跌落射流冲击竖井底部水池实验研究  

Experimental study on the falling jet impinging on the plunge pool in the dropshaft

作　　者：刘虹 刘甲春 LIU Hong;LIU Jiachun(School of Civil&Environmental Engineering and Geography Science,Ningbo University,Ningbo 315211,China)

机构地区：[1]宁波大学土木工程与地理环境学院,浙江宁波315211

出　　处：《宁波大学学报（理工版）》2023年第3期72-78,共7页Journal of Ningbo University：Natural Science and Engineering Edition

基　　金：国家自然科学基金(60874083);浙江省教育厅科研项目(Y200907622);宁波大学科技学院预研项目(003-21021003)。

摘　　要：在跌落式城市排水竖井中,水流跌落一定距离后,通常携带着大量能量.当它冲击竖井底部时,会产生明显压力脉动,对竖井结构安全产生风险.本文建立排水竖井物理实验模型,研究跌落射流对竖井底部消能池的冲击作用,分析竖井底部的压力脉动与分布以及竖井跌落高度和底部水池深度对冲击压力的影响.结果表明:水平射流冲击竖井井壁后,分为沿竖井壁向下的环形流和自由落体的射流.当跌落水流流量较小时,竖井底部高压区域集中在靠近下游管道一侧;随着流量逐渐增加,环形流面积持续增大,高压区域逐渐由下游侧向上游侧过渡.增加下游管道水深可有效降低竖井底部的平均冲击压力,增加水垫层深度可有效降低竖井底部冲击压力脉动.当水流在竖井中达到最终速度后,继续增加竖井跌落高度将不会产生更大冲击压力.In the plunging drop shaft,the water flow usually carries a large amount of energy after falling a certain distance.When it impinges the bottom of the dropshaft,it generates significant pressure pulsation,which poses a risk to the structural safety of the dropshaft.In this paper,an experimental model of a plunging dropshaft was constructed.The impact of the fall jet on the plunge pool at the bottom of the dropshaft was studied,and the pressure pulsation and distribution as well as the effect of the drop height of the dropshaft and the depth of the pool on the impact pressure were analyzed.The results show that the horizontal jet impacting the shaft wall is divided into a downward annular flow along the dropshaft wall and a free-falling jet.When the falling water flow is small,the high-pressure area at the bottom of the shaft is concentrated on the side near the downstream pipe;as the flow gradually increases,the annular flow area continues to increase and the high-pressure area gradually transitions from the downstream side to the upstream side.Increasing the water depth of the downstream pipe can effectively reduce the average impact pressure at the bottom of the shaft and increasing the depth of the water cushion can effectively reduce the impact pressure pulsation at the bottom of the shaft.When the water flow reaches its terminal velocity in the shaft,continuing to increase the drop height of the shaft will not generate more impact pressure.

关 键 词：跌落式竖井 冲击压力 水垫层 跌落高度 最终速度 

分 类 号：TU992[建筑科学—市政工程]