Cavitation is a destructive phenomenon in control valves.In order to delay cavitation,a multi-series of perforated cylindrical plates,called trims,are used.Previously,the effects of orifice diameter and different type...Cavitation is a destructive phenomenon in control valves.In order to delay cavitation,a multi-series of perforated cylindrical plates,called trims,are used.Previously,the effects of orifice diameter and different types of trims have been investigated.In this study,by numerical analysis,a globe control valve was investigated by employing four different cases(without trim,with one trim,with two and three trims)and the impact of the number of these trims on the intensity,formation region and the initiation point of cavitation was analyzed.It was found that the addition of one stage or two stages of trims reduces the intensity and delays the onset of cavitation,relative to the valve without trim.However,no significant differences in terms of intensity and initiation point of cavitation were observed in the cases where two or three trims were used.Therefore,due to the high cost of producing the trims,and the severe drop in flow coefficient,it is not economically and technically justified to increase the number of trims to more than three.展开更多
Globe control valve is widely used in chemical, petroleum and hydraulic industries, and its throttling feature is achieved by the adopting of valve plug. However, very limited information is available in literature re...Globe control valve is widely used in chemical, petroleum and hydraulic industries, and its throttling feature is achieved by the adopting of valve plug. However, very limited information is available in literature regarding the influence of valve plug on the internal and external features in globe control valves. Thus the effect of valve plug is studied by CFD and experiment in this paper. It is obtained from external features that the pressure drop between upstream and downstream pressure-sampling position increases exponentially with flow rate. And for small valve opening, the increment of pressure drop decreases with the increase of cone angle（β）. However, with the increase of valve opening, the effect of cone angle diminishes significantly. It is also found that the cone angle has little effect on flow coefficient（Cv） when the valve opening is larger than 70%. But for the cases less than 70%, Cv curve varies from an arc to a straight line. The variation of valve performance is caused by the change of internal flow. The results of internal flow show that cone angle has negligible effect on flow properties for the cases of valve opening larger than 70%. However, when valve opening is smaller than 70%, the pressure drop of orifice decreases with the increase of β, making the reduction in value and scope of the high speed zone around the conical surface of valve plug, and then results in a decreasing intensity of adjacent downstream vortex. Meanwhile, it is concluded from the results that the increase of cone angle will be beneficial for the anti-cavitation and anti-erosion of globe control valve. This paper focuses on the internal and external features of globe control valve that caused by the variation of cone angle, arriving at some results beneficial for the design and usage of globe control valve.展开更多
Valves are key components of the safety of fluid transportation systems because of induced disturbance and cavitation damage in them.In this study,a 2D model of a cryogenic globe valve with liquid nitrogen(LN_(2))as w...Valves are key components of the safety of fluid transportation systems because of induced disturbance and cavitation damage in them.In this study,a 2D model of a cryogenic globe valve with liquid nitrogen(LN_(2))as working fluid was established by Fluent,and thermal effects were specially considered in the simulation.The validity of the LN_(2) cavitation model was verified by the experimental data of hydrofoil LN_(2) cavitation from earlier studies by NASA.Cavitation characteristics of LN2 in the cryogenic globe valve under three typical working conditions were investigated.The average pressure and pressure pulse at different positions of the wall were further studied to reveal cavitation risks from fatigue and vibration.Results show that with similar valve structure and openings,the pressure pulsation frequencies of LN_(2) are lower than those of water,and the shape and location of the cavitation clouds also show significant differences.For LN_(2) cavitation,an extended period of valve opening at 66% should be avoided since its pressure pulse peak is the largest compared to openings of 33% and 100%,and reaches 5×10^(7) Pa.The opening of 33% should also be monitored because of the large torque caused by the pressure difference between the two sides of the valve baffles.To prevent resonance,a critical state for the valve opening and the connecting pipe length is proposed.These predictions of cryogenic cavitation in the globe valve are helpful for the safe and reliable operation of cryogenic fluid transport systems.展开更多
文摘Cavitation is a destructive phenomenon in control valves.In order to delay cavitation,a multi-series of perforated cylindrical plates,called trims,are used.Previously,the effects of orifice diameter and different types of trims have been investigated.In this study,by numerical analysis,a globe control valve was investigated by employing four different cases(without trim,with one trim,with two and three trims)and the impact of the number of these trims on the intensity,formation region and the initiation point of cavitation was analyzed.It was found that the addition of one stage or two stages of trims reduces the intensity and delays the onset of cavitation,relative to the valve without trim.However,no significant differences in terms of intensity and initiation point of cavitation were observed in the cases where two or three trims were used.Therefore,due to the high cost of producing the trims,and the severe drop in flow coefficient,it is not economically and technically justified to increase the number of trims to more than three.
基金Supported by National Natural Science Foundation of China(Grant Nos.51406184,21276241)Science Foundation of Zhejiang Sci-Tech University of China(Grant No.14022005-Y)
文摘Globe control valve is widely used in chemical, petroleum and hydraulic industries, and its throttling feature is achieved by the adopting of valve plug. However, very limited information is available in literature regarding the influence of valve plug on the internal and external features in globe control valves. Thus the effect of valve plug is studied by CFD and experiment in this paper. It is obtained from external features that the pressure drop between upstream and downstream pressure-sampling position increases exponentially with flow rate. And for small valve opening, the increment of pressure drop decreases with the increase of cone angle（β）. However, with the increase of valve opening, the effect of cone angle diminishes significantly. It is also found that the cone angle has little effect on flow coefficient（Cv） when the valve opening is larger than 70%. But for the cases less than 70%, Cv curve varies from an arc to a straight line. The variation of valve performance is caused by the change of internal flow. The results of internal flow show that cone angle has negligible effect on flow properties for the cases of valve opening larger than 70%. However, when valve opening is smaller than 70%, the pressure drop of orifice decreases with the increase of β, making the reduction in value and scope of the high speed zone around the conical surface of valve plug, and then results in a decreasing intensity of adjacent downstream vortex. Meanwhile, it is concluded from the results that the increase of cone angle will be beneficial for the anti-cavitation and anti-erosion of globe control valve. This paper focuses on the internal and external features of globe control valve that caused by the variation of cone angle, arriving at some results beneficial for the design and usage of globe control valve.
基金This work is supported by the Research Fund of State Key Laboratory of Technologies in Space Cryogenic Propellants(No.SKLTSCP1601)the Key Research and Development Program of Zhejiang Province(No.2020C01029)+1 种基金the Key Program of National Natural Science Foundation of China(No.51636007)the Natural Science Foundation of Zhejiang Province(No.LQ21E060011),China.
文摘Valves are key components of the safety of fluid transportation systems because of induced disturbance and cavitation damage in them.In this study,a 2D model of a cryogenic globe valve with liquid nitrogen(LN_(2))as working fluid was established by Fluent,and thermal effects were specially considered in the simulation.The validity of the LN_(2) cavitation model was verified by the experimental data of hydrofoil LN_(2) cavitation from earlier studies by NASA.Cavitation characteristics of LN2 in the cryogenic globe valve under three typical working conditions were investigated.The average pressure and pressure pulse at different positions of the wall were further studied to reveal cavitation risks from fatigue and vibration.Results show that with similar valve structure and openings,the pressure pulsation frequencies of LN_(2) are lower than those of water,and the shape and location of the cavitation clouds also show significant differences.For LN_(2) cavitation,an extended period of valve opening at 66% should be avoided since its pressure pulse peak is the largest compared to openings of 33% and 100%,and reaches 5×10^(7) Pa.The opening of 33% should also be monitored because of the large torque caused by the pressure difference between the two sides of the valve baffles.To prevent resonance,a critical state for the valve opening and the connecting pipe length is proposed.These predictions of cryogenic cavitation in the globe valve are helpful for the safe and reliable operation of cryogenic fluid transport systems.
