Hydraulic sandblasting perforation plays a crucial role in the fracturing and reconstruction of unconventional oil and gas reservoirs.The jet nozzle is an essential part of the hydraulic perforation tool.Insufficient ...Hydraulic sandblasting perforation plays a crucial role in the fracturing and reconstruction of unconventional oil and gas reservoirs.The jet nozzle is an essential part of the hydraulic perforation tool.Insufficient penetration depth,caused by excessive jet distances,presents challenges during the perforation process.To overcome this,an optimization design of the nozzle structure is required to enhance the perforation efficiency.In this paper,a computational fluid-dynamic model for conical-cylindrical nozzles has been elaborated.To further improve the rock-breaking efficiency of the jet nozzle,a fillet design is introduced at the nozzle inlet section.The SST k-ωmodel is employed to account for turbulent flow effects in submerged conditions.The results indicate that the nozzle’s geometric parameters greatly influence the flow characteristics.The orthogonal experimental method is employed to optimize the flow channel structure of the nozzle,taking the length of constant velocity core as the evaluation index.The following optimized geometric parameters for the conical-cylindrical nozzle have been determined accordingly:a cylindrical segment diameter of 3.2 mm,a contraction angle of 12°,a contraction segment length of 8 mm,a cylindrical segment length of 6.4 mm,and a fillet radius of 2 mm.展开更多
The core loss spectrum P(f) of magnetic alloy with constant permeability has been studied. It is found that P(f) has the fractal structure. The effect of the induced anisotropy energy Ku on the fractal dimension Df is...The core loss spectrum P(f) of magnetic alloy with constant permeability has been studied. It is found that P(f) has the fractal structure. The effect of the induced anisotropy energy Ku on the fractal dimension Df is discussed.展开更多
In order to check the traditional core loss formula, the core loss spectrum P(f) of Co-based amorphous soft magnetic alloy with constant permeability has been studied. It is found that within a high frequency range fr...In order to check the traditional core loss formula, the core loss spectrum P(f) of Co-based amorphous soft magnetic alloy with constant permeability has been studied. It is found that within a high frequency range from 10 kHz to 200 kHz and at Bm = 0. 1 T,the P(f) has the fractal structure P (f) = Po, and with the increasing of induced anisotropy energy Ku, the fractal dimension Dfrises, thus the total power loss at high frequency increases and the frequency characteristic of P(f) becomes worse.展开更多
Co-SiC core-shell powders were prepared by electroless plating. Scanning electron microscopy （SEM） revealed that Co-SiC core-shell powders were of nearly sphere-like shape and were about 0.3 pan. X-ray powder diffra...Co-SiC core-shell powders were prepared by electroless plating. Scanning electron microscopy （SEM） revealed that Co-SiC core-shell powders were of nearly sphere-like shape and were about 0.3 pan. X-ray powder diffraction （XRD） patterns showed that the cobalt powder was hexagonal crystallite. The complex dielectric constant and the complex permeability of Co-SiC core-shell powders-paraffin wax composite were measured by the rectangle wavegnide method. It showed that the dielectric loss was less than 0.1 and the magnetic loss was about 0.2 in 8.2-12.4 GHz for prepared Co-SiC core-shell comoosite oowders.展开更多
0.29Pb(Mg1/2W1/2)O3-0.41Pb(Ni1/3Nb2/3)O3-0.30PbTiO3 + 0.002 5MnO2 + xWO3(PMW-PNN-PT) ceramics were prepared by Semichemical Method. The Mg(Ac)2, Ni(Ac)2, and Mn(NO)3 solution rather than MgO, NiO and MnO2 were added t...0.29Pb(Mg1/2W1/2)O3-0.41Pb(Ni1/3Nb2/3)O3-0.30PbTiO3 + 0.002 5MnO2 + xWO3(PMW-PNN-PT) ceramics were prepared by Semichemical Method. The Mg(Ac)2, Ni(Ac)2, and Mn(NO)3 solution rather than MgO, NiO and MnO2 were added to the slurry of PbO, WO3, Nb2O5 and TiO2 and then calcined at 850 °C for 2 h. Then the sample was sintered at 1 100～1 200 °C for 2 h. The effect of sintering temperature and WO3-excess amounts on the phase constitute, microstructure and the dielectric characteristics was investigated. The result showed that the PMW-PNN-PT powders with pure pervoskite phase were prepared by single-step calcination. The development of sintered temperature contributes to the increase of dielectric constant and the flatness of dielectric temperature dependence. But the dielectric properties will be worse if the sintered temperature is too high. The increase of WO3-excess level lead to an increase of Pb2WO5 phase and the flatness of dielectric curves, but the dielectric constant will be decreased. The proper WO3-excess amount of X7R type PMW-PNN-PT ceramics is 5mol% and the proper sintering condition is 1 150 °C for 2 h, the maximum dielectric constant is 5 395.展开更多
基金The authors gratefully acknowledge the financial support by the National Natural Science Foundation of China(No.52405272)the CNOOC’s major project during the 14th Five-Year Plan period“Key Technologies and Equipment for Measurement,Recording,and Testing-Development and Engineering of Integrated Perforation Technology Equipment Based on Reservoir Geology”and the National Science Foundation of Jiangsu Province(No.BK20220533).
