Numerical Analysis of the Three-Dimensional Nonstationary Flow of Ideal Gas in the Last Stage of Turbine Machine Taking into Consideration the Nonaxisymmetric Exhaust Pipe Branch
DOI:
https://doi.org/10.20998/2078-774X.2016.08.06Анотація
A problem related to the forecast of the aeroelastic behavior and aeroelastic instability of blades (in particular self-oscillations, flutter, and resonance vibrations) becomes of great importance for the development of high-loaded compressor and vent rows and the last turbine stages whose long and flexible blades can be exposed to such phenomena. The solution of this problem requires the development of new models for the nonstationary three-dimensional flow, the use of contemporary numeric methods and the comparison of theoretical and experimental data. This scientific paper gives the data of numerical simulation of the 3-D flow of ideal gas passing through the last stage of turbine machine taking into account the flow nonuniformity caused by guide blades and nonuniform pressure distribution in the exhaust pipe branch and also nonstationary effects caused by blade vibrations. The numerical method is based on the solution of combined aeroelastic problem for the 3-D flow of ideal gas passing through the turbine stage and the nonaxisymmetric exhaust pipe branch including the annular diffuser. To solve the combined problem a partially integral method was used that includes integral equations of gas dynamics (Euler equations) and vibrating blade dynamics (modular approach) at each time step with the information exchange. The given method of the solution of combined aeroelastic problem allows us to predict the amplitude-frequency spectrum of blade vibrations in the three-dimensional flow of ideal gas including forced self-excited vibrations and self-vibrations to increase efficiency and reliability of the blade units of turbine machines.Посилання
Gnesin, V. I. and Kolodyazhnaya, L. V. (2009), ²Ajerouprugie javlenija v turbomashinah[TheAeroelasticphenomenaintheturbomachines]², Ajerodinamika i Ajeroakustika. Problemy i perspektivy[AerodynamicsandAeroacoustics. Problemsandprospects], no. 3, pp. 53–62.
Cinnella, P., Palma, De, Pascazio, G. and Napolitano M. (2004), ²A Numerical Method for TurbomachineryAeroelasticity²,Journal of Turbomachinery, vol. 126, April, pp. 310–316.
Bolcs, A. and Fransson, T. H. (1986), ²Aeroelasticity in Turbomachines: Comparison of Theoretical and ExperimentalCascadeResults², Communication du LTAT, no. 13, pp. 174, EPFL Switzerland.
Gnesin, V. I. and Kolodyazhnaya, L. V. (1999), ²Numerical Modelling of Aeroelastic Behaviour for Oscillating Turbine BladeRowin 3D Transonic Ideal Flow², J. Problems in Mach. Eng., vol. 1, no. 2, pp. 65–76.
Gnesin, V. I. and Kolodyazhnaya, L. V. (2003), ²Ajerouprugoe povedenie poslednej stupeni turbomashiny na nominal'nomichastichnom rezhimah [Aeroelastic behaviour of the last stage of turbomachine onnominalandpartialregimes]²,Probl.mashinostroenija [J. Problems in Mach. Eng.], vol. 6, no. 1, pp. 48–57.
Gnesin, V. I., Kolodyazhnaya, L. V. and Rzadkowski, R. (2004), ²A numerical modelling of stator- rotor interaction in aturbinestage with oscillating blades², Journal of Fluid and Structure, no. 19, pp. 1141–1153.
Gnesin, V. I. and Kolodyazhnaya, L. V. (2009), ²Chislennyj analiz vlijanija sootnoshenija chisel lopatok statora i rotorananestacionarnye nagruzki i rezhimy kolebanij lopatok [The Numerical Analysis for Influence of Stator-RotorBladeNumberRatioonUnsteady Loads and Blade Oscillations Regimes]², Bulletin of NTU "KhPI". Series:Powerandheatengineeringprocessesand equipment, no. 3, pp. 23–32, ISSN 2078-774X.
Godunov, S. K., Zabrodin, А. V., Ivanov, М. Y., Кrayko, А. N. and Prokopov, G. P. (1976), Chislennoeresheniemnogomernyh zadach gazovoj dinamiki [The Numerical solution of multidimensional tasks of gas dynamics], Nauka,Moscow,Russia.
