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LU Xu-xiang

Bio: LU Xu-xiang is an academic researcher. The author has contributed to research in topics: Vibration. The author has an hindex of 1, co-authored 1 publications receiving 2 citations.
Topics: Vibration

Papers
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Journal Article
TL;DR: In this paper, the Runge-Kutta method was used to solve the vibration response of integrally shrouded blades and the effects of the clearance, contact angle and the normal rigidity between blade tips on the impact damping were analyzed.
Abstract: An equivalent model of spring and dry friction damping for contact impact in shrouds with clearance was set up by harmonic balance method.Then the three degree-of-freedom lumped-parameter model that can reflect main dangerous vibration mode of steam turbine shrouded blades was obtained.The Runge-Kutta method was used to solve the vibration response of integrally shrouded blades. Meanwhile,the effects of the clearance,contact angle and the normal rigidity between blade tips on the impact damping were analyzed.Results show that the integrally shrouded blades of steam turbine has a good advantages of vibration reduction because of contact-impact between shrouds,but the phenomenon of multi-spectrum characteristics and right-shift of resonance frequency appears.The effect of impact damping for the shrouded blade becomes better with reducing the clearance.The vibration reduction effect of compact-impact between shrouds to the first order vibration is better than that to the second order vibration.The larger contacting angles between the shrouds make the effect of the vibration reduction to the tangential vibration better.The larger normal contacting rigidity between the shrouds may make the vibration reduction effect of the contact-impact between the shrouds well enough.

2 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the forced vibration response of a simplified turbine blade with a new kind of under-platform dry friction dampers is studied, and the Finite Element (FE) method and Modal Superposition (MS) method are applied to solve the dynamic response, together with an algorithm that can capture nonsmooth transitions from stick to slip and slip to stick.
Abstract: Dry friction dampers are widely used to reduce vibration. The forced vibration response of a simplified turbine blade with a new kind of under-platform dry friction dampers is studied in this paper. The model consists of a clamped blade as two rigidly connected beams and two dampers in the form of masses which are allowed to slide along the blade platform in the horizontal direction and vibrate with the blade platform in the vertical direction. The horizontal and vertical vibrations of the two dampers, and the horizontal and transverse platform vibrations are coupled by friction at the contact interfaces which is assumed to follow the classical discontinuous Coulomb’s law of friction. The vertical motion of the dampers leads to time-varying contact forces and can cause horizontal stick-slip motion between the contact surfaces. Due to the relative horizontal motion between the dampers and the blade platform, the vertical contact forces and the resultant friction forces act as moving loads. The Finite Element (FE) method and Modal Superposition (MS) method are applied to solve the dynamic response, together with an algorithm that can capture nonsmooth transitions from stick to slip and slip to stick. Quasi-periodic vibration is found even under harmonic excitation.

24 citations

Journal ArticleDOI
TL;DR: In this article, the collision damping among blades' tips is equivalent to a damping of spring and friction with a gap, and the nonlinear impact damping is obtained for a 300MW steam turbine.
Abstract: In order to obtain the collision damping of blades’ tips characteristics, around a blades for a 300MW steam turbine, the COMBIN40 element of ANSYS was adopted. The collision damping among blades' tips is equivalent to a damping of spring and friction with a gap. Under the conditions of exciting force and rotating blade natural frequency ,the vibration of a harmonic response was analysed, the nonlinear impact damping of blade response characteristics and the vibration damping mechanism of collision was got.

1 citations