Chunlei Shao, Ning Bao, Sheng Wang and Jianfeng Zhou
The purpose of this paper is to propose a prediction method of gas-liquid two-phase flow patterns and reveal the flow characteristics in the suction chamber of a centrifugal pump.
Abstract
Purpose
The purpose of this paper is to propose a prediction method of gas-liquid two-phase flow patterns and reveal the flow characteristics in the suction chamber of a centrifugal pump.
Design/methodology/approach
A transparent model pump was experimentally studied, and the gas-liquid two-phase flow in the pump was numerically simulated based on the Eulerian–Eulerian heterogeneous flow model. The numerical simulation method was verified from three aspects: the flow pattern in the suction chamber, the gas spiral length and the external characteristics of the pump. The two-phase flow in the suction chamber was studied in detail by using the numerical simulation method.
Findings
There are up to eight flow patterns in the suction chamber. However, at a certain rotational speed, only six flow patterns are observed at the most. At some rotational speeds, only four flow patterns appear. The gas spiral length has little relationship with the gas flow rate. It decreases with the increase of the liquid flow rate and increases with the increase of the rotational speed. The spiral flow greatly increases the turbulence intensity in the suction chamber.
Originality/value
A method for predicting the flow pattern was proposed. Eight flow patterns in the suction chamber were identified. The mechanism of gas-liquid two-phase flow in the suction chamber was revealed. The research results have reference values for the stable operation of two-phase flow pumps and the optimization of suction chambers.
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The purpose of this paper is to study the dimensionless characteristics of a molten salt pump and propose an approach to carry out the modeling experiment by using water instead…
Abstract
Purpose
The purpose of this paper is to study the dimensionless characteristics of a molten salt pump and propose an approach to carry out the modeling experiment by using water instead of molten salts.
Design/methodology/approach
External characteristics of the pump were estimated by using the steady flow model and compared with the experimental results. By taking water as the working fluid, the pathlines in the volute of the model pump were validated by the results obtained of high-speed photography. According to the derived dimensionless characteristics of the molten salt pump, the modeling experimental schemes were proposed. Adopting the validated numerical simulation model, the performance of the molten salt pump was studied in detail.
Findings
The modeling experimental schemes designed according to the dimensionless characteristics are theoretically feasible. However, to carry out the experiment successfully, factors such as rotational speed, geometric size, flow rate and head should be taken into account. The flow in the pumps is similar under the similar operating condition and the external characteristics of the similar pump can be converted to each other. Compared with transporting water, the decline of the head and efficiency is within 5 per cent when the viscosity is lower than 0.01453 Pa · s. The pump is not suitable for running under the critical Reynolds number of 1.0 × 107.
Originality/value
The current work revealed the relationships among the dimensionless performances of a molten salt pump and proposed a critical Reynolds number ReQcr for the pump running.
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Chunlei Shao, Aixia He, Zhongyuan Zhang and Jianfeng Zhou
The purpose of this paper is to study the transition process from the crystalline particles appearing before the pump inlet to the stable operation of the pump.
Abstract
Purpose
The purpose of this paper is to study the transition process from the crystalline particles appearing before the pump inlet to the stable operation of the pump.
Design/methodology/approach
Firstly, a modeling test method was put forward for the high-temperature molten salt pump. Then, according to a modeling test scheme, the experiment of the solid–liquid two-phase flow was carried out by using a model pump similar to the prototype pump. Meanwhile, the numerical method to simulate the transition process of a molten salt pump was studied, and the correctness of the numerical model was verified by the experimental results. Finally, the transition process of the molten salt pump was studied by the verified numerical model in detail.
Findings
In the simulation of the transition process, it is more accurate to judge the end of the transition process based on the unchanged particle volume fraction (PVF) at the pump outlet than on the periodic fluctuation of the outlet pressure. The outlet pressure is closely related to the PVF in the pump. The variation of the outlet pressure is slightly prior to that of the PVF at the pump outlet and mainly affected by the PVF in the impeller and volute. After 0.63 s, the PVF at each monitoring point changes periodically, and the time-averaged value does not change with time.
