DESIGN CONCEPTS
The standard labyrinth
ring assembly utilizes a carbon ring which is shrink fitted into a
low expansion stainless steel alloy. The assembly of these two parts
is designed to match the thermal and centrifugal growth of the shaft
that is to be sealed. Consequently, at elevated temperatures the
floating ring assembly grows at a rate similar to that of the shaft.
The linear pressure drop,
which occurs between the lateral sealing faces, provides the closing
force necessary to maintain contact between the carbon and the
mating surface. For low pressure or reverse pressure applications, a
wave spring is used to maintain face contact.
To minimize leakage, a
computer-aided analysis is used to determine the optimum clearance
between the labyrinth ring assembly and the shaft. Computer programs
are also used to analyze thermal expansion of the labyrinth ring
assembly and the shaft; stress in the labyrinth ring assembly;
centrifugal growth of the shaft; labyrinth ring stability; and
thermal gradients in the seal. Additionally, a finite element
analysis program is available to evaluate the seal assembly and the
shaft.
|
FINITE
ELEMENT ANALYSIS
OF
LABYRINTH SEAL
COMPONENTS
|
