Rectangular-Cellular Seals for Steam Turbines

Nowadays, to reduce leakage in steam turbines, seals with inserts that are commonly known as honeycomb inserts are widely used.  Their design features allow setting reduced radial clearances (down to 0.5 mm). However, the pursuit of greater efficiency could conflict with reliability requirements. In addition, honeycomb seals are expensive. An alternative solution to the problem is rectangular-cellular seals designed and manufactured by the National Research University Moscow Power Engineering Institute (NRU MPEI). This paper presents the results of comparative experimental studies of flow and power characteristics for three types of seals: rectangular-cellular seals, honeycomb seals, and standard seals with smooth stator parts. The new NRU MPEI seals show similar flow rate characteristics when compared with honeycomb seals and have significantly lower levels of non-conservative forces, capable of causing vapor low-frequency vibration. At the same time, the cost of manufacturing rectangular-cellular seals using the MPEI Pilot-Production Plant technology is 6–8 times lower than that of traditional honeycomb seals.

References

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