Study on critical chocked characteristics of supercritical carbon dioxide spiral groove dry gas seal under thermal-fluid coupling lubrication

doi:10.11949/0438-1157.20231101

Abstract

Abstract:

Under the premise of stable operation of the seal, promoting the formation of blocked flow at the seal end face outlet to increase the air film opening force and reduce end face leakage is an effective way to optimize dry gas sealing performance. Taking supercritical carbon dioxide (CO₂) spiral groove dry gas seal as the object, the finite difference method was used to solve the pressure and temperature governing equations on the basis of the effects of real gas, centrifugal inertia, turbulence and chocked flow. The critical chocked characteristics (e.g. critical chocked inlet pressure p_{o_cir}, critical chocked speed N_{_cir}, critical chocked film thickness h_{0_cir} and chocked critical instability film thickness h_sc) under thermal-fluid coupling lubrication were qualitatively studied. The results show that there is a chocked interval at the outlet of supercritical CO₂ dry gas seal in isothermal and adiabatic model. The intervals corresponding to the inlet pressure, film thickness and rotational speed are p_o>p_{o_cir},h_{0_cir}<h₀<h_sc and N<N_{_cir}, respectively. The increase of the rotating speed can continuously enhance the critical chocked inlet pressure and the critical chocked film thickness. The increase of the film thickness will lead to the decrease of the critical chocked pressure and the increase of the critical chocked speed. The high-pressure inlet will make the chocked zero stiffness corresponding to the film thickness (chocked critical instability film thickness h_sc) down. Compared with the isothermal flow hypothesis, the influence of gas film thermal effect on the critical chocked characteristic parameters of supercritical CO₂ dry gas seal is significant, and the influence rules are different.

Key words: supercritical carbon dioxide, dry gas seal, thermal-fluid coupling, critical choked characteristics, choked occurrence interval

摘要：

在密封稳定运行的前提下，促成密封端面出口形成阻塞流动以提升气膜开启力、降低端面泄漏不失为干气密封性能优化的有效途径。以超临界二氧化碳（CO₂）螺旋槽干气密封为研究对象，综合考虑实际气体、离心惯性、湍流和阻塞流效应，采用有限差分法耦合求解压力和温度控制方程，定性研究了热流耦合润滑下的临界阻塞特性（临界阻塞进口压力p_{o_cir}、临界阻塞转速N_{_cir}、临界阻塞膜厚h_{0_cir}和阻塞临界失稳膜厚h_sc）。结果表明：等温流动和绝热流动模型下超临界CO₂干气密封端面间隙出口均存在阻塞发生工况区间，进口压力、膜厚、转速对应的阻塞发生区间分别为p_o>p_{o_cir}、h_{0_cir}<h₀<h_sc和N<N_{_cir}；转速升高可以对临界阻塞进口压力和临界阻塞膜厚产生持续增强作用，增大膜厚则会导致临界阻塞压力降低、临界阻塞转速上升，高压进口将使阻塞零刚度对应的膜厚（阻塞临界失稳膜厚h_sc）下行；相较于等温流动假设，气膜热效应对超临界CO₂干气密封临界阻塞特性参数的影响程度较为显著，且影响规律各有不同。

关键词: 超临界二氧化碳, 干气密封, 热流耦合, 临界阻塞特性, 阻塞发生区间

CLC Number:

TH 136

Zhi ZHU, Hengjie XU, Wei CHEN, Wenyuan MAO, Qiangguo DENG, Xuejian SUN. Study on critical chocked characteristics of supercritical carbon dioxide spiral groove dry gas seal under thermal-fluid coupling lubrication[J]. CIESC Journal, 2024, 75(2): 604-615.

朱芝, 许恒杰, 陈维, 毛文元, 邓强国, 孙雪剑. 超临界二氧化碳螺旋槽干气密封热流耦合润滑临界阻塞特性研究[J]. 化工学报, 2024, 75(2): 604-615.

