Experimental and Numerical Investigations on Oil Leakage Across Labyrinth Seals in Aero Engine Bearing Chambers

Abstract

This paper presents experimental and numerical investigations of oil leakage across a conventional labyrinth seal commonly found in aero engine bearing chambers. Measurements and simulations were carried out in order to investigate the influence of chamber geometry and operating conditions on the reliability of the oil seal against leakage. The main goal of the experiments was to determine a minimum required pressure difference Δpleak to prevent oil from leaving the bearing chamber for any given operating point. To determine this variable, the pressure inside the test rig was continuously lowered from a high pressure difference until oil was found to leave the bearing chamber. Using two pressure supplies, this pressure could be negative or positive. The results show that the minimum pressure depends on component design and rotational speed. While certain component designs may increase this pressure at low rotational speeds, thereby creating a safety margin for oil leakage, the opposite effect can manifest itself at higher rotational speeds. Selected operating points were simulated using computational fluid dynamics employing the Volume-of-Fluid (VoF) approach. A comparison of the experimental and numerical results shows good qualitative agreement of the two phase flow phenomena inside the bearing chamber.