The feedback spring rod of the armature assembly is cancelled in the double redundance double nozzle flapper valve(DRDNFV),and the difficulty of valve core displacement control is increased.Therefore,this paper intend...The feedback spring rod of the armature assembly is cancelled in the double redundance double nozzle flapper valve(DRDNFV),and the difficulty of valve core displacement control is increased.Therefore,this paper intends to study the static characteristic of DRDNFV through the AMESet and AMESim simulation.It is explored under the circumstance of the fixed orifices being clogged and experimentally verified on the test bench.The results show that the pressure gain increases and the flow gain decreases with the increasing clogged degree of the fixed orifices on both sides.The zero bias increases synchronously with the increasing clogged degree of the unilateral fixed orifice.The experimental results are basically consistent with the theoretical curves and the theoretical correctness of the simulation model is effectively verified.The results can provide the theoretical reference for design,debugging,maintenance and fault diagnosis of DRDNFV.展开更多
Biological tiny structures have been observed on many kinds of surfaces such as lotus leaves and insect wings,which enhance the hydrophobicity of the natural surfaces and play a role of self-cleaning.We presented the ...Biological tiny structures have been observed on many kinds of surfaces such as lotus leaves and insect wings,which enhance the hydrophobicity of the natural surfaces and play a role of self-cleaning.We presented the fabrication technology of a superhydrophobic surface using high energy ion beam.Artificial insect wings that mimic the morphology and the superhydrophobocity of cicada's wings were successfully fabricated using argon and oxygen ion beam treatment on a polytetrafluoroethylene (PTFE)film.The wing structures were supported by carbon/epoxy fibers as artificial flexible veins that were bonded through an autoclave process.The morphology of the fabricated surface bears a strong resemblance to the wing surface of a cicada,with contact angles greater than 160°,which could be sustained for more than two months.展开更多
In situ pressure-preserved coring(IPP-Coring)technology is considered one of the most efficient methods for assessing resources.However,seal failure caused by the rotation of pressure controllers greatly affects the s...In situ pressure-preserved coring(IPP-Coring)technology is considered one of the most efficient methods for assessing resources.However,seal failure caused by the rotation of pressure controllers greatly affects the success of pressure coring.In this paper,a novel spherical-cylindrical shell pressure controller was proposed.The finite element analysis model was used to analyze the stress distribution and deformation characteristics of the pressure controller at different rotation angles.The seal failure mechanism caused by the rotation of the pressure controller was discussed.The stress deviation rate was defined to quantitatively characterize the stress concentration.Based on the test equipment designed in this laboratory,the ultimate bearing strength of the pressure controller was tested.The results show that the rotation of the valve cover causes an increase in the deformation on its lower side.Furthermore,the specific sealing pressure in the weak zone is greatly reduced by a statistically significant amount,resulting in seal failure.When the valve cover rotates 5°around the major axis,the stress deviation rate is-92.6%.To prevent rotating failure of the pressure controller,it is necessary to control the rotation angle of the valve cover within 1°around the major axis.The results of this research can help engineers reduce failure-related accidents,provide countermeasures for pressure coring,and contribute to the exploration and evaluation of deep oil and gas resources.展开更多
Nowadays,more and more attention has been paid to improve the performance of the nozzle flapper servo valve.As a core part of nozzle flapper servo valve,the armature assembly is affected by electromagnetic force,jet f...Nowadays,more and more attention has been paid to improve the performance of the nozzle flapper servo valve.As a core part of nozzle flapper servo valve,the armature assembly is affected by electromagnetic force,jet force and feedback force at the same time.Due to the complex structure of the pilot stage flow field and the high jet pressure,the prediction of the jet force has always been difficult in modeling the transient motion of the servo valve.Whereupon,a numerical simulation method based on the flow-solid interaction(FSI)is applied to observe the variation of the jet force when the flapper is moving.Different parameters are employed to seek a suitable numerical simulation model which can balance the accuracy and computational cost.By comparing with the experiment results,the effectiveness of numerical simulation method in predicting the variation of the jet force and cavitation is verified.By this numerical simulation model,the distribution of flow field and the force on the flapper predicted by the moving and fixed flapper are compared.The results show that more dynamic details are achieved by the transient simulation.By analyzing the numerical simulation results of different inlet pressures and flapper vibration frequencies,the relationship between the movement of the flapper,the flow field distribution,the jet force and the inlet pressure is established,which provides a theoretical basis for the subsequent modeling of the armature assembly.展开更多
