溢洪道外文文献翻译教学文案.doc

水工建筑物，29卷，9号，1995旋涡隧道溢洪道。液压操作条件M . A .戈蓝，B. zhivotovskii，我诺维科娃，V . B .罗季奥诺夫，和NN罗萨娜娃隧道式溢洪道，广泛应用于中、高压液压工程。因此研究这类溢洪道这是一个重要的和紧迫的任务，帮助在水工建筑中使用这些类型的溢洪道可以帮助制定最佳的和可靠的溢洪道结构。有鉴于此，我们希望引起读者的注意，基本上是新的概念（即，在配置和操作条件），利用旋涡流溢洪道1，2，3，4 。一方面，这些类型的溢洪道可能大规模的耗散的动能的流动的尾段。因此，流量稍涡旋式和轴向流经溢洪道的尾端，不会产生汽蚀损害。另一方面，在危险的影响下，高流量的流线型面下降超过长度时，最初的尾水管增加的压力在墙上所造成的离心力的影响。一些结构性的研究隧道溢洪道液压等工程rogunskii，泰瑞，telmamskii，和tupolangskii液压工程的基础上存在的不同的经营原则现在已经完成了。这些结构可能是分为以下基本组：-涡旋式（或所谓的single-vortex型）与光滑溢洪道水流的消能在隧道的长度时的研究的直径和高度的隧道；参看。图1），而横截面的隧道是圆或近圆其整个长度。涡旋式溢洪道-与越来越大的能量耗散的旋涡流在较短的长度- （6080）高温非圆断面导流洞（马蹄形，方形，三角形），连接到涡室或通过一个耗能（扩大）室（图2） 5，6 或手段顺利过渡断 7；-溢洪道两根或更多互动旋涡流动耗能放电室 8 或特殊耗能器，被称为“counter-vortex耗能” 2，4 。终端部分尾水洞涡流溢洪道可以构造的形式，一个挑斗，消力池，或特殊结构取决于流量的出口从隧道和条件的下游航道。液压系统用于链接的流量的尾管可能涉及可以使用overflowtype或自由落体式结构。涡旋式溢洪道光滑或加速 7 能量耗散的整个长度的水管道是最简单和最有前途的各类液压结构。设计技术涡溢洪道已开发和出版了许多研究 2，7，8 ；特别是，技术是目前可用于计算液压阻力的路线和流动率，涡旋式流量和压力。然而，每一个实际工程设计结构也必须进行评估。模型调查手段，因为它仍然是不可能评估所有的因素的操作溢洪道计算方式。因此，让我们一起关注一些重要理论问题。熟悉这些主题可以协助设计和研究涡式溢洪道。 评价设计溢洪道的尺寸。选择一个特定的溢洪道类型取决于很多因素，如有效的水头，巨大的escapage放电，这是配置的液压项目（例如，使用一个河引水隧道在运营期间或的水管道水力发电厂在施工期间），在放电的流入尾水渠道，地形及地质特征（特别是可能的长度，尾水腿），和技术经济特点。入口（入口段的形式，表面或地下输）。入口的设计是根据设计规范。其目的在保持其运输能力时，运作中的水能自由下泄。轴（垂直或倾斜）。轴的直径是由近等于尾水管的直径。最大平均流量在一个轴的范围是15 - 20米/秒。涡流产生装置。整个长度的尾段溢洪道，以及一定程度的洪水的轴（即，其水力工况Q (60 - 80)hT or (60 - 80)dT (where dT and hT are the diameter and height of the tunnel; cf.Fig. 1), while the cross-section of the tunnel is either circular or near-circular throughout its length.- vortex-type spillways with increasingly greater dissipation of the energy of the vortex-type flow over a shorterlength Lr - (60 - 80)hT of a noncircular section river diversion tunnel (horseshoe-shaped, square, triangular) which isconnected to the eddy chamber either by means of an energy-dissipation (expansion) chamber (Fig. 2) 5, 6 or by means ofa smooth transition leg 7;- spillways with two or more interacting vortex-type flows in energy-dissipation discharge chambers 8 or in specialenergy dissipators that have been termed counter-vortex energy dissipators 2, 4.The terminal portion of the tailrace tunnel of a vortex spillway may be constructed in the form of a ski-jump bucket,a stilling basin, or special structures depending on the flow rate at the exit from the tunnel and on the conditions in thechannel downstream. The hydraulic system used to link the flow to the tailrace canal may involve the use of either overflowtypeor free-fall type structures.Vortex spillways with smooth or accelerated 7 dissipation of energy over the entire length of the water conduitrepresent the simplest and most promising types of hydraulic structures.Techniques of designing vortex spillways have now been developed and published in numerous studies 2, 7, 8; inparticular, techniques are now available for calculating the hydraulic resistance of individual legs of a route and the flow ratesand pressures in vortex-type flow. However, for each actual hydraulic project a designed structure must also be evaluated bymeans of model investigations, since it is still not possible to evaluate all the elements of the operation of a spillway bymeans of calculations.Thus, let us turn our attention to a number of theoretically important problems. A familiarity with these topics willbe of assistance in the design and investigation of vortex spillways.Evaluation of the Design and Geometric Dimensions of the Elements of a Spillway. The selection of a particulartype of spillway depends on a number of factors, such as the effective head, the magnitude of the escapage discharge, theconfiguration of the hydraulic project (for example, the use of a river diversion tunnel during the operational period or of the water conduits of hydroelectric power plants in the construction period), conditions in the discharge of the flow into thetailrace channel, topographic and geological features (in particular, the possible length of the tailrace leg), and the technicaland economic characteristics.Inlet (entry segment in the form of surface or subsurface offtake). The inlet is designed on the basis of standardtechniques to maintain its conveyance capacity when functioning in the free-fall regime. Shafts (vertical or inclined). The diameter of the shaft is made nearly equal to the diameter of the tailrace leg:It should be noted that the eddy node is designed so that A = Areq, where Are q is the value of the geometric parameter of the vortex generator needed to maintain the required prerotation of the flow. For example, for the conditions of the Tupolangskii vortex-type spillway, Are q = 1.4; for the Telmamskii hydraulic works, Are q = 0.6; and for the Rogunskii spillway, Ar:q = 1.1.A second parameter which characterizes the degree of rotation of the flow on individual legs of the tailrace segment is the integral flow rotation parameter II 1, 2. The prerotation 17 0 behind the vortex generating device at a distance 3.0dTfrom the axis of the shaft may be determined on the basis of graphical dependences thus: 17_o = f(A) (Fig. 4).Tailrace tmmd. The overall widths of the tunnel are determined by the type of spillway design which is selected and the method decided on for dissipation of the excess energy (either by means of smooth or increasingly more intensive dissipation). Energy Dissipation Chamber. The choice of design and dimensions depends on the rate of rotation of the flow at the inlet to the chamber