Linyun Xu

Research on the Impact of the Characteristic Parameters of Air-blast Rotating Cage Sprayer to Droplet Size

The dose and the protection effect of pesticide are directly affected by the pesticide droplet size. Too Large droplet size can result in increasing the dose of pesticide or failing to reach the protection effect, too small droplet size can increase the drift. In this paper, axial air-blast rotating cage sprayer was used, besides, the characteristic variable parameters include three types of cage diameter 80, 100, 120mm, three kinds of cage mesh number 60,120,180, three kinds of cage speed 3000, 4000, 5000rpm, and three kinds of liquid flow 40, 60, 80L/h. Regardless of the characteristic parameters conditions, the flow had little effect on droplet size, on the condition of cage diameter of 80mm, cage rotating speed of 3000rpm, cage mesh number of 80, the corresponding droplet volume diameters (VMD) are respectively 165.4, 165.2, 166.2um under the flows 40, 60, 80L/h; on the condition of mesh number of 120, the cage diameter of 100mm, speed of 4000 rpm, VMD are respectively 129.3, 127.5, 126.5um under the flow of 40, 60, 80L/h. Droplet diameter decreases with the increase of cage rotating speed. When mesh number is 60, the cage diameter is 80mm, and the flow is 40L / h, the rotating speed ranged from 3000rpm to 5000rpm, and then the corresponding droplet diameters shrank from 165.4um to 127.5um. The droplet diameter was little influenced by the number of cage mesh and the cage diameter. The droplet diameter decreased slightly with the increase of the mesh number and the cage diameter. When the mesh number changed from 60 to 180, the droplet diameter only decreased from 142.7um to 127.5um, on the corresponding condition of cage diameter of 80mm, flow of 40L/h, speed of 4000rpm. Cage diameter increases from 80mm to 120mm, and the droplet diameter decreased from 142.7um to 122.4um, on condition of mesh number of 60, flow of 40L / h, speed of 4000rpm .The results showed that the droplet diameter was mainly influenced by the cage rotating speed, the cage diameter and mesh number were another factors, and the flow rate can hardly have impact on the droplet diameter. Regardless of any variable conditions, the droplet diameter formed by rotating cage sprayer is smaller than the normal one. In addition, the air-blasted droplets were transmitted to the target domain, which can effectively improve the using efficiency of pesticide, and yet decrease the dose of pesticide use and the drift.

Effect on Atomization of Rotation-cage-type Nozzle

For applying the pesticide onto the target surface effectively, it is very important to choose and design the atomization nozzle correctly. Primary parameters of rotation-cage-type centrifugal nozzle were studied to show the influence on droplet size, including 4 speeds of motor, 6 mesh screen specifications of rotation-cage, 3 diameters, 3 pesticide flows and 3 positions of droplet collection. It was shown that in all the cases above, more ideal droplet, namely more tiny and even than applied by common atomization nozzle, was obtained. VMD ranged from 66.6 to 144.1µm. D90 were less than 190µm. The diameters and mesh density impacted the droplet size obviously. In the case of 3000rpm and 80mm diameter, for 6 mesh-screen specifications ranged from 13 to 80 mesh, minimum VMD of 99.2µm in 80 L/h flow was obtained by 30 mesh; larger diameter didn’t mean less VMD, however when largest diameter of 120mm, minimum VMD of 67.8µm was obtained; when medium diameter of 100 mm, maximum VMD of 133.0µm was obtained. Pesticide flow and motor speed impacted droplet size slightly. For obtaining ideal droplet, the diameter and mesh density should be chosen and set correctly.