Practical implications
This study is of great significance to further improve the design method of molten salt pump and predict the abrasion characteristic of the pump due to interactions with solid particles.
Originality/value
A numerical method is established to simulate the transition process of a molten salt pump, and a method is proposed to verify the numerical model of two-phase flow by modeling test.
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Wenjie Cheng, Boqin Gu and Chunlei Shao
This paper aims to figure out the steady flow status in the molten salt pump under various temperatures and blade number conditions, and give good insight on the structure and…
Abstract
Purpose
This paper aims to figure out the steady flow status in the molten salt pump under various temperatures and blade number conditions, and give good insight on the structure and temperature-dependent efficiencies of all pump cases. Finally, the main objective of present work is to get best working condition and blade numbers for optimized hydraulic performance.
Design/methodology/approach
The steady flow in the molten salt pump was studied numerically based on the three-dimensional Reynolds-Averaged Navier–Stokes equations and the standard k-ε turbulence model. Under different temperature conditions, the internal flow fields in the pumps with different blade number were systematically simulated. Besides, a quantitative backflow analysis method was proposed for further investigation.
Findings
With the molten salt fluid temperature, sharply increasing from 160°C to 480°C, the static pressure decreases gently in all pump cases, and seven-blades pump has the least backflow under low flow rate condition. The efficiencies of all pump cases increase slowly at low temperature (about 160 to 320°C), but there is almost no variation at high temperature, and obviously seven-blades pump has the best efficiency and head in all pump cases over the wide range of temperatures. The seven-blades pump has the best performance in all selected pump cases.
Originality/value
The steady flow in molten salt pumps was systematically studied under various temperature and blade number conditions for the first time. A quantitative backflow analysis method was proposed first for further investigation on the local flow status in the molten salt pump. A definition about the low velocity region in molten salt pumps was built up to account for whether the studied pump gains most energy. This method can help us to know how to improve the efficiencies of molten salt pumps.
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Yunhao Zhang, Chunlei Shao, Jing Kong, Junwei Zhou and Jianfeng Zhou
This paper aims to prevent gasket sealing failure in engineering, accurately predict gasket life, extend system life and improve sealing reliability. The accelerated life test…
Abstract
Purpose
This paper aims to prevent gasket sealing failure in engineering, accurately predict gasket life, extend system life and improve sealing reliability. The accelerated life test method of flexible graphite composite–reinforced gaskets is established, the life distribution law of flexible graphite composite–reinforced gaskets is revealed, and the life prediction method of flexible graphite composite–reinforced gaskets with different allowable leakage rates is proposed, which can provide a reference for the life prediction of other types of gaskets.
Design/methodology/approach
In this study, flexible graphite composite–reinforced gaskets were tested for long-term high-temperature sealing performance on a multi-sample gasket accelerated life test rig. The data were also analyzed using the least squares method and the K-S hypothesis calibration method. A gasket time-dependent leakage model and an accelerated life model were also developed. Constant stress-accelerated life tests were conducted on flexible graphite composite–reinforced gaskets. On this basis, a gasket life prediction method at different allowable leakage rates was proposed.
Findings
The life distribution law of flexible graphite composite–reinforced gaskets is revealed. The results show that the life of the gasket obeys the Weibull distribution. The time-correlated leakage model and accelerated life model of the gasket were established. And the accelerated life test method of the flexible graphite composite–reinforced gasket was established. The life distribution parameters, accelerated life model parameters and life estimates of gaskets were obtained through tests. On this basis, a gasket life prediction method under different leakage rates was proposed, which can be used as a reference for other types of gaskets.
Practical implications
The research in this paper can better provide guidance for the use and replacement of gaskets in the project, which is also very meaningful for predicting the leakage condition of gaskets in the bolted flange connection system and taking corresponding control measures to reduce energy waste and pollution and ensure the safe operation of industrial equipment.