Figures/Tables 13

Fig.1 Schematic diagram of spiral groove dry gas seal

Table 1 Calculation parameters of dry gas seal

参数	数值	参数	数值
内径r_i/mm	30	槽宽比δ	1
槽根半径r_g/mm	33.6	密封腔温度T_o/K	450
外径r_o/mm	42	环境压力p_i/MPa	1.4
槽数N_g	12	进口压力p_o/MPa	10
非槽区膜厚h₀/μm	5	转速N/(r·min^-1)	10380.8
槽深h_g/μm	5	热导率λ_o/(W·m^-1·K^-1)	33.917
螺旋角β/(°)	15	Prandtl数Pr	0.83973

Fig.2 Flow chart of numerical calculation for critical chocked characteristics

Fig.3 Grid independence test

Fig.4 Validation of the calculation program

Fig.5 The variation of Pfic under isothermal and adiabatic model

Fig.6 The variation of pexit with N and h0 under isothermal and adiabatic model

Fig.7 The influence of inertia and turbulence effect on leakage ( isothermal and coercive boundary, h0=5 μm)

Fig.8 The variation of po_cir with N and h0 under isothermal and adiabatic model

Fig.9 The effect of film thickness on N_cir under isothermal and adiabatic model

Fig.10 The effect of rotational speed on h0_cir under isothermal and adiabatic model

Fig.11 The change of Fo with h0 under chocked flow (N=10380.8 r·min-1, po=10 MPa)

