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Simulation and experimental research on droplet flow characteristics and deposition in airflow field

International Journal of Agricultural and Biological Engineering 2020年第6期13卷 16-24页

作者： Bing Xiahou daozong sun Shuran Song Xiuyun Xue Qiufang Dai Logistics Department South China Agricultural UniversityGuangzhou 510642China College of Electronic Engineering College of Artificial IntelligenceSouth China Agricultural UniversityGuangzhou 510642China Division of Citrus Machinery China Agriculture Research SystemGuangzhou 510642China Guangdong Engineering Research Center for Monitoring Agricultural Information Guangzhou 510642China Guangdong Engineering Technology Research Center for Mountainous Orchard Machinery Guangzhou 510642China

In order to study the motion law of droplet flow under the airflow action of long-range air-blast sprayers,a CFD-based 3D model was established for the air-blast sprayer duct and its external airflow field,and the discrete phase model was introduced to simulate the motion of droplet flow in the *** simulation data of the droplet flow trajectory,droplet flow parameters and droplet deposition were obtained by establishing the monitoring sections and bilateral coupling calculation in the airflow *** showed that gravity had an obvious effect on droplets and large droplets settled *** of the larger droplets were formed by polymerization in droplets *** smaller droplets were transported further along with the airflow,and the long-range sprayer has a significant effect on the directional transport of small ***,the spraying swath in the direction perpendicular to the range enlarged gradually with the increase of the spraying *** the end of the range,the diffuse and drifting of the droplets were *** that the outlet airflow velocity of the sprayer duct was 25.01 m/s and the spray pressure 1.8 MPa,the maximum motion distances of aerosol,mist,fine mist and coarse mist in the airflow field were 18.5 m,19.5 m,17.5 m and 10.5 m,*** size and number as well as number density and volume density of droplet flow on all monitoring sections showed a regression function with changes in the distance of the spraying *** simulation results of the model adopted in this paper were verified by Chi-square test between the simulation results of the droplet deposition and the spray measurement *** results provide a new method for the study of orchard air-blast spraying technology and references for the optimization of spraying technology.

关键词： droplet flow droplet density air-blast sprayer computational fluid dynamics droplet deposition

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Response of droplet parameters to liquid viscosity in the flow field of an air-blast sprayer

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International Journal of Agricultural and Biological Engineering 2023年第5期16卷 28-34页

作者： Xi'en Zhou Bing Xiahou Long Zhang daozong sun Xiuyun Xue Qiufang Dai Shuran Song College of Engineering South China Agricultural UniversityGuangzhou 510642China General Affairs Department South China Agricultural UniversityGuangzhou 510642China Datang Hubei Energy Development Co. LtdWuhan430000China College of Electronic Engineering/College of Artificial Intelligence South China Agricultural UniversityGuangzhou 510642China Guangdong Engineering Research Center for Monitoring Agricultural Information Guangzhou 510642China Guangdong Laboratory for Lingnan Modern Agriculture Guangzhou 510642China

The physical properties of sprayed droplets such as viscosity affect their deposition on the *** order to understand the response characteristics of droplet parameters to the viscosity of a spray solution,a three-dimensional model of the external flow field of an air-blast sprayer based on computational fluid dynamics(CFD)was established according to the actual spray range and the sprayer duct *** change rules of droplet diameter and droplet density with distance under different viscosities of the spray solution in the flow field were obtained through numerical solution of the CFD *** reliability of the model was verified by a chi-squared test comparing the numerical calculations with the results of field *** results showed that the change rule of droplet parameters in an airflow field under different values of the spray solution viscosity was *** the increase in the axial distance,the droplet size decreased initially,then increased,and finally decreased,while the droplet density gradually ***,the greater the spray solution viscosity,the shorter the conveying distance of the droplets in the axial direction,although viscosity was helpful in reducing the droplet *** addition,at the same axis distance,with the increased viscosity of the spray solution,the droplet size increased,and the sedimentation of the droplets was more rapid,while the density of the droplets *** results provided a new framework for the study of air-blast spraying technology and serve as a reference for the optimization of the sprayer structure and the preparation method for spray solutions.

