Natural fibres are very versatile materials, their properties vary with chemical composition and physical structure. The effects of alkali, silane and combined alkali and silane treatments on the mechanical （tensile...Natural fibres are very versatile materials, their properties vary with chemical composition and physical structure. The effects of alkali, silane and combined alkali and silane treatments on the mechanical （tensile）, morphological, and structural properties of Pine Apple Leave Fibres （PALF） and Kenaf Fibres （KF） were investigated with the aim to improve their com- patibility with polymer matrices. The effectiveness of the alkali and saline treatments in the removal of impurities from the fibre surfaces was confirmed by Scanning Electron Microscopy （SEM） and Fourier Transform Infrared spectrometry （FTIR） ob- servation. The morphological study of treated PALF and KF by SEM indicates that silane treated fibres have less impurities and lignin and hemicelluloses removed than those by other chemical treatments. Silane treated PALF and KF display better tensile strength than those of untreated, alkaline and NaOH-silane treated. Droplet test indicates that the lnterfacial Stress Strength （IFSS） of alkali and silane treated PALF and KF are enhanced whereas silane treated fibres display highest IFSS. It is assumed that fibre treatments will help to develop high performance KF and PALF reinforced polymer composites for industrial appli- cations.展开更多
In the process of aeroponics cultivation,the atomizer is one of the most important influencing factors on the cultivation process.This study presented the design of an ultrasonic atomization nozzle using contact charg...In the process of aeroponics cultivation,the atomizer is one of the most important influencing factors on the cultivation process.This study presented the design of an ultrasonic atomization nozzle using contact charging and a root droplet adhesion test rig.The purpose of this study was to reveal the relationship between the main operating parameters of the high-voltage electrostatic ultrasonic atomization nozzle and the atomization effect using droplet adhesion measurements.In this study,the ultrasonic effect of nozzle was achieved by using Laval tube,and the design of the key parameters for the high-voltage electrostatic ultrasonic atomization nozzle were inlet pressure,electrostatic voltage root core electrode material and spray distance;the droplet size variation and root adhesion patterns were obtained through experiments.The best operating parameters were analyzed by using the orthogonal test method,and the droplet deposition distribution of the root system at different scales was investigated in the atomization chamber.The test results revealed that when the root core electrode material was coppe and the nozzle working parameters were at 0.4 MPa of inlet pressure,at 1.75 m the spray distance,at 12 kV of the electrostatic voltage,the root system has the highest droplet adhesion.展开更多
In order to obtain nozzle droplet deposition characteristics for sprayer mechanical design and variable spraying control algorithms,a nozzle droplet deposition characteristics test system for air-assisted spraying was...In order to obtain nozzle droplet deposition characteristics for sprayer mechanical design and variable spraying control algorithms,a nozzle droplet deposition characteristics test system for air-assisted spraying was designed.The test system can supply a stable wind site with precisely controlled air speed whose speed control ranges from 2 m/s to 16 m/s with maximum relative error of 4.5%.It can spray out a certain amount of liquid pesticide with adjustable spraying pressure which can be controlled with high precision while the maximum relative error is only 1.33%.The distribution of droplet deposition can be collected and measured by using the acquisition device and a pesticide deposition optical measurement system.The experiment of two-dimensional nozzle flow measurement was carried out.The results show that nozzle flow distribution is uniform and symmetric with“double-hump”shape in the spray range.Multi-nozzle overlapped droplet deposition ranges from 85%to 116%relative to the average.The nozzle droplet deposition experiment was completed.The experiment results show that in air-assisted spraying,the higher the wind speed,the less droplet deposition is affected by gravity.When the wind speed is higher than 12 m/s and spraying distance is 0.80 m,droplet deposition is concentrated on the originally designated point and hardly affected by gravity.The horizontal spray width becomes smaller with higher wind speed.When the wind speed is high,it can be considered that nozzle deposition only focuses on the nozzle center,if the position requirement is not very high in orchard spraying.展开更多
This paper presents an analytical, numerical, and experimental study on atomization characteristics and droplet distribution of a twin-fluid two-phase internal mixing atomizer to develop a Maximum Entropy Method(MEM)....This paper presents an analytical, numerical, and experimental study on atomization characteristics and droplet distribution of a twin-fluid two-phase internal mixing atomizer to develop a Maximum Entropy Method(MEM). A two-phase Eulerian-Lagrangian method is utilized for atomization modeling of the inside and outside atomizer. In order to modify energy and momentum sources in the MEM, parametric studies are performed, and experimental tests are carried out to verify the results by applying the shadowgraph method. An advanced test stand is developed to prepare a wide range of changes in atomization characteristics and mixing ratios. A high degree of consistency is found between numerical results from the developed MEM and experimental tests with different gas-phase pressures and liquid flow rates. The droplet diameter and velocity distribution are reviewed based on various Weber numbers, sources of energy, and momentum. Turbulence modeling assists to estimate the breakup length and time scale precisely in the developed MEM, and distribution ranges with mean values are achieved. With reference to a strong correlation between upstream turbulence flow and the developed MEM verified by experimental tests, an ideal droplet size and velocity distribution prediction is observed.展开更多
文摘Natural fibres are very versatile materials, their properties vary with chemical composition and physical structure. The effects of alkali, silane and combined alkali and silane treatments on the mechanical （tensile）, morphological, and structural properties of Pine Apple Leave Fibres （PALF） and Kenaf Fibres （KF） were investigated with the aim to improve their com- patibility with polymer matrices. The effectiveness of the alkali and saline treatments in the removal of impurities from the fibre surfaces was confirmed by Scanning Electron Microscopy （SEM） and Fourier Transform Infrared spectrometry （FTIR） ob- servation. The morphological study of treated PALF and KF by SEM indicates that silane treated fibres have less impurities and lignin and hemicelluloses removed than those by other chemical treatments. Silane treated PALF and KF display better tensile strength than those of untreated, alkaline and NaOH-silane treated. Droplet test indicates that the lnterfacial Stress Strength （IFSS） of alkali and silane treated PALF and KF are enhanced whereas silane treated fibres display highest IFSS. It is assumed that fibre treatments will help to develop high performance KF and PALF reinforced polymer composites for industrial appli- cations.
