【作者】 李利荣；

【导师】 文恒； 王福军；

【作者基本信息】 内蒙古农业大学 ， 农业水工建筑物， 2009， 博士

【摘要】 我国北方是水资源严重短缺的地区,但对于现有的水资源,有些却不能得到合理利用,如洪水资源中的多泥沙和高含沙洪水在利用过程中存在着一系列难题。对闸前有泥沙淤积时能自动启闭的新型水力自动滚筒闸门的研究,使得利用这部分洪水资源成为可能。通过水工模型试验,证明新型水力自动滚筒闸门的设想是可行的,可以保证在闸前有泥沙淤积时,闸门在水压力作用下开启自如。为了正确进行闸门设计,必须对作用在闸门体上的水压力进行准确地计算。闸门开启前闸体上的静水压力计算,毋庸置言容易解决。但闸门开启后作用在闸体上的动水压力的计算,目前尚无现成公式可利用。本文采用模型试验、数值模拟与理论分析相结合的方法,对水流中横置圆筒闸体上的动水压力分布规律进行研究。主要研究内容如下:(1)通过水工模型试验,研究了在上游水位变化和不同筒下开度工况下,圆筒表面动水压力时均值、脉动值的变化规律。(2)以物理模型为依据进行数学建模,采用数值模拟方法对水流中横置圆筒的水力学特性进行了深入研究。通过各模型的对比分析,本文最终采用RNG k-ε湍流模型和水气两相流VOF模型,对横置圆筒绕流流场进行了数值模拟。(3)采用数值模拟对现有条件物理模型无法完成的工况进行数值模拟,研究了筒下开度(h)、筒顶水深(h1)、上游水深(H)、筒径(R)对绕流流场速度、流线、压力变化及其圆筒表面速度和动水压力变化的影响。物理模型试验所得主要结论:(1)沿迎水面从圆筒顶部至底部动水压力呈先增大后减小趋势,筒上、下均过水时,在圆筒中心线以下,即φ=135°附近水压力值达到最大,圆筒顶部(φ=0°)及底部(φ=180°)动水压力值较小,且底部动水压力值略小于顶部值。(2)筒下开度h一定,圆筒迎水面动水压力随闸上游水深H的升高而增大。当闸上游水深H一定,筒下开度h变化时,圆筒迎水面动水压力在圆筒顶部至中心线范围内(0<φ<90°)没有明显的变化,而在圆筒中心线以下(90°<φ<180°)动水压力沿圆筒表面自上而下随h的增加而减小,该变化趋势在φ=135°附近表现较明显。(3)迎水面各点压力脉动主频为f=50Hz左右,圆筒顶部(φ=0°)的脉动幅值最大, (φ=45°)处脉动幅值最小,在90°<φ<180°范围内,沿圆筒表面向下主频幅值逐渐增大。数值模拟所得主要结论:(1)圆筒迎水面中心线(φ=90°)附近,流速较小,圆筒上、下方流速较大,中心线以上各点流速随着筒顶水深(h1)的增加而增大,中心线以下各点流速变化较小。圆筒背水面中心线以上各点流速随着h1的增加逐渐增大,而中心线以下区域流速变化梯度较大,并且速度变化较复杂;圆筒背水面流速大于迎水面流速。(2)圆筒迎水面动水压力随上游水深H的升高由筒顶向下逐渐增大,φ=135°附近达到最大,继而迅速减小,在圆筒底部降到最小,并形成负压区。圆筒背水面,中心线偏上部分压力值较小,沿圆筒壁面向筒底方向呈先增大后减小趋势,且变化梯度由小到大。(3)筒下开度h、筒顶水深h1一定,迎水面各点压力与R成正比,在圆筒背水面220°<φ<260°区域,圆筒表面动水压力与筒径R成反比。(4)通过对水工模型试验和数值模拟结果的分析,建立了水流中横置圆筒表面动水压力的计算公式,并利用该公式进行了验证性计算,通过回归模型的计算值和模拟值的相关分析,表明该计算模型计算结果较为准确。更多还原

【Abstract】 Water resources are serious shortage in the northern area of China, but it can’t be utilized reasonable for existing water resources, such as the utilizing of multi-slit and flood. Since this it is possible to utilize flood to research the new hydro-automatic roller gate which works automatically with the balance of driving moment engendered by water pressure, and returning moment engendered of self-weight and matched weight. And it has been proved feasibly by hydraulic-model experiment. It can be ensured opening and closing automatically while silting in front of gate. So it is important to calculate the force which acting on gate for designing gate exactly. The force can be calculated before gate opening. However, the hydraulic pressure can’t be calculated after opening, and the formula hasn’t been found. So the hydraulic characteristics of roller are studied by experimental, numerical simulation and theoretical methods in this paper. The main contents are as follows.(1) By the hydraulic model experiment, the change rule of roller surface’s time-averaged pressure and hydraulic pressure are analyzed in different jaw opening and upper level conditions.(2) To establish mathematical model according to physical model, hydraulic characteristic of transverse roller surface are studied through numerical simulation. Ultimately, The RNG k ?εturbulence model and volume of fluid method (VOF) are applied to simulate the flow around transverse roller in this paper.(3) Numerical simulation is applied to simulate the conditions that physical model experiment can’t carried out. the influence of jaw opening(h), roller top water depth(h1), upstream water depth (H)and roller radius(R)to around flow and hydraulic pressure of roller surface is analyzed.The main results of physical model experiment:(1) The hydraulic pressure presents the trend that increasing in the beginning and reducing afterward along the roller surface. When upper level is above the top, hydraulic pressure reaches maximum atφ=135°, hydraulic pressure is less atφ=0°andφ=180°, the bottom’s hydraulic pressure is less than the top’s.(2) When h is definite, roller surface’s hydraulic pressure increases gradually with upper level H increasing. H is definite, the hydraulic pressure in 0<φ<90°isn’t obvious change. While the hydraulic pressure in 90°<φ<180°reduces along the roller surface adown with h increasing. And the trend is obvious atφ=135°. The basic frequency of pulsation pressure is about f=50Hz. The Pulsation amplitude is maximal atφ=0°and atφ=45°pulsation amplitude is minimal. and in 90°<φ<180°extent, the pulsation amplitude of basic frequency increasing along the roller surface adown.The main results of numerical simulation: (1) The velocity reduces minimum at center line of roller, roller top and bottom’s velocity is relative great. The velocity of above center line increases with h1 increasing. At back surface, the velocity of above center line increases with h1 increasing, and its change is complicated.And the velocity of back side is greater than water wind.(2) With H rising, The hydraulic pressure of water wind increases and reach maximal atφ=135°, then rapidly decreased. At roller bottom, the hydraulic pressure reaches minimal and appears negative pressure zone. At back surface, the pressure is relative small; the hydraulic pressure presents the trend that increases in the beginning and reduce afterward along the roller surface adown, and the change gradient enlarge gradually.(3) The pressure and R is in direct proportion at water wind when h and h1 are definite. At back side, the pressure and R is in inverse proportion in 220°<φ<260°domain.(4) The formula of transverse roller surface’s hydraulic pressure is established through the result of physical model experiment and numerical simulation. And the results of calculational model are verified, it is comparatively exact.更多还原