Study On Sealing Characteristics Of Air Valve In Long-distance Water Conveyance Project

Long distance water conveyance project has gradually become the new trend of water supply system development,but its pipeline safety protection is extremely difficult,air valve because of its unique advantages,has become an important protection measure for the pipeline safety of long distance water conveyance system,has great significance for its research.In engineering practice,often as a result of the air valve type selection,internal structure,which brings the problems such as water supply pipe tube,the main reason is because of a shortage of exist within the air valve seal structure,the floating ball contact with O ring,causing the breakage of the O ring,causing the air valve seal failure,cause air valve inside and outside differential pressure,unable to effectively solve the problem of line pressure,resulting in the detonation tube happened frequently.According to the working principle of the sealing ring in the air valve and the problems encountered in the engineering practice,this paper summarizes the failure forms of the sealing ring,analyzes the failure reasons,and establishes the judging basis for the failure of the sealing ring.To further accurate solution to the problem of seal failure,this paper using ANSYS Workbench softwareplatform,using the finite element method,numerical simulation to solve the seal problem of rubber sealing ring,analysis O ring under different pressure,different materials,different hardness,the deflection of the seal ring,such as stress and strain change situation,according to the result of numerical simulation,can the selection of sealing ring,sealing ring of the failure problem put forward technical support,can also for the further experiment made beneficial exploration and try.The main research contents are as follows:(1)expound the research background of this topic,consult the literature,and understand the research status of finite element analysis of air valve and sealing ring at home and abroad(2)taking the new stone coal coking water supply project as an example,based on the numerical simulation of the pump stopping hydraulic transition process in the pump station,the pressure distribution under the safe operation condition of the pressure pipeline was calculated,and the installation position,pressure characteristics and specifications of the air valve were proposed,so as to study the deformation of the air valve sealing ring under different pressures.(3)the sealing principle of the sealing ring in the air valve is described.Combined with the problem of sealing failure of the air valve in practical engineering,the performance of sealing failure is summarized,and the failure reason is analyzed to establish the judging basis of sealing ring failure.(4)the ANSYS Workbench software module was briefly introduced,and the basic theory,method and calculation steps of the finite element method weresummarized.Considering the nonlinear characteristics of rubber sealing materials,the hyperelastic constitutive model for the numerical simulation of sealing rings was established,and the model was determined and derived by combining the finite element method.(5)using the finite element analysis software ANSYS Workbench to analyze the performance of o-ring sealing:Single factor change,different pressure,different hardness,different materials,O ring contact deformation,stress and strain distribution.The influence of different pressure and hardness,different pressure and different material on the contact deformation and stress and strain distribution of o-ring seal under the change of two factors.Main conclusions of the study:(1)combined with an engineering example,the pressure distribution of the water hammer pipeline for stopping the pump is calculated,and it can be known that the maximum pressure at the position where the air valve is installed is2.5mpa,which is taken as the limit working condition for the compression of o-shaped sealing ring.(2)in this study and calculation,all kinds of o-shaped sealing rings with different materials and hardness are not compressed and permanently deformed under extreme pressure,and the sealing structure can meet the needs of safe operation of pipelines.(3)o-ring is more prone to deformation and damage with the increase ofpressure and smaller hardness.Compared with the o-ring of EPDM material,the o-ring of NBR material is more prone to deformation and damage.Slight advantage.(4)with the increase of pressure,the o-ring,in order to resist deformation,the higher the hardness requirements;With the increase of pressure,NBR material is better than EPDM material in resisting deformation.(5)in the case of high pressure value,more attention should be paid to the selection of o-ring material and hardness.