CN101538840B - deflected flow energy dissipator in the stilling basin - Google Patents

Abstract

The invention relates to a deflector energy dissipator in a stilling pool, belonging to the field of engineering hydraulics. The deflecting flow energy dissipator is a triangular ridge installed in the stilling pool, which divides the stilling pool into two parts, the front pool and the rear pool; /4～2/3 range change. The angle of the facing surface of the triangular ridge changes between 5-45°; the angle of the water surface changes between 45° and 90°; 1/3; its width is the same as the length of the stilling pool; its height is 1/8 to 1/4 of the bottom edge of the triangular canopy. The setting of deflector energy dissipator in the present invention not only shortens the length of the stilling pool, which is beneficial to save the engineering cost; but also improves the energy dissipation rate, and can be used in any conventional stilling pool, or cooperate with other auxiliary energy dissipation in the conventional stilling pool It can be used by workers, and the effect is good.

Description

The deflected flow energy dissipator in the stilling basin

technical field

The invention relates to a deflector energy dissipator in a stilling pool, in particular to a triangular deflector energy dissipator in a stilling tank, which belongs to the field of engineering hydraulics. the

Background technique

In water conservancy projects, in some low dam spillway, spillway and gate dam and other discharge structures, due to their large outlet energy, it is necessary to set up stilling pools at their outlets to eliminate residual energy. The so-called "energy dissipation" in hydraulics does not refer to the "elimination" of energy, but refers to the conversion of energy. The conventional stilling tank mainly uses the hydraulic jump generated in the pool to dissipate the energy of the bottom flow, that is, the bottom flow energy dissipation is to use the stilling tank to make the discharged water flow generate a hydraulic jump within the limited range of the outlet of the discharge structure, and the hydraulic jump connects the upstream and downstream water flows. And through the violent turbulent turbulence and tumbling action on the surface of the upstream and downstream water flow of the hydraulic jump, the mechanical energy is converted into heat energy to achieve the purpose of energy dissipation. Underflow hydraulic jump has a long history of energy dissipation. It can adapt to high, medium and low levels of water head and different geological conditions. Dissipators have been widely used in hydraulic engineering [Katakam V.and Rama P., Spatial B-Jump at sudden channelenlargements with abrupt drop, J.of Hydraulic Engineering, ASCE, Vol.124, No.6, June, 1998.]. However, it also has shortcomings. For example, when the length of the conventional stilling pool is insufficient, the water jump cannot be formed because the downstream water depth matching the conjugate water depth cannot be provided; The bottom velocity often causes damage to the bottom plate of the stilling basin. the

In view of the problems mentioned above, on the discharge structures with high water head and large flow, a new type of energy dissipator arrangement combining surface hole-bottom hole-stilling basin is adopted, such as the current domestic Ankang, Wuqiangxi, Qingjiang Geheyan Contour-height dam hub hydraulic construction; for large single-width flow rate and low Floyd's number hydraulic jump, one-stage or multi-stage stilling basins can be used for bottom flow energy dissipation according to the actual situation of the project; for the centripetal flow of arch dam stilling basins, Some special measures have also been found, such as using surface holes plus asymmetric wide tail piers or adding "T" shaped piers in the stilling pool, which can restore the water flow to a uniform flow. In order to improve the energy dissipation rate and effectively ensure the occurrence of hydraulic jumps, various auxiliary energy dissipation devices in stilling basins have appeared in engineering applications, such as stilling sills, deep-dug stilling basins, toe tunnels and T-shaped piers, etc. [Rajaratnam N, The forced hydraulic jump, Part 1 and Part 2, Water Power, Vol.16, No.1 and No.2, Jan. and Feb., 1964. Ni Hangen. Simplified calculation of wide tail pier-stilling pool Methods, Journal of Hydraulic Science, No. 6, June 1998. Jiang Feng et al. Design and Energy Dissipation of Stilling Basin of T-shaped Pier with Low Freund number, Journal of Hydraulic Science, Supplement, January 1998.]. Although the use of these auxiliary energy dissipators is effective in most projects, there are also defects. On the one hand, the side effects such as cavitation damage caused by the auxiliary energy dissipaters arranged in the stilling pool to itself and the stilling pool are also obvious.[ Ai Keming, Scour damage and prevention of bottom flow energy dissipation, drainage engineering and high-speed water flow, 1995(3). ], on the other hand, the arrangement of auxiliary energy dissipators did not solve the fundamental problem of the large flow velocity at the bottom of the stilling pool [Wang Caihuan, Xiao Xingbin. Review of the research and application status of bottom flow energy dissipation design [J]. Sichuan Hydropower, Vol. 1 No. 1, March 2000]. the

