RU2736132C1 - Method of controlling flow mode in an open channel - Google Patents

Abstract

FIELD: hydraulic engineering.

SUBSTANCE: invention relates to hydrotechnical construction, namely, to water flow damping devices for open channels. Fast-flow channel includes expanding damping chamber 1 located between supply channel 2 and discharge channel 3. Expanding chamber 1 with bottom difference is equipped in the middle with additional channel 4 having vertical longitudinal walls 5 with two transverse partitions 6 and 7, each of which adjoins wall 5 of additional channel 4 at an angle towards longitudinal axis of channel 4. Expanding chamber 1 in front of additional channel 4 and at the middle of the latter is equipped with crosswise water overflow thresholds 8. Vertical overflow walls 9 are extension of walls 5 of rectangular additional channel 4 with transverse partitions 6 and 7. Drainage wall 9, which is the extension of walls 5, is placed in front of the spillway L-shaped threshold 13 with horizontal flange 14 interfaced with discharge channel 3. At the same time threshold 13 with flange 14 are located above bottom of drop of damping chamber 1 for connection with bottom of outlet channel 3. Due to separation of water flow at the beginning of rectangular additional channel 4 and creation of braking and backup, it enters into side channels 11 and 12, lowering of both bottom and surface speeds is achieved, and at outlet to discharge channel at merging of water flows smooth inlet.

EFFECT: improving operating efficiency in conditions of variable water flow rates and operating reliability of the structure, as well as simplifying the design of the method of controlling flow conditions coming from the supply channel-rapid flow into the expanding chamber with its elements towards the outlet channel.

3 cl, 2 dwg

Description

The invention relates to hydraulic engineering, in particular to devices for extinguishing the flow of water in open channels.

Known node for connecting open watercourses, including a supply channel connected to the transit channel and a stream-guiding device made in the form of vertical walls, while the walls are installed opposite the supply channel in a row oriented along the transit channel, parallel to each other and at an angle of 20 ... 30 ° to the axis transit channel, and the walls from the supply channel towards the axis of the transit channel are made with a decreasing height (Inventor's certificate SU No. 1511329, E02B 13/00 dated 09/30/1989).

The disadvantage of this device for the junction of open watercourses is a different non-coordinated orienting effect on the release of the flow directly into the transit channel, in which the bottom mark does not coincide with the bottom mark of the supply channel, i.e. the unit operates at different elevations with a well drop. In addition, the open flow connection unit orients the principle of operation only to swirling and collision of the flow jets towards the channel axis, and the middle flow is divided by a diffuser and directed towards the side flow. As a result, energy-intensive vortices of unsteadiness arise in the zone of local resistance, which drag out the time of the transient process. The accumulation of energy in the vortices of nonstationarity occurs during the period of the transient process. These vortices have a dominant rotation in the plane of nonstationarity in the local resistance, which is called the phenomenon of hydraulic induction.

Thus, the whole process takes place when the local resistance of a certain configuration is established. The type of local resistance, as well as the shape of the absorber, is selected depending on the specific task.

The known method is a flow energy absorber for open channels, consisting of the formation of currents in an open channel, and the currents are formed by a group of jet-directing elements of devices, which includes a fast-flow channel with lined walls and a bottom and a wave absorber made in the form of vertical walls installed parallel to the channel walls - rapid flow, between the vertical walls there is a vertical longitudinal flow-directing element in the form of a bull with a long length of vertical walls, which are equal in height to the walls, with a fairing in the lower part dividing into two sleeves with equal inlet cross-sections located relative to the end sections of the vertical walls, moreover, the wall of the flow-guide element along the channel axis is made equal to the channel height, while the side walls of the channel are made with annular damping chambers, and the lower end of the vertical walls is equipped with a flat vertical shutter, hingedly attached to the end of the vertical wall, spaced positioned diametrically opposite to the free space between the flow guide element, while the end section of the fairing has a convex shape, and the side walls of the channel are additionally equipped with flat vertical gates in the form of protrusions-restraints facing the fairing (Patent RU No. 2551992, E02В 8/06 dated 18.03.2014 ).

