utveckling av modeller för dynamiska svarsfunktioner i turbinrotorer
utveckling av modeller för dynamiska svarsfunktioner i turbinrotorer
utveckling av modeller för dynamiska svarsfunktioner i turbinrotorer
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INNEHÅLL<br />
1 – NOMENKLATUR .................................................................................................. 1<br />
2 – INLEDNING .......................................................................................................... 3<br />
2.1 Bakgrund ........................................................................................................... 3<br />
2.2 Arbetets syfte..................................................................................................... 4<br />
2.3 Arbetets mål ...................................................................................................... 5<br />
2.4 Avgränsningar ................................................................................................... 6<br />
2.5 Metodik och rapportupplägg .............................................................................. 6<br />
3 – TURBINROTORDYNAMIK ................................................................................. 11<br />
3.1 Svängningsmoder i blad och skiva .................................................................. 11<br />
3.2 Rotorexcitation................................................................................................. 13<br />
3.3 Dynamiska effekter på grund <strong>av</strong> rotation ......................................................... 15<br />
3.4 Mistuning ......................................................................................................... 15<br />
4 – DÄMPNING ........................................................................................................ 17<br />
4.1 Karakterisering <strong>av</strong> strukturdynamisk dämpning ............................................... 17<br />
4.1.1 Viskös dämpning ....................................................................................... 18<br />
4.1.2 Coulombdämpning..................................................................................... 19<br />
4.1.3 Materialdämpning ...................................................................................... 20<br />
4.1.4 Aerodynamisk dämpning ........................................................................... 24<br />
4.2 Ytterligare dämpningsmått och dämpningsbeskrivningar ................................ 24<br />
4.2.1 Kvalitetsfaktor ............................................................................................ 24<br />
4.2.2 Modal töjningsenergi.................................................................................. 25<br />
4.2.3 Specifik dämpningskapacitet ..................................................................... 26<br />
4.2.4 Logaritmiskt dekrement ............................................................................. 26<br />
4.2.5 Half-Power Bandwidth ............................................................................... 27<br />
4.2.6 Proportionell dämpning.............................................................................. 28<br />
4.2.6.1 Rayleighdämpning ............................................................................... 30<br />
4.2.6.2 Caugheydämpning............................................................................... 31<br />
4.3 Dämpningsbeskrivning i Ansys........................................................................ 31<br />
4.4 Dämpning i <strong>turbinrotorer</strong>.................................................................................. 32<br />
4.5 Rotorpåverkan från aerodynamisk dämpning .................................................. 34<br />
5 – VINCIBLISKEN................................................................................................... 35<br />
5.1 Beskrivning <strong>av</strong> modalprovet............................................................................. 35<br />
5.2 FE-analys <strong>av</strong> Vinciblisken................................................................................ 36<br />
5.2.1 Val <strong>av</strong> riggningsalternativ........................................................................... 36<br />
5.2.2 Solid<strong>modeller</strong>ing ........................................................................................ 37<br />
5.2.3 FE-<strong>modeller</strong>ing .......................................................................................... 41<br />
5.2.4 Beräkningsmetod....................................................................................... 43<br />
5.3 Odämpad modalanalys.................................................................................... 46<br />
5.3.1 Allmänna iakttagelser ................................................................................ 46<br />
5.3.2 Geometri med infästningarna i form <strong>av</strong> låsta frihetsgrader ........................ 47<br />
5.3.3 Geometri med <strong>modeller</strong>ad fixturplatta........................................................ 47<br />
5.3.4 Geometri med <strong>modeller</strong>ad probbult ........................................................... 47<br />
5.3.5 Geometri med fixturerna i form <strong>av</strong> tunna materiallager.............................. 47<br />
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