Study On The Method Of Turbulence Enhancement For Softness Abrasive Flow Finishing

As a no-tool fluid-based precise processing method,soft abrasive flow(SAF)processing method has been applied in the areas of advanced mechatronic system,complex module mould manufacturing,mobile/diesel engine coupling component and precise optical instrument.SAF is with low abrasive particle volume fraction,and has the matters of processing efficiency and surface uniformity,owing to its characteristics of micro-force and micro-cutting.To solve this problem,a SAF flow field enhancing processing method is proposed,and the involved research contents are described as follows.(1)According to the technical procedures of SAF processing,a trapezoid constrained module based flow field enhancing method is put forward.Referring to the Euler-Lagrange particle trajectory dynamic model,the shearing stress transport(SST)k-ω model and mixture multiphase model,a two-phase fluid dynamic model oriented to the SAF geometrical fluid flow enhancing is set up.The solving well-posed matter and closed condition are analyzed,and the flow field profiles of the constrained flow passage are obtained.(2)To increase the SAF velocity and trurbulence kinetic energy of near-wall region in constrained flow passage,a SAF ultrasonic coupling enhancing processing method is proposed.Based on the realizable k-turbulence model and mixture multiphase flow model,a basic fluid mechanic model for SAF ultrasonic coupling flow flied enhancing is built up.In combination with the sound/flow field coupling theories,the turbulence kinetic energy transport equation of the realizable k-ε turbulence model is revised,and the corresponding modeling-solving method is performed.(3)Considering the pressure pulse characteristics of SAF enhanced flow field,a flow field pressure pulse monitoring method is developed based on the Hilbert-Huang transform(HHT).The method can solve the hard matter of dynamical pressure and velocity because of the small space of constrained flow passage.Based on the above method and the flow field temperature from the temperature sensors,the nonlinear control method is adopted to trace the optimal velocity,and the online adjustment for SAF processing is perforamed to improve the processing efficiency and surface quality.(4)Based on the technologies of high-speed photomicrography and particle image velocimetry,a SAF observation experiment platform is established to capture the real-time micro photos of abrasive flow movement states in the transparent constrained flow passage,and the numerical computation results are verified.A processing experiment platform for SAF flow field enhancing processing method is developed,which contains the trapezoid constrained flow passage processing apparatus,the ultrasonic coupling enhancing processing apparatus and the pressure pulse monitoring system.Based on the above processing platform,the corresponding processing experiments are performed,results show that the processing efficiency of the trapezoidal constraint modular strengthening method can be increased by more than 35%,while the processing time of the ultrasonic vibration hardening method can be shortened by about 6 hours,and the effectiveness and advantage of the proposed method is verified.