Fig.12 The variation of hsc with operating parameters

References 17

18	马春红, 白少先, 彭旭东, 等. 螺旋槽端面微间隙高速气流润滑密封特性[J]. 摩擦学学报, 2015, 35(6): 699-706.
	Ma C H, Bai S X, Peng X D, et al. Properties of high speed airflow lubrication in micro-clearance of spiral-groove face seals[J]. Tribology, 2015, 35(6): 699-706.
19	马润梅, 朱鑫磊, 张楠楠, 等. 超临界二氧化碳气体端面密封阻塞效应研究[J]. 润滑与密封, 2020, 45(1): 16-22.
	Ma R M, Zhu X L, Zhang N N, et al. Study on blocking effect supercritical carbon dioxide of dry gas seal[J]. Lubrication Engineering, 2020, 45(1): 16-22.
20	章聪, 彭旭东, 江锦波, 等. 实际气体、阻塞和湍流效应对超临界CO₂干气密封性能的影响[J]. 中国电机工程学报, 2022, 42(20): 7563-7573.
	Zhang C, Peng X D, Jiang J B, et al. Influence of real gas, choked flow, and turbulence effect on performance of supercritical CO₂ dry gas seals[J]. Proceedings of the CSEE, 2022, 42(20): 7563-7573.
21	Xu H J, Song P Y, Mao W Y, et al. The performance of spiral groove dry gas seal under choked flow condition considering the real gas effect[J]. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2020, 234(4): 554-566.
22	Du Q W, Gao K K, Zhang D, et al. Effects of grooved ring rotation and working fluid on the performance of dry gas seal[J]. International Journal of Heat and Mass Transfer, 2018, 126: 1323-1332.
23	胡航领, 林志民, 虞翔宇, 等. 高参数超临界二氧化碳干气密封性能分析研究[J]. 化工设备与管道, 2022, 59(5): 62-68.
	Hu H L, Lin Z M, Yu X Y, et al. Simulation analysis on sealing performance of supernal parameters supercritical carbon dioxide dry gas seal[J]. Process Equipment & Piping, 2022, 59(5): 62-68.
24	Yan R Q, Chen H Q, Zhang W Z, et al. Calculation and verification of flow field in supercritical carbon dioxide dry gas seal based on turbulent adiabatic flow model[J]. Tribology International, 2022, 165: 107275.
25	江鹏, 江锦波, 彭旭东, 等. 传热模型对近临界工况CO₂干气密封温压分布和稳态性能影响[J]. 化工学报, 2021, 72(8): 4239-4254.
	Jiang P, Jiang J B, Peng X D, et al. Influence of heat transfer model on temperature and pressure distribution and steady state performance of CO₂ dry gas seal under near critical condition[J]. CIESC Journal, 2021, 72(8): 4239-4254.
26	王竹溪. 热力学[M]. 2版. 北京: 北京大学出版社, 2013.
	Wang Z X. Thermodynamics[M]. 2nd ed. Beijing: Peking University Press, 2013.
27	Zhang C, Jiang J B, Peng X D, et al. The influence and a direct judgement method of the flow state in supercritical CO₂ dry gas seal[J]. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2021, 43(11): 486.
28	李双喜, 宋文博, 张秋翔, 等. 干式气体端面密封的开启特性[J]. 化工学报, 2011, 62(3): 766-772.
	Li S X, Song W B, Zhang Q X, et al. Opening characteristics of dry gas seal[J]. CIESC Journal, 2011, 62(3): 766-772.
29	严如奇, 丁雪兴, 徐洁, 等. 基于湍流模型的S-CO₂干气密封流场与稳态性能分析[J]. 化工学报, 2021, 72(8): 4292-4303.
	Yan R Q, Ding X X, Xu J, et al. Flow field and steady performance of supercritical carbon dioxide dry gas seal based on turbulence model[J]. CIESC Journal, 2021, 72(8): 4292-4303.
30	Xu H J, Yue Y G, Song P Y, et al. Analysis on the dynamic characteristics of spiral groove dry gas seal based on the gas film adaptive adjustment model[J]. Industrial Lubrication and Tribology, 2023, 75(4): 406-414.
1	尹露, 张万福, 顾乾磊, 等. 超临界二氧化碳迷宫密封动力特性研究[J]. 振动与冲击, 2020, 39(22): 128-136.
	Yin L, Zhang W F, Gu Q L, et al. Study on dynamic characteristics of labyrinth seals with supercritical carbon dioxide[J]. Journal of Vibration and Shock, 2020, 39(22): 128-136.
2	申楠楠, 高明, 王治云, 等. 不同倾角条件下非均匀热流对超临界二氧化碳对流换热的影响[J]. 热能动力工程, 2023, 38(1): 164-172.