The disadvantage of this device is, although it significantly reduces the output speeds, the fact that there are large head losses in the below-placed water conduit, thereby increasing the filling of the channel, and it will be necessary to increase the above-water headroom of the channel directly in the unit for damping the flow energy. In addition, flow control in the tailwater is provided only by an additional jet-directing system made in the form of flat vertical gates with axes of rotation installed opposite the fairing, after which the flow again exits as a common flow. However, behind the lip of the fairing, a vacuum zone is formed, which affects the formation of a connection of hydraulic jets, forming a common flow along the width of the outlet channel (water conduit). This structure of flow formation is characterized by the external and internal boundaries of the hydraulic structure of the jet, interacting behind the fairing located between the additional jet-directing system, while it is not efficient enough when two flows merge in the center of the drainage system. The length and direction of the active current of the stream is not yet reliable enough; outside the flow expansion zone.

The closest to the proposed invention in terms of technical essence is a method for controlling the flow regime in an open channel, which provides for a fast-flow channel with lined walls and a bottom, where the zone of influence of the jet-guiding elements is formed, the installation of vertical walls, the side walls of the channel are equipped with vertical shields with the possibility of turning in the form of protrusions - restrictors in the direction of the flow, while the hydraulic structure itself is formed downstream. The flow guiding elements are made by means of a regulator section in the form of rotary shields, one vertical edge of which is fixed on the axis of rotation, and the other edge is connected to a drive for their horizontal movement and to a guide with the possibility of placement in a side niche made in the side wall of the channel, while the corner connection of the shield with the guide is pivotally connected additionally to the flow-guiding elements in the form of shields made of composite from the middle and side links, connected by means of hinges to each other, and the extreme side links of each shield are pivotally connected to the side wall of the channel towards the stream-guiding system in the form of vertical louvers connected to driven in the direction of flow direction (Patent RU No. 2615337, E02B 8/06, E02B 13/00 dated 04.04.2017).

The disadvantage of this design is the concentrated discharge of water along the path of the transit channel towards the spreading of the flow in front of the vertical louvers, which makes it possible to obtain favorable hydraulic conditions, but this, however, is not related to the method of device of the flow damper made in the form of an expanding quenching chamber, equipped with an additional one in the middle channel formed by transverse two at an angle partitions with vertical longitudinal walls at the bottom of the quenching chamber. In addition, the extension of the additional channel with vertical walls has vertical weir walls before mating them with the outlet L-shaped weir of the outlet (transit) channel, i.e. on a short section of the expanding extinguishing chamber, stationary elements for extinguishing the flow energy are placed, which improve its operating mode in comparison with the prototype.

It is known that the flow along its length has a sufficiently high velocity, both bottom and surface, and is unevenly distributed in the water column, i.e. damping of the flow along the filling height changes, respectively, this is due to the method of interconnection with the design solution with the water distribution itself, and this requires complex calculations in manufacturing with flow regulating elements and their design for different fillings in the channel with high water velocities.

Thus, for the proposed method of controlling the flow regime in an open channel, this is a simplification of the structure itself as a whole, where such conditions for the flow of water into the expansion chamber of the quenching, its component quenching elements with their gaps between the vertical walls, partitions and weir sills, respectively, must be taken into account. flow inlet into the outlet (transit) channel at variable flow rates in the supply channel with high flow rates with wave surface flows at the outlet into the outlet channel.

The technical result achieved by the present invention is to increase efficiency by improving the conditions for water entry into the expanding quenching chamber and increasing the backwater of an additionally created channel in the center of the expanding quenching chamber with damping overflow elements, as well as increasing the efficiency of operation under conditions of variable water flow rates.

The specified technical result is achieved by the fact that in the method of controlling the flow regime in an open channel, providing for the use of a high-flow channel with lined walls and a bottom, forming in the immediate vicinity of the zone of influence of flow-guiding elements, installing vertical walls, the hydraulic structure is formed downstream directly between the side walls channel, the flow guiding elements are performed by means of a transition section, according to the invention, along the route of the lined flow channel, a flow damper is arranged, made in the form of an expanding damping chamber, which is equipped with fixed transverse two at an angle partitions, each of which adjoins one of the walls of the rectangular channel towards the longitudinal the axis of the channel with vertical longitudinal walls at the bottom of the quenching chamber, and the lower end of the formed additional channel with the inlet section, which is a continuation of the vertical longitudinal walls, after the transverse The ditch is performed, in conditions of variable flow rate, with vertical weir walls, while in the additional channel with longitudinal walls in front of it, it is equipped with water overflow thresholds installed across the longitudinal axis of the additional channel, the latter being mated with the outlet water overflow L-shaped threshold of the outlet channel.

