某水利枢纽1~#泄洪排沙放空洞掺气设施体型试验研究

Experimental study on the shape of the aeration facility in the 1# spillway tunnel of a certain hydro-junction

摘要

某水利枢纽1~#泄洪排沙放空洞运行水头高达83 m,断面最高平均流速超过35 m/s,采用一坡到底形式，底坡为0.81%。设计三道坎槽结合的掺气设施。为了验证掺气设施设计方案的合理性，通过比尺1∶40的水工物理模型试验，对掺气设施体型进行了优化研究。结果显示：设计体型控制段后渐扩边墙局部压强值达-86.6 kPa,易发生空化水流。空腔回水严重，间歇堵塞通气孔，通气井面积小，气水流量比最大为1.8%,3~#掺气坎仅0.6%。经试验研究，提出取消渐扩段，1~#掺气设施上移并将体型调整为差动式突扩突跌形式，2~#、3~#掺气设施调整为差动式挑坎、坎后变坡形式。结果表明：优化后的体型能够满足掺气要求，汛限水位气水流量比超过4.2%,正常蓄水位以上气水流量比超过7.0%,掺气效果良好，成果对解决隧洞小底坡掺气设计有重要参考价值。

Abstract

The operating head of the 1~# spillway tunnel is as high as 83 m, with a maximum average flow velocity of over 35 m/s. Adopting a single slope with a bottom slope gradient of 0.81%. Three aerating facilities are designed with a combination of ridges and grooves. In order to verify the rationality of the design scheme of the aeration facility. Optimization research was conducted on the shape of the aeration facility through normal hydraulic model test with a scale of 1∶40. The result show that there is a significant negative pressure on the side wall of the diffusion section, with a negative pressure value of-86.6 kPa, and cavitation water flow is prone to occur at high speed water flow. The aeration facility has severe backflow in the cavity, intermittent blockage of the ventilation holes, small ventilation well area, and a maximum air-water flow ratio of 1.8%. The ratio of the 3~# aeration facility is only 0.6%. After experimental research, it is proposed to cancel the diffusion section, move the 1~# aeration facility forward and adjust its shape to a differential sudden expansion and drop form, and adjust the 2~# and 3~# aeration facilities to a differential form, and a steeper downstream bottom slope. The result show that the optimized body shape can meet the requirements of aeration, with an air-water flow ratio of over 4.2% at the flood control water level and over 7.0% above the normal high water level. The aeration effect is good, and it has important reference value for solving the aeration design of small bottom slopes in tunnels.

关键词

泄洪排沙放空洞 / 掺气槽 / 突扩突跌掺气坎 / 差动式掺气坎

Key words

spillway tunnel / aerator / sudden expansion and drop aerator / differential aerator

Author summay

高建标(1970—), 男, 高级工程师, 硕士, 主要从事高速水流与流激振动、泄洪消能与掺气减蚀的研究工作。E-mail: [e-mail]