Abstract
Finger seals are a new type of seal with good sealing performance and long service life. The noncontacting feature relies on the gas film force. However, when the seal works in an unsuitable environment or its design parameters are not reasonable, the lifting pad may not be able to generate sufficient air film force. This causes contact between the fingers and the rotor, resulting in a reduced service life of the seal. In view of this situation, this paper proposes a method that can quickly determine whether there is enough gas film force to lift the sealing finger at the design stage. The aeroelastic coupling characteristics of the noncontacting finger seal are studied in conditions where contact exists between the fingers and the rotor. The influences of various environmental and key structural parameters on the number of contact fingers, leakage, bearing force, and friction moment are studied. The results show that the pressure difference, eccentricity, and key design parameters have important effects on the number of contact fingers. The effect of rotation speed is relatively small. This paper provides a time-efficient tool for the design of noncontacting finger seals, which can quickly predict the performance of the sealing system.
Highlights
Gas turbines are widely used for high-power and high-efficiency applications
W L/B=0.5 FA L/B=0.5 W L/B=1.0 FA L/B=1.0 (c) the wider pads (L/B 0.5) because the square pads can generate more film force to lift the fingers, resulting in a higher increase in the clearances. e finger stiffness decreases with the increase in the number of fingers, and the finger deformations increase with the number of fingers under the same working environment. us, the clearances are increased, and the pressure distributions of each finger are almost the same, which results in the increase in the leakage and the decrease in the bearing force and friction moment
The static characteristics of noncontacting finger seals are studied when the seal works in an inappropriate environment or its design is unreasonable, which means contact may exist between the fingers and the rotor
Summary
Gas turbines are widely used for high-power and high-efficiency applications. To ensure the proper operation of gas turbines, stringent requirements are made on their internal components. E effects of different groove structure lifting pads on leakage flows and the lifting force on the finger were studied. Temis et al [17] proposed a two-way fluid-solid interaction method to calculate the seal characteristics of a noncontacting finger seal. We can see that the leakage performance, lifting ability, and effects of the structure and environmental parameters of noncontacting finger seals are widely studied. When the rotor is at high eccentricity or the seal is operating in an unsuitable working condition, the lifting forces may not be enough to keep the fingers noncontact with the rotor It results in contact during an operating rotor system. Static characteristics under various operating conditions when the contact exists can be quickly calculated, providing a time-efficient approach for the design of noncontacting finger seals
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