ラビリンスシールの振動学的動特性解析

概要

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A calculation method utilizing the computational fluid dynamics technique for the linear rotordynamic characteristics of labyrinth seals is presented. First, the static flow, in which the rotor is concentric with the seal, is calculated taking into account the viscosity change with turbulence and the compressibility. Next, the perturbation flow is computed based on this static flow. The perturbation equations may be treated as a two-dimensional problem by separating the angle variable. In this calculation, coefficients of spring, damping, and acceleration are separately calculated. The difference equations of control volumes adjacent to the rotor are first obtained in a three-dimensional form, then transformed into the two-dimensional one by applying the fast fourier transform technique to the coefficients of these equations. The present calculation method is verified by calculating for a straight-through labyrinth seal whose empirically determined flow state has been published. It is shown that rotor instability can be initiated through the cross-coupling term of spring, if the inlet swirl is intense enough, that its diagonal term differs greatly from the conventionally accepted value and that the mere determination of cavity pressure is insufficient to infer the pressure distribution that exists across a fin.
社団法人日本機械学会の論文
1993-12-25