Cavitation Characteristics And Random Response Analysis Of Key Parts Of Mechanical Seal

Mechanical seals are widely used in the petrochemical industry due to their excellent sealing performance,reliability,environmental protection and wide application range.During the operation of the mechanical seal system,the mechanical seal is flushed by the external flushing fluid,causing cavitation in the mechanical seal cavity,which in turn affects the patency of the flow field in the seal cavity.The cavitation phenomenon causes the welded metal bellows to vibrate due to random excitation in the flow field,which will reduce the sealing performance of the mechanical seal and shorten the service life.Therefore,it is necessary to study the vibration caused by cavitation in the mechanical seal cavity.The main research content of this paper is as follows.(1)Aiming at the cavitation of the flow field in the mechanical seal cavity in a certain area,based on the theory of computational fluid dynamics,a three-dimensional simulation model of the seal cavity was established,and the analysis software was used to numerically simulate the flow field cavitation in the mechanical seal cavity and its performance Optimize the analysis to obtain the position and distribution of air pockets in the flow field of the mechanical seal cavity.Analyze the influence of inlet pressure and rotation speed in the flow field on cavitation,and use the Kriging interpolation method to optimize the performance.The results show that under the same initial conditions,the inlet pressure and speed of different flushing fluids will promote or inhibit cavitation in the sealed cavity;Kriging interpolation method is used to fit the combined approximate surface and error,and the inlet pressure and speed are optimized.With the matching scheme of speed,this working condition can well inhibit the generation of cavitation.(2)Aiming at the random vibration phenomenon of welded metal bellows in work,using the theory of virtual excitation method,MATLAB programming is used to obtain the time domain signals of the bellows under random excitation in the axial and radial directions,and the time domain signals are used by fast Fourier transform(FFT)is converted into a frequency signal,the obtained frequency domain signal is imported into the simulation software for random vibration analysis,and then the wave plate thickness of the bellows,the radius of the welding band and the minimum bending radius are used as optimization variables,and the amount of radial deformation and the like The effect force is the optimization function for response surface optimization analysis.The research results show that the excitation frequency of the bellows under the excitation of the flow field is between the first-order natural frequency and the third-order natural frequency;the dangerous position of the radial deformation of the bellows is near the smallest bend of the welding hoop;the pass response Surface optimization analysis and adaptive multiobjective optimization method have obtained a set of structural optimization parameters,which greatly improves the vibration performance of the bellows and reduces the damage rate of the bellows.At the same time,it also provides for the structural parameter design of the welded metal bellows.Theoretical reference.