The deflecting flow energy dissipation is the most common energy dissipation method of the drainage structure. This energy dissipation method is to build a deflecting flow sill with a certain elevation angle at the downstream end of the drainage structure, and use the huge kinetic energy of the discharged water to deflect the water flow. into the air, and then connect with the downstream water flow when it lands away from the building. Its characteristics are: it can not only dissipate energy by means of the diffusion of the free jet in the air; it can also use the turbulent diffusion of the submerged jet after the water tongue enters the downstream water cushion and the shearing effect of the water strand and the swirl on both sides to eliminate able. The advantage of deflected flow energy dissipation is that it can save the downstream apron, the structure is simple, and it is easy to maintain. the

Xu Guangxiang and others proposed a compound stilling basin with longitudinal classification and lateral differential motion [Xu Guangxiang, Cui Yuda, Yang Zhongchao. Application research of compound stilling basins in small hydropower in mountainous areas[J]. Journal of Hydroelectric Power, Vol. 26, No. 2, 2007 April 1987-92], the main pool on the left is divided into two stages vertically, and the auxiliary pool on the right is a two-stage differential stilling pool whose bottom elevation is properly raised, and the model test of the energy dissipater of Banzhuyuan Hydropower Station in Yujiang, Chongqing A better energy dissipation effect was achieved in the research. However, the sill of this size is a conventional sill, which is relatively small in size compared with the whole stilling pool, and only plays the role of dividing the stilling pool into two stages, and does not play the role of deflecting the flow. Guo Weicheng proposed the concept of multi-stage stilling basins for Puning Wushi barrage project [Guo Weicheng. Application of multi-level stilling basins. Western Exploration Project. Total No. 98 2004(7): 11-12], but each The first-level stilling pool is a complete stilling pool, which belongs to the cascade type. Moreover, this cascade stilling basin itself needs to occupy a relatively large space, so it is limited by terrain and geological conditions. the

To sum up, the conventional stilling basin, either because the size of the stilling basin is too small to meet the generation of the hydraulic jump, cannot meet the requirements of sufficient energy dissipation; The flow velocity near the bottom of the large stilling basin often causes damage to the bottom plate of the stilling basin; therefore, the energy dissipation effect of the conventional stilling basin and the deflector energy dissipator arranged in the stilling basin is not ideal. The deflected flow energy dissipator provided can solve the above-mentioned problems well, and this is where the task of the present invention lies. the

Contents of the invention

The purpose of the present invention is aimed at the defects existing in the above-mentioned prior art, and proposes a method of shortening the length of the stilling pool on the basis of ensuring a relatively high energy dissipation rate, thereby saving engineering cost; and the structure is simple and easy to maintain; and can greatly Increased single-wide flow range from hydraulic jumps; and deflected flow dissipators that can be used alone or in conjunction with other auxiliary energy dissipators in any conventional stilling basin.

