【摘要】：隨著全球水利事業(yè)的高速發(fā)展,高速水流逐漸成為最值得關(guān)注的水力學(xué)科問題之一。陡槽中的高速水流容易形成局部低壓區(qū),這會有利于空化和空蝕的發(fā)生。為了避免空化和空蝕破壞的發(fā)生,施工工藝需嚴格控制建筑物過流邊壁的不平整度,并選用設(shè)計優(yōu)秀合理的建筑物體型,人為的在泄水建筑物中設(shè)置摻氣設(shè)施,盡可能避免空蝕破壞以保護過流邊壁。近年來,摻氣設(shè)施一直具有經(jīng)濟、高效的優(yōu)點。顯然,全斷面摻氣比單獨的底摻氣和側(cè)摻氣要復(fù)雜,研究成果相對較少。本文將對底板和側(cè)墻的聯(lián)合摻氣水流特性進行相關(guān)探究。 本文通過陡槽模型試驗,對不同體型的底摻氣坎和側(cè)摻氣坎進行組合,形成聯(lián)合摻氣坎,研究陡槽全斷面摻氣水流特性。研究方法是通過對底、側(cè)摻氣坎坡度的變化、來流條件的變化,利用控制變量法分析各種影響因素對聯(lián)合摻氣坎的摻氣空腔特性、坎后水流流態(tài)的影響,得出坎后摻氣濃度的縱、橫向分布規(guī)律和沿程衰減規(guī)律,探究聯(lián)合摻氣坎的摻氣效率及摻氣保護長度。 通過試驗研究和理論分析,本文得出了以下結(jié)論。首先,對于空腔特性而言：底空腔和側(cè)空腔長度都與底坎坡比呈正相關(guān)；側(cè)空腔長度與側(cè)坎坡比呈正相關(guān),但底空腔長度受到側(cè)坎坡比的影響是微弱的。其次,對于摻氣濃度的分布規(guī)律而言：沿程的分布呈現(xiàn)先增大后減小的規(guī)律,縱向先呈現(xiàn)底表大、中間小,后呈現(xiàn)自底而上逐漸增大的分布規(guī)律,橫向分布呈現(xiàn)兩側(cè)大,中央小的規(guī)律。最后對于摻氣濃度的影響因素,坎后水流的摻氣濃度與側(cè)坎坡比、底坎坡比、流量都呈正相關(guān)關(guān)系。相應(yīng)的,底板和側(cè)墻的摻氣保護長度也都與底坎坡比、側(cè)坎坡比和下泄流量呈正比關(guān)系的。但是摻氣坎的坡度對流態(tài)的影響較大,特別是側(cè)摻氣坎坡度較大時容易使水流在坎后交匯時碰撞,形成較大水翅,使水流流態(tài)惡化。因此,體型尺寸良好的聯(lián)合摻氣坎才能獲得好的流態(tài)和摻氣效果,延長對陡槽的保護范圍。 試驗研究表明：聯(lián)合摻氣坎對提高水流摻氣濃度,保護邊壁和底板不受到空蝕破壞是有利的。底摻氣坎體型不僅影響了底空腔特性,也制約著側(cè)空腔的形成。
[Abstract]:With the rapid development of global water conservancy, high-speed water flow has gradually become one of the most worthy of attention. The local low pressure region is easy to form in the high velocity flow in the steep channel, which is favorable for cavitation and cavitation erosion. In order to avoid cavitation and cavitation damage, the construction technology should strictly control the unevenness of the overflowing side wall of the building, select the excellent and reasonable design of the building shape, and set up the aeration facilities artificially in the drainage building. Avoid cavitation damage as much as possible to protect the flow side wall. In recent years, aeration facilities have been economic and efficient advantages. It is obvious that full section aeration is more complicated than single bottom aeration and lateral aeration, and the research results are relatively few. In this paper, the combined aeration flow characteristics of bottom slab and side wall are studied. In this paper, the combined aeration between the bottom aerator and the lateral aerator with different shapes is carried out to study the aeration flow characteristics of the whole section of the steep-trough by means of the model test of the steep-trough. The research method is to analyze the influence of various factors on the aeration cavity characteristics of the combined aerator and the water flow state after the combined aeration by using the control variable method through the change of the slope of the bottom and side aeration sill and the change of the incoming flow condition, and the control variable method is used to analyze the influence of various factors on the aeration cavity characteristics of the combined aerator. The longitudinal and lateral distribution and attenuation law of aeration concentration after the dam are obtained, and the aeration efficiency and the aeration protection length of the combined aerator are explored. Through experimental research and theoretical analysis, this paper draws the following conclusions. Firstly, the length of bottom cavity and side cavity are positively correlated with the ratio of bottom cavities and side cavities, and the length of side cavities is positively correlated with the ratio of side cavities to slope, but the influence of the length of bottom cavity on the ratio of side cavities to slope is weak. Secondly, for the distribution of aeration concentration, the distribution along the path increases first and then decreases. The longitudinal distribution presents the distribution law of large bottom surface, small middle, and gradually increasing from bottom to top, and the lateral distribution is large on both sides. A small central rule. Finally, for the influence factors of aeration concentration, there is a positive correlation between the aeration concentration and the side slope ratio, the bottom slope ratio and the flow rate. Accordingly, the aeration protection length of the bottom slab and side wall is proportional to the ratio of the bottom slope to the slope, the ratio of the side to the slope and the flow down. However, the gradient convection state of the aerator is more important, especially when the slope of the lateral aerator is high, the water flow will easily collide at the intersection behind the ridge, resulting in the formation of larger water wings, and the deterioration of the water flow state. Therefore, the better flow state and aeration effect can be obtained by the combination aerator with good size, and the protection range of the steep trough can be extended. The experimental results show that the combined aerator can improve the aeration concentration of water flow and protect the side wall and bottom plate from cavitation erosion. The shape of bottom aerator not only affects the characteristics of bottom cavity, but also restricts the formation of side cavity.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TV135.2;TV131.34

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