A series of air induction nozzles were tested in a high-speed wind tunnel.Droplet size spectra were measured for four air induction nozzles(IDK-120-01,IDK-120-02,IDK-120-03 and IDK-120-04)each at three spray pressures...A series of air induction nozzles were tested in a high-speed wind tunnel.Droplet size spectra were measured for four air induction nozzles(IDK-120-01,IDK-120-02,IDK-120-03 and IDK-120-04)each at three spray pressures(0.3,0.4 and 0.5 MPa)and seven different air velocities(121.7,153.4,185.5,218.4,253.5,277.5 and 305.5 km·h^(-1)).The measurement distance(0.15,0.25 and0.35 m)from the nozzle orifice was found to be important for the atomization of the droplets.The response surface method was used to analyze the experimental data.The results indicated that Dv_(0.1)and Dv_(0.5)of the droplets decreased quasi-linearly with increased wind speed,while Dv_(0.9)was affected by the quadratic of wind speed.Dv_(0.1),Dv_(0.5)and Dv_(0.9)of the droplets were all proportional to the orifice size,and were not markedly influenced by the spray pressure.The percentage of the spray volume consisting of droplets with a diameter below 100 mm(%<100 mm)was found to be quadratically related to wind speed,and was not markedly influenced by the spray pressure and orifice size.However,the effect of the orifice size on the %<200 mm could not be ignored.展开更多
云滴谱宽度对模式中云的光学厚度的参数化、气溶胶间接效应的评估以及降水形成过程的研究至关重要。本文利用美国POST(Physics of Stratocumulus Top)项目2008年7月19日的飞机观测资料,分析了微物理量和云滴谱的垂直分布及微物理过程。...云滴谱宽度对模式中云的光学厚度的参数化、气溶胶间接效应的评估以及降水形成过程的研究至关重要。本文利用美国POST(Physics of Stratocumulus Top)项目2008年7月19日的飞机观测资料,分析了微物理量和云滴谱的垂直分布及微物理过程。结果表明,该云系云滴谱宽度在云底附近较大,这是由低层核化过程导致的;中层凝结增长过程使得云滴谱宽度随高度增加逐渐减小;云顶附近夹卷混合过程导致云滴谱宽度增大。绝热云中垂直速度的增大会促进云凝结核的活化使云滴数浓度增大,促进凝结增长使云滴尺度增大、云滴谱宽度减小,云滴谱宽度与云滴数浓度、云滴尺度呈现负相关关系;云洞中受夹卷混合过程影响,垂直速度减小,云滴蒸发,云滴数浓度和云滴尺度减小、云滴谱宽度增大,且该效应随绝热程度减小而增强。建议云滴谱宽度的参数化将垂直速度、云滴数浓度、云滴尺度和绝热程度等考虑在内。展开更多
ABSTRACT This paper reports airborne measurements of midlatitude altostratus clouds observed over Zhengzhou, Henan Province, China on 3 March 2007. The case demonstrates mixed-phase conditions at altitudes from 3200 ...ABSTRACT This paper reports airborne measurements of midlatitude altostratus clouds observed over Zhengzhou, Henan Province, China on 3 March 2007. The case demonstrates mixed-phase conditions at altitudes from 3200 to 4600 m （0°C to -7.6°C）, with liquid water content ranging from 0.01 to 0.09 g m-3. In the observed mixed-phase cloud, liquid water content exhibited a bimodal distribution, whereas the maximum ice particle concentration was located in the middle part of the cloud. The liquid and ice particle data showed significant horizontal variability on the scale of a few hundred meters. The cloud droplet concentration varied greatly over the horizontal sampling area. There was an inverse relationship between the cloud droplet concentration and ice particle concentration. A gamma distribution provided the best description of the cloud droplet spectra. The liquid droplet distributions were found to increase in both size and concentration with altitude. It was inferred from the profile of the spectra parameters that the cloud droplet sizes tend to form a quasi-monodisperse distribution. Ice particle spectra in the cloud were fitted well by an exponential distribution. Finally, a remarkable power law relationship was found between the slope （λ） and intercept （No） parameters of the exponential size distribution.展开更多
Since the high temperature and humidity in a closed environment,pests and diseases are infecting and spreading seriously in greenhouses.However,the prevention and control of pests and diseases in greenhouses are still...Since the high temperature and humidity in a closed environment,pests and diseases are infecting and spreading seriously in greenhouses.However,the prevention and control of pests and diseases in greenhouses are still dominated by knapsack sprayers.For those reasons,based on twin-fluid atomization,droplet dispersion,and constant pressure transportation technique,a fixed-pipe cold aerosol spraying system composed of the control unit and the fixed-pipe spraying unit comes into being.The indoor pipeline execution unit of the spraying system could be interfaced with the liquid-supply or gas-supply equipment such as the liquid pump,air compressor,and tank of the outdoor master control unit through a quick coupling,which could realize the separation of operator and sprayer in hermetic greenhouse.The atomization