Study on the Influence of Damping Structure on Stress and Eigenfrequency of Long Twisted Blade
In order to study the influence of different damping structure on stress and eigenfrequency of long twisted blade,two models of long twisted blade,Model 1 with shroud only and Model 2 with shroud and snubber,were presented and analyzed in this paper.Firstly,the static stress analysis ofblade was conducted by ANSYS,stress of blade was obtained,and normal contact force of neighboring shroud and snubber contact surface of adjacent blade under different rotational speeds were also obtained.Then,the Greenwood Williamson contact model was used to convert normal contact force into contact stiffness.Contact stiffness was simulated by Matrix27 element in the finite analysis model,and blade's modal analysis was conducted by ANSYS.The results show that maximum stress onblade occurs at the intersection of the blade top section and the shroud,the ratio of maximum stress between Model 1 and Model 2 is 1.34∶1.Contact stiffness of Model 1's contact surface is smaller than that of Model 2's.Under the same order and same nodal diameter,model 1's eigenfrequency is lower than that of Model 2's.According to Campbell diagram,Model 1 has three resonance speeds,and the avoidance rate of resonance speed of the 2nd order nodal diameter 7 does not meet the requirements.Model 2 has two resonance speeds,and both avoidance rates meet the requirements.The results indicate that Model 2's stress and eigenfrequency meet the design requirements better than Model 1's.
long twisted bladedamping structurecontact stiffnessstress analysiseigenfrequency
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