【摘要】：濕法制備多晶硅太陽(yáng)電池表面絨面結(jié)構(gòu)，實(shí)際上是溶液中離子和多晶硅相互作用的過(guò)程，但是離子運(yùn)動(dòng)一般不可控，導(dǎo)致其腐蝕得到的微結(jié)構(gòu)始終不理想。“離子泡”有可能改變這一現(xiàn)象�！半x子泡”實(shí)際上是在濕法腐蝕過(guò)程中利用超聲產(chǎn)生的微氣泡表面帶電特性吸附離子，形成“離子+泡”結(jié)構(gòu)，從而可以實(shí)現(xiàn)離子的可控。但是對(duì)于這一模型研究依賴于對(duì)超聲產(chǎn)生的微氣泡帶電特性機(jī)理的研究，目前這方面還缺乏定性研究。為此首先要展開對(duì)超聲微泡裝置研究，為日后超聲微氣泡特性研究打下基礎(chǔ)。 首先，，對(duì)超聲氣泡產(chǎn)生過(guò)程進(jìn)行了分析，并根據(jù)超聲在水中產(chǎn)生空穴的所需要的聲壓條件計(jì)算模型出發(fā)，分析了相關(guān)因素對(duì)超聲氣泡形成過(guò)程，以此為基礎(chǔ)設(shè)計(jì)了超聲微氣泡的發(fā)生裝置。 其次，對(duì)超聲系統(tǒng)機(jī)械部分進(jìn)行了設(shè)計(jì)，分別用等效電路法設(shè)計(jì)和傳統(tǒng)解析法確定了超聲換能器和變幅桿的機(jī)械參數(shù)。為保證設(shè)計(jì)的可靠性，文中對(duì)設(shè)計(jì)的變幅桿進(jìn)行了有限元模擬。運(yùn)用模態(tài)分析得出其固有諧振頻率和設(shè)計(jì)工作頻率之間誤差在允許范圍之內(nèi)，運(yùn)用諧響應(yīng)分析得出其端面輸出位移和最大應(yīng)力要求也均滿足設(shè)計(jì)要求。 然后利用FLUNENT軟件建立了超聲微泡發(fā)生器數(shù)學(xué)計(jì)算模型及賦予相應(yīng)的初始邊界條件，對(duì)各種可能影響氣泡生成效果的因數(shù)進(jìn)行數(shù)值模擬。文中重點(diǎn)模擬了超聲功率、氣孔孔徑、氣體種類、變幅桿結(jié)構(gòu)等影響。通過(guò)流場(chǎng)的模擬得出，超聲功率對(duì)氣泡的影響最為顯著，在無(wú)功率以及低功率的條件下，只會(huì)產(chǎn)生宏觀的氣泡；同時(shí)氣孔孔徑影響在于與超聲功率協(xié)調(diào)性；從模擬的結(jié)果上看氣體種類對(duì)微氣泡產(chǎn)生的影響不顯著；在模擬中更改了發(fā)生器的結(jié)構(gòu)，將其由平面型結(jié)構(gòu)改成凹球面結(jié)構(gòu)，模擬結(jié)果說(shuō)明這種結(jié)構(gòu)對(duì)流場(chǎng)的壓力有顯著的加強(qiáng)過(guò)程，而這種壓力對(duì)流場(chǎng)局部作用明顯，對(duì)于氣泡產(chǎn)生過(guò)程也有較大的影響。 最后，開展了超聲氣泡發(fā)生器實(shí)際效果測(cè)試實(shí)驗(yàn)，測(cè)試實(shí)驗(yàn)中主要就功率對(duì)氣泡產(chǎn)生情況進(jìn)行分析，得出結(jié)果和實(shí)際模擬結(jié)果可以很好的符合。通過(guò)利用高速攝影機(jī)得到照片結(jié)果分析得到，可以產(chǎn)生微米級(jí)的氣泡。 通過(guò)論文研究，初步實(shí)現(xiàn)了超聲微氣泡裝置的研究，并通過(guò)二相流的模擬得出氣泡生成過(guò)程中影響關(guān)鍵因素。這為后期進(jìn)一步研制可控大小、可控?cái)?shù)目微氣泡用于超聲微氣泡特性研究提供了依據(jù)。
[Abstract]:Wet fabrication of surface suede structure of polycrystalline silicon solar cells is actually a process of interaction between ions and polysilicon in solution, but the ion movement is generally uncontrollable, resulting in the microstructure obtained by corrosion is always not ideal. Ion bubbles may change this phenomenon. In fact, "ion bubble" is used to adsorb ions on the surface of micro-bubble produced by ultrasonic in the process of wet corrosion, forming "ion bubble" structure, so that the ion can be controlled. However, the study of this model depends on the study of the mechanism of charge characteristics of microbubbles produced by ultrasound, which is still lack of qualitative research. Therefore, the research of ultrasonic microbubble device should be carried out first, which will lay a foundation for the study of ultrasonic microbubble characteristics in the future. Firstly, the process of ultrasonic bubble formation is analyzed, and based on the model of sound pressure conditions needed to generate holes in water, the relevant factors are analyzed. Based on this, a device for generating ultrasonic microbubbles is designed. Secondly, the mechanical part of ultrasonic system is designed, and the mechanical parameters of ultrasonic transducer and amplitude bar are determined by the method of equivalent circuit and the traditional analytical method. In order to ensure the reliability of the design, finite element simulation of the designed horn is carried out in this paper. The error between the inherent resonance frequency and the design working frequency is found to be within the allowable range by modal analysis, and the output displacement and maximum stress requirements of the end face are also satisfied by the harmonic response analysis. Then the mathematical calculation model of ultrasonic microbubble generator and the corresponding initial boundary conditions are established by using FLUNENT software. The various factors that may affect the effect of bubble formation are simulated numerically. The effects of ultrasonic power, pore aperture, gas type and amplitude-varying bar structure are simulated. Through the simulation of flow field, it is concluded that ultrasonic power has the most significant effect on bubbles, and only macrobubbles can be produced under the condition of no power and low power, meanwhile, the influence of pore aperture is the coordination with ultrasonic power. From the result of simulation, the effect of gas type on microbubble is not significant. In the simulation, the structure of generator has been changed from plane structure to concave spherical structure. The simulation results show that the pressure of the flow field of this kind of structure has a significant strengthening process, and the local effect of this pressure flow field is obvious, which also has a great influence on the bubble production process. Finally, the practical effect test experiment of ultrasonic bubble generator is carried out. In the test experiment, the power of the bubble is analyzed, and the results are in good agreement with the actual simulation results. By using the high speed camera to get the result of the photo, the micrometer bubble can be produced. Through the research of this paper, the research of ultrasonic micro-bubble device is realized, and the key factors of bubble formation are obtained through the simulation of two-phase flow. This provides a basis for the further development of controllable size and number of microbubbles for the study of ultrasonic microbubbles.
【學(xué)位授予單位】：杭州電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM914.4;TB559

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