In order to realize the purpose of the present invention, the present invention adopts the technical scheme that the following measures constitute to realize. the

The deflecting energy dissipator in the stilling basin of the present invention includes the stilling basin, and according to the present invention, also includes the energy dissipating unit provided in the stilling basin, and further the energy dissipating unit is a triangular shape along the water flow direction section Lifting ridge; the triangular ridge divides the stilling pool into two parts, the front pool and the rear pool; the lifting position can be changed between 1/4 and 2/3 of the length of the stilling pool. the

In the above technical solution, the angle between the bottom edge of the triangular ridge and the edge facing the water is 5-45°. the

In the above technical solution, the included angle between the bottom edge of the triangular ridge and the backwater edge is 45°-90°. the

In the above technical solution, the length of the bottom of the triangular ridge accounts for 1/6 to 1/3 of the total length of the stilling basin. the

In the above technical solution, the lateral width of the triangular sill is the same as the width of the stilling pool, and the vertical height of the triangular sill is 1/8 to 1/4 of the length of the bottom side of the triangular sill. the

The triangular energy dissipator provided in the stilling pool of the present invention can be used alone in the stilling pool, and can also be used in combination with other auxiliary energy dissipators arranged in the stilling pool, both of which can achieve ideal effects. the

Compared with the prior art, the present invention has the following characteristics and beneficial technical effects:

1. The deflector energy dissipator of the present invention can ensure that the length of the stilling pool is shortened compared with a high energy dissipation rate, which is beneficial to save engineering costs; or the energy dissipation rate can still be improved when the length of the stilling pool is the same. the

2. The deflecting flow energy dissipator of the present invention can greatly increase the single-wide flow range in which the hydraulic jump occurs, so the energy dissipation efficiency is high. the

3. The deflecting flow energy dissipator of the present invention divides a complete stilling pool into a front pool and a rear pool by using a triangular ridge. defect. the

4. The triangular-shaped ridge provided by the deflector energy dissipator of the present invention within the limited space of the stilling pool occupies a small space and has a wide range of use, and solves the problem that the cascaded stilling pool occupies a large space and is affected by the terrain. 1. For defects limited by geological conditions, the triangular canopy of the present invention can be used in any conventional stilling pool; it can also be used in conjunction with other auxiliary energy dissipators in the stilling pool. the

Description of drawings

Fig. 1 is the elevation schematic diagram of the triangular pick-up ridge in the stilling pool of the present invention;

Fig. 2 is a schematic plan view of a triangular ridge for deflecting flow energy dissipation in the stilling pool of the present invention;

Fig. 3 is a schematic diagram of the water flow in the stilling pool of the present invention with deflectors and energy dissipators set as triangular ridges;

Fig. 4 is a schematic diagram of an embodiment of the triangular ridge of the deflector energy dissipator of the present invention applied in the stilling pool;

Fig. 5 is a three-dimensional schematic diagram of the bottom plate of the stilling basin in the embodiment of Fig. 4 . the

In the figure, 1 stilling pool, 2 triangular sills, 211 the bottom edge of the triangular sill, 212 the facing water edge of the triangular sill, 213 the water edge of the triangular sill, A the angle between the bottom edge of the triangular sill and the facing water side, B Angle between the bottom edge of the triangle sill and the backwater side, b the horizontal width of the triangle sill, h the vertical height of the triangle sill, l the length of the bottom edge of the triangle sill, 3 stilling pool front pool, 4 stilling pool rear pool. the

Detailed ways

The present invention will be described in further detail below in conjunction with accompanying drawing and principle of work and with specific embodiment, the best embodiment that is considered to be used for carrying out the present invention is described below, is intended to describe the general principle of the present invention and triangular challenge composition; but it does not imply any limitation on the protection scope of the present invention. the

In Fig. 1 of the present invention, the deflector energy dissipator arranged in the stilling basin 1 is a triangular ridge 2, and the length of the bottom edge 211 of the triangular ridge 2 accounts for 1/6 to 1/3 of the total length of the stilling basin. The upstream edge of the triangular ridge is 212, and the backwater edge of the triangular ridge is 213; the angle A between the bottom edge 211 of the triangular ridge and the upstream edge 212 of the triangular ridge can be changed between 5° and 45°; The included angle B between the bottom edge 211 of the triangular canopy and the backwater side 213 of the triangular canopy can be changed between 45° and 90°; the

It can be known from the plan view of FIG. 2 of the present invention that the width b of the triangular ridge is the same as the width of the stilling pool 1 . the

