Numerical investigations on lifting and flow performance of finger seal with grooved pad

et al. 2020

Science Progress

To improve the intershaft seal performance of the dual-rotor turbofan engine and extend the life of the intershaft seal, a compliant cylindrical aerodynamic intershaft seal structure is proposed, which avoids the problem of leakage increase after tooth wear of intershaft labyrinth seal. According to the proposed seal structure, the force condition of the floating seal ring is analyzed, and an aeroelastic coupling method for the floating seal ring eccentricity is presented. And the leakage characteristics, with different seal structures and operating conditions are calculated and compared when the two rotors are under homodromy/counter-rotating condition. The results show that, for the dual-rotor cylindrical hydrodynamic gas film seal, the hydrodynamic effect under homodromy condition is enhanced greatly while the hydrodynamic effect is significantly weakened under counter-rotating condition; the rotational direction of rotors, seal width, rotor circular precession eccentricity, rotational speed and rotor radius all have pronounced influence on the seal performance. For the application of hydrodynamic form of compliant cylindrical intershaft seal, the seal performance under homodromy condition is better than that under counter-rotating condition.

Section: Introductionmentioning

confidence: 99%

Performance analysis of compliant cylindrical intershaft seal

Guo-qiang

et al. 2020

Science Progress

“…The following geometric relationship expressed by equation (1) exists between the aforementioned three eccentricities, rotor eccentricity OO 2 , seal ring eccentricity OO 1 , and gas lubrication eccentricity…”

Section: Geometric and Force Relationshipmentioning

confidence: 99%

“…Advanced seal technology is vital for the improvement of performance and efficiency of aviation gas turbines. 1,2 The intershaft seal, which is used to seal the intermediate bearing of a dual-rotor aeroengine, directly influences the service life of the intermediate bearing. Under special cases, the operating conditions of the intershaft seal are much worse than that of the conventional dynamic seal.…”

Section: Introductionmentioning

confidence: 99%

An analysis method for the performance of compliant cylindrical intershaft gas film seal considering centrifugal expansion effect

Guo-qiang

Proceedings of the Institution of Mechanical Engineers, Part C:

2021

A compliant cylindrical gas film seal has the potential to adapt to the complex operating conditions of a dual-rotor aeroengine, with radial runout and eccentricity, due to its special structural characteristics. To accurately investigate the seal performance of a compliant cylindrical gas film seal on dual-rotor shafts, an aeroelastic coupling method is proposed. This method analyzes the performance of a compliant cylindrical intershaft gas film seal by taking the centrifugal expansion effect into consideration. The seal performance under homodromy and counter-rotating conditions, with and without the centrifugal expansion effect, is calculated, and various performance parameters are compared and analyzed. Furthermore, the influence mechanism of the direction of rotation of the two rotors on seal performance is revealed. The results show that seal performance under homodromy condition is greater than under counter-rotating condition, and for an aeroengine under homodromy condition, it is advantageous to apply the compliant cylindrical intershaft gas film seal. The effect of centrifugal expansion (in large-diameter and high-speed rotors) and rotor eccentricity on the performance of a compliant cylindrical intershaft gas film seal, as well as the impact of inner and outer rotor speed on leakage rate, are analyzed and presented in this study. The proposed aeroelastic coupling method provides a promising guidance for the performance analysis of the compliant cylindrical gas film seal in single and dual- rotor systems.

“…Studies show the possibility of fingers contacting the rotor [15]. Jia et al [16] proposed a three-layer finger seal with grooved lifting pads. A numerical method was used to investigate the effects of the grooved structures on lifting and leakage performance.…”

Section: Introductionmentioning

confidence: 99%

Static Characteristics of Finger Seal considering Contact between Fingers and Rotor

Zhang

Jiao

et al. 2022

Shock and Vibration

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.