文摘Hydraulic sandblasting perforation plays a crucial role in the fracturing and reconstruction of unconventional oil and gas reservoirs.The jet nozzle is an essential part of the hydraulic perforation tool.Insufficient penetration depth,caused by excessive jet distances,presents challenges during the perforation process.To overcome this,an optimization design of the nozzle structure is required to enhance the perforation efficiency.In this paper,a computational fluid-dynamic model for conical-cylindrical nozzles has been elaborated.To further improve the rock-breaking efficiency of the jet nozzle,a fillet design is introduced at the nozzle inlet section.The SST k-ωmodel is employed to account for turbulent flow effects in submerged conditions.The results indicate that the nozzle’s geometric parameters greatly influence the flow characteristics.The orthogonal experimental method is employed to optimize the flow channel structure of the nozzle,taking the length of constant velocity core as the evaluation index.The following optimized geometric parameters for the conical-cylindrical nozzle have been determined accordingly:a cylindrical segment diameter of 3.2 mm,a contraction angle of 12°,a contraction segment length of 8 mm,a cylindrical segment length of 6.4 mm,and a fillet radius of 2 mm.
文摘The core loss spectrum P(f) of magnetic alloy with constant permeability has been studied. It is found that P(f) has the fractal structure. The effect of the induced anisotropy energy Ku on the fractal dimension Df is discussed.
文摘In order to check the traditional core loss formula, the core loss spectrum P(f) of Co-based amorphous soft magnetic alloy with constant permeability has been studied. It is found that within a high frequency range from 10 kHz to 200 kHz and at Bm = 0. 1 T,the P(f) has the fractal structure P (f) = Po, and with the increasing of induced anisotropy energy Ku, the fractal dimension Dfrises, thus the total power loss at high frequency increases and the frequency characteristic of P(f) becomes worse.
基金This work was financially supported by the Science Fund for Distinguished Young Scholars of Henan Province, China (No. 0512002400)
文摘Co-SiC core-shell powders were prepared by electroless plating. Scanning electron microscopy （SEM） revealed that Co-SiC core-shell powders were of nearly sphere-like shape and were about 0.3 pan. X-ray powder diffraction （XRD） patterns showed that the cobalt powder was hexagonal crystallite. The complex dielectric constant and the complex permeability of Co-SiC core-shell powders-paraffin wax composite were measured by the rectangle wavegnide method. It showed that the dielectric loss was less than 0.1 and the magnetic loss was about 0.2 in 8.2-12.4 GHz for prepared Co-SiC core-shell comoosite oowders.
文摘0.29Pb(Mg1/2W1/2)O3-0.41Pb(Ni1/3Nb2/3)O3-0.30PbTiO3 + 0.002 5MnO2 + xWO3(PMW-PNN-PT) ceramics were prepared by Semichemical Method. The Mg(Ac)2, Ni(Ac)2, and Mn(NO)3 solution rather than MgO, NiO and MnO2 were added to the slurry of PbO, WO3, Nb2O5 and TiO2 and then calcined at 850 °C for 2 h. Then the sample was sintered at 1 100～1 200 °C for 2 h. The effect of sintering temperature and WO3-excess amounts on the phase constitute, microstructure and the dielectric characteristics was investigated. The result showed that the PMW-PNN-PT powders with pure pervoskite phase were prepared by single-step calcination. The development of sintered temperature contributes to the increase of dielectric constant and the flatness of dielectric temperature dependence. But the dielectric properties will be worse if the sintered temperature is too high. The increase of WO3-excess level lead to an increase of Pb2WO5 phase and the flatness of dielectric curves, but the dielectric constant will be decreased. The proper WO3-excess amount of X7R type PMW-PNN-PT ceramics is 5mol% and the proper sintering condition is 1 150 °C for 2 h, the maximum dielectric constant is 5 395.