and on the length of the tailrace tunnel following the chamber. For a tailrace tunnel with LT/d T _ 60, it is best to use a converging tube (or cylindrical) segment as the conjugating element between the tangential vortex generator and the energy dissipation chamber. The segment will be responsible for the following functions: reduction of the rate of rotation of the flow at the inlet to the energy dissipation chamber, equalization of flow rates accompanied by a shift in the maximum axial component of the flow rate into the central portion, and reduction of the dynamic loads at the rotation node of the flow. From the foregoing discussion it follows that in those cases in which there is no entrapment of air, vortex spillwaysmay be modeled with respect to all the required criteria.The situation is different in the case of aerated flow, which is also difficult to model. In hydraulic models withexternal atmospheric pressure, the volumetric content of air varies slightly as the flow is transported down the shaft to thecritical section, whereas in the physical structure, the entrapped air, moving downwards, is compressed by the increasingpressure of the liquid. Thus, in the case of the spillway at the Teri hydraulic works (Fig. 1), the percent compression in the physical structure is as much as 15-fold, whereas in the open model constructed on a 1:60 scale, the percent compression is in the range 1.4-1.5, i.e., one-tenth that of the values found in the field. Moreover, in the experiments using the models, there was an increase noted in the angles of rotation of the flow in the initial segment of the tailrace tunnel as the escapagedischarge was decreased and the content of air in the mixture was increased.Inasmuch as in the physical object the air content in the critical section is always insignificant, the increase in theangles of rotation as the volume of escapage discharge was decreased was unexpected. To create a reliable model of vortextypeflow when there is a free level in the stem of the shaft and abundant air entrapment by the flow, it is necessary to isolatethe region of air in the upper and lower ponds from the external atmosphere and to reduce the air pressure in these regionsthrough creation of a vacuum in accordance with the geometric scale of the model. Hydraulic Conditions throughout the Spillway Segment. The hydraulic conditions of operation of vortex spillwaysdiffer substantially from the corresponding conditions for spillways constructed in the traditional configuration. Let usconsider these differences on the basis of the results of laboratory studies of the operational spillways of the Rogunskiihydroelectric plant (which includes an energy dissipation chamber) and the spillway of the Teri hydraulic works (whichoperates with smooth dissipation of energy throughout the length of the tunnel).The initial design of the Rogunskii hydroelectric plant called for a chute as the terminus structure of the operationalspillway; it was intended that the flow rate at the end of the chute was to reach 60 m/sec. Understandably, flow rates that arethis high entail adoption of special measures to protect the streamlined surfaces of the spillway from cavitation damage and the stream course from dangerous degradation. To meet this need, the Tashkent Hydroelectric Authority, working with the Division of Hydrodynamic Research (now the Central Hydraulic Institute, Society of the Scientific Research Institute on the Economics of Construction), developed several alternative versions of spillway designs intended to dissipate a significant portion of the energy of the flow within the spillway and to substantially reduce the flow rate in the tailrace tunnel and at the point where the flow is discharged into thestream course. In one of the versions that were considered, the bend in the turning segment that is part of the traditional configuration of a shaft spillway was replaced by a tangential flow vortex generator. Similarly. vortex-type flow is created throughout the entire length of the tailrace segment. Hydraulic studies were performed on a model that simulated a shaft spillway at a scale of 1:50 and consisted of a shaft measuring 13 m in diameter and 148 m in height, a tangential vortex generating device, and a tailrace tunnel.The studies that were performed showed that in the shaft which delivers water to the flow rotation node, an intermediate water level is maintained when the flow rate is less than the design rate. This bench mark depends on the magnitude of the escapage discharge and the resistance of the spillway segment situated at a lower level . In the constructions that have been considered here, maximum (design) flow rates through the shaft are achieved when the shaft is flooded and there is no access to the air. In the model nearly complete entrapment of air from the water surface occurred with intermediate water levels in the shaft; moreover, the lower the level of the water surface, the more the air restrained the water flow and transformed the flow into a rotation node (Fig. 7). Stable vortex-type flow with a peripheral water ring and internal gas-vapor core is formed beyond the tangential vortex generator. Due to asymmetric delivery of water into the vortex generator in the initial segments, the core of the flow is noncircular and situated away from the center of