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air pressure law of a reservoir constructed in karst sinkholes

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Journal of Mountain Science 2024年第3期21卷 1048-1057页

作者： YU Bo TAI Shengping ZHENG Kexun CHEN Shiwan HAN Xiao WANG Senlin ZUO Shuangying Power China Guiyang Engineering Corporation Limited Guiyang 550081China College of Resources and Environmental Engineering Key Laboratory of Karst Georesources and EnvironmentMinistry of EducationGuizhou UniversityGuiyang 550025China

Karst sinkholes with natural negative landform provide favorable conditions for the pumped storage reservoir construction for less excavation ***,the construction of the reservoir would plug the natural karst channels for water and air,which would cause remarkable air pressure in karst channels when the groundwater level fluctuates.A large laboratory simulation test was carried out to study the air pressure variation of a reservoir built on the karst *** air pressure in the karst channel and inside the model was monitored during the groundwater rising and falling *** showed that the variation of air pressure in the karst channel and the surrounding rock exhibited a high degree of *** air pressure increased rapidly at the initial stage of water level rising,followed by a slight decrease,then the air pressure increased sharply when the water level approached the top of the karst *** initial peak of air pressure and the final peak of air pressure were defined,and both air pressure peaks were linearly increasing with the water level rising *** negative air pressure was also analyzed during the drainage process,which was linearly correlated with the water level falling *** causes of air pressure variation in karst channels of a pumped storage reservoir built on the karst sinkhole were *** initial rapid increase,then slight decrease and final sudden increase of air pressure were controlled by the combined effects of air compression in karst channel and air seepage into the surrounding *** the drainage process,the instant negative air pressure and gradual recovering of air pressure were controlled by the combined effects of negative air pressure induced by water level falling and air supply from surrounding *** work could provide valuable reference for the reservoir construction in karst area.

关键词： Simulation test Karst sinkhole Pumped storage reservoir air pressure Flow rate

Impacts of air pressure on the evolution of nanosecond pulse discharge products

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Chinese Physics B 2013年第5期22卷 363-368页

作者：于锦禄何立明丁未王育虔杜纯 The Engineering Institute Air Force Engineering University Department of Training Air Force Engineering University

Based on the nonequilibrium plasma dynamics of air discharge, a dynamic model of zero-dimensional plasma is established by combining the component density equation, the Boltzmann equation, and the energy transfer equation. The evolution properties of nanosecond pulse discharge （NPD） plasma under different air pressures are calculated. The results show that the air pressure has significant impacts on the NPD products and the peak values of particle number density for particles such as O atoms, 03 molecules, N2（A3） molecules in excited states, and NO molecules. It increases at first and then decreases with the increase of air pressure. On the other hand, the peak values of particle number density for N2（B3） and N2（C3） molecules in excited states are only slightly affected by the air pressure.

关键词： plasma air pressure evolution numerical simulation

Experiments and Analysis of Corona Inception Voltage Under Combined AC-DC Voltages at Various air pressure and Humidity in Rod to Plane Electrodes

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CSEE Journal of Power and Energy Systems 2021年第4期7卷 875-888页

作者： Zichen He Junyu Zhu Jie Zhu Xingming Bian Boyang Shen State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China State Grid Suzhou Power Supply Company Suzhou 215000Jiangsu ProvinceChina Electrical Engineering Division University of CambridgeCambridge CB30FAUK

As the effect of climate plays a significant role in corona discharge under combined voltages,the variation of corona inception voltage with different air pressure and humidities is *** experimental platform,based on a rod-to-plane electrode,is constructed with adjustable air pressure from 0.06 MPa to 0.10 MPa and with a relative humidity(RH)from 20%to 90%.The variation of ultraviolet(UV)photon count and corona inception voltage is obtained at various climate conditions under different applied voltages:the single AC,single DC,and combined *** turns out that all the corona inception voltages decline with the drop of air pressure and the rise of humidity under different applied *** influence between different voltages primarily relies on space charge,as more AC components make it easier to accumulate positive *** existence of AC makes ions move forward and backward while the existence of DC dominates the polarity of corona and general drift *** last the fitting formula of hybrid corona inception voltage combining air pressure and relative humidity is given.

