共查询到20条相似文献，搜索用时 31 毫秒
1.
Model studies of the hydraulic operating conditions of an eddy tunnel outlet with an inclined shaft showed that:
| – |
for regimes without delivery of air into the flow core with swirler parameterA=1.1 and with delivery of air for all values ofA, submergence of the outlet section of the conduit in the lower pool noticeably affects the size of the core and promotes
the formation of a hydraulic jump zone along the tunnel;
|
| – |
insignificant (in value) submergences of the exit section of the tunnel have little effect on the discharge capacity of the
outlet (their differences is Δ=1.4% forA=0.6, Δ=2.71% forA=1.1, and submergence even increases the discharge of the outlet Δ=0.8% forA=0.83).
|
| – |
delivery of air into the flow core has little effect on the discharge capacity of the structure, with the exception of the
layout with a swirler withA=0.6 (Δ=4.31% forA=0.6, Δ=0.5%, and Δ=0.9% forA=1.1);
|
| – |
considerable vacuums are observed for regimes without air in the flow core, the absolute values of which with increase ofA drop intensely from Hfc=−4.5 m to Hfc=−0.3m;
|
| – |
delivery of air into the flow core markedly reduces the vacuums in it and their values are close to zero;
|
| – |
with increase of swirler parameterA the area occupied by the flow at the end of the tunnel decreases;
|
| – |
regimes without delivery of air into the flow core are the most favorable with respect to the conditions of the pressure distribution
on the conduit walls;
|
| – |
submergence on the downstream side does not lead to an increase of pressure on the conduit walls if the vacuum in the flow
core increases simultaneously with this.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 41–44, November, 1997. 相似文献
2.
| 1. |
In analyzing the boundaries of development of an undulating jump, it is necessary to distinguish the conditions of existence of departing and approaching undulating jumps.
| | 2. |
The breaking process of both a departing and approaching undulating jump does not occur suddenly, but can be divided into several intermediate stages.
| | 3. |
The scale effect makes itself felt to a certain degree on the criteria of the existence of an undulating jump.
| | 4. |
In the initial section of an approaching undulating jump, the Froude number Fr1 does not clearly define the formation and conditions of the existence of this phenomenon. An approaching jump that is formed during an inflow from beneath a gate can be broken by increasing the depth of the tailrace for any value of Fr1, which is close to unity as is desired.
| | 5. |
For field conditions, the Froude number Fr1=2.5 can, in first approximation, be considered a criterion characterizing the start of the break of the first wave for a departing undulating jump, and the coefficient of the degree of nonhydrostatics s1=1.07 as the criterion for an approaching jump; the Froude number Fr1=4.0 and the coefficient of the degree of nonhydrostatics s1=1.14 can be recommended as criteria characterizing the complete break of an undulating jump for the departing and approaching phenomena, respectively.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 12, pp. 29–34, December, 1990. 相似文献
3.
| 1. |
A comparison of laboratory and on-site data on a determination of the maximum range of oscillations at the end of a direct hydraulic jump when waves enter it from a chute with the results of calculations by theoretical formulas (1), (2), and (3) confirms the applicability of one of these formulas (2) for superrapid flow and flow transitional from superrapid to rapid.
| | 2. |
The stilling basin generates secondary waves, reaching half of the depth of the basin d with respect to its height. With submergence of the basin from the lower pool, the range of variations of the level increases additionally by 2.0–2.5 times.
| | 3. |
On the apron behind the stilling basin, the drop of waves is insignificant, since the wave transformation coefficient at distance (40–90)hn, where hn is the natural depth, remains equal to
.
| | 4. |
The periods and lengths of the waves transformed in the stilling basin decrease with increase of discharge and Froude number Fr0 and approach in value the wave periods.
| | 5. |
Formulas (6) and (10) were obtained for calculating the maximum amplitude of oscillations of the free surface and maximum depth at the crest of oblique waves on the narrowing sections of the wave chutes and they were checked experimentally, which proved the applicability of these formulas for calculating a nonstationary oblique hydraulic jump.
| | 6. |
The proposed empirical formulas (12)–(17) can be recommended for an approximate evaluation of the parameters of the largest first waves on the narrowing stretch.
| | 7. |
Under these conditions, the use of a stilling basin as an energy dissipator of a superrapid flow is not rational, since not dissipation but generation of secondary waves is observed in it.
