Session: 36-03 Fan and Engine Noise

Paper Number: 103709

103709 - Analytical and Numerical Prediction of Acoustic Resonance in Labyrinth Seals 

Labyrinth seals are an essential and widely used component of modern aero engines and can contribute significantly to their increased efficiency. Their often complex geometry is intended to generate pressure losses to reduce leakage flow over the blade row. Acoustic resonances can occur within the cavities used for this purpose, which, when combined with a matched excitation, can result in high noise emissions and vibration excitation of the blades.

In this work, an analytical model is developed and validated with numerical data to predict the resonant frequency of axial standing waves within the cavities for propagating acoustic modes. The model is based on a RANS simulation of the cavity flow and determines the axial characteristics of the acoustic modes propagating upstream and downstream at several axial positions. For the analytical estimation of sound propagation, a formulation of the acoustic wave equation that accounts for arbitrary radial distributions is extended to include the mean flows radial velocity in order to model the propagation near the sealings in greater detail. An overall axial wavelength across the cavity is then estimated based on the wavenumbers determined at several axial positions. This modeling is used to iteratively determine the resonant frequency of an axial standing wave for different acoustic mode orders. A validation of the model with numerical results of a generic cavity for several aerodynamic operating points shows a deviation of the analytically and numerically determined resonant frequency of approx. 8% with an average resonant frequency of approx. 13kHz. In the framework of numerical setup studies on the influence of turbulence models, turbulent production limiters, and modeling of rotational effects on the turbulence of the RANS results, a deviation of 1% of the numerically predicted resonance frequencies was also observed.

Presenting Author: Lars Wein Gottfried Wilhelm Leibniz Universität Hannover

Presenting Author Biography: https://www.tfd.uni-hannover.de/en/institute/team/dr-ing-lars-wein

Authors:

Janek Mahlstedt Gottfried Wilhelm Leibniz Universität Hannover
Felix Fischer Gottfried Wilhelm Leibniz Universität Hannover
Lars Wein Gottfried Wilhelm Leibniz Universität Hannover
Jörg Seume Gottfried Wilhelm Leibniz Universität Hannover