Study on vibration reduction [JP2]characteristics of the B-B type turbine blade [JP]under-platform damper system considering the normal load allocation

In order to improve the design level of the under-platform damper of aero-engine turbine blades,a B-B type under-platform damper structure based on stiffness design was proposed by comparing with structures of the B-G (blade to ground) type damper and the tangential unconstrained B-B (blade to blade) type damper.In the dynamic modeling,the allocation of the total normal load between the damper and adjacent platforms was analyzed with relative motions between left and right platforms and the damper,and the allocation method of the normal load based on the motion of the damper was put forward.The influence of normal load allocation on the vibration response of the damped system was analyzed by numerical simulation,and the effects of damper stiffness,external excitation phase difference,total normal load and external excitation amplitude on the vibration reduction characteristics of the system were discussed in detail.The simulation results show that the normal load can be evenly allocated when the contact surfaces between left and right platforms and the damper are completely stick or the motions of adjacent blades relative to the damper are fully symmetric.The B-B type damper based on stiffness design proposed in this paper has better vibration reduction performance comparing with the tangential unconstrained B-B type damper and the rigid B-G type damper.This study improves the computational accuracy of the contact normal load between the turbine blade platform and the damper,expands the design idea of the damper and provides a theoretical and engineering reference for the design of this kind of damper.