Study on Influences of Hydrodynamic Groove Depth Distribution on Static Surfaces on Lift-off and Temperature Rise Characteristics of Double-flow Ring Seals

doi:10.3969/j.issn.1004-132X.2026.08.007

Abstract

Abstract:

To address the problems of circumferentially non-uniform temperature distribution caused by eccentric clearance in classical double-flow ring seal pads， a novel variable-depth groove seal pad was proposed， featuring grooves with circumferentially varying depth on the air-side and hydrogen-side sealing surfaces. Considering fluid-structure thermal interactions， a conjugate heat transfer model was employed to numerically solve the flow fields in the sealing gaps and temperature field distribution of the double-flow ring seal pads. Comparative analyses of the lift-off and temperature rise characteristics of three seal pads with smooth， constant-depth groove， and variable-depth groove were conducted under both of specified eccentricity and radial force balance conditions. The influence law and mechanism of groove designs and groove depth variation on the static surfaces were also investigated. The results indicate that variable-depth groove seal pads may overcome the limitation of zero lift force at zero eccentricity inherent in traditional smooth and constant-depth groove seal pads. By selecting an appropriate groove depth variation ratio， zero-eccentricity operation may be achieved to balance the self-weight of different seal pads. Compared to smooth seal pads， grooved seal pads exhibit significant improvements in eccentricity， maximum temperature rise on the air and hydrogen sides， and circumferential temperature uniformity within the sealing gaps. However， these improvements come at the cost of increased flow rates of lubricating oil on both of the hydrogen and air sides.

Key words: double-flow ring seal, temperature rise characteristic, hydrodynamic groove, zero eccentricity operation

摘要：

为改善经典双流环密封瓦因偏心间隙引起的温度周向非均匀分布问题，提出了一种在密封瓦的空侧和氢侧密封面上开设槽深沿周向变化的变深槽密封瓦新结构，基于考虑流固热交换的共轭传热模型数值求解了双流环密封瓦的间隙流场和温度场分布，在给定偏心率和基于径向力平衡两种条件下对比分析了光滑面、等深槽和变深槽密封瓦的浮起和温升特性，探讨了静子面开槽及其槽深变深比的影响规律和作用机理。结果表明，静子面变深槽密封瓦能突破传统光滑面密封瓦和等深槽密封瓦在零偏心下无浮升力的限制，通过选取合理的槽深变深比以平衡不同的密封瓦自重从而实现零偏心运行；相较于光滑面密封瓦，开槽面密封瓦的偏心率、空侧和氢侧最高温升、整个密封间隙内温度周向非均匀性等性能指标都有大幅改善，但也带来了氢侧和空侧润滑油流量增加的不足。

关键词: 双流环密封瓦, 温升特性, 动压槽, 零偏心运行

CLC Number:

TH117

ZHANG Mengli, JIANG Jinbo, PENG Xudong, HONG Jun, XU Yongli, MENG Xiangkai. Study on Influences of Hydrodynamic Groove Depth Distribution on Static Surfaces on Lift-off and Temperature Rise Characteristics of Double-flow Ring Seals[J]. China Mechanical Engineering, 2026, 37(8): 1875-1888.

张孟丽, 江锦波, 彭旭东, 洪军, 许永利, 孟祥铠. 静子面动压槽深分布对双流环密封瓦浮起和温升特性影响研究[J]. 中国机械工程, 2026, 37(8): 1875-1888.

Figures/Tables 22

Fig.1 Schematic diagram of the double-flow ring sealing structure for hydrogen cooled generators

Fig.2 Schematic diagram of the depth distribution of sealing ring grooves with different sealing surface structures

Fig.3 Schematic diagram of the structural parameters of the floating sealing ring on the slotted surface of the stator

Fig.4 Schematic diagram of fluid domain and solid domain grids of sealing ring with different structural forms

Fig.5 Schematic diagram of heat exchange boundary of double flow ring sealing

Fig.6 Numerical solution flow chart of flow and heat transfer characteristics of double flow ring sealing

Tab.1 Structural parameters and working condition parameters of double-flow ring sealing

转轴半径r/mm	223.8	螺旋槽个数N_m	12
密封瓦内半径 r₁/mm	224	螺旋槽上部动压槽深h_u/mm	1
巴氏合金层外径r₂/mm	237.5	非均匀度t	0~1
密封瓦外半径r₄/mm	272	润滑油进口温度T_in/K	313
空/氢侧面轴向长度b₁/mm	16	空侧进口压力 p₁/kPa	484
空氢间轴向长度b₂/mm	9	氢侧进口压力 p₂/kPa	484
空/氢侧进口轴向长度b₃/mm	3	空侧出口压力 p₃/kPa	101
螺旋槽轴向槽宽比L_z	0.5	氢侧出口压力 p₄/kPa	400
螺旋槽周向槽宽比L_θ	0.5	转速n/（r ∙ min $- 1$ ）	3000
螺旋槽角度β/（°）	15	偏心率ε	0.4
螺旋槽周向开槽角度θ₁/（°）	15

Tab.1 Structural parameters and working condition parameters of double-flow ring sealing