关键词： air-blast sprayer computational fluid dynamics droplet diameter droplet density viscosity

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Monocular vision for variable spray control system

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International Journal of Agricultural and Biological Engineering 2022年第6期15卷 206-215页

作者： daozong sun Weikang Liu Runmei Luo Xurui Zhan Zehong Chen Tao Wei Xinrui Wang Xiuyun Xue Zhen Li Shuran Song College of Electronic Engineering(College of Artificial Intelligence) South China Agricultural UniversityGuangzhou 510642China Guangdong Engineering Research Center for Monitoring Agricultural Information Guangzhou 510642China National Citrus Industry Technology System Mechanization Research Laboratory Guangzhou 510642C

The monocular vision-based system can obtain the leaf wall area characterizing the canopy parameter for online detection and real-time variable spraying,aiming to improve the accuracy of orchard spraying equipment and the utilization efficiency of *** study established a spraying system,in which canopy parameters were collected by monocular vision,and the spray volume decision coefficient was constructed by the leaf wall area and the L^(*)value in International Commission on Illumination Lab color space to control the duty cycle of each solenoid valve to achieve variable *** spray flow models were designed to determine the spray volume decision *** coefficients of determination of the spray volumes with the duty cycle range of 15%to 65%were all over 94 and the error of the leaf wall area values obtained using the improved super green algorithm(calculated as ExG=2.1G–1.1R–1.1B)was only 0.5%.The test showed that there is a negative relationship between canopy denseness and L^(*),and the value of L^(*)is smaller in the dense area compared with the sparse area;the actual flow generated by the system is similar to the theoretical flow when the duty cycle is 65%.The field validation tests showed that the variable spraying system could refine the droplet size and increase the droplet density to a certain extent with the same coverage rate,which had advantages over the continuous *** terms of droplet deposition,DV0.1 and DV0.9 were reduced by 2μm and 18μm,respectively,and the increase of droplet density to 75 droplets/*** the same time,the improvement of droplet distribution uniformity and droplet penetration by 16%and 3%,*** with continuous spraying,variable spraying can achieve 55.64%*** study demonstrates the feasibility of monocular vision in guiding spraying operations and provides a reference for the use of monocular vision in plant protection operations.

关键词： monocular vision leaf wall area Lab color space pulse width modulation variable sprayi

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Effects of Liquid Viscosity on Agricultural Nozzle Droplet Parameters

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Agricultural Sciences 2019年第9期10卷 1217-1239页

作者： Long Zhang Shuran Song daozong sun Xiuyun Xue Qiufang Dai Zhen Li College of Electronic Engineering South China Agricultural University Guangzhou China Division of Citrus Machinery China Agriculture Research System Guangzhou China Guangdong Engineering Research Center for Monitoring Agricultural Information Guangzhou China Guangdong Engineering Technology Research Center for Mountainous Orchard Machinery Guangzhou China

To discuss the effects of pesticide viscosity on the atomisation characteristics of an agricultural nozzle, glycerite with different mass fractions was prepared to replace the pesticide. First, the atomisation region of the nozzle was meshed and sized. Second, the speed and kinetic energy of the droplets at different positions in the atomisation region were measured by Phase Doppler Anemometry. The results demonstrated that the Sauter mean diameter, volume mean diameter and arithmetic mean diameter of droplets first decreased and then increased gradually in the axial direction of the atomisation region. Surface waves of a certain pattern were formed on the liquid surface, which was ejected by the disturbance of external air resistance. As the distance increased, the amplitude increased and the wave crest was broken into small droplets. These droplets then collided and agglomerated into large droplets under the effect of gravity. Droplets had an approximately symmetric distribution on the radial direction of the atomisation region, and the droplets were small in the middle and large at the two ends. The droplet size was positively related to the radial distance. Compared with the droplet speed at the two ends, the droplet speed at the axis was higher and the droplet size was smaller. Moreover, the kinetic energy of the droplets along the axial direction decreased sharply and then increased slowly. Droplets with high viscosity at the near end of the nozzle had small kinetic energy, and the effects of liquid viscosity on the atomisation characteristics of a nozzle could not be neglected. The droplet kinetic energy slightly increased at the far end.

