【摘要】：高壓氣體微孔射流沖擊技術已廣泛應用在切割、掘土、引射噴霧防塵、注漿技術等工程領域。立式強力混合機對粉料具有較好的混勻效果,但攪拌槳葉受粉料的沖擊及摩擦阻力作用極易磨損,為改善堆積粉料的破散性和提高槳葉的使用壽命,將射流沖擊技術應用于通氣槳葉對堆積粉料破散過程。本文結合數值模擬和試驗研究兩種方式,對影響高壓氣體射流沖擊效果的參數進行系統研究,可為射流沖擊技術實現在球團堆積粉體領域的應用提供理論支持及技術指導。根據射流沖擊的流體動力學原理,分析單股、多股及旋轉高壓氣體微孔射流沖擊的流場特性,重點研究射流的流場結構、軸線速度相似性分布規(guī)律,掌握不同條件下射流沖擊過程的特性規(guī)律,并推導出圓斷面射流主體段和初始段的速度及流量的關系式,為工程應用計算提供指導。開展了射流沖擊參數試驗。測定堆積粉粒體的相關物性,得到孔隙率、壓縮度、外摩擦系數、內摩擦角和抗剪強度。物性參數試驗可為數值模擬提供準確的輸入參數,同時為進行射流沖擊破散性試驗提供相關依據。開展了射流沖擊形態(tài)和噴距試驗。確定不同噴嘴類型在不同射流壓強下的最佳噴距,為數值模擬和試驗研究提供思路和方案。采用氣固Eulerian多相流建立九孔噴嘴三維仿真模型,選擇Realizableκ-ε湍流模型對射流沖擊粉粒體過程進行數值模擬。研究分析了射流壓強、沖擊時間、粉料粒徑、噴嘴類型和噴距等參數對射流沖擊的影響,得到較優(yōu)的工況參數。開展了射流沖擊堆積粉料破散性參數試驗。研究不同射流壓強、沖擊時間、噴嘴類型和噴距等射流參數下沖擊堆積粉料的破散性效果。比較分析其孔口深度、切割寬度、破散體積的形成原因,得到沖擊效果最佳的一組參數,驗證了數值模擬的可靠性。
[Abstract]:High pressure gas microporous jet impingement technology has been widely used in the fields of cutting, digging, ejecting spray and dustproof, grouting technology and so on. The vertical strong mixer has better mixing effect on powder, but the impingement and friction resistance of agitating blade are easy to wear, in order to improve the breaking property of powder and the service life of blade, The jet impingement technique was applied to the process of breaking and dispersing of aerated propeller blades. In this paper, the parameters affecting the impingement effect of high pressure gas jet are systematically studied by numerical simulation and experimental study, which can provide theoretical support and technical guidance for the application of jet impingement technology in pelletizing powder field. According to the hydrodynamic principle of jet impingement, the flow field characteristics of single-strand, multi-strand and rotating high-pressure gas micro-hole jet impingement are analyzed. The characteristic law of jet impingement process under different conditions is grasped, and the relationship between velocity and flow of jet body and initial section of circular section is deduced, which provides guidance for engineering application calculation. The jet impingement parameter test was carried out. The porosity, compression degree, external friction coefficient, internal friction angle and shear strength were obtained. The physical parameter test can provide accurate input parameters for numerical simulation and provide relevant basis for jet impinging and breaking test. The jet impingement morphology and jet distance test were carried out. The optimum jet distance of different nozzle types under different jet pressure is determined, which provides ideas and schemes for numerical simulation and experimental study. Three-dimensional simulation model of nine-hole nozzle was established by gas-solid Eulerian multiphase flow, and Realizable 魏-蔚 turbulence model was selected to simulate the jet impingement process. The effects of jet pressure, impact time, particle size, nozzle type and injection distance on jet impingement were studied and the optimal operating conditions were obtained. The breakage parameter test of jet impingement piling powder was carried out. The breakage effect of impingement piling powder under different jet pressure, impact time, nozzle type and jet distance was studied. By comparing and analyzing the formation reasons of hole depth, cutting width and breaking volume, a set of parameters with the best impact effect is obtained, and the reliability of the numerical simulation is verified.
【學位授予單位】：湘潭大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TD92

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