When designing narrowing sections of chutes, it is necessary to take into account an increase of depth of the oblique jump with passage of roll waves. 相似文献
4.
| 1. |
The plant manufacturer's power and efficiency guarantees are fulfilled.
| | 2. |
The power performance curves obtained for the hydraulic unit at four heads make it possible to select the makeup of operating units that will deliver maximum economy with the load distributed between the units.
| | 3. |
In operating the hydraulic units, special attention should be given to adjustment of the combiner curves in connection with the fact that its mismatch downgrades not only the economy of the hydraulic-turbine operation, but also the vibrational state of the hydraulic unit.
| | 4. |
Measurements of the vibration levels of the hydraulic units under several heads made it possible to determine the boundary line with respect to power over the entire range of operating heads.
|
Translated from Gidrotechnicheskoe Stroitel'stvo, No. 4, pp. 26–30, April, 1991. 相似文献
5.
Conclusions
| 1. |
At the current stage of hydrotechnical construction designs of structures constructed with the complete or maximum use of
natural materials and providing complete mechanization of the construction and repair of structures can be most effective.
|
| 2. |
It is necessary to begin immediately experimental laboratory studies and to provide standards on the use of natural materials
of the sand-gravel mixture type in designs of hydraulic structures.
|
| 3. |
It is necessary to begin exploration of potential deposits of SGMs and to calculate their reserves.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 10, pp. 17–20, October, 1999. 相似文献
6.
| 1. |
Modeling of the processes of the interaction between outlet works and their foundation during passage of a flow by means of a model of the structure isolated from the channel, the flexibility index of which is less than unity, should be considered most correct, making it possible to completely reveal the mechanism of the effect of the flow on the structure and the reaction of the model of the foundation.
| | 2. |
Construction of the model as a primary detector made it possible to determine the main force parameters of the effect of the hydraulic jump on the basin and the frequency characteristics of the process of interaction of the basin and foundation.
| | 3. |
The character of oscillations of the basin model depends only on the method of supporting the model on the elastic foundation, and therefore for important structures it is necessary to model the base by trial and error.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 7, pp. 24–26, July, 1991. 相似文献
7.
| 1. |
The designs as well as the total safety factor of concrete-encased steel pressure conduits of operating hydraulic structures
were analyzed.
|
| 2. |
The principles of the existing standards related to calculations of concrete-encased steel pressure conduits were analyzed.
|
| 3. |
Methods of calculating concrete-encased steel pressure conduits (including forks and distributors), including elements of
the inside steel shell and reinforced-concrete part, were developed.
|
| 4. |
The calculation methods developed were experimental substantiated and tested during designing and constructing domestic and
foreign objects.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo No. 1, pp. 37–44, January, 1999 相似文献
8.
| 1. |
Modified wood is an effective substitute of the laminated wood lining of bearing bushings for vertical pump units.
| | 2. |
An investigation of modified wood showed that this material in some indices (friction coefficient and wear resistance) is better than laminated wood.
| | 3. |
Since there is no mass manufacture and centralized supply of modified wood, it is possible to create a technological department for its production.
| | 4. |
Organization of the department does not require capital expenditures and special accommodations.
| | 5. |
Machining of the wood is performed on ordinary metal-cutting machines with the use of the tools used when machining laminated woods.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 7, pp. 33–35, July, 1991. 相似文献
9.
| 1. |
In certain cases of constructing dams salt-containing soils serve as their foundation.
| | 2. |
Under these conditions reliable operation of the structures can be provided only by developing special engineering measures to control dissolution.
| | 3. |
All existing methods of protecting saliferous foundation soils of hydraulic structures from dissolution can be divided into passive, active, and combined.
| | 4. |
The combined methods should be considered the most effective for preventing removal of salts from foundation soils by the seepage flow.
| | 5. |
Large-scale field investigations of the work of the combined method of protecting saliferous foundation soils of the planned Lower Kafirnigan hydro development showed its high effectiveness even in the case of complex engineering-geological conditions at the construction site.
| | 6. |
Individual elements of the set of dissolution protective measures investigated under field conditions can be used in hydrotechnical and hydropower construction practice.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 10, pp. 10–14, October, 1994. 相似文献
10.
| 1. |
The energy-storage hydroelectric station (ESHES) can provide a 1.5–2-fold increase in peak capacity with a simultaneous threefold
decrease in daily fluctuations of the water level in the lower pool.
|
| 2. |
A decrease in the length of the concrete structures located in the river channel (especially the length) of the powerhouse)
reduces the consumption of concrete for the ESHES in comparison with the HES, which compensates for the cost of constructing
the additional structures of the ESHES.
|
| 3. |
Unlike the HES, the ESHES operates in a sharp-peak regime and also during passage of flood waters.