Electro-hydraulic servo-valves are widely used components in the mechanical industry,aerospace and aerodynamic devices which precisely control the airplane or missile wings.Due to the small size and complex structure ...Electro-hydraulic servo-valves are widely used components in the mechanical industry,aerospace and aerodynamic devices which precisely control the airplane or missile wings.Due to the small size and complex structure in the pilot stage of deflection flapper servo-valves,accurate mathematical models for the flow and pressure characteristics have always been very difficult to be built.In this paper,mathematical models for the pilot stage of deflection flapper servo-valve are investigated to overcome some gaps between the theoretical formulation and overall performance of the valve by considering different flow states.Here,a mathematical model of the velocity distribution at the flapper groove exit is established by using Schlichting velocity equations for incompressible laminar fluid flow.Moreover,when the flow becomes turbulent,a mathematical model of pressure characteristics in the receiving ports is built on the basis of the assumption of the collision between the liquid and the jet as the impact of the jet on a moving block of fluid particles.To verify the analytical models for both laminar and turbulent flows,the pressure characteristics of the deflection flapper pilot stage are calculated and tested by using numerical simulation and experiment.Experimental verification of the theory is also presented.The computed numerical and analytical results show a good agreement with experimental data.展开更多
In this paper, taking two degrees of freedom on the armature–flapper assembly into account, a seventh-order model is deduced and proposed for the dynamic response of a two-stage electro-hydraulic servo valve from non...In this paper, taking two degrees of freedom on the armature–flapper assembly into account, a seventh-order model is deduced and proposed for the dynamic response of a two-stage electro-hydraulic servo valve from nonlinear equations. These deductions are based on fundamental laws of electromagnetism, fluid, and general mechanics. The coefficients of the proposed seventhorder model are derived in terms of servo valve physical parameters and fluid properties explicitly.For validating the results of the proposed model, an AMESim simulation model based on physical laws and the existing low-order models validated by other researchers through experiments are used to compare with the seventh-order model. The results show that the seventh-order model can reflect the physical behavior of the servo valve more explicitly than the existing low-order models and it could provide guidance more easily for a linear control design approach and sensitivity analysis than the AMESim simulation model.展开更多
A new type nozzle flapper amplifier for double nozzle flapper electro-hydraulic servo valve is proposed in the paper.The electro-mechanical converter of new type nozzle flapper amplifier is designed by using the piezo...A new type nozzle flapper amplifier for double nozzle flapper electro-hydraulic servo valve is proposed in the paper.The electro-mechanical converter of new type nozzle flapper amplifier is designed by using the piezoelectric bimorph and beryllium-bronze materials.The structure and working principle of the new type nozzle flapper amplifier are introduced.Pressure characteristic and flowrate characteristic are analyzed by experimental method.The research results show that pressure characteristic has large amplification factor and output pressure;flowrate characteristic has large linear range and output flowrate.展开更多
基金Supported by the National Natural Science Foundation of China(52075468)the General Project of Natural Science Foundation of Hebei Prov-ince(E2020203052)+1 种基金the Open Fund Project of Shaanxi Provincial Key Laboratory of Hydraulic Technology(YYJS2022KF14)the BasicInnovation Research Cultivation Project of Yanshan University(2021LGZD003)。
文摘The feedback spring rod of the armature assembly is cancelled in the double redundance double nozzle flapper valve(DRDNFV),and the difficulty of valve core displacement control is increased.Therefore,this paper intends to study the static characteristic of DRDNFV through the AMESet and AMESim simulation.It is explored under the circumstance of the fixed orifices being clogged and experimentally verified on the test bench.The results show that the pressure gain increases and the flow gain decreases with the increasing clogged degree of the fixed orifices on both sides.The zero bias increases synchronously with the increasing clogged degree of the unilateral fixed orifice.The experimental results are basically consistent with the theoretical curves and the theoretical correctness of the simulation model is effectively verified.The results can provide the theoretical reference for design,debugging,maintenance and fault diagnosis of DRDNFV.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science and Technology(2009-0083068 and 2009-0082607)
文摘Biological tiny structures have been observed on many kinds of surfaces such as lotus leaves and insect wings,which enhance the hydrophobicity of the natural surfaces and play a role of self-cleaning.We presented the fabrication technology of a superhydrophobic surface using high energy ion beam.Artificial insect wings that mimic the morphology and the superhydrophobocity of cicada's wings were successfully fabricated using argon and oxygen ion beam treatment on a polytetrafluoroethylene (PTFE)film.The wing structures were supported by carbon/epoxy fibers as artificial flexible veins that were bonded through an autoclave process.The morphology of the fabricated surface bears a strong resemblance to the wing surface of a cicada,with contact angles greater than 160°,which could be sustained for more than two months.
