Experimental and numerical validation study of the labyrinth seal configurations

Abstract

This article presents a validation study of the labyrinth seal testing. Both experimental and numerical simulations are performed. Literature data focused on simple labyrinth seals are surveyed, and two different configurations widely described in literature are investigated: a labyrinth seal with two straight fins against a smooth and a honeycomb land and a seal with three straight fins against a smooth land only. For experimental testing the vacuum-feeding test rig is used, with the high-precision Hot Wire Thermoanemometry method applied for the mass flow evaluation. The dimensions of specimens described in literature are adapted to the in-house test rig conditions, meeting all the geometrical requirements mentioned by the author. The computational method is based on the Reynolds Averaged Navier Stokes scheme, with various turbulence models. The results of the simulations show good agreement with the in-house experiment, whereas some discrepancies are found compared to literature data. KEYWORDS LABYRINTH SEAL, HONEYCOMB, SECONDARY FLOWS, EXPERIMENT, TEST RIG NOMENCLATURE

Dimensionless Numbers Relationships for Outer Air Seal of Low Pressure Turbine

“…It is obvious that with the increasing cross-sectional area, the mass flow and the corresponding Re ax will be higher. The present results and the dependencies of Re ax upon Π and c/R are in agreement with [7,10]. Figure 3 also shows that the Reynolds number is independent of the circumferential Mach number, thereby also from the rotational speed.…”

“…The aim of the research was the identification of the key factors influencing the flow through OAS and their mutual dependency. Recent studies have proven that CFD results show good agreement with experiments in terms of general flow characteristics, see e.g., [7,10]. Therefore, RANS are the proper choice for this kind of investigation.…”

“…Conversely, for low roughness at higher pressure ratios (above 1.5), they indicated a very limited impact of the rotational speed. Later on, Szymanski et al [10] also compared two different experiments with the CFD outcomes, showing good agreements. Another very detailed numerical study about OAS with honeycomb is due to Fraczek et al [11].…”

“…A few variants of the mesh were checked. First, following [10], the analyses with y + ∼ 1 (approx. 3M cells) were prepared.…”

“…Most of them were steady state. The SST was applied as a turbulence model as advised in [10,11,15]. The limiting convergence value was set to 1 × 10 −4 (rms value), but frequently it dropped below 1 × 10 −5 .…”