Ming Feng, Hongyang Hu and Tianming Ren
To improve the load capacity and stability of gas foil journal bearings (GFJB), this paper aims to propose a novel GFJB with taper-grooved top foil.
Abstract
Purpose
To improve the load capacity and stability of gas foil journal bearings (GFJB), this paper aims to propose a novel GFJB with taper-grooved top foil.
Design/methodology/approach
A modified bump stiffness model is established considering rounding and friction. By considering the variation of clearance in the circumferential and axial direction, the static and dynamic characteristics of the novel bearing are calculated using the finite difference method, and perturbation method, respectively. The bearing performance under different groove parameters is studied and compared to the traditional bearings.
Findings
The results show that this novel GFJB can bring multi-extra local dynamic pressure and decrease the gas end leakage, which improves the static and dynamic properties. Moreover, as the increment of groove depth, the load capacity and direct stiffness are reinforced. There is an optimal groove width to maximize the load capacity, and the taper-groove is more beneficial to the improvement of bearing performance than other groove shapes. For the novel GFJB (Ng = 6, Hg = 10µm), the load capacity and direct stiffness increase by about 6.67 and 13.5 per cent, respectively. The stability threshold speed (STS) of a rotor supported by the novel bearings is also increased.
Originality/value
The performance of the presented novel GFJB is enhanced immensely compared to the traditional bearings, and the results are expected to be helpful to bearing designers, researchers and academicians concerned.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0307.
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Hongyang Hu, Ming Feng and Tianming Ren
The purpose of this paper is to study the effect law of roundness error on the properties of gas foil conical bearing (GFCB), and the performance of bearings with different…
Abstract
Purpose
The purpose of this paper is to study the effect law of roundness error on the properties of gas foil conical bearing (GFCB), and the performance of bearings with different non-circular sleeve shapes are calculated.
Design/methodology/approach
For the bump-type GFCB, the nonlinear bump foil stiffness model and 1-D beam top foil stiffness model are built. On this basis, the finite element method and finite difference method are used to solve the Reynolds equation and the film thickness equation coupled, and the static and dynamic properties of GFCB are calculated. The effect law of sleeve roundness error on the static performance under different conditions is obtained. Moreover, the dynamic stiffness and damping characteristics under different errors are also studied.
Findings
The roundness error will decrease the load capacity and friction torque of GFCB, and increase the attitude angle. The error effect is more dramatic when there is larger eccentric, small nominal clearance, larger error value and more error lobes, and the static performance exhibits a periodic change in the circumferential direction. The roundness error can also decrease the direct stiffness and cross-coupled damping of GFCB, while the cross-coupled stiffness increases largely, which will reduce the bearing stability.
Originality/value
The roundness error adversely affects the static and dynamic characteristics of GFCB, which should be concerned by bearing designers, researchers and academicians.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0019/
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Hongyang Hu, Ming Feng and Tianming Ren
The purpose of this paper is to study the characteristics of gas foil conical bearings (GFCBs) considering the misalignment, the static and dynamic performances with different…
Abstract
Purpose
The purpose of this paper is to study the characteristics of gas foil conical bearings (GFCBs) considering the misalignment, the static and dynamic performances with different misalignment cases were studied.
Design/methodology/approach
A test rig on the air compressor supported by GFCBs has been developed to measure the practicability. A nonlinear bump stiffness model and one-dimensional beam top foil stiffness model were used as a basis for the calculation of static and dynamic performance. The finite element method and finite difference method are adopted to solve the Reynolds equation and the film thickness equation coupled, in which different misalignment cases were considered by changing the film thickness.
Findings
The supporting performance of GFCB is excellent, and the film clearance plays a critical role. The misalignment effects depend on the assembled angle and the misalignment angle. The load capacity, friction torque, temperature of GFCB decrease when the misalignment assembled angle is between 120° and 240°, while the dynamic bearing stability is improved. The static and dynamic performances show the opposite law for the other assembled angles, and the misalignment effect is more dramatic when there is a larger misalignment angle. Moreover, the bearing and running parameters largely affect the bearing performance.
Originality/value
The present study focuses on the static and dynamic characteristics of GFCB and investigates the effects of misalignment on the bearing performance.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0117
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Hongyang Hu, Ming Feng and Tianming Ren
This paper aims to study the bearing performance with different cone angle errors, to study the effect law of manufacturing taper error on the properties of gas foil conical…
Abstract
Purpose
This paper aims to study the bearing performance with different cone angle errors, to study the effect law of manufacturing taper error on the properties of gas foil conical bearing (GFCB).
Design/methodology/approach
For the GFCB supported by separated bump foil strips, a nonlinear structure stiffness model considering Coulomb friction and arch characteristics was proposed. The finite element method and finite difference method were used to solve the Reynolds equation and the film thickness equation by coupling, and the properties of the GFCB were obtained. The effect of foil and bearing structure parameters on the static and dynamic performance under different taper error cases was analyzed. Moreover, a test on the air compressor supported by GFCBs was conducted to verify the practicability.
