Study On Key Parameters Of Numerical Simulation Of Wind Reduction Effect Of Windbreak

Numerical simulation,as an important means to study the wind reduction effect of windbreak,is an efficient method to solve the problem.However,there are still many imperfections and uncertain factors in the numerical simulation of wind field of windbreak: firstly,there is a lack of reliable convergence criterion,unified calculation domain and mesh generation and other key technical standards;secondly,when the mesh plate is replaced by the porous step model,its key parameter inertia resistance coefficient is only empirical formula reference,and its credibility and generality are also good In the end,the discussion of Reynolds number effect in numerical simulation and wind tunnel experiment is still less.In this paper,based on the previous research,CFD software FLUENT is used to simulate the wind reduction effect and flow field pattern of the windbreak.Firstly,the flow field under the shelter of two-dimensional and three-dimensional zigzag nets is simulated.By analyzing the fluctuation of wind speed behind the net,the convergence criteria and iteration steps suitable for this study are defined.Then,taking the wind speed value of the measuring points behind the network as the comparison data,the key parameters such as the calculation area,the calculation element partition and the boundary conditions are determined systematically.Secondly,through the momentum equation of the porous step model,the inertia resistance coefficient of the porous step model is obtained after the velocity pressure drop characteristics of the solid mesh plate are known.Finally,the numerical simulation combined with wind tunnel experiment was used to extract the volume flow of several sections and draw the relationship curve between Reynolds number and total wind speed reduction rate.It was found that when the Reynolds number changed within a certain range,the shielding effect of the wind screen would be different.If the Reynolds number exceeded this range,the Reynolds number effect would not be obvious.Finally,the critical value of Reynolds number was obtained.In addition,the numerical models of flat mesh,butterfly mesh and porous step mesh are established.Combined with the corresponding wind tunnel test data,the wind speed ratio of different types of mesh is compared,and the wind reduction effect of different cross-section windbreaks is studied.The results show that the porous step model can accurately realize the wind reduction effect of solid mesh plate.In particular,the wind tunnel experiments and numerical simulation results under different opening rates and different wind speed profiles are compared.The results show that the numerical simulation method in this paper is feasible and accurate.