本文選題：噴頭 + 超聲霧化��； 參考：《江蘇大學》2017年碩士論文

【摘要】：超聲霧化噴頭比起普通壓力噴頭,能夠產生尺寸更加細小的霧滴,使得其在滿足農作物生長需求的同時,達到了節(jié)約水資源和減少農藥使用的目的。對于農藥或者營養(yǎng)液等粘度較大的液體,超聲霧化噴頭能夠更容易地霧化,因而它在農業(yè)施肥領域具備得天獨厚的優(yōu)勢。為了解決現(xiàn)有的技術問題,進一步細化霧滴粒徑并提高噴霧的均勻性,增大噴霧角度,增強噴霧抗干擾能力,本文采用計算機建模與有限元分析結合的方法,設計了氣助式低頻超聲霧化噴頭,并在此基礎上發(fā)展了帶有渦流齒輪的設計方案及帶有金屬懸浮球的二次霧化設計方案。噴頭的基本結構包括機械振動結構和流體結構,通過使用計算機軟件建模和有限元模擬仿真相結合的方法對噴頭進行了設計驗證。噴頭的機械振動結構包括超聲換能器和超聲變幅桿兩大部分,通過理論計算得出結構中各個尺寸的具體數(shù)值,并給出了相應的數(shù)學計算過程及計算結果。采用模態(tài)分析、諧響應分析等CAE方法對設計的結構進行虛擬仿真,并將仿真結果與理論設計值相比較,驗證設計方案,從而確定結構各部分的最終參數(shù)。采用流體仿真的方法對噴頭的流體結構進行設計分析,通過觀察仿真結果中噴頭內部氣流的運動情況和在噴口處的射流情況來驗證結構設計的可行性。根據(jù)設計參數(shù)制造出噴頭樣機,并對樣機的具體特性進行試驗測試。對噴頭樣機的阻抗特性進行分析,測出樣機的諧振頻率為57984Hz,與噴頭的理論設計頻率60KHz相差3.4%;得到噴頭換能器的其他關鍵參數(shù),為噴頭驅動電源的設計提供了設計依據(jù)。對噴頭變幅桿的端面振幅及懸浮球的振幅進行了測量,得出電源電壓為40V時,噴頭變幅桿端面的平均振幅為3.30μm,懸浮球振幅為0.283mm;當電壓增加到46V時,噴頭變幅桿端面的平均振幅達到3.96μm,懸浮球振幅增加到0.301mm。由測試結果得出,噴頭樣機的工作性能滿足設計要求,且變幅桿端面振幅和懸浮球振幅正相關于驅動電壓。為了了解噴頭的實際工作性能,利用所設計的噴頭樣機完成了噴霧試驗。采用高清相機對噴頭噴霧角進行了測試,通過對比試驗可以發(fā)現(xiàn):在沒有采用渦流齒輪的情況下,噴頭噴霧角與氣壓呈現(xiàn)正相關關系;對于采用渦流齒輪的超聲霧化噴頭,當氣流壓力較小時,渦流齒輪對噴霧角的影響很小;當氣壓增加達到0.1MPa時,帶有渦流齒輪的噴頭噴霧角為36°,而不帶渦流齒輪的噴頭噴霧角僅為19°;當氣壓達到0.4MPa時,渦流齒輪幫助噴頭達到了平均66°的噴霧角,與不帶有渦流齒輪的噴頭相比,噴霧角的增加幅度達到60.9%,體現(xiàn)出渦流齒輪在增大噴霧角方面的重要作用。采用激光粒度分析儀對噴頭的霧滴粒徑進行了試驗研究,分析并比較了不同噴口收角、氣壓大小及懸浮球對于霧滴粒徑的影響。由試驗結果發(fā)現(xiàn):(1)驅動電壓對于60KHz超聲霧化噴頭的霧化效果具有一定的影響,40V的驅動電壓所產生的霧滴粒徑大于46V驅動電壓下產生的霧滴粒徑。(2)噴口收角對霧滴粒徑沒有明顯的影響。(3)氣流能夠明顯地影響到噴頭所產生霧滴的平均粒徑及粒徑分布寬度。當氣壓為0.05MPa時,噴頭產生的霧滴平均粒徑減小超過10%,粒徑分布寬度也同時減小;而當氣壓達到0.1MPa時,霧滴平均粒徑減小得不明顯,甚至有可能增大,但粒徑分布寬度進一步縮小。(4)帶有懸浮球的超聲噴頭所產生的霧滴粒徑要遠小于沒有懸浮球的噴頭,且懸浮球能夠比氣流更明顯地減小霧滴尺寸。如何更好地將輔助氣流與懸浮球這兩種手段相結合,對于提高噴頭的霧化質量具有重要意義。
[Abstract]:Ultrasonic atomizer can produce smaller droplets than ordinary pressure sprinklers, which make it meet the needs of crop growth and achieve the purpose of saving water resources and reducing the use of pesticides. For the liquid with large viscosity, such as pesticide or nutrient solution, the ultrasonic atomizer can be more easily atomized, so it is in agriculture. In order to solve the existing technical problems, in order to solve the existing technical problems, further refine the droplet size and improve the uniformity of the spray, increase the spray angle and enhance the anti interference ability of the spray, this paper sets up a gas assisted low frequency ultrasonic atomizer with the method of computer modeling and finite element analysis, and is based on this basis. The design scheme of the swirl gear and the two atomization design with a metal suspension ball are developed. The basic structure of the nozzle includes the mechanical vibration structure and the fluid structure. The design of the nozzle is verified by the method of combining the computer software modeling with the finite element simulation. The mechanical vibration structure of the nozzle includes the structure of the nozzle. Two parts of ultrasonic transducer and ultrasonic horn are calculated by theoretical calculation, and the corresponding mathematical calculation process and calculation result are given. The CAE method of modal analysis and harmonic response analysis is used to simulate the structure of the design, and the simulation results are compared with the theoretical design values. In order to determine the final parameters of the various parts of the structure, the fluid structure of the nozzle is designed and analyzed by the method of fluid simulation. The feasibility of the structure design is verified by observing the movement of the air flow inside the nozzle