Research on the leakage and dynamic characteristics of a new kind of radial annular seal and comparisons with labyrinth seals

Zhang, WF; Yang, JG; Tian, Yue; Cao, Hao; Gu, Jianying

doi:10.1177/0957650912474388

Cited by 9 publications

(4 citation statements)

References 39 publications

(38 reference statements)

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“…3,4 However, the labyrinth seal has been confirmed to be a major source of destabilizing forces resulting in rotor instability problems. 5 From a rotordynamics point of view, modern seal technology puts forward higher requirements in reducing leakage flow and improving rotor stability.…”

Section: Introductionmentioning

confidence: 99%

Rotordynamic characteristics of a novel labyrinth seal with partition walls and helical groove teeth

Xue,

Fang,

Wang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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To improve the stability of the conventional labyrinth seal (LS), in this paper, four novel fully partitioned helically labyrinth seals (FPHGLS) were designed and they were in comparison with one FPPGLS. The influences of the preswirl ratio and the helical groove pitch on the leakage flow and rotordynamic characteristics were numerically investigated, using the transient computational fluid dynamics (CFD) method based on the multi-frequency elliptical whirling orbit model. The accuracy and availability of the present transient numerical method were demonstrated based on the experiment data. The results show that the partition walls design can significantly increase the direct damping and cross-coupling stiffness for labyrinth seals and the helical teeth design can significantly decrease the cross-coupling stiffness and tangential force. When the helical groove pitch is equal to the seal length, the leakage nearly remains unchanged. Compared to the baseline design (LS), the FPPGLS and the FPHGLS have similar and significantly larger direct stiffness and direct damping. The two designs possess positive direct stiffness throughout the frequency range. The FPPGLS and FPHGLS possess significantly higher direct damping (∼323.7% larger than LS). But the FPPGLS possesses the largest cross-coupling stiffness among three seals at two preswirl ratios. From preswirl ratio = 0.13–0.84, the cross-coupling stiffness of the FPHGLS decreases by 53.4-310.1% compared with the FPPGLS. Increasing the helical groove pitch increases both direct stiffness and direct damping and reduces cross-coupling stiffness, but it also leads to greater leakage losses. In general, the novel FPHGLS whose helical groove pitch is equal to seal length possesses superior rotordynamic characteristics and similar leakage characteristic. This work provides the reference of the seal design and safety operation for the turbomachinery.

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Section: Introductionmentioning

confidence: 99%

Rotordynamic characteristics of a novel labyrinth seal with partition walls and helical groove teeth

Xue,

Fang,

Wang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…In Alford's analysis of steam flow exciting forces, the uneven force on rotor produced by steam can easily cause the eccentricity of the rotor, which results in circumferential uneven leakage flow and continuously aggravates the whirl motion of rotor [1]. To analyse the mechanism of steam exciting force, many different computational models of seal have been used by scholars [2] to [6]. With the deepening of research, the computational models of seal for steam flow exciting forces are constantly improved [7] and [8].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

Cao

2020

SV-JME

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In order to study the steam flow excited vibration caused by the eccentricity of a rotor, three-dimensional rotor whirl motion is simulated based on mesh deformation. The mechanism of steam flow excited vibration and its influence on the dynamic characteristics of the rotor are investigated. The results show that the exciting forces change with the displacement of the rotor’s centre. Rotor dynamic coefficients are nonlinear when the rotor whirls pass the mesh deformation. The rotor dynamic coefficients and effective damping increase with the increase of whirl frequency. When the whirl frequency is 24.41 Hz, the rotor dynamic coefficients are strongly affected by rotational velocity. The maximum fluctuations of average direct stiffness, cross-coupling stiffness, direct damping and cross-coupling damping are 8.1 %, 113.2 %, 45.8 %, and 121.0 %, respectively. Effective damping fluctuates greatly when both whirl and rotational frequency are 24.41 Hz. The direct stiffness, direct damping, and effective damping increase with the increase of pressure ratio, which can improve rotor stability. The pressure fluctuation on the rotor’s surface is a primary reason for steam flow excited vibration. The stability margin of the rotor can be estimated precisely via effective damping.

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“…Labyrinth seals are the most classic design of annular gas seals, comprising of a series of circular blades and annular grooves. Labyrinth seals have simplicity, reliability, and tolerance for large thermal and pressure variation [5,6]. However, numerous investigations have found that the labyrinth seals in turbomachinery are an important source of inducing rotor instability [7,8].…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on Static and Rotor-Dynamic Characteristics of Convergent-Tapered and Divergent-Tapered Hole-Pattern Gas Damper Seals

Sun

Zhao

et al. 2019

Materials

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To study the influence of taper seal clearance on the static and rotor-dynamic characteristics of hole-pattern damper seals, this paper develops three-dimensional transient computational fluid dynamic methods, which comprise single-frequency and multi-frequency elliptical orbit whirl model, by the transient solution combined with a mesh deformation technique. Through the investigations, it is illustrated that: (1) In the present paper, the leakage rates of convergent-tapered hole-pattern damper seals are less than divergent-tapered hole-pattern damper seals for the same average seal clearance, and the maximum relative variation reaches 16%; (2) Compared with a constant clearance hole-pattern damper seal, the maximum relative variation of the rotor-dynamic coefficients is 1,865% for nine taper degrees in this paper; (3) Convergent-tapered hole-pattern damper seals have smaller reaction forces and effective damping coefficient, larger cross-over frequency, and direct stiffness coefficient, while divergent-tapered damper seals have the opposite effects; (4) Divergent-tapered hole-pattern damper seals alleviate the rotor whirl because of a larger effective damping coefficient when the rotor system has large natural frequency and small eccentricity. Convergent-tapered damper seals provide both sealing and journal bearing capabilities at the same time, and are more advantageous to the stability of the rotor system when rotor eccentricity is the main cause of rotor instability.

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Research on the leakage and dynamic characteristics of a new kind of radial annular seal and comparisons with labyrinth seals

Cited by 9 publications

References 39 publications

Rotordynamic characteristics of a novel labyrinth seal with partition walls and helical groove teeth

Rotordynamic characteristics of a novel labyrinth seal with partition walls and helical groove teeth

Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

Numerical Investigation on Static and Rotor-Dynamic Characteristics of Convergent-Tapered and Divergent-Tapered Hole-Pattern Gas Damper Seals

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