关键词： Viscosity Atomisation Droplet Spectrum Droplet Size Droplet Kinetic Energy

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能量自给的果园信息采集无线传感器网络节点设计

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农业工程学报 2012年第9期28卷 153-158页

作者：姜晟王卫星孙道宗李震华南农业大学工程学院广州510642

针对果园中所存在的无线通信障碍与电池更换困难问题,该文设计了一款适合果园信息采集的无线传感器网络(wirelesssensor network,WSN)节点。节点以MSP430F149为核心,nRF905射频芯片及其外围电路作为无线通信模块,CN3058和HT6292智能充... 详细信息

针对果园中所存在的无线通信障碍与电池更换困难问题,该文设计了一款适合果园信息采集的无线传感器网络(wirelesssensor network,WSN)节点。节点以MSP430F149为核心,nRF905射频芯片及其外围电路作为无线通信模块,CN3058和HT6292智能充电芯片及其外围电路作为太阳能充电模块,电机驱动芯片ULN2003及水平、垂直电机作为太阳追踪模块,DHT22空气温湿度传感器和TDR-3土壤含水量传感器及其外围电路作为传感器模块,并以该硬件平台编写了通信协议、应用程序和时间同步算法。分析、测试了节点的功耗、通信距离以及太阳能充电时间,在空旷地带有效通信距离达到202m;主电路电池由3V充电至3.6V所需时间为580min,传感器电路电池由5.6V充电至7.2V所需时间为283min;在无太阳能充电且节点系统工作周期为30min情况下,主电路生命周期理论值为497d,传感器电路生命周期理论值为147d。组网试验结果表明:网络丢包率小于1.5%,能够满足果园信息采集以及能量自给的应用要求。

关键词：无线传感器网络太阳能信息采集能量自给低功耗果园

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基于二维马尔可夫过程全局模型的图像压缩

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光学技术 2020年第5期46卷 634-640页

作者：陈易平孙道宗朱岸青广东技术师范大学天河学院计算机科学与工程学院广东广州510540 华南农业大学电子工程学院广东广州510642 暨南大学管理学院广东广州510000

为了有效降低计算的复杂度并保证压缩质量,提出了一种基于可分二维马尔可夫过程全局模型的单模低复杂度图像压缩方法。在假定的全局图像模型上寻求最优的空间预测,其模型构建主要采用了可分二维马尔可夫过程;对预测残差块进行变换编码... 详细信息

为了有效降低计算的复杂度并保证压缩质量,提出了一种基于可分二维马尔可夫过程全局模型的单模低复杂度图像压缩方法。在假定的全局图像模型上寻求最优的空间预测,其模型构建主要采用了可分二维马尔可夫过程;对预测残差块进行变换编码进一步消除空间冗余。方法与视频编码中的帧内编码类似,但仅使用一种空间预测模式(单模)以便有效降低算法的复杂度。实验结果表明,与相似的低复杂度单模图像编码器相比,单模方法在平均编码/解码时间不变的情况下,平均比特率(BD-BR)有所改善(约12%),且在低比特率下没有产生明显的方块效应,证明了方法的有效性。

关键词：图像压缩马尔可夫过程离散余弦变换全局图像模型空间预测

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果园悬挂式柔性对靶喷雾装置研制与试验

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农业工程学报 2022年第18期38卷 11-20页

作者：陈泽鸿陈建泽宋淑然孙道宗华南农业大学电子工程学院广州510642 广东利元亨智能装备股份有限公司惠州516000 广东省农情信息监测工程技术研究中心广州510642 国家柑橘产业技术体系机械化研究室广州510642

