Compressed gas is usually used for the pressure compensation of the deep-sea pressure-maintaining sampler.The pressure and volume of the recovered fluid sample are highly related to the precharged gas. To better under...Compressed gas is usually used for the pressure compensation of the deep-sea pressure-maintaining sampler.The pressure and volume of the recovered fluid sample are highly related to the precharged gas. To better understand the behavior of the gas under high pressure, we present a new real gas state equation based on the compression factor Z which was derived from experimental data. Then theoretical calculation method of the pressure and volume of the sample was introduced based on this empirical gas state equation. Finally, the proposed calculation method was well verified by the high-pressure vessel experiment of the sampler under 115 MPa.展开更多
Based on the analysis of the-state-of-the-art of pressure compensation of underwater hydraulic systems (UHSs), a new method of pressure compensation of UHSs, whose hydraulic power unit is in the atmospheric circumst...Based on the analysis of the-state-of-the-art of pressure compensation of underwater hydraulic systems (UHSs), a new method of pressure compensation of UHSs, whose hydraulic power unit is in the atmospheric circumstance, is proposed. And a pilot-operated relief valve with pressure compensation is realized. The pressure compensation precision is guaranteed by direct detection. Its dynamic performance and stability are improved by a dynamic feedback. Theoretical study, simulation and experiment show that the pilot-operated relief valve with pressure compensation has a fine property of tracking underwater ambient pressure and meet the requirement of underwater ambient pressure compensation.展开更多
Aiming at the requirement of the full-ocean-depth(operating water depth 11000 m)manned submersible to carry out the gas-tight sampling operation of the abyss seabed sediment,a kind of full-ocean-depth carrier submersi...Aiming at the requirement of the full-ocean-depth(operating water depth 11000 m)manned submersible to carry out the gas-tight sampling operation of the abyss seabed sediment,a kind of full-ocean-depth carrier submersible mechanical hand-held,full-ocean-depth gas-tight sediment sampler(GTSS)with the function of pressure-retaining and coring is designed.Firstly,the volume change model of pressure compensator is established,and it is pointed out that the volume of pressure compensator is about 16.14%equal to the volume of gas-tight sediment sampler(GTSS).Secondly,the pressure compensator is analyzed and calculated,and the relationship between the precharge pressure of the pressure compensator,the nominal volume of the pressure compensator and the pressure holding effect of the gas-tight sediment sampler(GTSS)is studied.The results show that with the increase of gas precharge pressure in the pressure compensator,the final pressure of the sampler also increases.Under the same precharge pressure condition,the larger the nominal volume of the pressure compensator,the greater the final pressure of the sampler.Finally,the air tightness test method is designed by using the developed gas tightness sampler of the full-ocean-depth product,and the change of the final pressure in the gas tight sampler under different precharge pressure is observed.The test results are consistent with the simulation results,indicating the correctness of the pressure compensation system(PCS)model.展开更多
In this study,the pressure compensation mechanism of a reducer bellows is analyzed.This device is typically used to reduce the size of undersea instruments and improve related pressure resistance and sealing capabilit...In this study,the pressure compensation mechanism of a reducer bellows is analyzed.This device is typically used to reduce the size of undersea instruments and improve related pressure resistance and sealing capabilities.Here,its axial stiffness is studied through a multi-fold approach based on theory,simulations and experiments.The results indicate that the mechanical strength of the reducer bellows,together with the oil volume and temperature are the main factors influencing its performances.In particular,the wall thickness,wave number,middle distance,and wave height are the most influential parameters.For a certain type of reducer bellows,the compensation capacity attains a maximum when the wave number ratio is between 6:6 and 8:4,the wall thickness is 0.3 mm,and the wave height is between 4–5 mm and 5–6 mm.Moreover,the maximum allowable ambient pres-sure of the optimized reducer bellows can reach 62.6 MPa without failure,and the maximum working water depth is 6284 m.展开更多
Electro-hydraulic proportional valve is the core control valve in many hydraulic systems used in agricultural and engineering machinery.To address the problem related to the large throttling losses and poor stability ...Electro-hydraulic proportional valve is the core control valve in many hydraulic systems used in agricultural and engineering machinery.To address the problem related to the large throttling losses and poor stability typically associated with these valves,here,the beneficial effects of a triangular groove structure on the related hydraulic response are studied.A mathematical model of the pressure compensation system based on the power-bond graph method is introduced,and the AMESim software is used to simulate its response.The results show that the triangular groove structure increases the jet angle and effectively compensates for the hydrodynamic force.The steady-state differential pressure at the valve port of the new pressure compensation structure was 0.65 MPa.Furthermore,experimental results show that the pressure difference at the main valve port is 0.73 MPa,and that the response time is less than 0.2 s.It is concluded that the new compensation structure has good pressure compensation response characteristics.展开更多
