Non-stationary process characteristics of the gas outflow into a liquid

Abstract

A numerical simulation of the process of the outflow of gas under pressure into a closed container partially filled with liquid was carried out. For comparative theoretical analysis, an asymptotic model was used with assumptions about the adiabaticity of the gas outflow process and the ideality of the liquid during the oscillatory one-dimensional motion of the liquid column. In this case, the motion of the liquid column and the evolution of pressure in the gas are determined by the equation of dynamics and the balance of enthalpy. Numerical simulation was performed in the OpenFOAM package using the fluid volume method (VOF method) and the standard k-e turbulence model. The evolution of the fields of volumetric gas content, velocity, and pressure during the flow of gas from the high-pressure chamber into a closed channel filled with liquid in the presence of a ”gas blanket“ at the upper end of the channel is obtained. It was shown that the dynamics of pulsations in the gas cavity that occurs when the gas flows into the closed region substantially depends on the physical properties of the liquid in the volume, especially the density. Numerical modeling showed that the injection of gas into water occurs in the form of a jet outflow of gas, and for the outflow into liquid lead, a gas slug is formed at the bottom of the channel. Satisfactory agreement was obtained between the numerical calculation and the calculation according to the asymptotic model for pressure pulsations in a gas projectile in liquid lead. For water, the results of calculations using the asymptotic model give a significant difference from the results of numerical calculations. In all cases, the velocity of the medium obtained by numerical simulation and when using the asymptotic model differ by an order of magnitude or more.

Research of pressure pulsations during gas outlet to closed pipe area with liquid and installed disc barrier

“…The initial temperature of air and liquid lead is 650 K, and the temperature of water is 300 K. The simulation is carried out for three different cases, in which a disk barrier with a diameter of 0.1 m and a thickness of 0.01 m is installed at different distances from the hole: 100, 200, and 300 mm. A detailed description of the calculation methodology is presented in previous works [8,9].…”

“…The problem of numerical simulation of unsteady gas outflow from a high-pressure vessel into a closed tube region filled with liquid with a gas volume in the upper part was previously solved in an axisymmetric, two-dimensional [8] and three-dimensional formulation [9]. It was found that the gas outflow process differs significantly for water and liquid lead.…”

Modeling of nonstationary gas outflow at breaks of subsea gas pipelines

“…The number of cells in the calculation area was 658800. A detailed description of the calculation methodology is presented in previous works [9,10].…”