Comparing with usual continuous jet nozzle, the self-excited oscillationpulsed jet nozzle SEOPJN) can make jet generate a higher peak of pressure and larger scouringvolume. And it can make jet increase the effective s...Comparing with usual continuous jet nozzle, the self-excited oscillationpulsed jet nozzle SEOPJN) can make jet generate a higher peak of pressure and larger scouringvolume. And it can make jet increase the effective standoff distance, too. The basic theories of theSEOPJN are introduced. Some experimental results are shown. According to the results, using tricornbits assembled the SEOPJN to drill oil well, the ROP increases by 8 percent approx 77 percent, andthe rates of the footage for tricorn bit increases by 6.7 percent approx 44.0 percent.展开更多
Non-thermal plasma surface modification for epoxy resin(EP)to improve the insulation properties has wide application prospects in gas insulated switchgear and gas insulatedtransmission line.In this paper,a pulsed Ar...Non-thermal plasma surface modification for epoxy resin(EP)to improve the insulation properties has wide application prospects in gas insulated switchgear and gas insulatedtransmission line.In this paper,a pulsed Ar dual dielectrics atmospheric-pressure plasma jet(APPJ)was used for Si CxHyOzthin film deposition on EP samples.The film deposition was optimized by varying the treatment time while other parameters were kept at constants(treatment distance:10 mm,precursor flow rate:0.6 l min-(-1),maximum instantaneous power:3.08 k W and single pulse energy:0.18 m J).It was found that the maximum value of flashover voltages for negative and positive voltage were improved by 18%and 13%when the deposition time was3 min,respectively.The flashover voltage reduced as treatment time increased.Moreover,all the surface conductivity,surface charge dissipation rate and surface trap level distribution reached an optimal value when thin film deposition time was 3 min.Other measurements,such as atomic force microscopy and scanning electron microscope for EP surface morphology,Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy for EP surface compositions,optical emission spectra for APPJ deposition process were carried out to better understand the deposition processes and mechanisms.The results indicated that the original organic groups(C–H,C–C,C=O,C=C)were gradually replaced by the Si containing inorganic groups(Si–O–Si and Si–OH).The reduction of C=O in ester group and C=C in p-substituted benzene of the EP samples might be responsible for shallowing the trap level and then enhancing the flashover voltage.However,when the plasma treatment time was longer than 3 min,the significant increase of the surface roughness might increase the trap level depth and then deteriorate the flashover performance.展开更多
High-pressure pulsed water jet technology has considerable development potential in the field of rock fragmentation.To overcome the shortcomings of existing pulsed jets,a self-supercharging pulsed water jet(SSPWJ)gene...High-pressure pulsed water jet technology has considerable development potential in the field of rock fragmentation.To overcome the shortcomings of existing pulsed jets,a self-supercharging pulsed water jet(SSPWJ)generation method is proposed,which is based on the theory of the pulsed water jet and the principle of hydraulic boosting.The proposed method changes the flow direction of the fluid medium through the valve core to make the piston reciprocate in the cylinder and relies on the effective area difference between the front and rear chambers in the stroke stage of the piston to realize the organic combination of“pulse”and“supercharging”of the jet,thus forming an SSPWJ.On the basis of the formation principle of the SSPWJ,a SSPWJ testing platform was constructed,and tests were performed on the jet pressure acquisition,morphology capture,and granite erosion.Both the jet pressure and the jet morphology exhibited periodic changes,and a higher pulse pressure was obtained at lower inlet pressure.The error of the pressure ratio calculated according to the experimental results was<3%relative to the theoretical design value,confirming the feasibility of the method.The pulse pressure and pulse frequency are controllable;that is,as the inlet flow rate increases in the stroke stage of the piston,the pulse pressure and pulse frequency increase,and the pulse duration decreases.As the inlet flow rate increases in the backward-stroke stage of the piston,the pulse frequency increases,and the pulse pressure and pulse duration remain unchanged.Under the combined action of the waterhammer pressure,high-speed lateral flow,and high-frequency dynamic load of the SSPWJ,local flaky exfoliation was observed when the granite surface was eroded.The results of this study lay the foundation for enriching the theory of pulsed jet generation and expanding its application range.展开更多
In the background of electrothermal-chemical (ETC) emission,an investigation has been conducted on the characteristics of a freely expanding pulsed plasma jet in air.The evolutionary process of the plasma jet is exp...In the background of electrothermal-chemical (ETC) emission,an investigation has been conducted on the characteristics of a freely expanding pulsed plasma jet in air.The evolutionary process of the plasma jet is experimentally investigated using a piezoelectric pressure sensor and a digital high-speed video system.The variation relation in the extended volume,axial displacement and radial displacement of the pulsed plasma jet in atmosphere with time under different discharge voltages and jet breaking pressures is obtained.Based on experiments,a two-dimensional axisymmetric unsteady model is established to analyze the characteristics of the two-phase interface and the