Study on the Leakage and Deformation Characteristics of the Finger Seals by Using Numerical Simulation

Abstract

Depending on the throttling process of finger pad gap and the kinetic energy dissipation within the finger gap, finger seal can reduce the fluid leakage. But the deformation of the finger will increase the finger pad gap, which results in the increasing of overall leakage. To evaluate the performances of the finger seal, we used a two-way fluid-structure interaction method to analyse the seal deformation and flow field through the finger seal simultaneously. The numerical analyses show that a strengthened finger seal or a convergent type pad can be considered to reduce the leakage flow through finger pad gap. Finger pad deformation depends mainly on the pressure difference, but not the finger pad gap. There is a strong vortex in the finger gap, which blocks the fluid leakage. The leakage fluid is divided into many small vortices, the kinetic energy of the leakage fluid is dissipated in such a process and its pressure is decreased. When the finger pad deformed, its high pressure end moves toward the shaft, if the pressure difference increases or the shaft oscillated, this end could touch the shaft surface. The position of the maximum radial movement of finger pad does not coincide with the position of the maximum deformation of finger pad, which means the finger pad will be twisted to some extent rather than simply lift.