The elimination of rotor vibration is usually achieved by applying additional damping to the system.Squeeze film dampers are widely used in various aerospace and turbine equipments.The research is carried out on flow ...The elimination of rotor vibration is usually achieved by applying additional damping to the system.Squeeze film dampers are widely used in various aerospace and turbine equipments.The research is carried out on flow characteristics in the integral squeeze film dampers(ISFDs).The dynamic response to the operation condition is investigated through the computational fluid dynamics(CFD) model of ISFD.Due to the large pressure loss at the oil inlet,the oil film force only changes slightly with the increase of oil supply pressure,and the damping increases slightly.The vibration amplitude only affects the film force,but has no effect on the damping.The oil film force and damping show an upward tendency with the decrease of thickness of the end seal clearance.展开更多
This paper aims at investigating the effectiveness of squeeze oil film in suppressing the longitudinal vibration of propulsion shaft systems through a novel integral axial squeeze film damper(IASFD).After designing th...This paper aims at investigating the effectiveness of squeeze oil film in suppressing the longitudinal vibration of propulsion shaft systems through a novel integral axial squeeze film damper(IASFD).After designing the IASFD,a propulsion shafting test rig for the longitudinal vibration control is built.Longitudinal vibration control experiments of the propulsion shafting are carried out under different magnitude and frequency of the excitation force.The results show that both IASFD elastic support and IASFD elastic damping support have excellent vibration attenuation characteristics,and can effectively suppress the longitudinal vibration of the shaft system in a wide frequency range.However,IASFD elastic damping support has a more significant vibration reduction effect than the other supports,and increasing the damping of the system has obvious effect on reducing the shafting vibration.For an excitation force of 45 N,the maximum reduction of the vibration amplitude is 89.16%.Also,the vibration generated by the resonance phenomenon is also significantly reduced.展开更多
空气取水能够有效解决野外作业期间的供水问题.本文建立由常微分方程组构成的分布参数除湿转轮模型,搭建柴油机余热回收空气取水模型,研究柴油机工况变化过程中取水系统的动态工作状况.结果表明:在柴油机目标转速提高时,转轮取水量和吸...空气取水能够有效解决野外作业期间的供水问题.本文建立由常微分方程组构成的分布参数除湿转轮模型,搭建柴油机余热回收空气取水模型,研究柴油机工况变化过程中取水系统的动态工作状况.结果表明:在柴油机目标转速提高时,转轮取水量和吸附剂吸附率较再生空气和吸附剂温度稳定所需时间更长,需转轮循环工作6~7个周期后重新稳定;取水量受再生空气温度影响较大;在转轮环境空气流量较大时,系统变工况下运行稳定性更好.为保证系统高取水速率与稳定性,环境空气流量应维持在800~1000 m 3/h.本文模型可用于进一步研究转轮空气取水系统的控制与运行优化.展开更多
When the actual installation center distance between a pair of spur gears is greater than the theoretical center distance,backlash increases,leading to increased vibration and noise.The structural parameters of an int...When the actual installation center distance between a pair of spur gears is greater than the theoretical center distance,backlash increases,leading to increased vibration and noise.The structural parameters of an integral squeeze film damper(ISFD)were designed with the stiffness of rigid support as reference to investigate the effect of an ISFD on the dynamic characteristics of a spur gear transmission system with center-distance installation error.A spur gear test bench with center distance-error was built to investigate the vibration and noise reduction characteristics of ISFD.The experimental results indicate that,compared with a rigid support,the ISFD can reduce vibration by approximately 40%and noise by approximately 5 d B.ISFD can effectively absorb the impact energy caused by an increase of in backlash,which is conducive to the stable operation of the spur gear transmission system.展开更多
Conventional squeeze film dampers have numerous challenges including lock up,bistable response and incoordinate precession.In order to resolve these nonlinear problems,a novel G-type integral squeeze film damper(GISFD...Conventional squeeze film dampers have numerous challenges including lock up,bistable response and incoordinate precession.In order to resolve these nonlinear problems,a novel G-type integral squeeze film damper(GISFD)is proposed in this research.The experimental test rig is provided to investigate the rotor system with an unbalanced single disk.Numerical simulation results show that the structural design of GISFD is reasonable,which can ensure its safe and stable operation.The influence of different support stiffnesses on the first-order speed of the rotor system is analyzed.Experimental results show that GISFD can effectively suppress the unbalanced response vibration of the rotor.In a certain range,it is found that the suppression effect of GISFD increases with the increase in the kinematic viscosity of the damping fluid.When the silicone oil with kinematic viscosity coefficients v=30.0 cm^(2)/s is employed,the vibration reduction of GISFD is approximately 71.51%.Furthermore,the experimental results show that with the increase of the unbalance,there is a linear relationship between the unbalance and the corresponding amplitude of the unbalanced response.It is concluded that GISFD has excellent linear damping characteristics and reduces the sensitivity of the rotor system to the unbalanced mass.展开更多
基金Supported by the National Science and Technology Major Project (No.2017-ⅠV-0010-0047)China Postdoctoral Science Foundation Funded Project (No.2020M6701 13)Fundamental Research Funds for the Central Universities (No.JD2003)。
文摘The elimination of rotor vibration is usually achieved by applying additional damping to the system.Squeeze film dampers are widely used in various aerospace and turbine equipments.The research is carried out on flow characteristics in the integral squeeze film dampers(ISFDs).The dynamic response to the operation condition is investigated through the computational fluid dynamics(CFD) model of ISFD.Due to the large pressure loss at the oil inlet,the oil film force only changes slightly with the increase of oil supply pressure,and the damping increases slightly.The vibration amplitude only affects the film force,but has no effect on the damping.The oil film force and damping show an upward tendency with the decrease of thickness of the end seal clearance.
