【正文】 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 vortextype flow with a peripheral water ring and internal gasvapor 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 the cross section. Throughout the length of the initial cylindrical segment of the conduit, the gasvapor core possesses a wavelike curved axis which coincides with the axis of the tunnel even as close as 10dx from the axis of the shaft. As nonaerated flow enters the tailrace conduit through the rotation node, a vacuumgauge pressure is established in the gasvapor core, and in the case of highly aerated flow, gauge pressure, The reduction in pressure in the gasvapor core is associated with the effect of centrifugal forces in vortextype flow, while an increase in pressure is associated with nearly plete release of air from the aerated flow into the core induced by the transport of air bubbles from the periphery to the center under the effect of the pressure gradient. For a tailrace conduit with cylindrical initial segment, the free area downstream increases from in the section at a distance from the axis of the shaft to in the section at a distance , while the angle of flow rotation and the axial and circumferential flow rates all decrease. In the case of a conical initial segment, the relative area of the gasvapor core decreases from to over the length of the conical segment, while the angle of flow rotation decreases to between onehalf and twothirds its initial value over this segment. A characteristic feature of the construction that is being proposed in the present article is the presence of an energy dissipation chamber in which vortextype flow experiences an abrupt expansion and is rapidly transformed into axial flow if the discharge of flow from the tailrace tunnel is directed into the atmosphere. Equality of the centrifugal acceleration to the free fall acceleration is an essential condition for breakdown of the vortex structure of the flow in the tunnel. Once equality is achieved, the mass of water traveling along the roof of the tunnel caves in, and mixes easily with the air in the flow core. The transformation of vortexlike flow into axial flow that occurs here is acpanied by significant dissipation of energy. The rate of energy dissipation differs between the two versions that are being considered here (Fig. 8). In the case of a cylindrical initial segment, energy dissipation occurs smoothly, with only 60% of the initial energy of the flow dissipating over a distance of 15dw (Fig. 8a). In a system with a conical vortex generator and energy dissipation chamber behind the generator, 86% of the initial energy of the flow dissipates as it travels through this segment, CONCLUSIONS Application of the constructions ot vortex tunnel spillways that we have considered enable us to ensure effective dissipation of the excess kiic energy and overall reliability of the structure. The operating reliability of vortex spillways that are based on energy dissipation in the tailrace tunnel in accordance with the schemes that have been considered in the present article is confirmed by the fact that the pressure fluctuations and the intensity of the turbulence dissipate smoothly throughout the tunnel and by the fact that these quantities are low level at the point of discharge of the flow into the lower pond. The conditions imposed by the configuration of a vortex spillway that is part of a hydraulic pr