of twin-fluid nozzle and the droplet deposition and distribution of the spraying system in greenhouse were tested.Results showed that about 70%of the particle size of the twin-fluid flow nozzle concentrated in the range of 32-65μm under the spraying air pressure ranged from 0.2 MPa to 0.4 MPa.When the air pressure was 0.2 MPa,0.3 MPa,and 0.4 MPa,the wind speed at the nozzle outlet reached supersonic speed,as the corresponding VMD of droplets were 45.6μm,43.2μm,and 36.8μm,respectively.The higher the air pressure is,the more uniform the spray deposition is in the greenhouse.When the air pressure was 0.2 MPa,0.3 MPa,and 0.4 MPa,the CVs of the liquid deposition in the greenhouse were 109.1%,62.6%,and 35.4%,respectively.The droplets produced by the spraying system will rapidly disperse into the whole greenhouse.The average deposition was 2.99μL/cm2 in the front area of the nozzle,the deposition was 1.24μL/cm2 in the area between two nozzles,and the deposition was 0.58μL/cm2 in the area behind the nozzles.The spraying system is characterized by the distribution of spraying liquid throughout the entire greenhouse.展开更多
A complex interaction of controllable and uncontrollable factors is involved in aerial application of crop production and protection materials.Although it is difficult to completely characterize spray deposition and d...A complex interaction of controllable and uncontrollable factors is involved in aerial application of crop production and protection materials.Although it is difficult to completely characterize spray deposition and drift,these important factors can be estimated with appropriate sampling protocol and analysis.Application height is an important variable influencing off-target spray drift,but this variable has not been easily measured or logged.A custom-configured aircraft-mounted laser with logging capabilities makes this possible.This study was designed to investigate droplet size and deposition characteristics of a low drift CP flat-fan nozzle at application altitudes 3.7 m,4.9 m,and 6.1 m.In the study,CP flat-fan nozzles were set to a downward angle of 30 degrees applying a mixture of water,Syl-Tac®adjuvant,and Rubidium Chloride(RbCl)tracer at a 28.5 L/ha application rate.Spray droplets were collected using water sensitive paper(WSP)cards placed in the spray swath.Mylar sheets were also placed in the swath and downwind for drift sampling.Statistical analysis indicated that median droplet diameter as determined by WSP in the spray swath was not significantly influenced by spray application height.Similarly,statistical analysis also indicated that concentration of RbCl tracer from Mylar samplers in the spray swath was not significantly influenced by application height.Application height had a significant effect on spray deposition from drift samplers,along with wind direction and relative humidity.Final results for drift samplers may have been influenced by shifts in wind direction that altered the relationship between orientation of samplers and wind.展开更多
基金supported by the National Natural Science Foundation of China(31601228,31701315)the Youth Science Fund of the Beijing Natural Science Foundation(6164032)+1 种基金the Youth Science Fund of Beijing Academy of Agriculture and Forestry Sciences(QNJJ201631)Beijing Talent Program for Ruirui Zhang
文摘A series of air induction nozzles were tested in a high-speed wind tunnel.Droplet size spectra were measured for four air induction nozzles(IDK-120-01,IDK-120-02,IDK-120-03 and IDK-120-04)each at three spray pressures(0.3,0.4 and 0.5 MPa)and seven different air velocities(121.7,153.4,185.5,218.4,253.5,277.5 and 305.5 km·h^(-1)).The measurement distance(0.15,0.25 and0.35 m)from the nozzle orifice was found to be important for the atomization of the droplets.The response surface method was used to analyze the experimental data.The results indicated that Dv_(0.1)and Dv_(0.5)of the droplets decreased quasi-linearly with increased wind speed,while Dv_(0.9)was affected by the quadratic of wind speed.Dv_(0.1),Dv_(0.5)and Dv_(0.9)of the droplets were all proportional to the orifice size,and were not markedly influenced by the spray pressure.The percentage of the spray volume consisting of droplets with a diameter below 100 mm(%<100 mm)was found to be quadratically related to wind speed,and was not markedly influenced by the spray pressure and orifice size.However,the effect of the orifice size on the %<200 mm could not be ignored.
