Abstract
A dynamic model of the rotating shrouded blade is established, considering the shroud mass, the Coriolis force, and the centrifugal stiffening effect. And a macroslip model of dry friction with variable normal load is established to simulate the separation-contact-stick-slip state of the shroud. The Lagrangian equation is utilized to solve the differential motion equation, and the Galerkin method is used for discretization. The influence of shroud structure’s parameters such as rotational speed, contact angle, friction coefficient, clearance, and shroud position on the damping effect of the shroud is reviewed by means of amplitude-frequency response and energy through the Newmark-β numerical method. The results demonstrate that the damping effect of the shroud by contact is more obvious than by friction and the amplitude-frequency curve of the shrouded blade shows a strong hard nonlinear phenomenon.
Highlights
As an important component of aero-engines, blades are subjected to high-cycle fatigue
In order to further study the effect of the clearance on the damping effect of the shroud, the curves of the contact force and the friction force at different clearances can be drawn as shown in Figures 14(a) and 14(b), with the rotational speed of 1000 rad/s and the resonant frequency corresponding to the highest point of each curve in Figure 13 selected as the external excitation frequency
In order to further study the influence of the position on the damping effect of the shroud, the curves of the contact force and the friction force at different shroud positions are depicted in Figures 17(a) and 17(b), with the rotational speed of 1000 rad/s and the resonant frequency corresponding to the highest point of each curve in Figure 16 selected as the external excitation frequency
Summary
As an important component of aero-engines, blades are subjected to high-cycle fatigue. Choi and Chou [12] modeled a shrouded blade as a pretwisted Timoshenko beam with varying cross section and used the modified differential quadrature method to analyze the vibration of elastically supported blades They only considered the effect of the shroud’s mass and did not study the effect of the contact surface. Researchers have constantly been improving the contact model of the shroud and used a variety of methods to solve the response of the blade, but few scholars analyzed the damping mechanism of the shroud comparing the damping effect of friction and contact and consider the influences of the shroud mass, and the contact force generated by the shroud during the contact process is not always linear. Based on Hunt KH’s [28] nonlinear contact theory and considering the influences of the shroud mass, this paper established a contact force model with dry friction model to simulate the contact state of rotating shrouded blades. en, taking the rotational speed, contact angle, friction coefficient, clearance, and shroud position as parameters, the vibration mechanism of the rotating shrouded blade is investigated from the perspective of nonlinear response and energy
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