Abstract:
This work aims to perform the detailed experimental
investigation of the flow field in labyrinth seal specimen using
optical methods: LDA (Laser Doppler Anemometry) and
schlieren visualization. Preliminary tests were performed on a
stationary (rotor model with labyrinth does not move), linear –
where the curvature of the specimen is omitted – measuring
stand supplied by a vacuum pump. The installation makes it
possible to achieve critical pressure ratios, up to two. This
investigation was also supported by CFD (Computational Fluid
Dynamics) calculations performed using the Ansys CFX v.17
commercial code with a flow model based on the RANS
equations. Prediction scheme simulated the experimental
campaign parameters. In CFD study, different types of mesh
resolution were tested, with variable volume discretization in
the area of labyrinth fin tip. Presented study shows challenges
as well as the possibilities of flow field visualization including
three-dimensional vortexes and strong jets occurring
downstream the fin tips. Some limitations of LDA method
application were pointed out, especially in areas of rapid fluid
expansion. Moreover paper presented that schlieren method is a
very efficient way of giving the turbulence structures in linear
labyrinth seal fins. In the end, experimental results were
compared with CFD study, which reviled the best method for
labyrinth seal structures flow field simulation. Comparison of
experimental and computed results showed some agreement
between those two approaches. Flow visualization also allowed
to understand better the flow behavior in cavities, which is
crucial for design tools development.
Description:
Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .
