Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump units....Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump units.The mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation model.UDF(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh technology.The results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually decreases.And the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely manner.The maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance amplitude.The mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial values.Compared with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and leakage.During actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.展开更多
Direct contract between the sealed liquid and the magnetic fluid in a dynamic system under magnetic field may lead to an unstable interface, consequently, break down the seal. Aiming at this problem, a new magnetic fl...Direct contract between the sealed liquid and the magnetic fluid in a dynamic system under magnetic field may lead to an unstable interface, consequently, break down the seal. Aiming at this problem, a new magnetic fluid seal (MFS) was developed. In this new MFS, a soft iron bushing with high permeability was introduced on the shaft and nonferrous shields were installed beside the bushing and the pole pieces. The parameters of the bushing and the shields were optimized in a seal simulation facility The results show that the bushing with a thickness of 7 mm and shields with a width of 8 mm are best for sealing a shaft 20 mm in diameter. The MFS designed based on the optimum parameters shows good performance and long life span for sealing lubricating oil.展开更多
基金the support of the National Natural Science Foundation of China(52372368)。
文摘Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump units.The mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation model.UDF(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh technology.The results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually decreases.And the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely manner.The maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance amplitude.The mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial values.Compared with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and leakage.During actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.
基金Project 2002AA302608 supported by Hi-Tech R & D Program of China (863 Program) and scientific research foundation of China University of Mining& Technology
文摘Direct contract between the sealed liquid and the magnetic fluid in a dynamic system under magnetic field may lead to an unstable interface, consequently, break down the seal. Aiming at this problem, a new magnetic fluid seal (MFS) was developed. In this new MFS, a soft iron bushing with high permeability was introduced on the shaft and nonferrous shields were installed beside the bushing and the pole pieces. The parameters of the bushing and the shields were optimized in a seal simulation facility The results show that the bushing with a thickness of 7 mm and shields with a width of 8 mm are best for sealing a shaft 20 mm in diameter. The MFS designed based on the optimum parameters shows good performance and long life span for sealing lubricating oil.
