Hongxing Wu, Wenyuan Mao, Feng Jiao, Qiangguo Deng, Xuejian Sun and Hengjie Xu
The purpose of this paper is to obtain the matching relationship between spiral groove, equalizing groove and operation parameters through the biparametric analysis for the…
Abstract
Purpose
The purpose of this paper is to obtain the matching relationship between spiral groove, equalizing groove and operation parameters through the biparametric analysis for the bidirectional pumping hydrodynamic-static hybrid dry gas seal (BP-HHDGS).
Design/methodology/approach
The large eddy simulation (LES) model in Fluent is used to simulate the flow field of BP-HHDGS, and the biparameter variables method is chosen to analyze the effects of different parameters on the performance of BP-HHDGS.
Findings
BP-HHDGS has a greater opening force than hydrostatic dry gas seal (HDGS); the vortex is formed after lubricating gas is exhausted from the throttle. Increasing the depth of the equalizing groove and spiral groove has a synergistic enhancement effect on the opening force and leakage of BP-HHDGS. There is a matching relationship between spiral angle and rotational speed. The preferred parameter ranges in current conditions are found as follows: spiral angle αa = 15°–24°; groove-dam ratio λ = 0.4–0.7; equalizing groove depth hj > 35 µm; spiral groove depth hg = 5-10 µm.
Originality/value
The high starting capacity of HDGS is given to the hydrodynamic type seal, and thus the application promotion of HDGS in high-speed working condition is realized at the same time. This work also provides precise and quick theoretical guidance for the selection and design of hydrodynamic-static dry gas seal and further promotion.
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Wei Chen, Hengjie Xu, Wenyuan Mao, Meihong Liu, Xuejian Sun and Qiangguo Deng
This study aims to investigate the influence mechanism of thermal-mechanical deformations on the CO2 mixture gases dry gas seal (DGS) flow field and compare the deformation…
Abstract
Purpose
This study aims to investigate the influence mechanism of thermal-mechanical deformations on the CO2 mixture gases dry gas seal (DGS) flow field and compare the deformation characteristics and sealing performance between two-way and one-way thermal-fluid-solid coupling models.
Design/methodology/approach
The authors established a two-way thermal-fluid-solid coupling model by using gas film thickness as the transfer parameter between the fluid and solid domain, and the model was solved using the finite difference method and finite element method. The thermal-mechanical deformations of the sealing rings, the influence of face deformation on the flow field and sealing performance were obtained.
Findings
Thermal-mechanical deformations cause a convergent gap between the two sealing end faces, resulting in an increase in the gas film thickness, but a decrease in the gas film temperature and sealing ring temperature. The axial relative deformations of rotating and stationary ring end faces caused by mechanical and thermal loads in the two-way coupling model are less than those in the one-way coupling (OWC) model, and the gas film thickness and leakage rate are larger than those in the OWC model, whereas the gas film stiffness is the opposite.
Originality/value
This paper provides a theoretical support and reference for the operational stability and structural optimization design of CO2 mixture gases DGS under high-pressure and high-speed operation conditions.
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Hengjie Xu, Yinggang Yue, Pengyun Song, Wenyuan Mao, Qiangguo Deng and Xuejian Sun
This study aims to acquire the influence mechanism of gas film adaptive adjustment (GFAA) acted on the dynamic characteristics of spiral groove dry gas seal (S-DGS) and then…
Abstract
Purpose
This study aims to acquire the influence mechanism of gas film adaptive adjustment (GFAA) acted on the dynamic characteristics of spiral groove dry gas seal (S-DGS) and then propose a sealing stability enhancement measure.
Design/methodology/approach
The gas film dynamic stiffness and damping of S-DGS are obtained by numerically solving the transient Reynolds equation based on perturbation method and finite difference method. The dynamic coefficients in GFAA model and constant gas film thickness (CGFT) model are compared and analyzed.
Findings
There is the risk to misestimate the instability of DGS with rotational speed or medium pressure grows under the condition of CGFT assumption. Based on GFAA model, increasing balance ratio B properly is an effective measure to improve the stability of DGS. The balance ratio can stimulate the sensitivity of gas film dynamic coefficients to the variation of rotational speed. Increasing medium pressure in small balance ratio range will be conducive to reducing the risk of angular instability.