Dynamic Modeling of Eccentric-mass Type of Forest Fruit Harvest Machine

Dynamic modeling and theoretical analysis are important for the optimal design of eccentric-mass type of forest fruit harvest machine. Based on the principle of eccentric-mass type of forest fruit harvest machine, a simple three-element dynamic model of the harvest machine-fruit tree system was constructed by equivalent mass, spring and damping. The vibration differential equations were established with the simplified model method. By means of analyzing motion process of the vibration system, expressions of displacement, velocity, acceleration, amplitude, phase difference were derived, and inertia force of forest fruit, fruit removal condition and power consumption of the harvest machine were analyzed. The dynamic model showed that steady-state responses of displacement, velocity, and acceleration of the vibration system were periodical motion. Fruit removal rate was main relationship with response amplitude of fruit tree and excitation frequency of forest fruit harvest machine. Vibration amplitude of fruit tree was not only affected by the characteristics of the system itself, such as natural frequency and damping ratio etc., but also related to the excitation frequency. So the multiple effects of the factors resulted in vibration amplitude of fruit tree. Power consumption of the system was proportional to amplitude and the cube of frequency. The conclusion was that excitation frequency was a key working parameter of the harvest machine. In order to get the best effective harvest of fruit, selecting fitting frequency for a special fruit tree was a key step in the limited power of the harvest machine.

Noise Analysis of Small-size Pulse-jet Engine

Based on theoretical analysis of acoustic structure, the corresponding acoustic model of the pulse-jet engine was established. Pertinence measurement and near-field measurement were set up to test the noise. It was shown that the exhaust noise was the main noise-composition, secondly the intake noise. The combustion noise was much weaker. Simultaneously, the exhaust noise and intake noise had the one-way directivity property, namely that the noise intensity of exhaust noise, along the axial direction of exhaust tube, and the intake noise, along the axial direction of carburetor intake valve, were the highest. The noise intensity got weakened when the axial direction was offset. The more deflection angle, the more weakened. Especially it was outstanding on exhaust outlet. It was beneficial for the further study of low-noise pulse-jet engine.

Analysis of Emissions from Pulse-jet Engines

The conventional internal-combustion engines can generate pollutions due to emissions of CO, HC, NOx, etc. into air if ratio of the fuel/air mixture entering into the combustion chamber is high. The exhaust gas ingredient of new pulse engines was tested with five combustion-chamber capacities and three fuel restrictor opening sizes at different points of the exhaust tube. The excess air coefficient of mixer of fuel and air feeding into the combustion chamber were obtained by measuring the fuel consumption rate and air mass flow rate. In order to determine the chemical composition and content of exhaust gas, the CO, HC contents and the coefficient were also measured with an NHA-501 exhaust gas analyzer at 4 different points (0cm, 15cm, 30cm and 60cm) from the end of exhaust tube. Test results illustrated the amount of pollutants in the fume of exhaust gas was very low even if the excess air level was less than 1 or even much less than 1, i.e. a=0.6. For all circumstances, the content of HC was zero and the content of CO was about 0.02%. Therefore, the application of pulsation combustors would not result in harmful pollutants to the environment.

From Precision Agriculture and Precision Forestry to Biomechinfotronics

The deteriorating of global environments, decreasing of biological diversity, increasing of natural disasters, exhausting of biological resources and fast-growing of desertification has pushed us to consider how to provide the human-beings with the suitable environments. Nowadays, the precision agricultural and precision forestry has been emphasized to obtain the maximum output through the minimum input and the least impact on environments., so the agricultural and forestry engineering systems require multi-disciplinary design groups and the importance of biomechinfotronics is need of the time. In the paper, the prospects, mission analysis, education system, research areas of biomechinfotronics were studied. The particular characteristics of biomechinfotronics are the synergistic integration of biological engineering with mechatronics, bioinformatics, infotronics, bioelectronics and intelligent computer system.

Gas-Flow Fluctuation Velocity in Portable Pesticide Fogger’s Exhaust Tube with Helmholtz Pulse-jet Engine

A portable pulse fogger, in which the fog can be produced by injecting pesticide into the Pulse-jet engine’s exhaust tube full of high temperature and high speed exhaust gas, can be applied in disease and insect control in forestry, greenhouse and sanitation with the advantages of high efficiency and low environmental pollution. A measuring system for the gas-flow fluctuation velocity was set up to obtain the pressure signals at different axial positions of exhaust tube. On the principle of correlation between pressure signals from one signal source, the correlation analysis of two pressure signals at various positions of exhaust tube had been carried out. The autocorrelation function chart showed that the pressure signals in the exhaust tube were characterized as the sinusoidal or the cosinoidal waves with a little of random signals. The average gas-flow fluctuation velocity could be derived from mutual correlation analysis of two signals at two positions. The average maximal gas flow velocity obtained by this measuring system was 5883m/s, which was 8.72 times as fast as local sonic velocity 669 m/s.