【摘要】：無葉風扇由出風圈和微型風機組成,微型風機內(nèi)置于無葉風扇內(nèi)部,這使得無葉風扇變得更安全、更環(huán)保,目前無葉風扇的問題主要集中在風力和噪音上。其中傳統(tǒng)無葉風扇出風圈內(nèi)表面均設置成擴散面,結構單一,風力較小,因此設計研究新型出風圈內(nèi)表面對繼續(xù)創(chuàng)新無葉風扇結構具有指導意義。同時,微型風機在高速運轉時噪音較大,因此設計低噪聲風機對無葉風扇降噪具有重要意義。 本文提出了帶收縮型出風內(nèi)表面的無葉風扇結構,并依此為依據(jù)設計了兩款無葉風扇。對小間隙無葉風扇模型進行數(shù)值計算,驗證了收縮型內(nèi)表面能夠高效地實現(xiàn)風量放大作用。同時研究了收縮角和入口速度環(huán)量對小間隙無葉風扇性能的影響,為無葉風扇和內(nèi)置風機設計提供了依據(jù)。 設計了配套的兩級低速微型風機結構,取代單級高速風機。風機葉輪采用非均勻布置葉片,通過基于RANS+FW-H方法對不同葉片分布形式下風機氣動聲學特性分析,表明非等距葉片布置可以降低風機葉片通過頻率處的噪聲值,葉片分布不均勻度越大,對該頻率噪聲降低效果越明顯；但不均勻度過大,會導致低頻噪聲聲壓級的大幅增加,葉片不均勻度存在一個最優(yōu)區(qū)間。 對小間隙無葉風扇和兩級風機樣機進行實驗研究,結果表明新型無葉風扇較傳統(tǒng)無葉風扇性能和降噪效果都有了明顯提高,同時將實驗結果與模擬結果進行對比,驗證了研究思路的可行性。 針對大出風間隙結構無葉風扇無法形成穩(wěn)定射流的問題,通過格柵結構設置保證了大出風間隙條件下的均勻出風,數(shù)值模擬結果表明無葉風扇間隙越大,需要的格柵密度越大。而收縮角對大出風間隙結構的性能和風向也具有顯著影響,夾角過大或過小都會使風向偏離中心位置。 本文給出了無葉風扇及其內(nèi)置低噪聲風機的設計方法,給出了帶收縮型出風內(nèi)表面的無葉風扇結構、無葉風扇專用低速兩級風機結構、不等距風機葉片結構以及帶格柵的大間隙出風結構,給出了關鍵結構參數(shù)對風扇性能與噪聲指標的影響,設計的新型無葉風扇達到了設計目的,分析結果為新型無葉風扇的結構創(chuàng)新和產(chǎn)品開發(fā)提供了參考。
[Abstract]:The vaneless fan is composed of an outlet fan and a micro fan, which is built into the blade free fan, which makes the fan safer and more environmentally friendly. At present, the problems of the vaneless fan are mainly focused on the wind and noise. The inner surface of the traditional vaneless fan outlet ring is set as diffusion surface, the structure is single and the wind is small. Therefore, the design and study of the new type of inner surface of the exhaust fan is of guiding significance for the continuous innovation of the structure of the vaneless fan. At the same time, the noise of micro fan is high when running at high speed, so it is very important to design low noise fan for noiseless fan. In this paper, the structure of vaneless fan with constrictive inner surface of outlet air is presented, and two vaneless fans are designed according to the structure. The model of vaneless fan with small clearance is numerically calculated, and it is verified that the shrinking inner surface can efficiently realize the effect of air volume amplification. At the same time, the influence of shrinkage angle and inlet velocity ring on the performance of small clearance vaneless fan is studied, which provides the basis for the design of vaneless fan and built-in fan. A two-stage low-speed micro fan structure is designed to replace one-stage high-speed fan. Based on the RANS FW-H method, the aerodynamic acoustic characteristics of the fan with different blade distribution forms are analyzed. The results show that the non-equidistant blade arrangement can reduce the noise value of the fan blade passing through frequency. The greater the uneven distribution of the blade, the more obvious the effect of reducing the frequency noise, but the larger the inhomogeneity, the larger the sound pressure level of the low frequency noise will be, and there is an optimal range of the uneven degree of the blade. The experimental study on the small clearance vaneless fan and the two-stage fan prototype shows that the performance and noise reduction effect of the new type vaneless fan are obviously improved compared with the traditional vaneless fan, and the experimental results are compared with the simulation results. The feasibility of the research idea is verified. In view of the problem that the vaneless fan with large outlet gap structure can not form a stable jet, the uniform outlet air under the condition of large outlet air gap is ensured by the grid structure setting. The numerical simulation results show that the larger the fan clearance is, the greater the grid density is required. The shrinkage angle also has a significant effect on the performance and wind direction of the large outlet gap structure. Too large or too small an angle will cause the wind direction to deviate from the center. In this paper, the design method of the vaneless fan and its built-in low noise fan is given. The structure of the vaneless fan with the inner surface of the outlet wind and the structure of the low speed two-stage fan for the vaneless fan are given. The blade structure of non-equidistant fan and the large gap outlet structure with grid are given. The influence of key structural parameters on the performance and noise index of fan is given. The new type of vaneless fan is designed to achieve the purpose of the design. The results provide a reference for the structure innovation and product development of the new type vaneless fan.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM925.11

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