关键词： air pressure combined AC and DC voltages corona discharge humidity inception voltage

Effect of air pressure on Hardened Layer of U75V 60 kg/m Heavy Rail after Heat Treatment

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Journal of Harbin Institute of Technology(New Series) 2013年第1期20卷 52-56页

作者： Hao Kang Xian-Ming Zhao Di Wu State Key Lab of Rolling and Automation Northeastern University

The samples cut from U75V 60 kg/m heavy rail are heated to 900 ℃ in resistance furnace and then put into air spraying channel to be cooled for 80 s, and change air pressure from 0.16 MPa to 0.33 MPa, and observe the effect of air pressure on hardened layer. The thickness and hardness of hardened layer increases with the increase of air pressure, and the thickness is more than 24 mm at the center and top fillets of rail head, and more than 15 mm at the blow fillets of rail head when air pressure is more than 0.26 MPa. During the tempering after heat treatment, tempering temperature of rail head is more than 570 ℃ when air pressure is separately 0.16 MPa, 0.20 MPa and 0.23 MPa, which is higher than finishing temperature of pearlite transformation at the cooling rate of 3 ℃/s according to CCT curve of U75V steel. When air pressure is separately 0.26, 0.30 and 0.33 MPa, the tempering temperature is 529 ℃ lower than finishing temperature of pearlite transformation at the cooling rate of 3 ℃/s. Under this condition, pearlite transformation is finished totally, so in order to reduce air consumption and control the cost, proper air pressure for U75V 60 kg/m heavy rail heat treating should be 0.26 MPa; the cooling rate increases with the increase of air pressure, and the average cooling rate on the surface of rail head is more than 3.21 ℃/s when air pressure is more than 0.26 MPa, and the largest cooling rate occurs at the top fillets of rail head.

关键词： air pressure hardened layer heavy rail heat treatment

Influence of air pressure on mechanical effect of laser plasma shock wave

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Chinese Physics B 2007年第9期16卷 2752-2756页

作者：章玉珠王广安朱金荣沈中华倪晓武陆建 Department of Applied Physics Nanjing University of Science & Technology Nanjing 210094 China

The influence of air pressure on mechanical effect of laser plasma shock wave in a vacuum chamber produced by a Nd：YAG laser has been studied. The laser pulses with pulse width of 10ns and pulse energy of about 320mJ at 1.06μm wavelength is focused on the aluminium target mounted on a ballistic pendulum, and the air pressure in the chamber changes from 2.8 × 10^ 3 to 1.01 × 10^5pa. The experimental results show that the impulse coupling coefficient changes as the air pressure and the distance of the target from focus change. The mechanical effects of the plasma shock wave on the target are analysed at different distances from focus and the air pressure.

关键词： mechanical effect plasma shock wave impulse coupling coefficient air pressure

About the Change in air pressure in the Pipeline during the Pneumatic Transportation of Cotton

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Engineering（科研） 2022年第7期14卷 228-234页

作者： Farhod Kholmirzaev Maftuna Yusupova Abdul-Malik Kayumov Olimjon Sarimsakov Namangan Institute of Engineering and Technology Namangan Uzbekistan

The article is devoted to the study of the issues of determining the patterns of changes in air pressure along the length of a pneumatic transmission pipeline for raw cotton at different flow parameters and different pipeline diameters. Theoretical studies have proved the reduction of static and total pressure along the line of pneumatic cotton transportation. The dependence of the pressure change on the diameter of the transport line and the aerodynamic drag of the pipeline is obtained. The results obtained are recommended for use in the design of raw cotton pneumatic transport systems.