基金supported by the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315)National Natural Science Foundation of China No.51827901 and U2013603
文摘In situ pressure-preserved coring(IPP-Coring)technology is considered one of the most efficient methods for assessing resources.However,seal failure caused by the rotation of pressure controllers greatly affects the success of pressure coring.In this paper,a novel spherical-cylindrical shell pressure controller was proposed.The finite element analysis model was used to analyze the stress distribution and deformation characteristics of the pressure controller at different rotation angles.The seal failure mechanism caused by the rotation of the pressure controller was discussed.The stress deviation rate was defined to quantitatively characterize the stress concentration.Based on the test equipment designed in this laboratory,the ultimate bearing strength of the pressure controller was tested.The results show that the rotation of the valve cover causes an increase in the deformation on its lower side.Furthermore,the specific sealing pressure in the weak zone is greatly reduced by a statistically significant amount,resulting in seal failure.When the valve cover rotates 5°around the major axis,the stress deviation rate is-92.6%.To prevent rotating failure of the pressure controller,it is necessary to control the rotation angle of the valve cover within 1°around the major axis.The results of this research can help engineers reduce failure-related accidents,provide countermeasures for pressure coring,and contribute to the exploration and evaluation of deep oil and gas resources.
基金Supported by the National Natural Science Foundation of China(51675119)。
文摘Nowadays,more and more attention has been paid to improve the performance of the nozzle flapper servo valve.As a core part of nozzle flapper servo valve,the armature assembly is affected by electromagnetic force,jet force and feedback force at the same time.Due to the complex structure of the pilot stage flow field and the high jet pressure,the prediction of the jet force has always been difficult in modeling the transient motion of the servo valve.Whereupon,a numerical simulation method based on the flow-solid interaction(FSI)is applied to observe the variation of the jet force when the flapper is moving.Different parameters are employed to seek a suitable numerical simulation model which can balance the accuracy and computational cost.By comparing with the experiment results,the effectiveness of numerical simulation method in predicting the variation of the jet force and cavitation is verified.By this numerical simulation model,the distribution of flow field and the force on the flapper predicted by the moving and fixed flapper are compared.The results show that more dynamic details are achieved by the transient simulation.By analyzing the numerical simulation results of different inlet pressures and flapper vibration frequencies,the relationship between the movement of the flapper,the flow field distribution,the jet force and the inlet pressure is established,which provides a theoretical basis for the subsequent modeling of the armature assembly.
基金The National Natural Science Foundation of China(No.51675119)。
文摘Electro-hydraulic servo-valves are widely used components in the mechanical industry,aerospace and aerodynamic devices which precisely control the airplane or missile wings.Due to the small size and complex structure in the pilot stage of deflection flapper servo-valves,accurate mathematical models for the flow and pressure characteristics have always been very difficult to be built.In this paper,mathematical models for the pilot stage of deflection flapper servo-valve are investigated to overcome some gaps between the theoretical formulation and overall performance of the valve by considering different flow states.Here,a mathematical model of the velocity distribution at the flapper groove exit is established by using Schlichting velocity equations for incompressible laminar fluid flow.Moreover,when the flow becomes turbulent,a mathematical model of pressure characteristics in the receiving ports is built on the basis of the assumption of the collision between the liquid and the jet as the impact of the jet on a moving block of fluid particles.To verify the analytical models for both laminar and turbulent flows,the pressure characteristics of the deflection flapper pilot stage are calculated and tested by using numerical simulation and experiment.Experimental verification of the theory is also presented.The computed numerical and analytical results show a good agreement with experimental data.
基金the National Natural Science Foundation of China (No. 50975055) for financial support
文摘In this paper, taking two degrees of freedom on the armature–flapper assembly into account, a seventh-order model is deduced and proposed for the dynamic response of a two-stage electro-hydraulic servo valve from nonlinear equations. These deductions are based on fundamental laws of electromagnetism, fluid, and general mechanics. The coefficients of the proposed seventhorder model are derived in terms of servo valve physical parameters and fluid properties explicitly.For validating the results of the proposed model, an AMESim simulation model based on physical laws and the existing low-order models validated by other researchers through experiments are used to compare with the seventh-order model. The results show that the seventh-order model can reflect the physical behavior of the servo valve more explicitly than the existing low-order models and it could provide guidance more easily for a linear control design approach and sensitivity analysis than the AMESim simulation model.
基金Item Sponsored by National Natural Science Foundation of China[51105170]Program of Science and Technology Development Plan of Jilin province of China[201105015]
文摘A new type nozzle flapper amplifier for double nozzle flapper electro-hydraulic servo valve is proposed in the paper.The electro-mechanical converter of new type nozzle flapper amplifier is designed by using the piezoelectric bimorph and beryllium-bronze materials.The structure and working principle of the new type nozzle flapper amplifier are introduced.Pressure characteristic and flowrate characteristic are analyzed by experimental method.The research results show that pressure characteristic has large amplification factor and output pressure;flowrate characteristic has large linear range and output flowrate.