variation of flow-field parameters resulting from a pulsed plasma jet into air at a pressure of 1.5-3.5 MPa under three nozzle diameters (3 mm,4 mm and 5 ram,respectively).The images of the plasma jet reveal a changing shape process,from a quasiellipsoid to a conical head and an elongated cylindrical tail.The axial displacement of the jet is always larger than that along the radial direction.The extended volume reveals a single peak distribution with time.Compared to the experiment,the numerical simulation agrees well with the experimental data.The parameters of the jet field mutate at the nozzle exit with a decrease in the parameter pulse near the nozzle,and become more and more gradual and close to environmental parameters.Increasing the injection pressure and nozzle diameter can increase the parameters of the flow field such as the expansion volume of the pulsed plasma jet,the size of the Mach disk and the pressure.In addition,the turbulent mixing in the expansion process is also enhanced.展开更多
Offshore drilling has attracted more attention than ever before due to the increasing worldwide energy demand especially in China. High cost, long drilling cycles, and low rate of penetration (ROP) represent critica...Offshore drilling has attracted more attention than ever before due to the increasing worldwide energy demand especially in China. High cost, long drilling cycles, and low rate of penetration (ROP) represent critical challenges for offshore drilling operations. The hydraulic pulse generator was specifically designed, based on China offshore drilling technologies and parameters, to overcome problems encountered during offshore drilling. Both laboratory and field tests were conducted to collect the characteristics of the hydraulic pulse generator. The relationships between flow rate and pressure amplitude, pressure loss and pulse frequency were obtained, which can be used to optimize operation parameters for hydraulic pulse jet drilling. Meanwhile a bottom hole assembly (BHA) for pulse jet drilling has been designed, combining the hydraulic pulse generator with the conventional BHA, positive displacement motor, and rotary steerable system (RSS) etc. Furthermore, the hydraulic pulse jet technique has been successfully applied in more than 10 offshore wells in China. The depth of the applied wells ranged from 2,000 m to 4,100 m with drilling bit diameters of 311 mm and 216 mm. The field application results showed that hydraulic pulse jet technique was feasible for various bit types and formations, and that ROP could be significantly increased, by more than 25%.展开更多
The development of new drilling methods is important for the exploration and production of oil fields.The pulsed jet is a drilling technology of high potentiality.This article proposes a new concept of suck-in pulsed ...The development of new drilling methods is important for the exploration and production of oil fields.The pulsed jet is a drilling technology of high potentiality.This article proposes a new concept of suck-in pulsed jet with self-excited oscillation,by which a full use of the hydraulic power can be made in the annular space.A hydrodynamic analysis of suck-in pulsed jet with self-excited oscillation is carried out by numerical simulations and rock-breaking experiments.It is shown that with the jet,a negative pressure zone will be formed in the oscillation cavity to ensure automatic sucking of enough annular fluids and the formation of an efficient pulsed jet.The rock-breaking and pressure testing results have verified the reliability of the numerical simulation.The research provides a basis for the development of the pulsed jet drilling technology.展开更多
On the hypothesis that the turbulent flow is practically not affected in character by pulsation of the flow, the formula for sound pressure level of pulsed jet noise is obtained in 90 °direction and 1 meter away ...On the hypothesis that the turbulent flow is practically not affected in character by pulsation of the flow, the formula for sound pressure level of pulsed jet noise is obtained in 90 °direction and 1 meter away from the nozzle. The steady jet noise is , then, a special case when the pulsating frequency is zero. The results agree well with experiments.展开更多
Nickel coatings with different microstructures were synthesized by pulse jet electrodeposition technique.Their morphology and microstructure were investigated by scanning electron microscopy(SEM)and transmission ele...Nickel coatings with different microstructures were synthesized by pulse jet electrodeposition technique.Their morphology and microstructure were investigated by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The corrosion property of the coatings was studied by using polarization,electrochemical impedance spectroscopy(EIS),potential of zero free charge(PZFC) measurements and Mott-Schottky(M-S) relationship.The results showed that the coating with grain size of 50 nm possessed higher corrosion resistance than that with grain size of 10 nm.This abnormal behavior may be related to the existence of nanoscale twins in the coatings and the lower concentration of acceptor in the passive films.展开更多
基金National Natural Science Foundation of China (No.59979029)
文摘Comparing with usual continuous jet nozzle, the self-excited oscillationpulsed jet nozzle SEOPJN) can make jet generate a higher peak of pressure and larger scouringvolume. And it can make jet increase the effective standoff distance, too. The basic theories of theSEOPJN are introduced. Some experimental results are shown. According to the results, using tricornbits assembled the SEOPJN to drill oil well, the ROP increases by 8 percent approx 77 percent, andthe rates of the footage for tricorn bit increases by 6.7 percent approx 44.0 percent.
