Forced Response in axial turbines under the influence of partial admission
2012 (English)In: ASME Turbo Expo 2012 - Turbine Technical Conference and Exposition, Copenhagen, June 11-15, 2012: Volume 7, Issue PARTS A AND B, 2012, ASME Press, 2012, 1419-1429 p.Conference paper (Refereed)
High cycle fatigue (HCF) due to unforeseen excitation frequencies or due to under predicted force magnitudes, or a combination of both causes control stage failures for steam turbine stakeholders. The objectives of this paper is to provide an extended design criteria toolbox and validation data for control stage design based on experimental data, with the aim to decrease HCF incidents for partial admission turbines. The upstream rotor in a two stage air test turbine is instrumented with pressure transducers and strain gauges. Admission degrees stretching from 28.6% to 100% as one or two admission arcs are simulated by blocking segmental arcs immediately upstream of first stator vanes by aerodynamically shaped filling blocks. Sweeps across a speed range from 50 to 105% of design speed are performed at constant turbine pressure ratio during simultaneous high speed acquisition. A forced response analysis is performed and results presented in Campbell diagrams. Partial admission creates a large number of low engine order forced responses because of the blockage, pumping, loading and unloading processes. Combinations of the number of rotor blades and low engine order excitations are the principal sources of forced response vibrations for the turbine studied herein. Altering the stator and/or rotor pitches will change the excitation pattern. A relation between the circumferential lengths of the admitted and non-admitted arcs that dictates the excitation forces is observed that may serve as a design parameter.
Place, publisher, year, edition, pages
ASME Press, 2012. 1419-1429 p.
, Proceedings of the ASME Turbo Expo, 7
Engine order excitations, Excitation frequency, Excitation pattern, Experimental datum, Forced response analysis, High cycle fatigue, High speed acquisition, Loading and unloading
IdentifiersURN: urn:nbn:se:kth:diva-53665DOI: 10.1115/GT2012-68303ISI: 000335868800141ScopusID: 2-s2.0-84881165627ISBN: 978-079184473-1OAI: oai:DiVA.org:kth-53665DiVA: diva2:470595
ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012; Copenhagen; Denmark; 11 June 2012 through 15 June 2012
QC 201201092011-12-292011-12-292014-10-08Bibliographically approved