为减少农药飘移损失,保护生态环境,该研究从提高喷雾有效性和降低喷雾装置对果树枝叶的机械性损伤出发,研制了一种悬挂式柔性对靶喷雾装置。该装置以东方红MS-304拖拉机为载体,采用超声波传感器探测树冠位置,利用霍尔传感器构建测速模... 详细信息

为减少农药飘移损失,保护生态环境,该研究从提高喷雾有效性和降低喷雾装置对果树枝叶的机械性损伤出发,研制了一种悬挂式柔性对靶喷雾装置。该装置以东方红MS-304拖拉机为载体,采用超声波传感器探测树冠位置,利用霍尔传感器构建测速模块。对株距4.0 m、树高1.6 m、树冠直径1.4 m的橘树进行对靶喷雾试验验证悬挂式柔性对靶喷雾装置作业性能。试验结果表明:拖拉机行驶速度为0.5 m/s时,喷雾压力0.4、0.5及0.6 MPa对应的平均药液附着率分别为84.7%、91.7%、88.9%,药液附着率较高且接近,喷雾压力对药液附着率的影响不明显;拖拉机行驶速度为1.0 m/s时,喷雾压力0.4、0.5和0.6 MPa对应的平均药液附着率分别为64.2%、70.3%、75.8%,喷雾压力越大,药液附着率越高;拖拉机行驶速度为1.5 m/s时,平均药液附着率低于50%,且喷雾飘移较为严重,不适宜进行自动对靶喷雾;拖拉机行驶速度和喷雾压力相同时,药液附着率按树冠上、中、下层顺序呈递减规律,且速度越高,递减规律越明显。研究结果对提高果园对靶喷雾的药液附着率具有较好的实用价值。

关键词：植保机械果园对靶喷雾柔性超声波测距附着率

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柑橘全爪螨虫害快速检测仪的研制与试验

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农业工程学报 2014年第14期30卷 49-56页

作者：李震洪添胜王建李楠孙道宗林瀚华南农业大学工程学院广州510642 南方农业机械与装备关键技术教育部重点实验室广州510642 国家柑橘产业技术体系机械研究室广州510642 华南农业大学公共基础课实验教学中心广州510642

为实现在果园现场快速、准确和无损地检测果树受柑橘全爪螨为害程度,该文研制了基于光学测量技术的柑橘全爪螨虫害快速检测仪,并通过试验检验了仪器的使用效果。检测仪采用光反射法,测量果树冠层叶片对红光和近红外光的反射率,根据反射... 详细信息

为实现在果园现场快速、准确和无损地检测果树受柑橘全爪螨为害程度,该文研制了基于光学测量技术的柑橘全爪螨虫害快速检测仪,并通过试验检验了仪器的使用效果。检测仪采用光反射法,测量果树冠层叶片对红光和近红外光的反射率,根据反射率计算全爪螨为害程度指数作为仪器的输出结果,进而按照无、轻度和重度3个级别判定柑橘全爪螨虫害程度。硬件设计中选取中心波长为665和815 nm的发光二极管阵列作为红光和近红外光源,通过光调制/解调技术、专门设计的光路和光电探测适配电路,克服了自然光线对检测结果的影响。仪器使用效果为:通过标准白板试验确定检测系数k等于2.622;检测结果受树叶密度影响较小;检测结果受自然环境光线影响较小,但气温对检测结果有一定影响;检测仪可区分无、轻度和重度3个级别的全爪螨虫害程度,当虫害程度较低时,检测结果稳定;检测仪输出结果与叶片表面柑橘全爪螨卵数间具有较高的相关性。进一步研究的方向为引入温度补偿的方法以减小温度对检测结果的影响,同时分析当为害程度较严重时结果稳定性较低的原因。

