Study On Resistance Of Gas Laminar Flow In Porous Media

Percolation in porous media has always been a hot and difficult topic in engineering and fluid mechanics.Darcy's law seems to end the problem of laminar flow in porous media.However,in recent years,many scholars have found that the relationship between resistance and velocity of Darcy's law is not linear,which indicates that the mechanism of laminar flow in porous media is still unclear,and further research is necessary and urgent.Based on the shortcomings of traditional pipe flow model,we analyze and explore this problem from another way of thinking.Seepage resistance of porous media is regarded as the sum of innumerable average local resistance.The formula of total resistance loss in laminar flow is deduced theoretically.The local resistance coefficient is obtained by using Darcy's experimental data.It is found that the average local resistance coefficient is not a fixed value.With the change of Reynolds number,the resistance loss of porous media is not completely linear with the velocity.Based on this,we obtain the average local resistance coefficient,which is much larger than that of the traditional pipe flow model.This shows that the traditional pipe flow model underestimates the calculation of resistance loss.In addition,we use the new experimental data and several traditional laminar flow formulas to compare and analyze the results.It is found that the results of the traditional formulas are smaller than those of the new formulas.The reason for this result may be that in the traditional formulas,some local resistance is neglected while considering laminar flow calculation,and only the resistance along the way is considered.The ideas put forward in this paper regard resistance as countless.This local resistance just makes up for this deficiency.In addition,this paper attempts to further explore the complex flow mechanism of porous media flow as the flow around numerous equivalent spheres.The formula of total resistance loss in laminar flow is deduced theoretically.It is found that the theoretical value is far less than the experimental value.It shows that the resistance loss is much underestimated in the flow model of porous media.Compared with Darcy's experimental data,the underestimated multiple varies with the Reynolds number.In addition,we use new conclusions and several traditional laminar flow formulas to compare and analyze the results of traditional formulas and find that the results of traditional formulas are smaller than those of new formulas.The reason for this result may be that in traditional formulas,some local resistance is neglected while considering laminar flow calculation,and only the resistance along the course is considered.This problem can be avoided in the flow around model.Based on the above two models,we derive new formulas,and obtain new local drag coefficient E and circumfluence interference coefficient E_R.On this basis,we use the experimental data of Darcy and Charles Ritter to determine that the average local drag coefficient of porous media is 200,and the circumfluence interference coefficient is no more than 45.Compared with the authoritative Kozeny Carman equation and Ergun equation,the new formula is obtained.Cheng has the best consistency and the least error among all the experimental data predictions.At the same time,we derive the fractal analytical expressions under the local resistance model and the flow around the model based on the fractal theory.It is found that the fractal analytical formula under the fractal theory is reasonable.