基金supported by National Natural Science Foundation of China under contract No.11575194the National Basic Research Program of China(973 Project) under contract No.2014CB239505-3+2 种基金Natural Science Foundation of Hebei Province under contract No.E2015502081the Fundamental Research Funds for the Central Universities under contract No.2016ZZD07the Young Scholar of the Chang Jiang Scholars Program,Ministry of Education,China
文摘Non-thermal plasma surface modification for epoxy resin(EP)to improve the insulation properties has wide application prospects in gas insulated switchgear and gas insulatedtransmission line.In this paper,a pulsed Ar dual dielectrics atmospheric-pressure plasma jet(APPJ)was used for Si CxHyOzthin film deposition on EP samples.The film deposition was optimized by varying the treatment time while other parameters were kept at constants(treatment distance:10 mm,precursor flow rate:0.6 l min-(-1),maximum instantaneous power:3.08 k W and single pulse energy:0.18 m J).It was found that the maximum value of flashover voltages for negative and positive voltage were improved by 18%and 13%when the deposition time was3 min,respectively.The flashover voltage reduced as treatment time increased.Moreover,all the surface conductivity,surface charge dissipation rate and surface trap level distribution reached an optimal value when thin film deposition time was 3 min.Other measurements,such as atomic force microscopy and scanning electron microscope for EP surface morphology,Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy for EP surface compositions,optical emission spectra for APPJ deposition process were carried out to better understand the deposition processes and mechanisms.The results indicated that the original organic groups(C–H,C–C,C=O,C=C)were gradually replaced by the Si containing inorganic groups(Si–O–Si and Si–OH).The reduction of C=O in ester group and C=C in p-substituted benzene of the EP samples might be responsible for shallowing the trap level and then enhancing the flashover voltage.However,when the plasma treatment time was longer than 3 min,the significant increase of the surface roughness might increase the trap level depth and then deteriorate the flashover performance.
基金National Natural Science Foundation of China(Grant Nos.51774055,51625401)National Natural Science Foundation of Chongqing(Grant No.cstc2018jcyjAX0542)Changjiang Scholar Program of Chinese Ministry of Education(Grant No.IRT17R112).
文摘High-pressure pulsed water jet technology has considerable development potential in the field of rock fragmentation.To overcome the shortcomings of existing pulsed jets,a self-supercharging pulsed water jet(SSPWJ)generation method is proposed,which is based on the theory of the pulsed water jet and the principle of hydraulic boosting.The proposed method changes the flow direction of the fluid medium through the valve core to make the piston reciprocate in the cylinder and relies on the effective area difference between the front and rear chambers in the stroke stage of the piston to realize the organic combination of“pulse”and“supercharging”of the jet,thus forming an SSPWJ.On the basis of the formation principle of the SSPWJ,a SSPWJ testing platform was constructed,and tests were performed on the jet pressure acquisition,morphology capture,and granite erosion.Both the jet pressure and the jet morphology exhibited periodic changes,and a higher pulse pressure was obtained at lower inlet pressure.The error of the pressure ratio calculated according to the experimental results was<3%relative to the theoretical design value,confirming the feasibility of the method.The pulse pressure and pulse frequency are controllable;that is,as the inlet flow rate increases in the stroke stage of the piston,the pulse pressure and pulse frequency increase,and the pulse duration decreases.As the inlet flow rate increases in the backward-stroke stage of the piston,the pulse frequency increases,and the pulse pressure and pulse duration remain unchanged.Under the combined action of the waterhammer pressure,high-speed lateral flow,and high-frequency dynamic load of the SSPWJ,local flaky exfoliation was observed when the granite surface was eroded.The results of this study lay the foundation for enriching the theory of pulsed jet generation and expanding its application range.