关键词：检测仪无损检测光谱分析柑橘果树虫害全爪螨

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远射程风送式喷雾机气流场分布及喷雾特性试验

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农业工程学报 2017年第24期33卷 72-79页

作者：陈建泽宋淑然孙道宗洪添胜张龙华南农业大学工程学院广州510642 华南农业大学电子工程学院广州510642 国家柑橘产业技术体系机械研究室广州510642 广东省农情信息监测工程技术研究中心广州510642 广东省山地果园机械创新工程技术研究中心广州510642

由于远射程风送式喷雾机的空间风场及喷雾特性尚未明确,该文利用风速测量定位网架,进行了远射程风送式喷雾机空间风场特性试验和喷幅试验。试验结果发现,远射程风送式喷雾机轴心上的纵向时均风速随采样点距喷嘴距离的增加而衰减,两者呈... 详细信息

由于远射程风送式喷雾机的空间风场及喷雾特性尚未明确,该文利用风速测量定位网架,进行了远射程风送式喷雾机空间风场特性试验和喷幅试验。试验结果发现,远射程风送式喷雾机轴心上的纵向时均风速随采样点距喷嘴距离的增加而衰减,两者呈负对数关系,这一特征符合淹没射流的流速变化规律;远射程风送式喷雾机轴心方向同一采样点上的风速与风机供电频率之间呈线性正相关,决定系数最低为0.609 1;远射程风送式喷雾机的水平喷幅关于喷筒轴心方向左右对称;而垂直喷幅在喷筒轴心方向的上下方呈现为不对称;远射程风送式喷雾远射程风送式喷雾机的送风量及出风口气流的时均风速均与风机供电电源的频率成正比;采用纸卡法测量了喷雾机的水平作业幅宽,该试验样机的水平作业幅宽为22 m。卷吸引起的伯努利效应和附壁效应是形成垂直喷幅不对称的重要原因,采用喷筒仰角喷雾可消除此效应。研究结果为远射程风送式喷雾机的生产和使用提供理论基础与参考。

关键词：农业机械喷雾风速远射程风送空间风场喷幅附壁效应

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风机电源频率对风送式喷雾机喷雾沉积的影响

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农业工程学报 2011年第1期27卷 153-159页

作者：宋淑然洪添胜孙道宗朱余清罗承华南农业大学南方农业机械与装备关键技术省部共建教育部重点实验室广州510642 华南农业大学工程学院广州510642

风送式喷雾机的风机速度影响雾滴的沉积分布及喷幅。以D400型风送式喷雾机为试验平台,用染色剂Rhodamine-B与水混合成1g/L浓度的溶液代替农药进行喷雾试验。改变风机供电电源的频率进行喷雾,借助于荧光分光光度计计算雾滴在采样点上的... 详细信息

风送式喷雾机的风机速度影响雾滴的沉积分布及喷幅。以D400型风送式喷雾机为试验平台,用染色剂Rhodamine-B与水混合成1g/L浓度的溶液代替农药进行喷雾试验。改变风机供电电源的频率进行喷雾,借助于荧光分光光度计计算雾滴在采样点上的沉积量。结果表明:喷嘴在喷口处不同高度上的分布在喷筒轴向上形成了3个雾滴沉积高峰区;随着风机供电频率的降低,雾滴沉积的高峰区向喷口处移动,沉积高峰区数目及沉积高峰区之间的间距变小;喷幅试验中(44.5～49.5Hz),距离喷筒轴线±2m以内的采样点上雾滴沉积量占喷幅范围内采样点上雾滴沉积总量的百分比的平均值为97.11%,越偏离这部分区域,雾滴沉积量越小,表明风送式喷雾具有很好的方向性,能防止雾滴漂移,且变频喷雾不会改变这一特性;环境自然风对喷口前方前8m以外的雾滴沉积有明显的影响。在实际喷雾作业时,可根据喷施目标物与风送式喷雾机间的距离,调节合适的供电频率,使雾滴主要沉积在目标区域,减少雾滴在非目标区域的沉积;减小喷头位置在高度层间的差异,可以改善喷雾效果。

关键词：风送式喷雾机雾滴沉积喷幅变频

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