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  • SAGE Publications  (4)
  • Luo, Xingqi  (4)
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  • SAGE Publications  (4)
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  • 1
    Online Resource
    Online Resource
    Numerical investigation on vibration and pressure fluctuation characteristics in a centrifugal pump under low flow rate
    SAGE Publications ; 2021
    In:  Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science Vol. 235, No. 19 ( 2021-10), p. 3888-3899
    Details
    In: Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, SAGE Publications, Vol. 235, No. 19 ( 2021-10), p. 3888-3899
    Abstract: Vibration characteristic is an important factor in evaluating operation stability of centrifugal pump. The vibration of main shaft was measured using a laser vibrometer, internal flow field was simulated via the shear stress transport turbulence model, and distribution law of vibration and pressure fluctuation in the impeller were analysed to explore the induction factor of vibration and the inherent relationship with pressure fluctuation in a semi-open centrifugal pump under low flow rate condition. Results of the numerical simulation are consistent with the experimental data. In addition to rotation frequency caused by impeller rotation, vibration frequency also includes characteristic frequency with high amplitude induced by unstable flow. The complex vortex in the impeller is composed of tip leakage vortex (TLV), reverse flow vortex, passage vortex and tip separation vortex. The primary tip leakage vortex (PTLV) formed by the streamline spills from 0 to 0.2λ where λ is the dimensionless distance from leading edge to trailing edge collides with tip leakage flow, the leading edge overflow and reverse flow vortex at the frequency of 1.6 f n ( f n is the rotating frequency) and 2.2 f n appear, respectively. The tip separation vortex formed in the tip clearance induced a frequency of 1.2 f n . The frequency of unstable flow phenomenon was consistent with the vibration frequency of main shaft, which induced the vibration of centrifugal pump.
    Type of Medium: Online Resource
    ISSN: 0954-4062 , 2041-2983
    URL: Article
    DOI: 10.1177/0954406220969724
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
    detail.hit.zdb_id: 2024890-8
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Numerical analysis of the transient leakage flow in axial clearance of a scroll refrigeration compressor
    SAGE Publications ; 2022
    In:  Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering Vol. 236, No. 1 ( 2022-02), p. 47-61
    Details
    In: Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, SAGE Publications, Vol. 236, No. 1 ( 2022-02), p. 47-61
    Abstract: The transient flow model of a scroll refrigeration compressor which included axial clearance was established in the paper using PUMPLINX based on the computational fluid dynamics and the dynamic grid methodology. According to the actual size in the physical compressor, the flank and the axial clearances were set equal to 0.030 mm and 0.015 mm, respectively. As the fluid domain of the axial clearance was too small to generate enough layers of grids in PUMPLINX, it was first magnified 100 times to generate grids of high quality, and then the fluid domain and grids were recompressed to the original size. The simulation results were verified experimentally. The influence of the radial leakage on the downstream flow field was investigated. Moreover, the characteristics of radial and tangential leakage flows were analyzed. It was concluded that the predictions of the compressor performance, except the discharge temperature, are improved after the axial clearance was included in the model. The radial leakage is dominant while a portion of involute leakage flow exists near the flank clearance. The influence of radial leakage on the downstream temperature is lower than that of the tangential leakage in flank clearance. The tangential leakage flow is turbulent basically while the radial leakage flow is laminar. The tangential leakage is severer at the beginning of the discharge process, and the radial leakage is more remarkable at the end of the compression process. When the pressure ratio across the leakage path is higher than the critical pressure ratio, the tangential leakage flow becomes supersonic for the converging–diverging clearance structure, while the radial leakage flow remains subsonic due to the larger flow losses. The results obtained through this research could be applied to modify the current leakage models and optimize the clearances of scroll compressors.
    Type of Medium: Online Resource
    ISSN: 0954-4089 , 2041-3009
    URL: Article
    DOI: 10.1177/0954408919870910
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
    detail.hit.zdb_id: 2024897-0
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  • 3
    Online Resource
    Online Resource
    Experimental study on forced convective heat transfer of supercritical carbon dioxide in a horizontal circular tube under high heat flux and low mass flux conditions
    SAGE Publications ; 2019
    In:  Advances in Mechanical Engineering Vol. 11, No. 3 ( 2019-03), p. 168781401983080-
    Details
    In: Advances in Mechanical Engineering, SAGE Publications, Vol. 11, No. 3 ( 2019-03), p. 168781401983080-
    Abstract: This study focuses on the convective heat transfer characteristics of supercritical carbon dioxide flowing in a horizontal circular tube under high heat flux and low mass flux conditions. The influences of thermophysical property, buoyancy effect, and thermal acceleration on the heat transfer characteristics are discussed. The parameters are as follows: system pressure is 7.6–8.4 MPa, mass flux is 400–500 kg/m 2  s, heat flux is 30–200 kW/m 2 , fluid temperature is 20°C −62°C, and Reynolds number is 1.23 × 10 4 to 4.3 × 10 4 . The wall temperature and heat transfer coefficient of supercritical carbon dioxide are obtained. The results show that, under the condition of high heat flux and low mass flux, heat transfer deterioration would happen, in which thermophysical property and buoyancy effect are the main factors. When the pressure is 7.6 MPa, the buoyancy factor is greater than 10 −3 in the whole heat transfer area, and the buoyancy effect cannot be ignored, while the thermal acceleration factor is 9.5 × 10 −8 to 4 × 10 −6 and the effect of thermal acceleration can be negligible. The experimental data are compared with the predictions using seven empirical correlations, in which the Liao–Zhao correlation shows the best performance.
    Type of Medium: Online Resource
    ISSN: 1687-8140 , 1687-8140
    URL: Article
    DOI: 10.1177/1687814019830804
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
    detail.hit.zdb_id: 2501620-9
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  • 4
    Online Resource
    Online Resource
    Characteristic analysis of the efficiency hill chart of Francis turbine for different water heads
    SAGE Publications ; 2017
    In:  Advances in Mechanical Engineering Vol. 9, No. 2 ( 2017-02), p. 168781401769007-
    Details
    In: Advances in Mechanical Engineering, SAGE Publications, Vol. 9, No. 2 ( 2017-02), p. 168781401769007-
    Abstract: According to several model test results of Francis turbines, complete model efficiency hill charts were constructed. The formation and inevitability of diversified hydraulic phenomena on model efficiency hill chart for typical head range were analyzed and the difference is compared, as well as characteristics and commonness toward the curves are discussed and summarized. Furthermore, hydraulic performance and geometric features are presented by particularly analyzing the efficiency hill charts. The inherent characteristics of Francis turbine is expressed by all kinds of curves on the model efficiency hill charts, and these curves can be adjusted and moved in a small range but cannot be removed out. Due to wide range of unit speed in terms of medium-low-head hydraulic turbines, incipient cavitation curve on suction side can be observed and it is positioned close to the operation zone; however, it fails to be visualized for the high-head turbine. The blade channel vortex curves are in the vicinity of optimum region for low-head hydraulic turbines, while high-head shows reverse trend. The interaction between zero incidence angle and zero circulation curve has a significant influence on isoefficiency circles. All comparisons and analyses could provide hydraulic design basis and retrofit references.
    Type of Medium: Online Resource
    ISSN: 1687-8140 , 1687-8140
    URL: Article
    DOI: 10.1177/1687814017690071
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
    detail.hit.zdb_id: 2501620-9
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