Study On The Mechanism Of Water Noise And Noise Reduction Measures Of Bottom-transverse Shaft Turnover Gate

At present,many cities have built various kinds of landscape dams to optimize the urban environment and enrich the lives of residents.However,the noise problem brought about by the problem also let the surrounding residents’ life has been seriously affected.In the long run,it will cause serious harm to physical and mental health.In this paper,based on the horizontal axis flip gate dam in the north bottom of Miyi County,physical model test and numerical simulation were carried out for the gate.Using Flow-3d software,the water pressure and turbulence intensity caused by the water flowing through the gate falling into the bottom plate were numerically simulated.The results show that after changing the three conditions of upstream flow rate,gate height and downstream water depth,the main causes of water noise are the impact of the water flow on the bottom plate and the turbulent movement caused by the turbulence of the water flow itself.It is concluded that the water pressure generated when the water falls into the bottom plate after passing through the gate increases with the increase of upstream flow rate and gate height,and decreases with the increase of downstream water depth;Turbulence intensity increases with the increase of upstream flow rate,downstream water depth and gate height.After the linear gentle slope proposed by Yang Pan was taken as the optimal noise reduction measure,this paper studied the connection mode between gate and gentle slope to reduce the water noise caused by impact and turbulence.By combining physical test and numerical simulation,four connection modes between gate and gentle slope were studied.The results show that the second interface has the smallest water pressure and turbulence intensity at the connection,and the third interface forms a closed space at the connection and flow,which leads to resonance and turbulence between the discharged water flow and the building.At the water inlet,the water pressure and turbulence intensity of the third type interface are the smallest due to the small gradient of the gentle slope,while the increased of the water pressure and turbulence intensity of the first,second and fourth types are small and similar.The total water noise of the second type interface is the smallest,and the third type interface is the largest,which shows that the influence amplitude of water pressure and turbulence intensity at the junction is greater than that at the water inlet,that is,the influence amplitude of turbulent water noise and impact water noise at the junction is greater than that at the water inlet.Therefore,the second interface is the best noise reduction measure among the four interfaces.In order to further study the water noise at the entrance of the water,the gentle slope directly connected to the stilling basin for numerical simulation research,the results show that:the water pressure at the entrance of the stilling basin distance between the stilling basin and the gate,the length of the stilling basin influence less,with the depth of the stilling basin increases and decreases;turbulence intensity at the water inlet by the distance between the stilling basin and the gate,the length of the stilling basin and the depth of the stilling basin influence less.