Abstract：In order to increase efficiency and achieve a further CO2-reduction, the next generation of power plant turbines will have steam turbine inlet temperatures that are considerably higher than the current ones. The high pressure steam turbine inlet temperature is expected to be increased up to approximately 700°C with a live steam pressure of 30MPa. The elevated steam parameters in the high and intermediate pressure turbines can be encountered with Ni-base alloys, but this is a costly alternative associated with many manufacturing difficulties. Collaborative research centre 561 “Thermally Highly Loaded, Porous and Cooled Multi-Layer Systems for Combined Cycle Power Plants” at RWTH Aachen University proposes cooling the highly loaded turbines instead, as this would necessitate the application of far less Ni-base alloys. To protect the thermally highly loaded components, a sandwich material consisting of two thin face sheets and a core made from a woven wire mesh is used to cover the walls of the steam turbine casing. The cooling steam is led through the woven wire mesh between the two face sheets to achieve a cooling effect. The wire mesh provides the grid-sheet with structural rigidity under varying operating conditions. In the present work, the cooling performance of the grid-sheets will be investigated applying the conjugate heat transfer method to ultra-supercritical live and cooling steam conditions for a section of the cooling structure. The behaviour of the flow and the heat transfer in the grid-sheet will be analyzed in detail using a parameter variation. The numerical results should give a first prediction of the cooling performance under future operating conditions.
Bohn D. Advanced steam and gas turbine technologies for future power plantgeneration. Invited Lecture to the A.S.I./SKODAConference on Steam Turbines and Other Turbomachinery, Plzen, CzechRepublic, 2007
Luby P. Supercritical systems: the market for supercritical steam turbineshas undergone dramatic changes in the last ten years. But the future outlook appears positive and the indications are thatfurther growth lies ahead. Modern PowerSystems, 2003, 27―32
Retzlaff K M, Ruegger W A. Steam turbines for ultrasupercriticalpower plants. GER-3945A (first presentedat PowerGen Europe ’96), 1996
Obara I, Tanaka Y, Magoshi R, et al. Design of 600°C class 1000?MW steamturbine. JSME International Journal, SeriesB, 1998, 41(3): 734―739
Dilthey U, Ohse P, Piontek D. Welding of hollow structures made of high-temperaturematerials. Schweiβen und Schneiden, 2004, 56(1): 11―15
Dilthey U, El-Magd E, Brandenburg A,et al. Lasergeschweiβte Hohlraumstrukturen ausdem martensitischen Werkstoff P92 als neuartiges Kühlkonzeptfür hochbelastete Teile der Dampfturbine. Proceedings of the 28th Vortragsveranstaltung der ForschungsvereinigungWarmfeste Stähle (FVW), Düsseldorf, 2005
Kopp R, Franzke M, Hohmeier P, et al. Bending of sandwich structures with usable cavitiesfor active cooling applications in steam turbines. Annals of the German Academic Society for Production Engineering, 2005, 12(1): 71―76
El-Magd E, Stuhrmann J, Gebhard J. Low cycle fatigue behaviour of sandwich structures ofP92 and Nicrofer 6025HT. Proceedings ofthe 8th Liege Conference on Materials for Advanced Power Engineering,Part II, Liege, Belgium, 2006, 1147―1156
Kopp R, Wiedner C, El-Magd E, et al. Comparison between visioplasticity measurementsand finite element computations for tensile tests on cold rolled perforatedferritic chromium steel P92. Comp Mat Sci, 2004, 31(3,4): 439―447
Bohn D, Ren J, Kusterer K. Cooling performance of the steam-cooled blade in a steamturbine cascade. ASME Turbo Expo, PaperNo. GT2005-68148, Reno, Nevada, U.S.A., 2005
Bohn D, Kusterer K, Wolff A, et al. Experimental and numerical investigations ofa steam-cooled vane. ASME Turbo Expo, PaperNo. GT2002-30210, Amsterdam, The Netherlands, 2002
Eberle A, Schmatz M A, Bissinger N. Generalized flux vectors for hypersonic shock-capturing. AIAA-Paper 90-0390, 1990
Anderson W K, Thomas J L, van Leer B. A comparison of finite volume flux vector splitting forthe euler equations. AIAA-Paper 85-0122, 1985
Schmatz M A. Three-dimensional viscous flow simulations using an implicit relaxationscheme. Notes on Numerical Fluid-Mechanics(NNFM), 1988, 22: 226―242
Baldwin B S, Lomax H. Thin layer approximationand algebraic model for separated turbulent flows. AIAA-Paper78-257, 1978
Bohn D, Bonhoff B, Schönenborn H, et al. Validation of a numerical modelfor the coupled simulation of fluid flow and diabatic walls with applicationto film-cooled turbine blades. VDI-Berichte, 1995, 1186: 259―272
Bohn D, Schönenborn H, Bonhoff B, et al. Prediction of the film-coolingeffectiveness in gas turbine blades using a numerical model for thecoupled simulation of fluid flow and diabatic walls. ISABE95-7105, 1995
Wagner W, Cooper J R, Dittmann A, et al. The IAPWS-1997 Industrial Formulation for theThermodynamic Properties of Water and Steam. Berlin: Springer, 1998