	Shen N N, Gao M, Wang Z Y, et al. Influence of non-uniform heat flux on convective heat transfer of supercritical carbon dioxide under different inclination angles[J]. Journal of Engineering for Thermal Energy and Power, 2023, 38(1): 164-172.
3	刘柯炜, 李振涛, 王昕, 等. 超临界二氧化碳干气密封稳态性能研究[J]. 润滑与密封, 2020, 45(9): 71-77.
	Liu K W, Li Z T, Wang X, et al. Study on steady-state performance of supercritical carbon dioxide dry gas seal[J]. Lubrication Engineering, 2020, 45(9): 71-77.
4	Park J H, Park H S, Kwon J G, et al. Optimization and thermodynamic analysis of supercritical CO₂ Brayton recompression cycle for various small modular reactors[J]. Energy, 2018, 160: 520-535.
5	王绩德, 冯岩. 超临界二氧化碳动力循环关键部件研究综述[J]. 能源与节能, 2019(1): 96-97.
	Wang J D, Feng Y. Review on key components of supercritical carbon dioxide power cycle[J]. Energy and Energy Conservation, 2019(1): 96-97.
6	李志刚, 袁韬, 方志, 等. 超临界二氧化碳旋转机械动密封技术研究进展[J]. 热力透平, 2019, 48(3): 166-174, 191.
	Li Z G, Yuan T, Fang Z, et al. A review on dynamic sealing technology of supercritical carbon dioxide rotating machinery[J]. Thermal Turbine, 2019, 48(3): 166-174, 191.
7	沈伟, 彭旭东, 江锦波, 等. 高速超临界二氧化碳干气密封实际效应影响分析[J]. 化工学报,2019, 70(7): 2645-2659.
	Shen W, Peng X D, Jiang J B, et al. Analysis on real effect of supercritical carbon dioxide dry gas seal at high speed[J]. CIESC Journal, 2019, 70(7): 2645-2659.
8	许恒杰. 实际气体及其阻塞和惯性效应对干气密封动力学特性影响规律研究[D]. 昆明: 昆明理工大学, 2019.
	Xu H J. Dynamic characteristics of dry gas seal influenced by the real gas, choked flow and inertia effects[D]. Kunming: Kunming University of Science and Technology, 2019.
9	丁俊华, 俞树荣, 王世鹏, 等. 多重效应下超高速干气密封流场模拟及密封性能试验[J]. 化工学报, 2023, 74(5): 2088-2099.
	Ding J H, Yu S R, Wang S P, et al. Flow simulation and sealing performance test of ultra-high speed dry gas seal under multiple effects[J]. CIESC Journal, 2023, 74(5): 2088-2099.
10	Bai S X, Ma C H, Peng X D, et al. Thermoelastohydrodynamic behavior of gas spiral groove face seals operating at high pressure and speed[J]. Journal of Tribology, 2015, 137(2): 021502.
11	丁雪兴, 刘勇, 张伟政, 等. 螺旋槽干气密封微尺度气膜的温度场计算[J]. 化工学报, 2014, 65(4): 1353-1358.
	Ding X X, Liu Y, Zhang W Z, et al. Calculation of temperature field of micro-scale gas film in spiral groove dry gas seal[J]. CIESC Journal, 2014, 65(4): 1353-1358.
12	严如奇, 洪先志, 包鑫, 等. 超临界二氧化碳干气密封相态分布规律与密封性能研究[J]. 化工学报, 2020, 71(8): 3681-3690.
	Yan R Q, Hong X Z, Bao X, et al. Phase-distribution regularity and sealing performance of supercritical carbon dioxide dry gas seal[J]. CIESC Journal, 2020, 71(8): 3681-3690.
13	唐大全, 洪先志, 黎磊, 等. 超临界CO₂干气密封流动场数值计算与试验验证[J]. 化工机械, 2021, 48(2): 209-212, 305.
	Tang D Q, Hong X Z, Li L, et al. Microscale calculation and experiment of the flow field of dry gas seal with supercritical carbon dioxide[J]. Chemical Engineering & Machinery, 2021, 48(2): 209-212, 305.
14	Zuk J, Ludwig L P, Johnson R L. Compressible flow across shaft face seals[C]//5th International Conference on Fluid Sealing. Coventry, England: BHRA, 1971: 1-35.
15	Thomas S, Brunetière N, Tournerie B. Numerical modelling of high pressure gas face seals[J]. Journal of Tribology, 2006, 128(2): 396-405.
16	Thomas S, Brunetière N, Tournerie B. Thermoelastohydrodynamic behavior of mechanical gas face seals operating at high pressure[J]. Journal of Tribology, 2007, 129(4): 841-850.
17	许恒杰, 宋鹏云, 毛文元, 等. 考虑氢气实际气体效应和阻塞流效应的螺旋槽干气密封动态特性分析[J]. 化工学报, 2017, 68(12): 4675-4684.
	Xu H J, Song P Y, Mao W Y, et al. Dynamic characteristics of spiral groove dry gas seals with consideration of hydrogen real gas and choked flow effects[J]. CIESC Journal, 2017, 68(12): 4675-4684.

