Effects of High Rotational Speed on Leakage and Windage Heating of Staggered Labyrinth Seals With Smooth and Honeycomb Lands

Abstract

Being an important component of aero-engines, the labyrinth seal has always been the focus of research for leakage characteristics. Rotation is usually neglected or taken for minimal effect on seal leakage in previous studies. However, the effect of high rotational speed is inevitable to understand the leakage characteristics of labyrinth seal accurately. Meanwhile, due to high rotational speed, viscous heat is generated massively to result in the rapid temperature rise of leakage flow. Also, the influence of rotational speed on windage heating inside the seal clearance has not been indicated completely. Therefore, the leakage and windage heating of staggered labyrinth seals with smooth and honeycomb lands were experimentally and numerically studied. The large-scale and multifunctional sealing test rig were employed to carry out the experiments with rotational speed 12,000 rpm and pressure ratio range 1.1–2.2. The simulation data obtained by three-dimensional computational fluid dynamics methodology show great agreement with experimental results. Notably, the leakage coefficient is not monotonically decreasing with increased rotational speed, but exists a maximum peak at RPM = 8000. The variation of axial kinetic energy in seal clearance entrances provides a clear explanation of the phenomenon. Rotational speed plays an important role in windage heating, and honeycomb cell size is of secondary importance. Based on simulation data, the calculating formula of windage heating is fitted and shows great performance. This study can provide theory and data support for the follow-up structural optimum design of the labyrinth seal.