本文關鍵詞：自吸泵自吸過程氣液兩相流動試驗研究　出處：《江蘇大學》2017年碩士論文　論文類型：學位論文

  更多相關文章： 自吸泵 自吸過程 瞬態(tài)測試 高速攝影 圖像處理 氣泡

【摘要】：泵的自吸過程包含了氣液混合、氣液分離等氣液兩相間復雜的物理變化,特別是自吸過程中泵內(nèi)氣泡的分布和運動規(guī)律等與泵的自吸性能和自吸機理有著密切的聯(lián)系。目前國內(nèi)外對自吸泵的研究著重于水力性能參數(shù)的變化對自吸性能的影響等宏觀自吸現(xiàn)象,缺乏對泵內(nèi)氣液兩相流態(tài)變化的微觀研究,沒有深入研究自吸機理。本文通過水力性能試驗、自吸性能試驗、自吸過程的瞬態(tài)測試和高速攝影試驗研究,外混式自吸離心泵在不同水力性能參數(shù)下的自吸過程,建立自吸過程中氣泡數(shù)量、大小和運動軌跡與自吸性能之間的關系,進一步揭示泵的自吸機理,為自吸泵的自吸結(jié)構(gòu)設計提供理論基礎。本文主要的研究內(nèi)容和成果如下:1.以65ZB-40C型外混式自吸離心泵為基礎,根據(jù)自吸泵設計理論,設計了有機玻璃樣機,設計了可移動的隔舌部件。搭建了自吸泵水力性能閉式試驗臺,對自吸泵樣機進行水力性能試驗研究葉輪出口圓周速度以及隔舌間隙對自吸性能的影響,結(jié)果表明泵自吸時間隨著葉輪圓周速度的增大或者隔舌間隙的減小而縮短。2.搭建自吸泵的高速攝影試驗系統(tǒng),測量不同隔舌間隙以及葉輪出口圓周速度條件下,轉(zhuǎn)速、泵進出口壓力和流量等參數(shù)的變化,同時拍攝自吸過程葉輪、氣液分離室、蝸殼等關鍵部件內(nèi)氣液兩相流態(tài)的變化。結(jié)果表明自吸過程可以分為自吸啟動階段、自吸穩(wěn)定階段和自吸突變階段,自吸穩(wěn)定階段是一個動態(tài)穩(wěn)定的過程,這個過程占整個自吸過程的時間的比例最大,對自吸過程的影響最大。葉輪外緣的氣液混合層以及氣液分離室內(nèi)的氣相空穴是自吸穩(wěn)定進行的必要條件。3.通過濾波去噪、圖像的二值化和圖像填充等方法對高速攝影拍攝到的自吸過程的中氣泡的數(shù)字圖像進行預處理。本文使用了差影法去除背景噪聲,比較中值濾波、高斯濾波和Wiener濾波三種平滑去噪方式,并將這三種方式得到的結(jié)果圖像分別使用最大類間方差法和迭代法求閾值進行圖像的二值化比較效果,選擇高斯濾波和最大類間方差法的處理過程,再用MATLAB的imfill函數(shù)進行圖像填充,重新獲得因二值化丟失的氣泡中心的信息。4.在圖像預處理的基礎上,提取二值圖像中氣泡的數(shù)量、大小、運動軌跡和運動速度等信息,研究微觀自吸過程的氣泡特征與宏觀的自吸性能變化的內(nèi)在聯(lián)系。結(jié)果表明,蝸殼擴散段靠近氣液分離室的左邊區(qū)域的氣泡群對比右邊區(qū)域顯得直徑小而且數(shù)量密集。直徑較小的氣泡群相比于直徑較大的更容易排出泵體,即減小氣液兩相流中氣泡的尺寸,把更多的停滯氣泡轉(zhuǎn)化為移動氣泡是一個縮短自吸時間,提高自吸性能的有效途徑,這也是泵的自吸時間隨著隔舌間隙的減小而縮短的原因。
[Abstract]:The self-priming process includes gas-liquid mixing, gas-liquid separation and other physical changes of gas-liquid two phase complex, especially since the bubble pump suction in the process of distribution and movement law and pump self-priming performance of self-priming and mechanism are closely linked. At home and abroad to study the change of emphasis on self suction pump the hydraulic parameters of the self-priming performance influence of macro self absorption phenomenon, lack of microscopic study on the changes of the gas-liquid two-phase flow pattern inside the pump, there is no in-depth study of self suction mechanism. The hydraulic performance test, self-priming performance test, experimental study on the transient test and high speed photography absorption process, external mixing type self suction the process of suction centrifugal pump in different hydraulic performance parameters, the establishment of self absorption in the process of bubble size and quantity, relationship between trajectory and self-priming performance, self suction pump to further reveal the mechanism, structure design of self suction self suction pump For the theoretical basis. The main research contents and results are as follows: 1. to 65ZB-40C outside the mixed type self-priming centrifugal pump based on self-priming pump design theory, design a prototype design of organic glass, the tongue part can be moved. To build a self suction pump hydraulic performance test rig, the self suction the pump prototype test on the hydraulic performance of outlet circumferential speed of impeller and volute tongue clearance effect on the performance of self-priming pump self-priming time, results show that with the decrease of the circumference of the impeller speed increases or tongue clearance and shorten the.2. to build a self suction pump with high speed photography test system, measuring different separation tongue gap and impeller circumferential velocity under the condition of changing speed, pump inlet and outlet pressure and flow parameters, while filming the self-priming process of impeller, gas-liquid separation chamber, the gas-liquid two-phase flow pattern changes in key parts of the volute. The results show that the self absorption process can Divided into self suction start-up stage, stable stage and self suction self suction self suction mutation stage, stable stage is a dynamic stabilization process, this process accounted for the entire process of self absorption time was the highest, the greatest impact on the process of self absorption. The outer edge of the impeller gas-liquid mixing layer and separation chamber gas hole is a necessary condition for self absorption of the stability of.3. by filtering, self suction process of the air bubbles in the digital image binarization and image filling method of image of high-speed photography to the pretreatment. The removal of background noise subtraction method, comparison of median filter, Gauss filter and Wiener filter three denoising method, and will be the three kinds of results using the two value image Otsu method and iterative threshold method for image comparison, Gauss filtering and Otsu method. Process, the imfill function with MATLAB for image filling, to regain lost due to binarization bubble center information.4. based on image preprocessing, extracting two value image, bubble size, trajectory and velocity information of micro and macro bubble characteristics of self suction self relation suction performance change process. The results show that the bubble group compared the right area of the left area of volute diffuser near the gas-liquid separation chamber is small in diameter and quantity. The smaller diameter bubble group compared to the larger diameter more easily out of the pump body, which reduce the air liquid two-phase flow in bubble size, the more stagnant bubble into mobile bubble is a shortened self-priming time, improve the effective way of self suction performance, self-priming time shortened with decreasing separation tongue gap this also is the cause of the pump.

【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】：TH317

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