The availability of a spillway system capable of conveying and regulating large flows within a wide range of heads up to 200-300 m and over would permit reducing subsrantially the volume of work and the construction costs for hydraulic developments; thus, the problem of creating such spillway systems becomes extremely important. However, this calls for the solution of many complex problems involved in the construction of high-head gates and the protection against cavitation and dissipation of hydraulic energy.A11 known gates in hydraulic developments operate on the principle of flow contraction, that is, they regulate the flow by varying the area of the hydraulic passage (Fig. la), which leads to the development of high fiowvelocities. The velocity at the contracted section is determined from the equationin which H is the head and ~ is the velocity coefficient (q = 1).Thus, downstream from the gate practically ali the excess energy is transformed into kinetic energy, which quickiy increases as the head increases and which is the cause of the difficulties.The cavitation coefficient or parameter for any element around which the water flows can be expressed by the equation (P/'Oabs-(p/y) wp ~ca~-

The Nurek hydroelectric station [1] is a peak-load station and will participate in automatic power regulation by means of a control computer installed at the dispatcher point of the integrated power system of Central Asia. The installed capacity of the station is 2,700,000 kW in nine units.The water-conducting structures of the station (three deep water intakes, three headraces with shafts for the emergency repair gates, three surge shafts, and nine penstocks to the station power house) are unique in their parameters (see Fig. 1 of [1]).Over their entire length the water-conducting structures (see Fig. 1) pass through fractured rock of average toughness which has been grouted around the conduits. To start up the first line of the hydroelectric station an intermediate intake was located 100 m below the permanent intakes and connected with the penstocks by a 6.5-mdiameter tunnel which divided by horizontal forks into three branches with a diameter of 4.5 m each. The shaft of the emergency gate, controlled from an underground room, was placed in the initial section of the intermediate tunnel.When working out the design of the Nurek hydroelectric station, the Central Asian Branch of the All-Union Planning, Surveying, and Scientific-Research Institute (Saogidroproekt) with the help of the Kuibyshev Moscow Institute of Civil Engineering (MISI) calculated* the unsteady regimes in the penstocks for the following equipment parameters (suggested by the plant): flywheel moment of the generator rotor, 21,500 tons; m2; maximum head in the spiral casing, not more than 380 m; temporary unsteady running of the units, not more than 57%.For the adopted scheme of the conduits with the fork located directly beyond the surge shaft, a simultaneous drop of the load from three units was used in the calculation, although in the given case the number of units dropping the load had practically no effect on the magnitude of water hammer. For r lv = 5400 m2/sec, control was guaranteed for a 57% temporary uneven running of the units and dynamic head of 365 m.During further planning, Saogidroproekt and MISI sought solutions which would eliminate the surge shafts. The following was the basis for this search: in the earlier design of the Charvak hydroelectric station the surge shafts were eliminated owing to the safety factors that existed in the water turbine used (developed earlier for another hydroelectric station), which made it possible to increase the design value of the dynamic head. The slight increase of the diameter of the headrace tunnels that was required proved to be economically justified. There is a tendency to increase the response time and magnitude of temporary uneven running of the units, which has found reflection both abroad [2] and in our country (e.g., in the design of the Kuban'-Kalaus hydroelectric stations). During development of the design of the generator of the Nurek station it was found that the flywheelmasses ofits rotor could be increased.The search for solutions was carried out in two directions: along the line ...

No abstract

621.224.003.13 In the construction of high dams, which as a rule takes a long time (8-10 years), the possibility of starting up the turbine units of the 8rst line before the dam is completed is determined by the opesational capabili~r of the turbines at low reservoir water-level elevations. The selected minimum elevation determines the volume and composition of the structures of the so-called starting complex. However, the possibility of operating high-head, mixedflow turbines at low heads is limited. Thus, themanufacturing plant of the turbines for the Nurek hydroelectric station, which are in.haled to operate during normal service in the 207-275-m head range, does not permit their use at heads below 165 m.

The attainment of specific technicoeconomic indicators suggesting a high technical level of development in equipment models is the responsibility of the plants when they develop new water-power equipment --hydraulic turbines, hydraulic units, and hydraulic turbine gates. By indicating the economic value of the equipment, one of these indicators --reduction in specific metal consumption --often contradicts the objective requirements dictated by the layout and design of the hydraulic projects and may lead to their overall cost increase. This can be explained by specific examples.