文摘云滴谱宽度对模式中云的光学厚度的参数化、气溶胶间接效应的评估以及降水形成过程的研究至关重要。本文利用美国POST(Physics of Stratocumulus Top)项目2008年7月19日的飞机观测资料,分析了微物理量和云滴谱的垂直分布及微物理过程。结果表明,该云系云滴谱宽度在云底附近较大,这是由低层核化过程导致的;中层凝结增长过程使得云滴谱宽度随高度增加逐渐减小;云顶附近夹卷混合过程导致云滴谱宽度增大。绝热云中垂直速度的增大会促进云凝结核的活化使云滴数浓度增大,促进凝结增长使云滴尺度增大、云滴谱宽度减小,云滴谱宽度与云滴数浓度、云滴尺度呈现负相关关系;云洞中受夹卷混合过程影响,垂直速度减小,云滴蒸发,云滴数浓度和云滴尺度减小、云滴谱宽度增大,且该效应随绝热程度减小而增强。建议云滴谱宽度的参数化将垂直速度、云滴数浓度、云滴尺度和绝热程度等考虑在内。
基金supported by the National Natural Science Foundation of China (Grant No. 41175120)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-EW-203)
文摘ABSTRACT This paper reports airborne measurements of midlatitude altostratus clouds observed over Zhengzhou, Henan Province, China on 3 March 2007. The case demonstrates mixed-phase conditions at altitudes from 3200 to 4600 m （0°C to -7.6°C）, with liquid water content ranging from 0.01 to 0.09 g m-3. In the observed mixed-phase cloud, liquid water content exhibited a bimodal distribution, whereas the maximum ice particle concentration was located in the middle part of the cloud. The liquid and ice particle data showed significant horizontal variability on the scale of a few hundred meters. The cloud droplet concentration varied greatly over the horizontal sampling area. There was an inverse relationship between the cloud droplet concentration and ice particle concentration. A gamma distribution provided the best description of the cloud droplet spectra. The liquid droplet distributions were found to increase in both size and concentration with altitude. It was inferred from the profile of the spectra parameters that the cloud droplet sizes tend to form a quasi-monodisperse distribution. Ice particle spectra in the cloud were fitted well by an exponential distribution. Finally, a remarkable power law relationship was found between the slope （λ） and intercept （No） parameters of the exponential size distribution.
基金supported by the National Basic Research Program of China(973 Program)[Grant 2014CB441403]the National Natural Science Foundation of China [Grants41275147]+1 种基金the National Key Research and Development Program of China [2016YFC0209000]Ningxia scientific supporting program [Grants 2015KJHM31]
基金subsidized by the National Natural Science Foundation of China(Grant No.31901419)the Natural Science Foundation of Jiangsu Province(Grant No.BK20200280)+1 种基金the Jiangsu Agricultural Science and Technology Innovation Fund[Grant No.CX(20)1005]the China Postdoctoral Science Foundation(Grant No.2020M671390).
文摘Since the high temperature and humidity in a closed environment,pests and diseases are infecting and spreading seriously in greenhouses.However,the prevention and control of pests and diseases in greenhouses are still dominated by knapsack sprayers.For those reasons,based on twin-fluid atomization,droplet dispersion,and constant pressure transportation technique,a fixed-pipe cold aerosol spraying system composed of the control unit and the fixed-pipe spraying unit comes into being.The indoor pipeline execution unit of the spraying system could be interfaced with the liquid-supply or gas-supply equipment such as the liquid pump,air compressor,and tank of the outdoor master control unit through a quick coupling,which could realize the separation of operator and sprayer in hermetic greenhouse.The atomization of twin-fluid nozzle and the droplet deposition and distribution of the spraying system in greenhouse were tested.Results showed that about 70%of the particle size of the twin-fluid flow nozzle concentrated in the range of 32-65μm under the spraying air pressure ranged from 0.2 MPa to 0.4 MPa.When the air pressure was 0.2 MPa,0.3 MPa,and 0.4 MPa,the wind speed at the nozzle outlet reached supersonic speed,as the corresponding VMD of droplets were 45.6μm,43.2μm,and 36.8μm,respectively.The higher the air pressure is,the more uniform the spray deposition is in the greenhouse.When the air pressure was 0.2 MPa,0.3 MPa,and 0.4 MPa,the CVs of the liquid deposition in the greenhouse were 109.1%,62.6%,and 35.4%,respectively.The droplets produced by the spraying system will rapidly disperse into the whole greenhouse.The average deposition was 2.99μL/cm2 in the front area of the nozzle,the deposition was 1.24μL/cm2 in the area between two nozzles,and the deposition was 0.58μL/cm2 in the area behind the nozzles.The spraying system is characterized by the distribution of spraying liquid throughout the entire greenhouse.
文摘A complex interaction of controllable and uncontrollable factors is involved in aerial application of crop production and protection materials.Although it is difficult to completely characterize spray deposition and drift,these important factors can be estimated with appropriate sampling protocol and analysis.Application height is an important variable influencing off-target spray drift,but this variable has not been easily measured or logged.A custom-configured aircraft-mounted laser with logging capabilities makes this possible.This study was designed to investigate droplet size and deposition characteristics of a low drift CP flat-fan nozzle at application altitudes 3.7 m,4.9 m,and 6.1 m.In the study,CP flat-fan nozzles were set to a downward angle of 30 degrees applying a mixture of water,Syl-Tac®adjuvant,and Rubidium Chloride(RbCl)tracer at a 28.5 L/ha application rate.Spray droplets were collected using water sensitive paper(WSP)cards placed in the spray swath.Mylar sheets were also placed in the swath and downwind for drift sampling.Statistical analysis indicated that median droplet diameter as determined by WSP in the spray swath was not significantly influenced by spray application height.Similarly,statistical analysis also indicated that concentration of RbCl tracer from Mylar samplers in the spray swath was not significantly influenced by application height.Application height had a significant effect on spray deposition from drift samplers,along with wind direction and relative humidity.Final results for drift samplers may have been influenced by shifts in wind direction that altered the relationship between orientation of samplers and wind.
