SU1110866A1 - Flow energy damper - Google Patents

Description

(rig, 1

The invention relates to hydraulic construction and can be used to quench the energy of a stream in the downstream of a dump discharge.

Known absorber energy flow in the form of a deep relatively ordinary, but short water well 1.

In such a quencher, at a certain range of hydraulic parameters, due to the compression of the jump in the longitudinal direction, the rotational speed of the surface drum increases, thereby increasing the interaction between the transit and roller parts of the flow. This increases the efficiency of energy flow quenching per unit of baying site.

The disadvantage of this extinguisher is the narrow range of flow rates and head pressures at which effective energy dissipation takes place. At the same time, an increase in efficiency is observed at greater depths of the well. Maximum (on the order of 35% relatively smooth waterway), the effect of slaking is achieved by deepening the bottom of the well by 1.49R, where P is the height of the dam from the bottom of the diverting channel, the length of the well being equal to 1.925 R. The significant depth makes such an absorber economically unprofitable.

Also known is a flow energy absorber made in the form of a deep water well of vertical type 2.

However, studies have shown that in order to ensure the stability of a jump in such a well, it is necessary, by 30-50% of the length of a free hydraulic jump, to deepen its bottom, which increases the cost of construction. The transit jet does not disintegrate completely within the quencher and gushes over the ledge, forming a significant difference in water levels at the end of the well and in the discharge channel. The delta forms two additional jumps behind the absorber; wherein the first one with the bottom whirlpool is located directly behind the ledge of the well, the second one with the surface roller is further behind the compressed section. The last jump forms the bottom velocity mode in the diverting channel.

The presence of jumps behind the absorber necessitates an increase in the thickness of the mount within the roller zones. As a result of large pulsations during spouting, considerable vertical and longitudinal oscillations of the flow occur, as a result of which the surface agitation increases and a buildup of flow increases over a large length of the discharge channel. This makes it necessary to further increase the length of the lower pool.

The purpose of the invention is to increase work efficiency, reduce construction costs and calm the flow downstream of the absorber.

This is achieved by the fact that the damper is provided with a split wall of piers installed at the bottom of the well, with a height of (3-5) h, width bn (0.7-0.8) -1 and a distance between them equal to their width, where hi is the depth of the flow is compressed at the bottom of the outlet channel.

Moreover, the depth and length of the well are determined by dependencies

ctK h, (l, 70VFr, -5.93);

K 8,60h r + dC ctg -0,36),

gdes {i1u.- respectively depth and length

water well; hi — compressed flow depth at the bottom level of the discharge channel; Gg4 - Froude number in compressed section

with depth h; R, 120; SL is the angle of inclination of the stream entering the well,.

FIG. 1 shows a damper, longitudinal section; in fig. 2 is a section A-A in FIG. one; in fig. 3 is a plot of the relative dimensions of the energy flow quencher versus the variation of the parameter F at 70.

The flow energy absorber is a relatively deep but short water well (Fig. 1). The front face 1 of the well is formed by the continuation of the drainage slope with a slope of 50-70 ° to the horizon. On the horizontally located bottom 2 of the extinguisher, the normal main flow movement is set by a wall of piers 3, which serves to redistribute the flow within the water well. The well ends with a vertical water break edge 4.

The damper works as follows.

The turbulent flow (Fig. 1) enters the well through the drain and then along face 1 located at an angle of 50-70 ° to the horizon, which is necessary to ensure the formation of a bottom jump in the extinguisher. Transit jet, reaching the bottom of the well 2, changes its direction to the horizontal. Upon reaching the front face of the split wall of the piers 3, the turbulent flow splits into jets, the number of which corresponds to the number of piers 3 and cuts in the wall (Fig. 2). A part of the flow (about half of it) takes a vertical, ascending along the frontal face of piers 3, a direction.

In the front part of the well bounded by the front face of the split wall, in the direction of the main movement of water, a flow is formed similar to the flow in the quencher of the prototype. There is a vertically developed surface drum with a high rotational speed.

