METHOD FOR DETERMINING DEPENDENCE OF PERMEABILITY COEFFICIENT OF PLASTICALLY DEFORMABLE POROUS MATERIAL AS FUNCTION OF WEIGHT CONTENT AND PRESSURE OF FLUID Russian patent published in 2014 - IPC G01N15/08 

FIELD: mechanical engineering.

SUBSTANCE: sample is placed into a closed cylindrical cavity between a piston, creating pressure and a fluid-permeable bottom. Pressure levels under examination are specified; cyclic force loading of a sample by pressure is created for each of them. Using the selected pressure to deactivate loading and the pressure equal to 0.85-0.95 of the selected pressure, and to activate loading, change of the sample length and time interval of the pressure decrease at a discharge cycle, as well as the amount of the squeezed fluid are recorded in time. Then the permeability coefficient at a cycle is calculated by formula $$K_{fi}=\frac{B_i\cdot m_{sami}\cdot (l_i-l_{i-1})}{{\rho }_f\cdot S_n\cdot (P-P_1)},$$ the residual weight content of the fluid in the sample is calculated by formula $$C_i=\frac{C_0{m}_{sam0}-m_i}{m_{sam0}-m_i}$$ in each cycle; where $$B_i=\frac{1}{t_{ki}-t_{0i}}\cdot \ln (\frac{P}{P_1}),$$ m_sami=m_sam0-m_i, u_fi=S_n·(l_i-l₁), m_i=ρ_f·u_fi P - pressure level under examination, P₁=0.85P÷0.95P - minimum pressure, S_n - piston area, l₁ - sample length at the beginning of the 1-st cycle, l_i-1 - sample length at the beginning of the i-th cycle, l_i - sample length at the end of the i-th cycle, t_0i - starting time of pressure reduction in the i-th cycle, t_ki - end time of i-th cycle, m_sam0 - initial sample weight, m_sami - sample weight in the i-th cycle, ρ_f - density of the filtered fluid, u_fi - total volume of the filtered fluid before the i-th cycle, m_i - weight of the squeezed fluid before the i-th cycle, C₀ - initial fluid weight content, C_i - current fluid weight content in the i-th cycle, i - changes from 1 to k, k - number of cycle in which the condition (K_f(k-1)-K_fk)/K_fk≤0.01 is fulfilled. Then, the dependence of a permeability coefficient as a function of the fluid weight content and pressure level is determined using the obtained values of the permeability coefficient and the fluid weight content in all the selected pressure levels.

EFFECT: possibility to obtain characteristics for a plastically deformable porous material in the wide range of pressures when measuring the fluid weight content, in particular during the fluid squeezing-out from the material, improvement of the measurement accuracy.

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