The energy dissipation principle of the energy dissipation of the triangular ridge in the stilling pool of the present invention is shown in Fig. 3 . When the triangular ridge energy dissipator is applied to water conservancy projects, the reflection and deflection of the jet flow at the outlet of the flood discharge structure on the water surface of the triangular ridge will make the turbulence and backflow in the stilling pool more intense; The pool is divided into two stilling pools, the front pool 3 and the rear pool 4, so that the hydraulic jump can be formed stably within a large single-width flow range. When the single-width flow rate is small, the hydraulic jump energy dissipation may be sufficient in the front pool. The back pond effectively protects the downstream apron section as a water cushion pond; when the single-width flow rate is large, the front and rear stilling ponds both play a role, and the backflow and water cushion formed at the bottom effectively reduce the flow velocity at the bottom and the outflow of the pond. flow rate, thereby greatly improving the energy dissipation rate. the

Example

Fig. 4 is the example that the present invention adopts in the stilling basin optimization hydraulic model test that triangular ridges 2 are arranged in the stilling basin in a certain hydraulic engineering. Structurally, the stilling basin 1 and the triangular ridges 2 manufactured as a continuous whole. The triangular ridge 2 divides the stilling pool into two parts, the front pool 3 and the rear pool 4, wherein the length of the triangular ridge along the water flow direction is l=20m, which is about 0.3 times the total length of the stilling pool. The included angle A of the side 212 is 10°, the angle B between the backwater side 213 and the bottom edge is 80°, the vertical height h of the triangular canopy is 3m, which is 0.15 times of the length of the bottom side, and the horizontal width b of the triangular cantilever is equal to that of the stilling force The width of the pool is the same, which is 30m, and its lifting position is 30m away from the entrance of the stilling pool, which is about 1/3 of the length of the stilling pool. The experimental results show that after adding a triangular ridge in the stilling pool, a stable hydraulic jump can be formed, and the position of the jump head is stable within 10m downstream of the cave entrance. The water flow in the pool is turbulent and the energy dissipation effect is remarkable; Reflection is formed on the ridge surface, and the water splashes tumbling; after the ridge is lifted, backflow is also formed, and the water cushion is deep, which effectively protects the bottom plate of the stilling pool. If a conventional stilling basin is used, the length of the stilling basin needs to be about 130m. After adding a triangular ridge, the length of the stilling basin is shortened to 87m. The energy dissipation effect and flow state of the stilling basin are very good under the level flow. Therefore, the present invention can directly install triangular ridge energy dissipators in the conventional stilling pool, and can also add triangular ridge energy dissipators on the basis of other auxiliary energy dissipators in the stilling pool, all of which can achieve ideal results. the

Claims (5)

1. A deflecting flow energy dissipator in a stilling pool, comprising a stilling pool (1), characterized in that it also includes a pick-up ridge provided in the stilling pool (1), and the pick-up ridge is a triangular section along the direction of water flow Riding ridge (2); the triangular ridge divides the stilling pool into two parts, the front pool (3) and the rear pool (4); the lifting position is between 1/4 and 2/3 of the length of the stilling pool. 2. The deflecting flow energy dissipator in the stilling pool according to claim 1, characterized in that the angle (A) between the bottom edge (211) of the triangular ridge (2) and its water-facing edge (212) is 5~45°. 3. The deflecting flow energy dissipator in the stilling pool according to claim 1, characterized in that the angle (B) between the bottom edge (211) of the triangular ridge (2) and its backside (213) is 45° °～90°. 4. The deflecting flow energy dissipator in the stilling basin according to claim 1 or 2, characterized in that the length (1) of the bottom edge (211) of the triangular-shaped cantilever (2) accounts for the total length (1) of the stilling basin (1). 1/6~1/3 of the length. 5. The deflector energy dissipator in the stilling pool according to claim 1 or 2, characterized in that the transverse width (b) of the triangular ridge is the same as the width of the stilling pool (1), and the vertical height of the triangular ridge is (h) is 1/8～1/4 of the length of the bottom edge (211) of the triangular canopy.

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