基金financially supported by the National Natural Science Foundation of China Program(Grant No.51975255)Jiangsu Agriculture Science and Technology Innovation Fund(Grant No.CX(18)3048)the“Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions”(Grant No.37,(2014))。
文摘In the process of aeroponics cultivation,the atomizer is one of the most important influencing factors on the cultivation process.This study presented the design of an ultrasonic atomization nozzle using contact charging and a root droplet adhesion test rig.The purpose of this study was to reveal the relationship between the main operating parameters of the high-voltage electrostatic ultrasonic atomization nozzle and the atomization effect using droplet adhesion measurements.In this study,the ultrasonic effect of nozzle was achieved by using Laval tube,and the design of the key parameters for the high-voltage electrostatic ultrasonic atomization nozzle were inlet pressure,electrostatic voltage root core electrode material and spray distance;the droplet size variation and root adhesion patterns were obtained through experiments.The best operating parameters were analyzed by using the orthogonal test method,and the droplet deposition distribution of the root system at different scales was investigated in the atomization chamber.The test results revealed that when the root core electrode material was coppe and the nozzle working parameters were at 0.4 MPa of inlet pressure,at 1.75 m the spray distance,at 12 kV of the electrostatic voltage,the root system has the highest droplet adhesion.
基金China National 863 Project(2012AA101904)project 31201128 supported by NSFC,project KFZN2012W13-013IEA and project 2452013QN070 supported by Northwest A&F University.
文摘In order to obtain nozzle droplet deposition characteristics for sprayer mechanical design and variable spraying control algorithms,a nozzle droplet deposition characteristics test system for air-assisted spraying was designed.The test system can supply a stable wind site with precisely controlled air speed whose speed control ranges from 2 m/s to 16 m/s with maximum relative error of 4.5%.It can spray out a certain amount of liquid pesticide with adjustable spraying pressure which can be controlled with high precision while the maximum relative error is only 1.33%.The distribution of droplet deposition can be collected and measured by using the acquisition device and a pesticide deposition optical measurement system.The experiment of two-dimensional nozzle flow measurement was carried out.The results show that nozzle flow distribution is uniform and symmetric with“double-hump”shape in the spray range.Multi-nozzle overlapped droplet deposition ranges from 85%to 116%relative to the average.The nozzle droplet deposition experiment was completed.The experiment results show that in air-assisted spraying,the higher the wind speed,the less droplet deposition is affected by gravity.When the wind speed is higher than 12 m/s and spraying distance is 0.80 m,droplet deposition is concentrated on the originally designated point and hardly affected by gravity.The horizontal spray width becomes smaller with higher wind speed.When the wind speed is high,it can be considered that nozzle deposition only focuses on the nozzle center,if the position requirement is not very high in orchard spraying.
文摘This paper presents an analytical, numerical, and experimental study on atomization characteristics and droplet distribution of a twin-fluid two-phase internal mixing atomizer to develop a Maximum Entropy Method(MEM). A two-phase Eulerian-Lagrangian method is utilized for atomization modeling of the inside and outside atomizer. In order to modify energy and momentum sources in the MEM, parametric studies are performed, and experimental tests are carried out to verify the results by applying the shadowgraph method. An advanced test stand is developed to prepare a wide range of changes in atomization characteristics and mixing ratios. A high degree of consistency is found between numerical results from the developed MEM and experimental tests with different gas-phase pressures and liquid flow rates. The droplet diameter and velocity distribution are reviewed based on various Weber numbers, sources of energy, and momentum. Turbulence modeling assists to estimate the breakup length and time scale precisely in the developed MEM, and distribution ranges with mean values are achieved. With reference to a strong correlation between upstream turbulence flow and the developed MEM verified by experimental tests, an ideal droplet size and velocity distribution prediction is observed.
