Maximum depth of reservoir drawdownDenisov, P.
doi: 10.1007/BF01425062pmid: N/A
Calculation of the firm power of a hydrostation as a function of the drawdown depth of the reservoir, giving material for a technical and economic determination of the maximum drawdown depth, should be carried out for a prescribed power regime in the design dry year. Calculation for a prescribed discharge regime distorts the general notion about the character of this functional relation. To avoid errors in calculations of the firm capacity and power production corresponding to it as a function of drawdown depth, it is necessary to take into account thatin the case of streamflow regulation for purposes of the power industry a reservoir drawdown regime with a constant discharge is contraindicated, which should be indicated in the pertinent textbooks.
Passage of waste discharges through blocks with vertical unitsVasil'ev, Yu.; Minigulov, A.; Samorukov, I.
doi: 10.1007/BF01425063pmid: N/A
1.
The investigations showed that passage of waste discharges through the waterway of the turbine-generator unit block with the turbine runner or blades disassembled is an acceptable scheme of passage in the operating period of a hydrostation when repairing the unit. In this case the maximum discharge capacity of the turbine block fora
omax, Hd is Q=l.62Qmax (for the disassembled turbine runner) and Q=l.65Qmax (for the disassembled runner blades).
2.
The maximum discharge capacity in the case of an assembled blade system of the unit is obtained also fora
omax, ϕ=+22.5°. However, passage of the waste discharge while preserving the rotational speed of the unit close to the nominal is possible only for small heads H=0.35−0.54. When nt=nn, ϕ=+22.5°,a
omax, the head at which discharge of water through the unit is possible is 0.45Hd.
3.
The presence in the waterway of an additional resistance in the form of gates in the outlet diffuser of the draft tube makes it possible to pass waste discharges Q=(l−1.2) Qmax is a wide range of heads acting on the hydrostation H=(0.35−1.3)Hd while preserving the rotational speed of the unit close to the nominal nt=(0.9–l.l) nn.
4.
An additional check of the indicated variants with an investigation of the strength of individual elements and components of the turbine block for particular conditions of the hydropower plant is necessary for a final recommendation of the scheme of passing waste discharges through the powerhouse part of a hydrodevelopment.
Estimation of the reliability of a high earth-rock damRasskazov, L.; Zhelankin, V.
doi: 10.1007/BF01425064pmid: N/A
1.
The magnitudes of the statistical variability of physical and mechanical characteristics of soils and loads have a decisive effect on the probability scatter of stresses, strain and safety factors as well as on the level of reliability of a dam.
2.
The given method of estimating reliability makes it possible to determine the probability that a dam will not reach the limit state of the first group (B) and expected value of the safety factor (¯Ks). The use of these criteria in calculating structures opens the possibility of a well-founded determination of the level of reliability of earth dams in coordination with the calculated coefficients of the method of limit states.
3.
The level of reliability of an earth-rock dam with a height of 350 m with respect to the most dangerous surface of sliding (with the soil characteristics used in the calculation on the basis of analogues) is 0.999941, which is higher than the level of reliability corresponding to a first-class structure. This provices safe operation of a real dam with a sufficiently economical profile in the case of a possible increase of the variability of soil characteristics during construction.
Estimation of the strength parameters of soils with consideration of the different density of samplesBukhartsev, V.
doi: 10.1007/BF01425066pmid: N/A
In each particular case it is possible to judge from the relationship of the values of the standard deviations the advisability of taking into account variations of the density (water content) of soil samples and admissibility of assuming a linear relation between the ultimate value of the shear stress and density in the range of variation of soil samples represented by the sample. In a large range of variation of the density of soil samples the relation between the ultimate value of the shear stress and density can be represented as a piecewise-linear function.
A model of a high-head bottom spillway with interaction of concentric swirled flowsZuikov, A.; Chepaikin, G.
doi: 10.1007/BF01425069pmid: N/A
1.
Eddy spillways compared with, traditional schemes have a number of advantages: possibility of re-equipping temporary diversion spillways into service spillways and eliminating the construction of multilevel systems, which can effect a considerable reduction of the volumes of works and capital investments on spillways of high-head hydro developments. The need to construct large energy-dissipating structures at the tunnel outlet — stilling basins, walls, dissipators, ski-jumps, etc. — is eliminated. An improvement of the cavitation conditions in the waterway as a consequence of reducing the flow velocity can effect in some cases a saving due to a reduction of the requirements imposed on the quality of making the linings and in others can eliminate the danger of erosion of the linings and thereby reduce operating expenses.
2.
The investigated spillway is intended for using conventional service vertical-lift and radial gates operating in normal free-flow regimes with a high capacity and possibility of passing trash. Its construction does not cause technological difficulties.
3.
The investigated spillway system based on the effect of the interaction of concentric, oppositely swirled flows satisfies the requirements of passage and regulation of the discharge and necessary dissipation of the excess kinetic energy of the flow at a low level of fluctuation loads on the conduit walls.
4.
Dissipation of the bulk of the excess energy is accomplished on a short section with a length of 1.5–2 diameters of the exit conduit, which permits making it short. This leads to convenient layouts under mountain conditions and In the case of small spillway lengths, for example, in the lower parts of gravity and arch dams.
5.
The layout of the investigated spillway system can be different depending on the local conditions, restrictions are not imposed on it with respect to the design and route of the entrance and exit conduits and location of the intakes, gate chambers, hydromechanical equipment, and transition of the swirled flows. The exit conduit can be made both in pressure and free-flow variants. This permits wide variation during designing.
Stabilized aeration on chutesAivazyan, O.
doi: 10.1007/BF01425070pmid: N/A
1.
Relation (8) was established, according to which the coefficient of aeration of a rapid uniform flow (coefficient of stabilized aeration), regardless of the roughess of the bed, is uniquely determined by the measure of the dissipation of specific energy — its gradient (I).
2.
Relation (15), being a more accurate realization than (4) of relation (8) for cross sections bounded by a conditional free surface with a local value of the water saturation coefficient βloc=0.01−0.02 (a
loc=0.99−0.98), was developed. Relation (15) is recommended for engineering calculations in the entire practical range.
3.
The establishment of relation (8) clears up the problem of modeling the phenomenon of stabilized aeration in prismatic channels, reducing it to the condition I=idem, with simultaneous provision of the necessary path length of stabilization.
4.
Relation (6) does not correspond to the actual data on aeration of rapid flows.