Originality/value
The influence mechanism of GFAA on S-DGS dynamic characteristics is analyzed. The interactions between rotational speed and balance ratio, medium pressure and balance ratio acted on gas film dynamic characteristics are explored based on the GFAA model.
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Robert G. Tian and Yan Wu
The purpose of this paper is to examine the construction of virtual community identities among Chinese internet users and their motivation for lurking, posting or flaming.
Abstract
Purpose
The purpose of this paper is to examine the construction of virtual community identities among Chinese internet users and their motivation for lurking, posting or flaming.
Design/methodology/approach
Taking Qiangguo Luntan as an online study site the authors apply an ethnographic approach for the research, a method that is becoming more and more favourable by scholars in study virtual communities. The data gathered are mainly through participant observation and in‐depth interviews.
Findings
The findings suggest that internet bulletin boards enable ordinary Chinese to have their identities as politically activated citizens constructed in cyberspace. A consistent enthusiasm for political participation can be found in user's pennames, signature files, political clusters, and online behaviours.
Originality/value
This is an original case study.
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The paper aims to reveal how the Chinese government has tried to regulate transnational cultural flows by applying cultural policies.
Abstract
Purpose
The paper aims to reveal how the Chinese government has tried to regulate transnational cultural flows by applying cultural policies.
Design/methodology/approach
The paper compares the dissemination of different foreign television programmes in China since the 1980s. The documents of cultural policy released since 1990s, news reports and the statistics of imported dramas since 2000s will be analyzed.
Findings
The research finds that the Chinese government has treated cultural products from different countries in unequal ways. Political-diplomatic relationships and the need for ideological control, influence the making of cultural policy. Restricting the quota of imported dramas, censorship and propaganda are measures taken by the Chinese government to regulate transnational cultural flows.
Research limitations/implications
The paper mainly focuses on platforms such as state-owned television stations and internet. The role of pay-cable channel in disseminating imported dramas should be taken into consideration in the future research.
Practical implications
The paper provides a systematic understanding on the development of Chinese cultural policy.
Originality/value
The paper offers an alternative approach to explore the policy-oriented dissemination of transnational cultural flows other than market-oriented dissemination.
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Along with the “reform and open door” policy launched in the late 1970s, China has experienced an annual average GDP growth rate of 9.8% between 1978 and 2002 (Hu, 2003, October 19…
Abstract
Along with the “reform and open door” policy launched in the late 1970s, China has experienced an annual average GDP growth rate of 9.8% between 1978 and 2002 (Hu, 2003, October 19). China's economy system has also gone through a fundamental transition from a central planning system to a socialist free market economy. To cope with the booming economy and radical social changes, the higher education system of China has been undergoing a process of expansion with marketization (World Bank, 1997).
The purpose of this paper is further leveraging the advantages of the basic socialist economic system and exploring the realistic way of transforming the advantages of the…
Abstract
Purpose
The purpose of this paper is further leveraging the advantages of the basic socialist economic system and exploring the realistic way of transforming the advantages of the socialist economic system with Chinese characteristics into governance efficacy. At its Fourth Plenary Session, the 19th Central Committee of the Communist Party of China (CPC) elevated the socialist market economy system to China's basic economic system, further affirming the significant advantages embedded in the socialist market economy from an institutional perspective.
Design/methodology/approach
The essence of the basic socialist economic system consists of the ownership structure with public ownership as the mainstay, the income distribution system with distribution according to work as the mainstay and the socialist market economy, which are interrelated, supportive and reinforcing mutually, forming an organic whole.
Findings
Over the past 40 years of reform and opening-up, it has been proven through practice that the basic socialist economic system has played a fundamental role in guaranteeing rapid economic development and social stability. The system not only corresponds to the development level of the productive forces in the primary stage of socialism in China but also demonstrates its strengths in eliminating polarization between the poor and the rich and achieving common prosperity.
Originality/value
It is necessary to make the basic economic system more coordinated and consistent and be committed to the philosophy that the whole is greater than the sum of its parts to form a systemic synergy, so as to achieve synergistic enhancement of institutional advantages and governance efficacy.