关键词： Pneumatic Conveying Pipeline Raw Сotton air pressure A Fan

Study on the Relationship of Spray Rate to air pressure and Gravity Drop of Siphonic Nozzle

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Agricultural Science & Technology 2017年第10期18卷 1960-1962页

作者： Xianyan SU Xuexiang REN Weiwei HE Fei HU Zhenghe YE Institute of Plant Protection and Agricultural Product Quality Safety Anhui Academy of Agricultural Sciences Hefei 230031 China Anhui Agriculture University Hefei 230001 China

In order to further clarify the spraying performance of siphonic nozzle, the spray rate of siponic cone nozzle with aperture of 1.0 mm was determined at 15 different air pressure levels and 12 gravity drop levels, and DPS and SPSS were used to make the difference analysis and modeling, which clarified the relationship between the spray rate of the siphonic cone nozzle with aperture of 1.0 mm and air pressure and gravity drop, getting the regression equation of Y=406.854P＋ 1.904G＋77.524. The study could provide a theoretical basis for the optimization and improvement of plant protection spraying equipment.

关键词： Siphonic nozzle Spray rate air pressure Gravity drop

Effects of Gamma-Ray Irradiation on Dielectric Surface Breakdown of Polybutylene Naphthalate and Polybutylene Terephthalate Under Reduced pressure

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Transactions of Tianjin University 2007年第4期13卷 247-253页

作者：杜伯学刘弘景刘勇孟令飞 School of Electrical Engineering and Automation Tianjin University

With the increasing application of electric and electronic devices in space and nuclear power stations, the polymeric insulation materials are inevitably exposed to various kinds of environments. Accordingly, it becomes necessary to investigate the effects of the radiation and air pressure on insulation materials. This paper describes the effects of gamma-ray irradiation and reduced pressure on dielectric breakdown of polybutylene naphthalate (PBN) and polybutylene terephthalate (PBT) by applying a DC pulse voltage. Both PBN and PBT were irradiated in air up to 100 kGy and then up to 1 000 kGy with a dose rate of 10 kGy/h by using a60Co gamma-source. The effects of total dose and reduced pressure on the time to dielectric breakdown and discharge quantity were discussed. Obtained results show that, while increasing the total dose, the discharge quantity decreased with PBN, but increased with PBT. With decreasing the air pressure, the discharge quantity increased with PBN, but decreased with PBT. With increasing the total dose, the time to dielectric breakdown increased with PBN, but decreased with PBT. With decreasing the air pressure, the time to dielectric breakdown increased with both PBN and PBT. The experimental results suggest that the chemical structure of polybutylene polymers plays a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction.

关键词： polybutylene naphthalate (PBN) polybutylene terephthalate ( PBT) air pressure total dose gamma-ray irradiation discharge quantity dielectric breakdown cross-linking degradation

EFFECTS OF ENTRAINED air MANNER ON CAVITATION DAMAGE

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Journal of Hydrodynamics 2011年第3期23卷 333-338页

作者： WU Jian-hua LUO Chao College of Water Conservancy and Hydropwer Engineering Hohai University Nanjing 210098 China

Early in 1953 the experiments by Peterka proved that air entrainment has effects on decreasing cavitation damage. This technology has been widely used in the release works of high dams since the inception of air entrainment in the Grand Goulee Dam in 1960. Behavior, mechanism and application of air entrainment for cavitation damage control have been investigated for over half century. However, severe cavitation damage happened due to complex mechanism of air entrainment. The effects of air entrainment are related to many factors, including geometric parameters, hydraulic parameters and entrained air manners. In the present work an experimental set-up for air entrainment was specially designed, the behavior of reducing cavitation damage was experimentally investigated in the three aspects of entrained air pressure, air tube aera and air tube number. The results show that magnitude of reduction of cavitation damage is closely related to the entrained air tube number as well as entrained air pressure, air tube aera, and that the effect through three air tubes is larger than that through single air tube although the entrained air tubes have the same sum of tube aera, that is, 1 ＋ 1 ＋ 1 〉 3. Therefore, it is important to design an effective manner of air entrainment.

关键词： air entrainment air pressure air tube area cavitation damage entrained air manner