【正文】 ssipation Tunnel spillways are widely used in medium and highpressure hydraulic works. It is therefore an important and pressing task to improve the constructions used in these types of spillways and to develop optimal and reliable spillway this in mind, we would like to turn the reader39。s attention to essentially novel (., in terms of configuration and operating conditions) vortex spillways which utilize vortextype flows. On the one hand, these types of spillways make possible largescale dissipation of the kiic energy of the flow on the initial leg of the tailrace segment, and, as aconsequence, flow rates of slightly vortextype and axial flows through the subsequent legs that do not produce cavitation damage. On the other hand, the dangerous effect of high flow rates on the streamlined surface decreases over the length of the initial tailrace leg as a consequence of the increased pressure on the wall caused by the effect of centrifugal forces. A number of structural studies of tunnel spillways for hydraulic works such as the Rogunskii, Teri, Tel39。 spillways with two or more interacting vortextype flows in energydissipation discharge chambers or in specialenergy dissipators that have been termed countervortex energy dissipators.The terminal portion of the tailrace tunnel of a vortex spillway may be constructed in the form of a skijump bucket, a stilling basin, or special structures depending on the flow rate at the exit from the tunnel and on the conditions in the channel downstream. The hydraulic system used to link the flow to the tailrace canal may involve the use of either overflowtype or freefall type spillways with smooth or accelerated dissipation of energy over the entire length of the water conduit represent the simplest and most promising types of hydraulic of designing vortex spillways have now been developed and published in numerous studies。 for the Tel39。 and for the Rogunskii spillway, Ar:q = 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. The prerotation 17 0 behind the vortex generating device at a distance from 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 acpanied by a shift in the maximum axial ponent 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 spillways may 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 with external atmospheric pressure, the volumetric content of air varies slightly as the flow is transported down the shaft to the critical section, whereas in the physical structure, the entrapped air, moving downwards, is pressed by the increasing pressure of the liquid. Thus, in the case of the spillway at the Teri hydraulic works (Fig. 1), the percent pression in the physical structure is as much as 15fold, whereas in the open model constructed on a 1:60 scale, the percent pression