Numerical Study Son Gas-Solid Two-Phase Flow Of Insulator Contamination Based On LBM

With the development of industrialization and urbanization in China,the demand for safe operation of power grids in China is also increasing.Therefore,the safe operation of ultra-high and extra-high voltage power grids is extremely important.One of the important tasks of maintaining the safe operation of power grid is to avoid the occurrence of insulator flashover accidents.This paper explores the mechanism of insulator surface contamination.It provides a theoretical basis for predicting the pollution degree of insulators under different weather conditions and studying pollution flashover accidents.It has important research and application significance.The contamination process of insulators is a typical gas-solid two-phase flow,which includes continuous phase air flow and discrete phase contaminated particles.Insulator flow field is a complex unsteady flow field with high Reynolds number.Because the shape of the insulator is complicated,a large number of body-fitted grids are needed,and the large eddy simulation method also requires a large number of grids.Therefore,this paper chooses LBM for numerical calculation.The natural boundary processing ability and parallel processing ability of LBM are utilized to improve the efficiency of numerical calculation and save computing time and cost.LBM numerical calculation program development is carried out using the open source OpenLB library.The numerical calculation model LBM+LES is obtained by the LBM coupled LES.And in this model,the high Reynolds number cylindrical flow case is completed.The particle phase is numerically calculated by the discrete element method.The numerical model of gas-solid two-phase flow,LBM+DEM,was built.The particle velocity is obtained by the 3-line difference,and the particle transport in the flow field is completed For the collision between particles and insulators,JKR contact model and energy dissipation model are used as the collision adsorption model.The energy loss of particle collision is calculated by using the experimental adhesion force.Finally,LBM+LES model and LBM+DEM model are coupled into LBM+LES+DEM model.Under this model,a numerical wind tunnel with high Reynolds number turbulent gas-solid two-phase flow is built.The physical model of insulator is built.The contamination of insulators was numerically simulated through the completed turbulent gas-solid two-phase flow numerical wind tunnel.In addition,the experiments of insulator natural contamination and adhesion force of contaminated particles are carried out in this paper.In the experiment of natural contamination,the size distribution of insulator surface contamination under natural contamination was analyzed by means of scanning electron microscopy and image processing.Statistical results show that most of the contaminated particles have a particle size below 10?m.The probability distribution of the contaminated particles satisfies the law of lognormal distribution.The cumulative probability distribution of the contaminated particles satisfies the Boltzmann distribution.In the adhesion test,the adhesion between the particles and the substrate was measured by scanning electron microscopy and sphere probe.It was found that the greater the particle size,the greater the adhesion force between the ceramic substrate and the BTG spheres.Adhesion force measurements ranged from 0.02?N to 0.09?N.The larger the particle size of BTG spheres,the greater the needle withdrawal adhesion force of ordinary glass materials,while the needle insertion adhesion force fluctuates.Its adhesion measurement is between 0.04?N and 0.24?N.The adhesion force measured by experiment is used as the contact force between particles and insulators.This contact force is used in the energy dissipation model to calculate the energy loss in particle collisions.