Findings
The taper error has a largely adverse effect on the load capacity of GFCB. When the taper error is −0.03°, the radial load capacity Fr and axial load capacity Fz decrease by 37.5 and 58.3%, respectively. The taper error decreases the direct stiffness and cross-coupled damping of GFCB, which will weaken the bearing stability. Moreover, the performance of GFCB is closely related to the foil and bearing parameters.
Originality/value
The taper error adversely affects the static and dynamic characteristics of GFCB, which should be concerned by bearing designers, researchers and academicians.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0089/
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Hongyang Hu, Ming Feng and Tianming Ren
This paper aims to improve the load capacity of gas foil thrust bearing (GFTB) and to introduce and study a novel bearing with stacked bump foils.
Abstract
Purpose
This paper aims to improve the load capacity of gas foil thrust bearing (GFTB) and to introduce and study a novel bearing with stacked bump foils.
Design/methodology/approach
For the proposed novel GFTB supported by stacked foils, some bump-type gaskets with several partial arches are inserted below the regular bump foil, and the height of each arch can be made differently. These features make the bump foil thickness and height gradually increase, which can bring enhanced support stiffness and convergent film at the trailing edge. Based on a new nonlinear bump stiffness model considering bump rounding and friction force, the finite element and finite difference method were used to solve the coupling Reynolds equation, energy equation and foil deformation equation. Finally, the structural stiffness and static characteristics of the novel GFTB were gained and compared with the traditional bearing.
Findings
The novel GFTB has an additional convergence effect in the parallel section, which improves the static performance of bearing. The bearing capacity, friction moment, power loss and temperature rise of the novel GFTB are all higher than those of the traditional bearing, and the static characteristics are related to the parameters of stacked bump foils.
Originality/value
The stacked bump foils bring a fundamental enhancement on the load capacity of GFTB. The results are expected to be helpful to bearing designers, researchers and academicians concerned.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0449/
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Vasilii Erokhin and Tianming Gao
Sustainable development is inseparable from rational and responsible use of resources and promotion of green entrepreneurship. The contemporary green development agenda…
Abstract
Sustainable development is inseparable from rational and responsible use of resources and promotion of green entrepreneurship. The contemporary green development agenda encompasses climate, economic, technical, social, cultural, and political dimensions. International efforts to greening the global development are conducted by the major economies, including China as the world’s largest consumer of energy and the biggest emitter of greenhouse gases. China is aware of its environmental problems, as well as of its part of the overall responsibility for the accomplishment of the sustainable development goals. By means of the decarbonization efforts, the latter are integrated both into the national development agenda (the concept of ecological civilization) and China’s international initiatives (the greening narrative within the Belt and Road Initiative). Over the past decade, China has made a breakthrough on the way to promoting green entrepreneurship and greening of its development (better quality of air and water, renewable energy, electric vehicles, and organic farming). On the other hand, emissions remain high, agricultural land loses productivity, and freshwater resources degrade due to climate change. In conventional industries (oil, coal mining, and electric and thermal energy), decarbonization faces an array of impediments. In this chapter, the authors summarize fundamental provisions of China’s approach to building an ecological civilization and measures to reduce emissions and achieve the carbon neutrality status within the nearest decades. The analysis of obstacles to the decarbonization of the economy and possible prospects for the development of green entrepreneurship summarizes China’s practices for possible use in other countries.
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Jiale Yang, Xianfeng Chen, Chuyuan Huang and Tianming Ma
With the acceleration of global energy structure transformation, hydrogen has been widely used for its non-pollution and high efficiency, and hydrogen detection is used to…
Abstract
Purpose
With the acceleration of global energy structure transformation, hydrogen has been widely used for its non-pollution and high efficiency, and hydrogen detection is used to guarantee the hydrogen safety. The purpose of this paper is to study the research foundation, trend and hotspots of hydrogen detection field.
Design/methodology/approach
A total of 4,076 literature records from 2000 to 2021 were retrieved from the core collection of the Web of Science database selected as data sources. The literature information mining was realized by using CiteSpace software. Bibliometrics was used to analyze information, such as keywords, authors, journals, institutions, countries and cited references, and to track research hotspots.
Findings
Since the 21st century, the number of publications in the hydrogen detection field has been in a stable stepped uptrend. In terms of research foundation, the hotspots such as core-shell structures, nano-hybrid materials and optical fiber hydrogen sensors have been studied extensively. In combination with the discipline structure and research frontier, the selectivity, sensitivity, response speed and other performance parameters of hydrogen sensors need further improvement. The establishment of an interdisciplinary knowledge system centered on materials science and electronic science will become a long-term trend in the research of hydrogen detection.
Originality/value
This study presents an overview of research status, hotspots and laws in hydrogen detection field, through the quantitative analysis of much literature in the field and the use of data mining, so as to provide credible references for the research of hydrogen detection technology.