To address the control accuracy of large fuel flowrate during pressure fluctuation,a novel electro-hydraulic fuel metering unit(FMU)is constructed for afterburner fuel system of military aeroengine.Different from the ...To address the control accuracy of large fuel flowrate during pressure fluctuation,a novel electro-hydraulic fuel metering unit(FMU)is constructed for afterburner fuel system of military aeroengine.Different from the previous FMU,the proposed FMU can achieve the higher precision opening control by a new metering valve with double control chambers(MVDCC),and realize the lower pressure difference fluctuation regulating by a novel two-stage constant pressure difference compensated valve(CPDCV)with dynamic damping orifice and damping piston.The experimental and AMESim simulation results verify the validity and superiority of the novel FMU.Since the temperature-induced variation in fuel properties and device capabilities may degrade or even impair the properties of novel FMU,the discharge flowrate is analyzed by global sensitivity analysis to research the effect proportion of each factor,the temperature effect is explored to ensure the working reliability in long-span temperature variation.Finally,the optimization of structure parameters for novel CPDCV can further reduce pressure difference fluctuation during pressure regulation,and the overshoot,adjust time and the integral of time multiplied by absolute value of error(ITAE)can be reduced by 24%,30%and 26%,respectively.This paper provides a reference for improving the stability of large flowrate during pressure fluctuation.展开更多
Based on the asymmetric base region transistor, a pressure sensor with temperature compensation circuit is proposed in this paper. The pressure sensitive structure of the proposed sensor is constructed by a C-type sil...Based on the asymmetric base region transistor, a pressure sensor with temperature compensation circuit is proposed in this paper. The pressure sensitive structure of the proposed sensor is constructed by a C-type silicon cup and a Wheatstone bridge with four piezoresistors(R_1, R_2, R_3 and R_4/locating on the edge of a square silicon membrane. The chip was designed and fabricated on a silicon on insulator(SOI) wafer by micro electromechanical system(MEMS) technology and bipolar transistor process. When the supply voltage is 5.0 V, the corresponding temperature coefficient of the sensitivity(TCS) for the sensor before and after temperature compensation are -1862 and -1067 ppm/℃, respectively. Through varying the ratio of the base region resistances r_1 and r_2, the TCS for the sensor with the compensation circuit is -127 ppm/℃. It is possible to use this compensation circuit to improve the temperature characteristics of the pressure sensor.展开更多
基金The National Key Research and Development Program of China under contract Nos 2018YFC0310600 and2016YFC0300500。
文摘Compressed gas is usually used for the pressure compensation of the deep-sea pressure-maintaining sampler.The pressure and volume of the recovered fluid sample are highly related to the precharged gas. To better understand the behavior of the gas under high pressure, we present a new real gas state equation based on the compression factor Z which was derived from experimental data. Then theoretical calculation method of the pressure and volume of the sample was introduced based on this empirical gas state equation. Finally, the proposed calculation method was well verified by the high-pressure vessel experiment of the sampler under 115 MPa.
基金This project is supported by National Natural Science Foundation of China(No.50475105).
文摘Based on the analysis of the-state-of-the-art of pressure compensation of underwater hydraulic systems (UHSs), a new method of pressure compensation of UHSs, whose hydraulic power unit is in the atmospheric circumstance, is proposed. And a pilot-operated relief valve with pressure compensation is realized. The pressure compensation precision is guaranteed by direct detection. Its dynamic performance and stability are improved by a dynamic feedback. Theoretical study, simulation and experiment show that the pilot-operated relief valve with pressure compensation has a fine property of tracking underwater ambient pressure and meet the requirement of underwater ambient pressure compensation.
基金Supported by National Key Research and Development Program of China(Grant No.2016YFC0300502)National Natural Science Foundation of China(Grant No.517779092)+1 种基金Special Project for the Construction of Innovative Provinces in Hunan(Grant No.2019GK1012)Postgraduate Scientific Research Innovation Project of Hunan Province(Grant No.CX20210985).
文摘Aiming at the requirement of the full-ocean-depth(operating water depth 11000 m)manned submersible to carry out the gas-tight sampling operation of the abyss seabed sediment,a kind of full-ocean-depth carrier submersible mechanical hand-held,full-ocean-depth gas-tight sediment sampler(GTSS)with the function of pressure-retaining and coring is designed.Firstly,the volume change model of pressure compensator is established,and it is pointed out that the volume of pressure compensator is about 16.14%equal to the volume of gas-tight sediment sampler(GTSS).Secondly,the pressure compensator is analyzed and calculated,and the relationship between the precharge pressure of the pressure compensator,the nominal volume of the pressure compensator and the pressure holding effect of the gas-tight sediment sampler(GTSS)is studied.The results show that with the increase of gas precharge pressure in the pressure compensator,the final pressure of the sampler also increases.Under the same precharge pressure condition,the larger the nominal volume of the pressure compensator,the greater the final pressure of the sampler.Finally,the air tightness test method is designed by using the developed gas tightness sampler of the full-ocean-depth product,and the change of the final pressure in the gas tight sampler under different precharge pressure is observed.The test results are consistent with the simulation results,indicating the correctness of the pressure compensation system(PCS)model.
