Abstract
Labyrinth seals are widely used in rotating machinery and can be prone to aeroelastic instabilities. The rapid development of computational fluid dynamics now provides a high-fidelity approach for predicting the aeroelastic behavior of labyrinth seals in three dimension and exhibits great potential within industrial application, especially during the detailed design stages. In the current publication a time-marching unsteady Reynolds-averaged Navier-Stokes solver was employed to study the various historically identified parameters that have essential influence on the stability of labyrinth seals. The findings from the numerical approach agree well with analytical criteria in determining the overall stability of the seal structure while being able to capture the acoustic behavior of the upstream or downstream large cavities and its influence on the inter-fin cavities. The high-fidelity approach provides additional insights on the effects of nodal diameter, travelling wave direction, pressure ratio, and the linearity of the phenomenon for relatively large vibration amplitudes, all of which can aid during the design space exploration.
Highlights
Labyrinth seals are commonly found in turbomachinery
Using time-marching CFD techniques with morphing meshes, extensive high-fidelity flutter analysis has been performed to assess the aeroelastic stability of rotor seals
Several parameters were varied to see their effects on the perceived instability, namely the support side of the seal, mechanical frequency, nodal diameter, traveling wave direction, pressure ratio, and seal deflection amplitude
Summary
Labyrinth seals are commonly found in turbomachinery. They are comprised of one rotating and one stationary component. The sealing fins, or so-called teeth, grow radially outward from the rotor cylinder surface towards the stator (sometimes in a reverse direction when the fins are attached to the stator) and maintain a certain clearance in-between. The members directly opposite to the fin tips (or knife edges) are usually coated with abradable and soft materials such as honeycomb structures. They are in place to accommodate the variable tip clearance during engine operation, especially when the two parts come into direct contact
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