Study On The Noise Reduction Measures Of The Water Flow Under The Broad Crested Weir Without Ridge

With the people's increasing demand for a better life,many cities have optimized the living environment by constructing water conservancy facilities.When the water flows through the landscape facilities and discharges,it will generate large water noise,which will not only have a serious impact on the lives of the residents around the landscape facilities,but also lead to safety accidents caused by people who work around the landscape facilities due to inattention.In order to reduce the harm caused by urban water conservancy landscape facilities to people,this paper will take the Chengbei dam project in Miyi County as a prototype,and use Flow-3d numerical simulation software to establish a numerical model of a sillless wide crested weir according to similar principles.On the basis of the study,the mechanism of the discharge noise of the sluiceless wide crest weir is studied from two aspects: impact water noise and turbulent water noise.The results show that the impact water noise generated by the interaction between the water flow and the weir toe floor will increase with the increase of the upstream flow and weir height,and decrease with the decrease of the downstream water depth;the turbulent water noise caused by the turbulence of the water flow will It will increase with the increase of upstream flow,weir height and downstream water depth.However,with the increase of the downstream water depth,the impact water noise showed a decreasing trend,and the turbulent water noise showed an increasing trend.However,the total water noise generated by the discharge flow under the wide crested weir without ridges decreased with the increase of the downstream water depth.The turbulent water noise is smaller than the impact water noise generated by the interaction of the water flow and the weir toe.In this paper,Yang Pan improved the linear noise reduction gentle slope,changed the height of the linear noise reduction gentle slope,and continuously adjusted the ratio(A)of the water flow fall height(d)to the weir height(H),so that the water flow fall part of the Water pressure reduces the water pressure at the place where the water flows into the water,thereby reducing the impact water noise generated by the interaction of the water flow with the gentle slope and weir toes.In order to obtain the best A value for noise reduction,this paper uses physical model tests and numerical simulations to study the noise reduction ability of different A values.The results of the study show that:(1)With the increase of A value,the water pressure,turbulence intensity and water noise at the place where the water flow falls gradually increase,but the increase ranges are different.The water pressure at the drop of the flow basically changes linearly and has a good linear relationship.However,when the value of the turbulence at the drop of the flow decreases and the water noise increases from 0.244 to 0.255,the increase is larger.Therefore,when the value of A is less than or equal to 0.244,the water noise at the water drop is mainly composed of impact water noise;when the value of A is greater than or equal to 0.244,the water noise at the water drop is mainly composed of impact water noise and turbulent water noise.(2)With the increase of A value,the water pressure,turbulence intensity and water noise at the inflow of water basically decrease linearly,so the impact water noise and turbulent water noise at the inflow of water will both decrease with the increase of A value.Combined with physical tests,when A = 0.244,the total water noise at the place where the water flow falls and where the water flows into the water is the minimum,and the best noise reduction effect can be obtained,that is A = 0.244.