The dry gas seal（DGS） has been widely used in high parameters centrifugal compressor, but the intense vibrations of shafting, especially in high-speed condition, usually result in DGS＇s failure. So the DGS＇s abili...The dry gas seal（DGS） has been widely used in high parameters centrifugal compressor, but the intense vibrations of shafting, especially in high-speed condition, usually result in DGS＇s failure. So the DGS＇s ability of resisting outside interference has become a determining factor of the further development of centrifugal compressor. However, the systematic researches of which about gas film disturbance characteristics of high parameters DGS are very little. In order to study gas film disturbance characteristics of high-speed and high-pressure spiral groove dry gas seal（S-DGS） with a flexibly mounted stator, rotor axial runout and misalignment are taken into consideration, and the finite difference method and analytical method are used to analyze the influence of gas film thickness disturbance on sealing performance parameters, what＇s more, the effects of many key factors on gas film thickness disturbance are systematically investigated. The results show that, when sealed pressure is 10.1MPa and seal face average linear velocity is 107.3 m/s, gas film thickness disturbance has a significant effect on leakage rate, but has relatively litter effect on open force; Excessively large excitation amplitude or excessively high excitation frequency can lead to severe gas film thickness disturbance; And it is beneficial to assure a smaller gas film thickness disturbance when the stator material density is between 3.1 g/cm3 to 8.4 g/cm3; Ensuring sealing performance while minimizing support axial stiffness and support axial damping can help to improve dynamic tracking property of dry gas seal. The proposed research provides the instruction to optimize dynamic tracking property of the DGS.展开更多
A transient thickness distribution measured with a high temporal resolution is elemental for exploring the flow characteristics and mechanism of a liquid film formed by an impinging jet.Therefore,this paper develops a...A transient thickness distribution measured with a high temporal resolution is elemental for exploring the flow characteristics and mechanism of a liquid film formed by an impinging jet.Therefore,this paper develops a high-speed Light-Emitting Diode-Induced Fluorescence(LEDIF)system based on the brightness measured directly above the liquid film.An Ultraviolet(UV)LED lamp is used to provide sufficient and continuous excitation light.Then,a system performance analysis proves that the system can continuously measure the global film thickness at a high acquisition frequency of 5000 Hz when the dye concentration is 200 mg/L.The influence of the irregularity of the excitation intensity,including the spatial non-uniformity,temporal instability,and long-term instability,on the measurement uncertainty is analyzed in detail.The analysis indicates that the system has an acceptable uncertainty of 10%.Compared with theoretical results,experimental results verify that the LEDIF system can accurately measure the global thickness of a liquid film formed by a water jet obliquely impinging onto a plate.An experimental investigation of the radial section of the raised zone demonstrates that the radial section changes from a sewing needle to an oval when the azimuth angle increases from 10°to 90°.Meanwhile,the dynamic contact angle exponentially decreases from 41.4°to 30.1°.A dynamic analysis of surface waves shows that the measured wave velocity decreases from 12 m/s to 1 m/s and the dominant frequency decreases from 1000 Hz to 10 Hz along the flow direction.展开更多
Knowledge of droplet dynamics provides the basis of predicting pressure drops, holdups and corrosion inhibitor distribution in multiphase flow. Droplet size and its distribution also determine the separation efficienc...Knowledge of droplet dynamics provides the basis of predicting pressure drops, holdups and corrosion inhibitor distribution in multiphase flow. Droplet size and its distribution also determine the separation efficiency between different phases. Experimental observations were conducted for droplet impingements with different fluids, droplet sizes and velocities, and film thicknesses. The observed transition boundaries were compared with the models developed by different authors. For impingement on a deep pool surface, the Marengo and Tropea correlation for splashing does not agree with the experimental results in this study. The Bai and Gosman critical Weber number for bouncing agrees with the water results but not the oil results. Three new correlations for transition boundaries between bouncing, coalescence, jetting and splashing were proposed and compared with the experimental observations.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51575490)National Key Basic Research Program of China(973 Program,Grant No.2014CB046404)Natural Science Key Foundation of Zhejiang Province,China(Grant No.LZ15E050002)
文摘The dry gas seal（DGS） has been widely used in high parameters centrifugal compressor, but the intense vibrations of shafting, especially in high-speed condition, usually result in DGS＇s failure. So the DGS＇s ability of resisting outside interference has become a determining factor of the further development of centrifugal compressor. However, the systematic researches of which about gas film disturbance characteristics of high parameters DGS are very little. In order to study gas film disturbance characteristics of high-speed and high-pressure spiral groove dry gas seal（S-DGS） with a flexibly mounted stator, rotor axial runout and misalignment are taken into consideration, and the finite difference method and analytical method are used to analyze the influence of gas film thickness disturbance on sealing performance parameters, what＇s more, the effects of many key factors on gas film thickness disturbance are systematically investigated. The results show that, when sealed pressure is 10.1MPa and seal face average linear velocity is 107.3 m/s, gas film thickness disturbance has a significant effect on leakage rate, but has relatively litter effect on open force; Excessively large excitation amplitude or excessively high excitation frequency can lead to severe gas film thickness disturbance; And it is beneficial to assure a smaller gas film thickness disturbance when the stator material density is between 3.1 g/cm3 to 8.4 g/cm3; Ensuring sealing performance while minimizing support axial stiffness and support axial damping can help to improve dynamic tracking property of dry gas seal. The proposed research provides the instruction to optimize dynamic tracking property of the DGS.
基金supported by the Provincial or Ministerial Level Project,China。
文摘A transient thickness distribution measured with a high temporal resolution is elemental for exploring the flow characteristics and mechanism of a liquid film formed by an impinging jet.Therefore,this paper develops a high-speed Light-Emitting Diode-Induced Fluorescence(LEDIF)system based on the brightness measured directly above the liquid film.An Ultraviolet(UV)LED lamp is used to provide sufficient and continuous excitation light.Then,a system performance analysis proves that the system can continuously measure the global film thickness at a high acquisition frequency of 5000 Hz when the dye concentration is 200 mg/L.The influence of the irregularity of the excitation intensity,including the spatial non-uniformity,temporal instability,and long-term instability,on the measurement uncertainty is analyzed in detail.The analysis indicates that the system has an acceptable uncertainty of 10%.Compared with theoretical results,experimental results verify that the LEDIF system can accurately measure the global thickness of a liquid film formed by a water jet obliquely impinging onto a plate.An experimental investigation of the radial section of the raised zone demonstrates that the radial section changes from a sewing needle to an oval when the azimuth angle increases from 10°to 90°.Meanwhile,the dynamic contact angle exponentially decreases from 41.4°to 30.1°.A dynamic analysis of surface waves shows that the measured wave velocity decreases from 12 m/s to 1 m/s and the dominant frequency decreases from 1000 Hz to 10 Hz along the flow direction.
文摘Knowledge of droplet dynamics provides the basis of predicting pressure drops, holdups and corrosion inhibitor distribution in multiphase flow. Droplet size and its distribution also determine the separation efficiency between different phases. Experimental observations were conducted for droplet impingements with different fluids, droplet sizes and velocities, and film thicknesses. The observed transition boundaries were compared with the models developed by different authors. For impingement on a deep pool surface, the Marengo and Tropea correlation for splashing does not agree with the experimental results in this study. The Bai and Gosman critical Weber number for bouncing agrees with the water results but not the oil results. Three new correlations for transition boundaries between bouncing, coalescence, jetting and splashing were proposed and compared with the experimental observations.