In a plane transverse to the main direction of flow (Fig. 2), vortices are formed between the jets separated by piers and ascending along them, rotating in different directions. The jets of water collide, which contributes to additional energy conservation and improves the flow regimes. Another part of the flow, passing through the incisions in the wall and the loss of the kinetic energy as a result, is directed along the bottom 2 of the well to the water-borne ledge 4 (Fig. 1), where it changes its direction to the vertical, also forming upward jets . In the second part of the quencher, located behind the plane of the front face of the split wall, a second drum is formed, somewhat smaller in size than in the first part of the well and rotating in the opposite direction to the first drum. This direction of rotation of the roller is associated with a somewhat higher flow rate of the rising wall along the front edge of the split wall as compared with the flow rate of the converging along the ledge, where transit jets lose part of the kinetic energy when moving through piers 3. As a result of this phenomenon, the collision of parts of the flow, and the bottom velocities behind the absorber decrease (Fig. 1). Behind the split wall and along the water ledge 4 between transit jets, vortex formation occurs with a collision similar to the process that occurs in the transverse plane A – A in front of the front face of the piers 3 (Fig. 2). In order to determine the optimal dimensions of the dampers, a series of experiments was carried out on a model installation with the coupling of a turbulent flow through a weir of a practical profile. In the course of the experiments, the length and depth of the water well were varied, where for each selected size the hydraulic parameters of the flow were selected by varying the water flow rate at the installation. The criteria for satisfactory performance of the Gasitel were the absence of a jump behind the ledge and the correspondence of the depth hj to the minimum. The household depth hffjnin (Fig. 1), where is, is the conjugate depth behind the absorber, less than the similar depth on a smooth water shell. According to the research results, the dependences of the relative depth of the quencher J (Ff,) and its relative length EK / fi, f (Fr,) (Fig. 3) are determined. The curves f (Fr,) and Bjh, f (Fr.,) (Fig. 3) are constructed from the values of the smallest depths and their corresponding smallest relative lengths k / b, at which the most effective quenching of the flow energy is ensured. The proposed flow energy quencher was used in studies on a model installation, where the flow of a turbulent flow occurred through a weir of a practical profile with an angle of inlet flow into the well "70 °. The relative elevation of the ridge crest of the weir and bottom of the diverting channel was P / hnp 5.8–14.3 at the studied expenditures of 3.0–13.0 l / s, where Lcr is the critical depth of the flow. Froude numbers were in the range of 20 F 120. The damper can be used at water disposal structures with differences P l, 5bgH at 20 "EG, 120, where the water depth is in the lower reach. As a result of the mutual influence of the piers and the water-ledge on the flow within the limits of the size of the proposed extinguisher, the turbulent jet is completely destroyed, which significantly increases the damping efficiency and improves the flow conditions in the discharge channel. The absence of significant agitation, the buildup of the flow, and the distribution of averaged velocities behind the damper, which is close to the uniform mode of motion, allows a considerable reduction (by 40-50%) in the length of the mounting of the discharge channel. As a result of effective quenching of the flow energy in the vertical type extinguisher, the well depth o (k (Fig. 1) decreases by 54-VO / o, depending on the hydraulic parameters of the lower pool, and the horizontal projection of the total length (Fig. 1) decreases to 45% , which reduces the construction cost of the facility. The absence of jumps behind the absorber reduces the dynamic loads in the initial part of the diversion channel and makes it possible to use an easier attachment here.

Claims (2)

(, 57) 1. FLOW ENERGY EXTINGUISHER, made in the form of a deep vertical water well, characterized in that, in order to increase work efficiency, reduce construction cost and calm the flow behind the damper, it is equipped with a split pier wall at the bottom of the well t _n . = '(3-5) h _f, width b _n = (0,7-0,8) ί _claim with the distance between them equal to the width of the piers where ft, - the depth of the compressed stream at the bottom of the exhaust channel. 2. The absorber of the flow energy in π. 1, characterized in that the depth and length of the well are determined by the dependences = ^ (1.70 ^, - 5.93)? K = 8.60 / 1 ^ 2, ^ + 4 _K (ctg < ₃ C-0.36 ), where Z _to and - respectively, _the depth and length of the well; - compressed depth of flow at the bottom of the outlet channel; F _rf is the Froude number in the compressed section β with depth hf ' _} 20 $ F _ri 120; “C (. - the angle of inclination of the flow entering the well, 50 ° έοΐ £ 70 °.