AUTHORS: Dawid Zaniewski, Piotr Klimaszewski, Piotr Klonowicz, Piotr Lampart, Łukasz Witanowski, Łukasz Jędrzejewski, Tomasz Suchocki, Łukasz Antczak
An important issue during the design of turbine seal areas is the selection of a suitable structural solution. The article presents a short review of different types of seals already in use in turbine engineering with a view of their application in small ORC turbines. The main objective of the article is to investigate the performance of a one-sided labyrinth seal over shrouded rotor blades with honeycomb in a 10 kW ORC turbine supplied with a working medium R7100. The comparative CFD investigations of labyrinth seals with a flat wall (reference case) and with a honeycomb filling are performed. The results are presented in the form of characteristics of the leakage reduction factor, isentropic efficiency and gland friction power as a function of relative radial clearance. A short Life Cycle Costs analysis is included as well. The obtained results indicate that the use of honeycomb labyrinth seal in ORC microturbines can reduce leakage flow rate. However, this does not easily translate into improvements in turbine stage efficiency, mainly due to increased gland friction losses. The stage efficiency is improved mainly for cases with a relatively high radial tip clearance. Small honeycomb dimensions remain a manufacturing challenge, requiring detailed techno-economic analysis.
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