In addition, the end of the additional channel is narrowed, in the place of which a backwater and compression of a part of the flow is formed, and then expands in front of the associated water-overflow L-shaped threshold of the outlet channel.

In addition, the beginning of the longitudinal vertical walls of the additional channel in the expanding quenching chamber is set with a gap before the outlet of the supply channel.

In the proposed method, there is a redistribution of water flow rates in the quenching chamber due to the additional channel installed in it in the middle of its axis with vertical longitudinal walls somewhat distant from the entrance of the feed channel into the expanding quenching chamber, equipped with vertical longitudinal walls of the additional channel at the bottom with adjoining to them at an angle two transverse partitions towards the longitudinal axis of the channel and the movement of water, respectively, narrow the central part in the additional rectangular channel, while their walls towards the outlet channel have a continuation, reduced height and form vertical weir walls before mating the channel with the outlet water overflow threshold of the outlet channel. In view of the fact that the backwater still arises at the entrance to the additional channel, part of the flow bypasses it from the outside of the vertical longitudinal walls, i.e. spreads to several specific costs, the speed of advancement by the weir walls, which are reduced in height and are a continuation of the vertical longitudinal walls of the additional channel, which are supplied at the end with two partitions fixed at an angle to the longitudinal axis of the channel, and each of which is adjacent to the vertical wall of the rectangular channel in the final its parts in front of the vertical weir walls, which are a continuation of the walls of the rectangular channel, and at the bottom in front of the channel and in the middle of it are fixed with water-overflow thresholds installed across the additional rectangular channel. In this case, a part of the flow receives a thrust and due to spreading in the plan and in the vertical plane, turns towards the direction of motion with side channels, while losing part of the excess kinetic energy, i.e. from the side of the external rectangular vertical walls of the rectangular channel, and the other part of the flow passes into an additional tapering channel also with a back-up of the flow, where it is compressed, then it is connected with the overflowing parts of the flow through the vertical weir walls, thus colliding with each other, mutually extinguishing transverse velocity components, residues of excess energy of the flow entering under the conjugate water-overflow L-shaped threshold of the outlet channel. In this part of the chamber, the connecting jets form a continuous flow in the outlet channel over the entire width. There is an additional effect of extinguishing the excess kinetic energy of water in all elements along the length of the expanding chamber, i.e. increases the uniformity of the flow in the plan at the outlet to the outlet channel. Installation of a water-overflow L-shaped threshold, in the form of the formation of a horizontal shelf towards the bottom of the outlet channel after the expanding chamber, taking into account the presence of a curved side wall in front of the vertical weir walls.

Based on the foregoing, the author considers it possible to assert that the proposed technical solution meets the criterion of "significant differences".

Graphic material illustrating the proposed method is presented in the following drawings:

fig. 1 is a diagram of a method for controlling a flow mode in an open channel;

fig. 2 - section a-a in Fig. 1.

The method is carried out in the following sequence. An expanding quenching chamber 1 with a bottom drop is located between the supply channel 2 and the outlet channel 3 with lined walls and a flat bottom. The expanding chamber 1 with a bottom drop is provided in the middle with an additional channel 4, which has vertical longitudinal walls 5 with two existing transverse partitions 6 and 7, each of which adjoins the wall 5 of the additional channel 4 at an angle towards the longitudinal axis of the channel 4, in the entrance part of it performed at some distance from the entrance of the supply channel 2 and inside its transverse water overflow thresholds 8. The dividing vertical walls 5, thus, form a rectangular channel 4 with two at an angle with partitions 6 and 7 of the same width in front of the beginning of the vertical weir walls 9, which are a continuation of the walls 5, and the weir walls 9 are mated with the transitional curved walls 10, facing the concavity towards the side channels 11 and 12 of the same width, and located in front of the entrance to the water overflow L-shaped threshold 13. The top of the L-shaped threshold 13 is mated with the bottom of the outlet channel 3 in one plane, which is made in the form of a horizontal shelf 14 in the upper part above the bottom at the end of the expanding chamber 1. The length of the vertical weir walls 9 depends on the ratio of the proportion of the flow distribution in front of the inlet part of the rectangular channel 4 with vertical longitudinal walls 5, at the end of which two partitions 6 and 7 are fixed at an angle to the longitudinal axis of the rectangular channel 4 with fastening and at its bottom (geometric dimensions are selected by calculation, not shown).

