Study On The Mechanism Of Solid-liquid Two-phase Cyclone Separation Of Non-Newtonian Fluid

Hydrocyclone separation is one of the important methods in drilling solid control system, which was the key link of drilling engineering.the working principle of hydrocyclone separation is according to the density difference between the two phase under the action of centrifugal force.But at present,the research of drilling fluid flow field in hydrocyclone mostly based on Newtonian fluids or power-law fluid as the liquid medium.But in real situation.drilling fluid presented on non-Newtonian rheology.and the power-law fluid cannot describe the non-Newtonian rheological properties of drilling fluid accurately.and studies had shown that the Four parameters rheological model was more conformed to the physical situation of mostly drilling fluid.Therefore.in order to understand the flow field distribution and separation performance of drilling fluid in hydrocyclone.we adopted four parameters fluid describing the non-Newtonian rheological properties of drilling fluid to do the numerical simulation.which can provided reference evidence for deepen understanding the separation mechanism and structure optimization.Firstly.the article did numerical simulation for the four-parameters fluid by FLUENT.the software of Computational Fluid Dynamics,obtained the distributions of velocity and pressure.and contrast to power-law fluid and water simulations results under the same condition.The results showed that:the simulation results are qualitative consistent with previous experiment results;the static pressure of four-parameter fluid was lower than power-law and greater than water.and the tangential was on the contrary:the axial was not very different:the apparent viscosity of four-parameter fluid was in large variation especially near the wall.which was inversely proportional to strain rate.Secondly,the article analyzed the influence of rheological parameter change on flui d flow characteristics:increased b and decreased n led to increased static pressure;tang ential velocity decreased with the increase of b and n;the axial velocity changed incon spicuous;moreover the influence of n was outstanding than b.Once more.based on the results of single phase flow field of four parameter fluid, the article simulated and analyzed the flow field distribution and separation characterist ic of solid-liquid phase flow field in the hydrocyclone,used mixture model.Through co mparing the separation performance of three medium found that:the separation efficienc y of four-parameter was lowest and changed most slowly.lt showed that the necessary of considering the Non-Newtonian rheological of drilling fluid when studied the separ ation properties of hydrocyclone.Lastly,the article analyzed the effect of different Operating parameters and physica 1 parameters on separation properties,the results showed that:the increase of velocity particle diameter and the decrease of solid concentration led to higher separation effici ency;the increase of velocity?solid concentration and the decrease of particle diameter led to increased pressure drop;the increased b led to the dcrease of separation efficien cy and the pressure drop first increase then decrease, the influence were small compar ed to n;the increase of n resulted decreased both separation efficiency and pressure dr op.It showed that in actual conditions, suitable conditions and operation parameters sho uld be defined.The results of numerical provided reference for the further study the effect of dril ling fluid Non-newtonian rheological property on flow field distribution and the separa tion performance,provided a reference for parameter optinization.of hydrocyclone in th e solid control system.