基金Key Laboratory of Petroleum and Natural Gas Equipment of Ministry of Education.
文摘In this study,the pressure compensation mechanism of a reducer bellows is analyzed.This device is typically used to reduce the size of undersea instruments and improve related pressure resistance and sealing capabilities.Here,its axial stiffness is studied through a multi-fold approach based on theory,simulations and experiments.The results indicate that the mechanical strength of the reducer bellows,together with the oil volume and temperature are the main factors influencing its performances.In particular,the wall thickness,wave number,middle distance,and wave height are the most influential parameters.For a certain type of reducer bellows,the compensation capacity attains a maximum when the wave number ratio is between 6:6 and 8:4,the wall thickness is 0.3 mm,and the wave height is between 4–5 mm and 5–6 mm.Moreover,the maximum allowable ambient pres-sure of the optimized reducer bellows can reach 62.6 MPa without failure,and the maximum working water depth is 6284 m.
基金This research was funded by the 2020 Shandong Province Key Research and Development Programs(Major Technological Innovation Projects):Construction Machinery Integration Research and Application of Key Technologies for Intelligent Integration and Matching of Vehicle Assembly(2020CXGC011005)Large Tractor Hydraulic CVT Intelligent Continuously Variable Transmission Integration Research and Application(2020CXGC010806)Development and Application of High-Horsepower High-Efficiency Intelligent Tractors(2021CXGC010812).
文摘Electro-hydraulic proportional valve is the core control valve in many hydraulic systems used in agricultural and engineering machinery.To address the problem related to the large throttling losses and poor stability typically associated with these valves,here,the beneficial effects of a triangular groove structure on the related hydraulic response are studied.A mathematical model of the pressure compensation system based on the power-bond graph method is introduced,and the AMESim software is used to simulate its response.The results show that the triangular groove structure increases the jet angle and effectively compensates for the hydrodynamic force.The steady-state differential pressure at the valve port of the new pressure compensation structure was 0.65 MPa.Furthermore,experimental results show that the pressure difference at the main valve port is 0.73 MPa,and that the response time is less than 0.2 s.It is concluded that the new compensation structure has good pressure compensation response characteristics.
基金co-supported by the National Key Basic Research Program of China(No.2014CB046403)the National Science and Technology Major Project(2017-V-0015-0067)。
文摘To address the control accuracy of large fuel flowrate during pressure fluctuation,a novel electro-hydraulic fuel metering unit(FMU)is constructed for afterburner fuel system of military aeroengine.Different from the previous FMU,the proposed FMU can achieve the higher precision opening control by a new metering valve with double control chambers(MVDCC),and realize the lower pressure difference fluctuation regulating by a novel two-stage constant pressure difference compensated valve(CPDCV)with dynamic damping orifice and damping piston.The experimental and AMESim simulation results verify the validity and superiority of the novel FMU.Since the temperature-induced variation in fuel properties and device capabilities may degrade or even impair the properties of novel FMU,the discharge flowrate is analyzed by global sensitivity analysis to research the effect proportion of each factor,the temperature effect is explored to ensure the working reliability in long-span temperature variation.Finally,the optimization of structure parameters for novel CPDCV can further reduce pressure difference fluctuation during pressure regulation,and the overshoot,adjust time and the integral of time multiplied by absolute value of error(ITAE)can be reduced by 24%,30%and 26%,respectively.This paper provides a reference for improving the stability of large flowrate during pressure fluctuation.
基金supported by the National Natural Science Foundation of China(No.61471159)the Natural Science Foundation of Heilongjiang Province(No.F201433)+1 种基金the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(No.2015018)the Special Funds for Science and Technology Innovation Talents of Harbin in China(No.2016RAXXJ016)
文摘Based on the asymmetric base region transistor, a pressure sensor with temperature compensation circuit is proposed in this paper. The pressure sensitive structure of the proposed sensor is constructed by a C-type silicon cup and a Wheatstone bridge with four piezoresistors(R_1, R_2, R_3 and R_4/locating on the edge of a square silicon membrane. The chip was designed and fabricated on a silicon on insulator(SOI) wafer by micro electromechanical system(MEMS) technology and bipolar transistor process. When the supply voltage is 5.0 V, the corresponding temperature coefficient of the sensitivity(TCS) for the sensor before and after temperature compensation are -1862 and -1067 ppm/℃, respectively. Through varying the ratio of the base region resistances r_1 and r_2, the TCS for the sensor with the compensation circuit is -127 ppm/℃. It is possible to use this compensation circuit to improve the temperature characteristics of the pressure sensor.