旋流式竖井涡室水力特性研究

发布时间：2017-12-31 03:19

本文关键词：旋流式竖井涡室水力特性研究　出处：《西北农林科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：旋流式竖井作为一种新型的内消能工,由于其良好的水力特性与高消能率,作为泄洪洞体现了愈来愈高的工程价值,并且其研究越来越受到人们的追捧。目前,对旋流式竖井涡室体型的选择,主要是依靠流量来进行选择:圆弧涡室泄流能力较小,适用于流量小于500 m3/s;椭圆曲线涡室泄流能力要大一些,适用于流量小于3000 m3/s。但是,旋流式竖井的流量是与竖井直径紧密联系的,共同影响着旋流式竖井的泄流能力,仅以流量来界定是不准确的;另外,旋流式竖井涡室水面线的计算,暂没有明确的计算方法,而水面线作为水力学研究的重点之一,在旋流式竖井涡室边墙高度选择上起着非常重要的作用。本文采用模型试验的方法,来研究旋流式竖井涡室的水力特性,对旋流式竖井涡室的流态、水面线、压强、流速等水力要素进行测量分析,并且分别以试验研究以及论证流量管径数的方法来研究旋流式竖井涡室体型的选择标准,另外提出采用刘韩生冲击波简化式计算涡室水面线问题。具体表现在以下几个方面:(1)栗西沟尾矿库排洪管是小流量泄洪设施,现有方法不能选定涡室体型,通过水工模型试验比较了圆弧涡室和椭圆曲线涡室对栗西沟的适用性,表明:a.圆弧形涡室在各种流量下,泄流流态都不如椭圆曲线涡室,后者各流量状态下都能够形成理想的贴壁螺旋流。b.椭圆曲线涡室体型流态良好,在加大涡室来流段底坡坡度,可以使涡室过流面积增加,减少壅水发生的可能性;导流坎可以减小入流与旋转回流之间的夹角,减轻壅水的作用;能够形成良好的贴壁旋流流态,并且不会产生空化空蚀问题,是其适合的涡室体型,并且能为以后小流量的旋流式竖井工程涡室体型选择提供借鉴。(2)椭圆曲线涡室流态相对于圆弧涡室流态更加稳定,旋转效果更好;涡室及其下渐变段内皆为正压情况,因此不会出现负压,对工程产生影响;涡室及其下渐变段压强的分布具有明显的分布特点;涡室水流流速较低,在最大流量22 m3/s下,涡室边壁流速最大仅为8.54m/s,如此较低的流速保证涡室不会发生空蚀破坏。(3)栗西沟工程实例计算结果表明,在旋流式竖井涡室水面线计算方面,刘韩生缓冲击波简化式相对Ippen冲击波理论计算精度更高,能够更加准确的计算涡室水面线。另外,前者较后者,计算过程更加简单快捷,不需要繁琐迭代试算过程,更适合实际工程的需要。因此,刘韩生缓冲击波简化式能够比较精确的计算涡室水面线问题,能够为以后的实际工程提供借鉴。(4)流量管径数η能够非常清晰的描述旋流式竖井的泄流能力,当流量管径数η越大,说明旋流式竖井的泄流能力越强;反之亦然。实际工程实例和栗西沟水工模型试验表明椭圆曲线涡室为大流量管径数旋流式竖井的合适体型,不仅能够保持很好的旋流流态,还可以保持良好的工程经济性。并且,椭圆涡室体型也适合小流量管径数旋流式竖井的要求。
[Abstract]:Cyclone shaft as a new type of energy dissipation, because of its good hydraulic properties and high energy dissipation, as Hongdong relief reflects the increasingly high engineering value, and its research has become more and more popular. At present, the cyclone shaft vortex chamber type selection, mainly rely on the flow of selection: circular vortex chamber discharge capacity is small, suitable for the flow rate is less than 500 m3/s; elliptic curve of vortex chamber discharge capacity to be big, suitable for the flow of less than 3000 m3/s. but the cyclone shaft flow is closely related with the diameter of the shaft, to affect the discharge capacity of cyclone shafts, only to flow to define is not accurate; in addition, the calculation of water level line of cyclone shaft vortex chamber, there is no clear method of calculation, and the water line as one of the key to the study of hydraulics, the cyclone shaft vortex chamber side wall height selection plays a very heavy To function. This paper uses the method of model test, the hydraulic characteristics of cyclone shaft vortex chamber, the cyclone shaft flow, vortex chamber water line, pressure, velocity measurement and analysis of hydraulic elements, selection criteria and were in the experimental research and demonstration method to study the flow diameter number of vortex cyclone shaft room size, also put forward by the shock wave of Liu Hansheng type simplified calculation of water surface line vortex chamber. The specific performance in the following aspects: (1) the tailings of Lixigou drainage pipe is small discharge facilities, the existing methods can not be selected vortex chamber size, the applicability of circular vortex chamber and volute chamber of Lixi elliptic curve ditch the comparison through the hydraulic model test shows that the A. arc shaped vortex chamber in various flow conditions, the discharge flow pattern as the elliptic curve vortex chamber can form an adherent.B. elliptic vortex flow state the latter song Line type vortex chamber flow, vortex chamber flow to increase in the bottom slope, can make the vortex chamber flow area increases, reduce the possibility of occurrence of backwater; diversion bank can be reduced into the angle between the rotation flow and return, reduce the backwater effect; can form good adherent swirl flow, and not produce cavitation, which is suitable for vortex chamber size, and can provide reference for the future of small flow vortex chamber type cyclone shaft project. (2) the elliptic curve of vortex chamber flow relative to the circular vortex chamber flow is more stable, the rotation effect is better; and the transition in the vortex chamber is positive pressure therefore, does not appear negative impact on engineering; distribution of vortex chamber and transition pressure distribution has the obvious characteristics of the vortex chamber; flow velocity is low, the maximum flow rate of 22 m3/s, the maximum velocity of vortex chamber wall is only 8.54m/s, so low To ensure the flow of vortex chamber will not produce cavitation damage. (3) Lixigou computational results show that the calculation of water surface profile in cyclone shaft vortex chamber, Liu Hansheng shock wave type Ippen shock wave theory simplified relative higher calculation accuracy, can accurately calculate the vortex chamber water surface line. In addition, the former is the calculation process is more simple and quick, do not need tedious iterative process, more suitable for the actual needs of the project. Therefore, the Liu Hansheng shock wave can simplify the calculation of vortex chamber water line accurately, can provide a reference for future projects. (4) the number of flow diameter ETA discharge capacity can describe the cyclone the shaft is very clear, when the number of the larger diameter flow is, that discharge capacity of more strong cyclone shaft; and vice versa. The actual project and water Li Xi model test show that elliptic curve of vortex chamber for large diameter flow The suitable shape of a number of swirling shaft can not only maintain a good swirling flow pattern, but also maintain good engineering economy. Moreover, the elliptical vortex chamber shape is also suitable for small flow diameter pipe swirling shaft.

【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV135.2

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