The way to control the flow mode in an open channel is as follows.

The flow of water entering the expanding chamber 1 from the supply channel 2, after a drop without spreading in the plan, is first supplied to the transverse water overflow sills 8, where the bottom layers of the flow are inhibited by the advancement of some part, and form a backwater (stopping part of the flow) in front of the rectangular channel 4 with vertical walls 5 and the loss of part of the kinetic energy, then, if there is an installation at an angle of two transverse partitions 6 and 7, which creates a narrowing of the water flow at the exit from the rectangular channel 4, the rise in the water level increases, but the water continues to move in the middle after the crosspieces at the angle of partitions 6 and 7 In addition, it should be noted that a larger backwater is formed at the beginning of the entrance to the rectangular water channel 4. As a result, the flow of water into the side channels 11 and 12 increases more towards the entrance to the vertical weir wall 9 walls, where the water overflows and enters the bottom of the chamber 1 in front of the weir L-shaped threshold 13 with a horizontal shelf 14. When part of the flow enters the transverse partitions 6 and 7, forms one horizontal stream directed rectilinearly towards the L-shaped sill 13 with a horizontal flange 14, where it collides with the lateral overflow parts of the water entering through the weir sills 9, mutually extinguishing the transverse velocity components, the remnants of excess flow energy entering before the L-shaped threshold 13.

Since the water level rises in the rectangular channel 4, and the bottom layers of the flow are slowed down in the presence of the installation of transverse water overflow thresholds 8, the backwater in the upper part of the additional rectangular channel 4 increases, respectively, the water level in the side channels 11 and 12 also increases across the entire width, there is movement water towards the vertical spillway walls 9, and as a consequence, at the end of the channel 4 after the partitions 6 and 7 collision of flows. It should be noted that the hydrodynamic pressure above the L-shaped sill 13 with a horizontal flange 14 increases, where the upward flow along the axis of the outlet channel 3 decreases, and also prevents the formation of ascending flows and large waves from propagation along the outlet channel when the total flow rate changes under the flange 14 This significantly increases the efficiency of flow control in the discharge duct and increases its productivity, while reducing washout in the discharge duct.

Thus, the cost is sufficient in conditions of small deepening of the bottom of the expanding quenching chamber relative to its bottom with a discharge channel, affecting the conditions of work, the proposed method provides for the implementation of sequential operations: installation of transverse overflow thresholds on the way, as well as two ledges in the form of transverse partitions under an angle to the longitudinal axis of the additional rectangular channel, with the abutment of the crosspieces to the walls of the additional channel in its end part before the beginning of the water-overflow vertical walls. Ultimately, there is not only deceleration and some part of stopping of flows with backwater, but they are mutually extinguished at the end of the rectangular channel, ensuring the uniformity of the flow in the plan at the outlet to the outlet channel, and this also reduces the possibility of the formation of local erosion of its bottom, by simplifying the layout devices for speed control in the expanding chamber.

In general, the invention extends the functionality of such high-flow canals on irrigation systems.

Claims (3)

1. A method for controlling the flow regime in an open channel, providing for the use of a high-flow channel with lined walls and a bottom, the formation in the immediate vicinity of the zone of influence of the flow-directing elements, the installation of vertical walls, the hydraulic structure is formed downstream directly between the side walls of the channel, the flow-directing elements are performed by transition section, characterized in that a flow damper is arranged along the route of the lined flow channel, made in the form of an expanding damping chamber, which is equipped with two transverse partitions fixed at an angle, each of which adjoins one of the walls of the rectangular channel towards the longitudinal axis of the channel with vertical longitudinal walls at the bottom of the quenching chamber, and the lower end of the formed additional channel with an inlet section, which is a continuation of the vertical longitudinal walls, after the transverse partitions, is performed, in conditions of variable flow, vertical spillway walls, while in the additional channel with longitudinal walls and in front of it, it is equipped with water overflow thresholds installed across the longitudinal axis of the additional channel, the latter being mated with the outlet water overflow L-shaped threshold of the outlet channel. 2. The method according to claim. 1, characterized in that the end of the additional channel is narrowed, in the place of which a backwater and compression of a part of the flow is formed, and then it expands in front of the associated water-overflow L-shaped threshold of the outlet channel. 3. The method according to claim 1, characterized in that the beginning of the longitudinal vertical walls of the additional channel in the expanding quenching chamber is set with a gap before the outlet of the supply channel.

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