|
| 4. |
Contrarotating pump-turbines are best suited for an ESHES because of various combinations of heads on its turbine and pump
parts.
|
| 5. |
With increase in the speed of multistage hydraulic machines their placement depth decreases and the cost of the powerhouse
is reduced.
|
相似文献
11.
| 1. |
One of the new approaches to the use of wave power plants can be their use as a source of compressed air for operating a pneumatic breakwater.
| | 2. |
The use of wave power plants for protecting marine hydraulic structures from the effect of storm loads makes it possible to increase the cost effectiveness both of the WPPs themselves and of the hydraulic structures.
| | 3. |
A rough estimate of the cost of wave power plants shows their effectiveness as a source of electrical energy for remote regions of the USSR.
| | 4. |
The simplicity of the design of wave power plants enables organizing their mass production at shipyards or at the site of construction.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 2, pp. 7–10, February, 1992. 相似文献
12.
| 1. |
A pressure dangerous with respect to cavitation is observed in those places where the vortex core closely approaches the conduit wall (there are places where with formal conversion to the prototype vacuums m H2O are observed, actually the absolute values will be close to the vaporization pressure).
| | 2. |
Delivery of air to ducts for the given spillway design reduces but does not remove the dangerous vacuum on the conduit walls.
| | 3. |
Large vacuums are recorded both over the length of the outlet conduit and in the dissipation chamber.
| | 4. |
The most effective (of those investigated) means of eliminating the vacuum on the conduit wall and in the dissipation structure are the installation of longitudinal ribs and transverse diaphragms in the outlet tunnel and delivery of air to the end of the swirler and dissipation chamber.
|
Deceased. 相似文献
13.
| 1. |
The real deformation of elastic chambers of the thrust bearing on a hydraulic support under a load is plane-inclined in certain cases.
| | 2. |
Adjustment of the load on the bearing segments with installation of one indicator on the chamber does not always provide the necessary accuracy.
| | 3. |
It is advisable to adjust the bearing according to the method presented with the installation of two indicators on the chamber, which provides the necessary accuracy of distributing the load between segments.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 30–32, May, 1995. 相似文献
14.
An analysis of the experience in the Soviet Union and in foreign countries with conveyor transportation in the mining industry,
as well as with use of conveyors in hydraulic construction shows that the introduction of conveyor transportation in the field
of construction of embankment dams in this country, for delivery of earth-rock material from quarries, as well as for carrying
raw materials to concentrating plants processing nonmetallic minerals, will make it possible.
| 1) |
To reduce substantially the personnel nees.
|
| 2) |
To lower significantly the transportation costs for delivery of earth-rock materials to construction sites and to concentrating
plants processing nonmetallic mateirals (rubble, gravel, and sand);
|
| 3) |
To reduce the need for trucks, by replacing them with conveyors;
|
| 4) |
To increase the rate of delivery of earth-rock materials from quarries for dam, construction and, consequently, to reduce
the times of completion.
|
| 5) |
To reduce the volume of housing, cultural-welfare, and auxiliary-subsidiary construction in owing to the lower needs for personnel
in conveyor transportation;
|
| 6) |
To eliminate the need for constructing a large number of roads with rigid pavements for large-capacity dump trucks;
|
| 7) |
To raise the technical level of the earth-rock work.
|
相似文献
15.
| 1. |
Investigations showed that when constructing dams of fine-grained silty soils by hydraulic filling, it is expedient to use the technology of layerwise placement of soil with consolidation of each layer.
| | 2. |
Dependences are given for calculating the thickness of the layers and period of consolidation of the soil on the basis of investigations of the dynamics of the hydrophysical properties of these soils in relation to technological factors.
| | 3. |
Dependences are also proposed for predicting the density of the hydraulic-filled soil during construction, as well as the distribution of soil in the profile of the structure.
| | 4. |
A method is proposed for calculating the technological parameters, in particular, the rate of construction of hydraulic-fill structures, calculating the size and number of the hydraulic-fill plots referred to one dredge, and prediction of the seepage discharge into the foundation of the dams during their hydraulic filling.
| | 5. |
The proposed calculation methods make possible a more substantiated approach to the design of hydraulic-fill structures of fine-grained silty soils and technology of their construction.
|
Translated from Gidrotekhicheskoe Stroitel'stvo, No. 6, pp. 5–9, June, 1990. 相似文献
16.