Originality/value
A multi-specimen gasket-accelerated life test device has been developed, and the design parameters of the device have reached the international advanced level. The life distribution law of the flexible graphite composite–reinforced gasket was revealed. The accelerated life test method for the flexible graphite composite–reinforced gasket was established. The life prediction method of the flexible graphite composite–reinforced gasket under different allowable leakage rates was proposed.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2023-0254/
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Chunlei Shao, Zhongyuan Zhang and Jianfeng Zhou
The purpose of this paper is to accurately predict the cavitation performance of a cryogenic pump and reveal the influence of the inlet pressure, the surface roughness and the…
Abstract
Purpose
The purpose of this paper is to accurately predict the cavitation performance of a cryogenic pump and reveal the influence of the inlet pressure, the surface roughness and the flow rate on the cavitation performance.
Design/methodology/approach
Firstly, the Zwart cavitation model was modified by considering the thermodynamic effect. Secondly, the feasibility of the modified model was validated by the cavitation test of a hydrofoil. Thirdly, the effects of the inlet pressure, the surface roughness and the flow rate on cavitation flow in the cryogenic pump were studied by using the modified cavitation model.
Findings
The modified cavitation model can predict the cavitation performance of the cryogenic pump more accurately than the Zwart cavitation model. The thermodynamic effect inhibits cavitation development to a certain extent. The higher the vapor volume fraction, the lower the pressure and the lower the temperature. At the initial stage of the cavitation, the head increases first and then decreases with the increase of the roughness. When the cavitation develops to a certain degree, the head decreases with the increase of the roughness. With the decrease of the flow rate, the hydraulic loss increases and the cavitation at the impeller intensifies.
Originality/value
A cavitation model considering the thermodynamic effect is proposed. The mechanism of the influence of the roughness on the performance of the cryogenic pump is revealed from two aspects. Taking the hydraulic loss as a bridge, the relationships among flow rates, vapor volume fractions, streamlines, temperatures and pressures are established.
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Jie Li, Jiyuan Wu, Chunlei Tu and Xingsong Wang
Automatic robots can improve the efficiency of liquefied petroleum gas (LPG) tank inspection and maintenance, but it is difficult to achieve high-precision spatial positioning and…
Abstract
Purpose
Automatic robots can improve the efficiency of liquefied petroleum gas (LPG) tank inspection and maintenance, but it is difficult to achieve high-precision spatial positioning and navigation on tank surfaces. The purpose of this paper is to develop a spatial positioning robotic system for tank inspection. The robot can accurately identify and track weld paths. The positioning system can complete robot’s spatial positioning on tank surfaces.
Design/methodology/approach
A tank inspection robot with curvature-adaptive transmission mechanisms is designed in this study. A weld path recognition method based on deep learning is proposed to accurately identify and extract weld paths. Integrated multiple sensors, the positioning system is developed to improve the robot’s spatial positioning accuracy. Experiments are conducted on a cylindrical tank to test weld seam tracking accuracy and spatial positioning performance of the robotic system. The practicality of the robotic system is then verified in field tests.
Findings
The robot can accurately identify and track weld seams with a maximum drift angle of 4° and a maximum offset distance of ±30 mm. The positioning system has excellent positioning accuracy and stability. The maximum angle and height errors are 3° and 0.08 m, respectively.
Originality/value
The positioning system can improve the autonomous performance of inspection robots and solve the problems of weld path recognition and spatial positioning. Application of the robotic system can promote the automatic inspection and maintenance of LPG tanks.
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The aim of this study was to investigate the impact of the transactive memory system (TMS) on green innovation and examine the mediation role of the social network at all…
Abstract
Purpose
The aim of this study was to investigate the impact of the transactive memory system (TMS) on green innovation and examine the mediation role of the social network at all hierarchical levels.
Design/methodology/approach
Three hypotheses were examined by performing regression analyses on survey data from manufacturing firms in China. Especially, the nested sets of data from 389 individual observations nested in 53 work teams, including individual level and collective level have been investigated.
Findings
The study results show that the TMS has a positive effect on green innovation. Furthermore, the results indicate that at the team level, structure holes' mediation in this relationship is stronger than degree centrality; at the individual level, weak ties mediation in the relationship of specialization and green innovation is stronger than strong ties, conversely, strong ties mediation in the relationship of credibility and green innovation is stronger than weak ties.
Originality/value
This study expands previous research by highlighting the significance of multilevel social network elements in the context of the TMS and sustainable development and enriches the present research on green innovation.