G., Gutnik M.N., Artemenko A.A. Prospects for creating high-temperature low-emission combustors for stationary gas-turbine units. Thermal Engineering, 2000, vol. 47, no. 10, pp. 879–882.

[9] Sudarev A.V., Antonovskiy V.I. Kamera sgoraniya gazoturbinnyh ustanovok [Combustion chamber of gas turbine units]. Moscow, Mashinostroenie publ., 1985. 272 p.

[10] Molyakov V.D., Tumashev R.Z. Osobennosti proektirovaniya protochnyh chastey turbin gazoturbinnyh ustanovok v zavisimosti ot sostava i parametrov rabochey sredy [Peculiarities of Designing Turbine Flow Sections for Gas-Turbine Facilities]. Vestnik MGTU im. N.E. Baumana. Ser. Mashinostroenie [Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering]. 2003, no. 2(51), pp. 52–62.

[11] Kuzmenko M.L., Nagoga G.P., Karelin D.V. Sposoby razresheniya protivorechivyh trebovaniy pri proektirovanii vysokotemperaturnyh gazovyh turbin [The ways of resolving conflicting requirements when designing high-temperature gas turbines]. Aviadvigateli 21 veka: materialy konferentsii. Sbornik dokladov [Aircraft engines 21 century: conference materials. Collection of reports]. Moscow, TSIAM im. P.I. Baranova publ., 2010, pp. 261–266.

[12] Bachovchin D.M., Lippert T.E., Newby R.A., Cizmas P.G.A. Gas turbine reheat using in situ combustion. Siemens Westinghouse Power Corporation, Final Report, May, 2004. 112 p.

[13] Haliba E.E., Lenahan D.T., Thomas T.T. Energy Efficient Engine. High Pressure Turbine Test Hard Ware Detailed Design Report, NASA CR-167955, 1982.

[14] Vazquez R., Codrecha D., Torre D. High Stage Loading Low Pressure Turbine. A New Proposal for an Efficiency Chart, GT2003-38374.

[15] Stepanov G.Yu., Epshteyn V.A., Gol’tsev V.V., Vahomchik V.P., Muhtarov M.H. Atlas eksperimental’nyh harakteristik ploskih turbinnyh reshetok [Atlas experimental characteristics of two-dimensional turbine arrays]. Moscow, TSIAM im. P.I. Baranova publ., 1964. 136 p.