and the jet situation at the nozzle. The specific characteristics of the machine are tested. The impedance characteristics of the prototype of the nozzle are analyzed, the resonance frequency of the prototype is 57984Hz, and the difference between the theoretical design frequency 60KHz of the nozzle is 3.4%, and the other key parameters of the nozzle transducer are obtained, which provide the design basis for the design of the driving power of the nozzle. The amplitude of the floating ball is measured. When the voltage of the power supply is 40V, the average amplitude of the end face of the nozzle is 3.30 mu m and the amplitude of the suspension ball is 0.283mm. When the voltage is increased to 46V, the average amplitude of the end face of the nozzle is 3.96 M, and the amplitude of the suspension ball is increased to 0.301mm. by the test result, and the working performance of the prototype of the nozzle is satisfied. In order to understand the actual working performance of the nozzle, the spray test is completed by using the prototype of the designed nozzle. The spray angle of the nozzle is tested with a high definition camera, and the spray head can be found in the case of no swirl gear. There is a positive correlation between the spray angle and the air pressure; for the ultrasonic atomizing nozzle with swirl gear, the effect of the swirl gear on the spray angle is small when the air pressure is small. When the pressure increases to 0.1MPa, the spray angle of the nozzle with the swirl gear is 36 degrees, and the spray angle of the nozzle without the swirl gear is only 19 degrees; when the pressure reaches 0.4MPa When the swirl gear helps the nozzle to reach the spray angle of an average of 66 degrees, the increase of the spray angle is 60.9%, compared with the nozzle without the swirl gear, which reflects the important role of the swirl gear in increasing the spray angle. The particle size of the spray head is studied by the laser particle size analyzer, and the different spray is analyzed and compared. The effect of mouth angle, pressure size and suspension ball on droplet size is found. The results are as follows: (1) the driving voltage has a certain influence on the atomization effect of 60KHz ultrasonic atomizing nozzle. The droplet diameter produced by the driving voltage of 40V is larger than that of the 46V driving voltage. (2) the nozzle angle is not obvious to the droplet size. (3) the air flow can obviously affect the average particle size and the size distribution width of the droplets produced by the spray head. When the pressure is 0.05MPa, the average particle size of the spray droplets is reduced by more than 10%, and the size distribution width decreases at the same time. When the pressure reaches 0.1MPa, the average particle size of the droplet decreases not obviously, even if it is likely to increase, but the grain size is even larger. The diameter distribution width is further reduced. (4) the droplet diameter produced by the ultrasonic sprinkler with the suspension ball is much smaller than that without the suspended ball, and the suspension ball can reduce the droplet size more obviously than the air flow. How to better combine the auxiliary air and the suspended ball are important to improve the atomization quality of the nozzle. Righteousness.
【學位授予單位】：江蘇大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：S237;TH122

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