基金Supported by the National Science and Technology Major Project(No.2017-Ⅳ-0010-0047)Key Laboratory Fund for Ship Vibration and Noise(No.614220406020717)+1 种基金China Postdoctoral Science Foundation Funded Project(No.2020M670113)the Fundamental Research Funds for the Central Universities(No.JD2003)。
文摘This paper aims at investigating the effectiveness of squeeze oil film in suppressing the longitudinal vibration of propulsion shaft systems through a novel integral axial squeeze film damper(IASFD).After designing the IASFD,a propulsion shafting test rig for the longitudinal vibration control is built.Longitudinal vibration control experiments of the propulsion shafting are carried out under different magnitude and frequency of the excitation force.The results show that both IASFD elastic support and IASFD elastic damping support have excellent vibration attenuation characteristics,and can effectively suppress the longitudinal vibration of the shaft system in a wide frequency range.However,IASFD elastic damping support has a more significant vibration reduction effect than the other supports,and increasing the damping of the system has obvious effect on reducing the shafting vibration.For an excitation force of 45 N,the maximum reduction of the vibration amplitude is 89.16%.Also,the vibration generated by the resonance phenomenon is also significantly reduced.
文摘空气取水能够有效解决野外作业期间的供水问题.本文建立由常微分方程组构成的分布参数除湿转轮模型,搭建柴油机余热回收空气取水模型,研究柴油机工况变化过程中取水系统的动态工作状况.结果表明:在柴油机目标转速提高时,转轮取水量和吸附剂吸附率较再生空气和吸附剂温度稳定所需时间更长,需转轮循环工作6~7个周期后重新稳定;取水量受再生空气温度影响较大;在转轮环境空气流量较大时,系统变工况下运行稳定性更好.为保证系统高取水速率与稳定性,环境空气流量应维持在800~1000 m 3/h.本文模型可用于进一步研究转轮空气取水系统的控制与运行优化.
基金Supported by the National Science and Technology Major Project(No.2017-IV-0010-0047)China Postdoctoral Science Foundation FundedProject(No.2020M670113)Fundamental Research Funds for the Central Universities(No.JY2105)。
文摘When the actual installation center distance between a pair of spur gears is greater than the theoretical center distance,backlash increases,leading to increased vibration and noise.The structural parameters of an integral squeeze film damper(ISFD)were designed with the stiffness of rigid support as reference to investigate the effect of an ISFD on the dynamic characteristics of a spur gear transmission system with center-distance installation error.A spur gear test bench with center distance-error was built to investigate the vibration and noise reduction characteristics of ISFD.The experimental results indicate that,compared with a rigid support,the ISFD can reduce vibration by approximately 40%and noise by approximately 5 d B.ISFD can effectively absorb the impact energy caused by an increase of in backlash,which is conducive to the stable operation of the spur gear transmission system.
基金Supported by the National Science and Technology Major Project(No.2017-Ⅳ-0010-0047)the Fundamental Research Funds for the Central Universities(No.JD2003)。
文摘Conventional squeeze film dampers have numerous challenges including lock up,bistable response and incoordinate precession.In order to resolve these nonlinear problems,a novel G-type integral squeeze film damper(GISFD)is proposed in this research.The experimental test rig is provided to investigate the rotor system with an unbalanced single disk.Numerical simulation results show that the structural design of GISFD is reasonable,which can ensure its safe and stable operation.The influence of different support stiffnesses on the first-order speed of the rotor system is analyzed.Experimental results show that GISFD can effectively suppress the unbalanced response vibration of the rotor.In a certain range,it is found that the suppression effect of GISFD increases with the increase in the kinematic viscosity of the damping fluid.When the silicone oil with kinematic viscosity coefficients v=30.0 cm^(2)/s is employed,the vibration reduction of GISFD is approximately 71.51%.Furthermore,the experimental results show that with the increase of the unbalance,there is a linear relationship between the unbalance and the corresponding amplitude of the unbalanced response.It is concluded that GISFD has excellent linear damping characteristics and reduces the sensitivity of the rotor system to the unbalanced mass.