[1]	Zexin ZHANG, Weizhong ZHENG, Yisheng XU, Dongdong HU, Xinyu ZHUO, Yuan ZONG, Weizhen SUN, Ling ZHAO. Research progress of wafer cleaning and selective etching in supercritical carbon dioxide media [J]. CIESC Journal, 2024, 75(1): 110-119.
[2]	Yifei ZHANG, Fangchen LIU, Shuangxing ZHANG, Wenjing DU. Performance analysis of printed circuit heat exchanger for supercritical carbon dioxide [J]. CIESC Journal, 2023, 74(S1): 183-190.
[3]	Rui HONG, Baoqiang YUAN, Wenjing DU. Analysis on mechanism of heat transfer deterioration of supercritical carbon dioxide in vertical upward tube [J]. CIESC Journal, 2023, 74(8): 3309-3319.
[4]	Junhua DING, Shurong YU, Shipeng WANG, Xianzhi HONG, Xin BAO, Xuexing DING. Flow simulation and sealing performance test of ultra-high speed dry gas seal under multiple effects [J]. CIESC Journal, 2023, 74(5): 2088-2099.
[5]	Bingguo ZHU, Jixiang HE, Jinliang XU, Bin PENG. Heat transfer characteristics of supercritical pressure CO₂ in diverging/converging tube under cooling conditions [J]. CIESC Journal, 2023, 74(3): 1062-1072.
[6]	Yifan HE, Shuai YU, Xingqing YAN, Jianliang YU. Construction of CO₂ decompression wave propagation model based on method of characteristics and research on crack arrest wall thickness [J]. CIESC Journal, 2023, 74(12): 5038-5047.
[7]	Senlin WANG, Zhaozhi LI, Yingjuan SHAO, Wenqi ZHONG. Numerical simulation on heat transfer deterioration of supercritical carbon dioxide in vertical tube [J]. CIESC Journal, 2022, 73(3): 1072-1082.
[8]	Jianguo YAN, Shumin ZHENG, Pengcheng GUO, Bo ZHANG, Zhenkai MAO. Prediction of heat transfer characteristics for supercritical CO₂ based on GA-BP neural network [J]. CIESC Journal, 2021, 72(9): 4649-4657.
[9]	Xuejian SUN, Pengyun SONG, Wenyuan MAO, Qiangguo DENG, Hengjie XU, Wei CHEN. Dynamic contact analysis of dry gas seal during start-stop process considering material properties and surface topography of seal rings [J]. CIESC Journal, 2021, 72(8): 4279-4291.
[10]	Ruqi YAN, Xuexing DING, Jie XU, Xianzhi HONG, Xin BAO. Flow field and steady performance of supercritical carbon dioxide dry gas seal based on turbulence model [J]. CIESC Journal, 2021, 72(8): 4292-4303.
[11]	Peng JIANG, Jinbo JIANG, Xudong PENG, Xiangkai MENG, Yi MA. Influence of heat transfer model on temperature and pressure distribution and steady state performance of CO₂ dry gas seal under near critical condition [J]. CIESC Journal, 2021, 72(8): 4239-4254.
[12]	HONG Yanzhen, WANG Di, LI Zhuoyu, XU Yanan, WANG Hongtao, SU Yuzhong, PENG Li, LI Jun. Catalytic isomerization of α-terpineol to 1,8-cineole in supercritical carbon dioxide [J]. CIESC Journal, 2021, 72(7): 3680-3685.
[13]	SHANG Hao, CHEN Yuan, LI Xiaolu, WANG Bingqing, LI Yuntang, PENG Xudong. Study on the influence of nonlinear effect on performance of dry gas seal under film thickness disturbance [J]. CIESC Journal, 2021, 72(4): 2213-2222.
[14]	JIANG Jinbo, TENG Liming, MENG Xiangkai, LI Jiyun, PENG Xudong. Dynamic characteristics of supercritical CO₂ dry gas seal based on multi variables perturbation [J]. CIESC Journal, 2021, 72(4): 2190-2202.
[15]	Chen YU,Jinbo JIANG,Wenjing ZHAO,Jiyun LI,Xudong PENG,Yuming WANG. Geometrical model of surface groove based on micro-segment combination for dry gas seal and its parameter influence [J]. CIESC Journal, 2021, 72(10): 5294-5309.