转轴半径r/mm	223.8	螺旋槽个数N_m	12
密封瓦内半径 r₁/mm	224	螺旋槽上部动压槽深h_u/mm	1
巴氏合金层外径r₂/mm	237.5	非均匀度t	0~1
密封瓦外半径r₄/mm	272	润滑油进口温度T_in/K	313
空/氢侧面轴向长度b₁/mm	16	空侧进口压力 p₁/kPa	484
空氢间轴向长度b₂/mm	9	氢侧进口压力 p₂/kPa	484
空/氢侧进口轴向长度b₃/mm	3	空侧出口压力 p₃/kPa	101
螺旋槽轴向槽宽比L_z	0.5	氢侧出口压力 p₄/kPa	400
螺旋槽周向槽宽比L_θ	0.5	转速n/（r ∙ min $- 1$ ）	3000
螺旋槽角度β/（°）	15	偏心率ε	0.4
螺旋槽周向开槽角度θ₁/（°）	15

Tab.2 Physical parameters of sealing ring and rotating shaft materials

结构及

材料

密度

ρ/（kg ∙ m $- 3$ ）

质量热容

c_p /（J ∙ kg $- 1$ ∙K $- 1$ ）

热导率

λ/（W ∙ m $- 1$ ∙ K $- 1$ ）

45号

钢转轴

7850

453.6

Tab.2 Physical parameters of sealing ring and rotating shaft materials

结构及

材料

密度

ρ/（kg ∙ m $- 3$ ）

质量热容

c_p /（J ∙ kg $- 1$ ∙K $- 1$ ）

热导率

λ/（W ∙ m $- 1$ ∙ K $- 1$ ）

青铜材料密封瓦

8666

343

巴氏合金密封瓦

10 000

140

45号

钢转轴

7850

453.6

Fig.7 Verification of the correctness of sealing or bearing temperature and pressure solution based on conjugate heat transfer model

Fig.8 Pressure distribution of double flow ring sealing gap under different sealing clearances

Fig.9 Pressure circumferential distribution at the root of the air side and hydrogen side grooves under different sealing clearances

Fig.10 The variation law of sealing ring buoyancy force with groove depth ratio under different sealing clearances

Fig.11 Schematic diagram of characteristic cross-section in the fluid domain of the double flow ring sealing

Tab.3 Comparison of performance parameters of three structures of double flow ring sealing with eccentricity of 0.4

密封

结构

浮升力F/N

空氢间

最高

温度T_max/K

空侧出口最高温度T_a/K

氢侧

出口

最高

温度T_h/K

空侧出口流量q_a/（kg · s

- 1

）

氢侧出口流量q_h/（kg · s

- 1

等深

槽面

变深

槽面

Tab.3 Comparison of performance parameters of three structures of double flow ring sealing with eccentricity of 0.4

密封

结构

浮升力F/N

空氢间

最高

温度T_max/K

空侧出口最高温度T_a/K

氢侧

出口

最高

温度T_h/K

空侧出口流量q_a/（kg · s

- 1

）

氢侧出口流量q_h/（kg · s

- 1

）

光滑面

294.50

363.88

343.61

361.61

1.00

0.28

等深

槽面

794.78

362.65

332.58

338.89

1.55

0.67

变深

槽面

1260.75

361.98

335.91

340.72

1.35

0.51

Fig.12 Average pressure distribution at three characteristic cross-sections of sealing ring under eccentricity of 0.4

Fig.13 Temperature distribution of characteristic cross-sections of sealing ring with different structures under eccentricity of 0.4

Fig.14 Maximum temperature at the outlet of the air-side and hydrogen-side of the sealing ring with different structures

Fig.15 Variation of buoyancy force of sealing ring with eccentricity for different structures

Tab.4 Lubricating oil flow rate and temperature of three types of sealing ring under actual operating eccentricity

密封

结构

最小

密封

间隙h_min/mm

空/氢间最高

温度

T_max/K

空侧

出口

最高

温度

T_a/K

氢侧

出口

最高

温度

T_h/K

空侧出口流量q_a/（kg · s

- 1

）

氢侧出口流量q_h/（kg · s

- 1

Tab.4 Lubricating oil flow rate and temperature of three types of sealing ring under actual operating eccentricity

密封

结构

最小

密封

间隙h_min/mm

空/氢间最高

温度

T_max/K

空侧

出口

最高

温度

T_a/K

氢侧

出口

最高

温度

T_h/K

空侧出口流量q_a/（kg · s

- 1

）

氢侧出口流量q_h/（kg · s

- 1

）

光滑面

0.115

364.08

345.44

362.38

1.020

0.285

等深槽

0.17

359.34

327.14

332.58

1.466

0.656

变深槽

0.20

358.43

327.48

333.82

1.367

0.589

Fig.16 Distribution of circumferential pressure at the root of the air side groove and in the middle of the air hydrogen gap of sealing ring with different structures

Fig.17 Distribution of peak and average pressure values at the root of the air side groove of sealing ring with different structures

Fig.18 Circumferential distribution of fluid film temperature at different positions of three types of structural sealing ring

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