基金supported by National Natural Science Foundation of China(No.51506094)
文摘In the background of electrothermal-chemical (ETC) emission,an investigation has been conducted on the characteristics of a freely expanding pulsed plasma jet in air.The evolutionary process of the plasma jet is experimentally investigated using a piezoelectric pressure sensor and a digital high-speed video system.The variation relation in the extended volume,axial displacement and radial displacement of the pulsed plasma jet in atmosphere with time under different discharge voltages and jet breaking pressures is obtained.Based on experiments,a two-dimensional axisymmetric unsteady model is established to analyze the characteristics of the two-phase interface and the variation of flow-field parameters resulting from a pulsed plasma jet into air at a pressure of 1.5-3.5 MPa under three nozzle diameters (3 mm,4 mm and 5 ram,respectively).The images of the plasma jet reveal a changing shape process,from a quasiellipsoid to a conical head and an elongated cylindrical tail.The axial displacement of the jet is always larger than that along the radial direction.The extended volume reveals a single peak distribution with time.Compared to the experiment,the numerical simulation agrees well with the experimental data.The parameters of the jet field mutate at the nozzle exit with a decrease in the parameter pulse near the nozzle,and become more and more gradual and close to environmental parameters.Increasing the injection pressure and nozzle diameter can increase the parameters of the flow field such as the expansion volume of the pulsed plasma jet,the size of the Mach disk and the pressure.In addition,the turbulent mixing in the expansion process is also enhanced.
基金financial support from the Program for New Century Excellent Talents in University (No. NCET-12-0971)
文摘Offshore drilling has attracted more attention than ever before due to the increasing worldwide energy demand especially in China. High cost, long drilling cycles, and low rate of penetration (ROP) represent critical challenges for offshore drilling operations. The hydraulic pulse generator was specifically designed, based on China offshore drilling technologies and parameters, to overcome problems encountered during offshore drilling. Both laboratory and field tests were conducted to collect the characteristics of the hydraulic pulse generator. The relationships between flow rate and pressure amplitude, pressure loss and pulse frequency were obtained, which can be used to optimize operation parameters for hydraulic pulse jet drilling. Meanwhile a bottom hole assembly (BHA) for pulse jet drilling has been designed, combining the hydraulic pulse generator with the conventional BHA, positive displacement motor, and rotary steerable system (RSS) etc. Furthermore, the hydraulic pulse jet technique has been successfully applied in more than 10 offshore wells in China. The depth of the applied wells ranged from 2,000 m to 4,100 m with drilling bit diameters of 311 mm and 216 mm. The field application results showed that hydraulic pulse jet technique was feasible for various bit types and formations, and that ROP could be significantly increased, by more than 25%.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50974130)the Major State Basic Research Development Program of China (973 Program, Grant No. 2010CB226703)supported by the China University of Petroleum Ph. D. Thesis Excellent Training Fund (Grant No. Z10-04)
文摘The development of new drilling methods is important for the exploration and production of oil fields.The pulsed jet is a drilling technology of high potentiality.This article proposes a new concept of suck-in pulsed jet with self-excited oscillation,by which a full use of the hydraulic power can be made in the annular space.A hydrodynamic analysis of suck-in pulsed jet with self-excited oscillation is carried out by numerical simulations and rock-breaking experiments.It is shown that with the jet,a negative pressure zone will be formed in the oscillation cavity to ensure automatic sucking of enough annular fluids and the formation of an efficient pulsed jet.The rock-breaking and pressure testing results have verified the reliability of the numerical simulation.The research provides a basis for the development of the pulsed jet drilling technology.
文摘On the hypothesis that the turbulent flow is practically not affected in character by pulsation of the flow, the formula for sound pressure level of pulsed jet noise is obtained in 90 °direction and 1 meter away from the nozzle. The steady jet noise is , then, a special case when the pulsating frequency is zero. The results agree well with experiments.
基金financial support from the National Basic Research Program of China (No.2014CB643301)the National Natural Science Foundation of China (Nos.50971050 and 51001036)+3 种基金the Program for New Century Excellent Talents in University (No.NCET-11-0575)the Ministry of Science and Technology of the People’s Republic of China (No.2012FY113000the Key Laboratory of Superlight Materials and Surface Technology (Harbin Engineering University)Ministry of Education (HEUCF20151011)
文摘Nickel coatings with different microstructures were synthesized by pulse jet electrodeposition technique.Their morphology and microstructure were investigated by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The corrosion property of the coatings was studied by using polarization,electrochemical impedance spectroscopy(EIS),potential of zero free charge(PZFC) measurements and Mott-Schottky(M-S) relationship.The results showed that the coating with grain size of 50 nm possessed higher corrosion resistance than that with grain size of 10 nm.This abnormal behavior may be related to the existence of nanoscale twins in the coatings and the lower concentration of acceptor in the passive films.