Conclusions
| 1. |
The expediency of hydraulic-fill grading of marshy coastal territories and city dumps for housing construction and recreation
park and beach zones was proved practically.
|
| 2. |
Underwater coastal borrow pits in the shallow-water zone can be used for direct dredging of soil.
|
| 3. |
In the absence of sand borrow pits, fine-grained loamy sand soils can be used for hydraulic filling the construction sites.
|
| 4. |
To operate dredges on large water areas under conditions of violent wind-wave action, it is necessary to work out a special
works organization plan taking into account the preservation of supply lines, machines, and crew during a storm and under
ice conditions in the winter.
|
| 5. |
The possibility of using the ash of heat and power plants for engineering grading of a marshy territory for housing construction
on a pile foundation was proved.
|
Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 9, pp. 29–33, September, 1997. 相似文献
17.
Conclusions
| 1. |
The systems of elongated triangles located at elevations 413, 467, and 344 m do not give reliable results, as a consequence
of which they cannot be used as horizontal displacement meters.
|
| 2. |
The displacements of the ends of the adits recorded from the NET readings are a consequence of measurement errors.
|
| 3. |
The use of string systems as horizontal displacement meters of hydraulic structures can be used only with their complete protection
from airflows, which is practically impossible to do.
|
| 4. |
The use of 3-m invar bars, used as meters of the small sides of the NET, for determining deformations of concrete and bank
adits is possible.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 9, pp. 52–54, September, 1998. 相似文献
18.
| 1. |
The method of hydraulic investigations used by VNIIG for substantiating the Leningrad flood control project is based on the theory of hydraulic modeling generally accepted in the USSR and abroad. It has a methodological basis and has undergone necessary testing in the Soviet Union and abroad.
| | 2. |
Substantiated layouts of the water-passage structures were obtained on the basis of investigations of Lengidroproekt together with VNIIG, and the sizes of the water- and shippassage structures and their individual elements were established.
| | 3. |
The results of the hydraulic investigatons are confirmed by on-site data obtained both for natural conditions and for the structures under constructicn.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 9, pp. 22–25, September, 1991. 相似文献
19.
| 1. |
An increase in the oil temperature in baths of bearings with EMP segments from 30–35 to 60°C leads to a decrease of friction losses by 20–30% due to a decrease of the oil viscosity in the oil film, and also produces an additional effect from a reduction of the consumption of water for cooling.
| | 2. |
A decrease of the operating reliability of the bearings with EMP segments does not occur when the oil temperature in the bath is increased to 60°C. Therefore there is no need to introduce restrictions in the operating regimes of the units.
| | 3. |
The existing systems of sealing the oil baths of the bearings do not prevent the escape of oil vapors from the oil baths at an oil temperature of 55–60°C. Therefore reconstruction of the seals is necessary before changing to an oil temperature increased to 60°C.
| | 4. |
On operating units of hydrostations it is expedient to increase the oil temperature in the baths of the bearings from 30–35° to 45–50°C by reducing the flow rate of the cooling water or disconnecting a part of the coolers, which leads to a decrease of friction losses by 12–15% and does not noticeably increase the escape of oil vapors from the bearing baths.
| | 5. |
On newly designed bearings with EMP segments it is expedient to specify a smaller number of oil coolers, and it is possible to do away with them entirely by increasing the cooling capacity of the walls of the oil baths, for example, by means of fins on them.
| | 6. |
To reduce losses in the bearings, the use of other, less viscous oils or other low-viscosity liquids is possible.
|
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 20–24, November, 1990. 相似文献
20.
| 1. |
The hydraulic projects awarded prizes by the Council of Ministers of the USSR in 1976 solve a set of critical national-economic
problems and are distinguished by high cost effectiveness.
|
| 2. |
Structures distinguished by originality and progressiveness of technical solutions, which ensure their reliable operation,
have been constructed as the result of a set of scientific-research and design studies. This was made possible only by the
close creative understanding and interaction between the scientific-research, planning, construction, and operating organizations.
|
| 3. |
In building hydraulic structures, all the more attention is focused on industrial aesthetics. The architectural-planning solutions
of the prizewinning projects are new, represent examples of the progressive development of industrial architecture, and have
obtained widespread public recognition.
|
| 4. |
The bold and economic solutions relative to the organization of the passage of flood waters over incomplete structures merit
attention; this makes it possible to reduce the volumes of the enclosing foundation pits of the cofferdams, or eliminate them
entirely.
|
| 5. |
The experience gained with the design and construction of the prizewinning projects should be studied in detail and publicized
for purposes of utilization in subsequent design and construction.
|
相似文献
|
|
