ISSN 2658–5782
DOI 10.21662
DOI 10.21662
Electronic Scientific Journal
The features of the unsteady process of a cavity formation inside the jet at a sudden outflow of water vapor through a thin nozzle from a pressure vessel, initially in a supercritical state, are studied. A numerical study was carried out by using the sonicFoam solver of the OpenFOAM library with the Peng-Robinson equation of state in a two-dimensional axisymmetric approximation. Visualization of the obtained solutions is presented in the form of pictures dynamics for fields of velocities and temperatures. It is shown that the mode of formation and maintenance of the cavity inside the jet is supported more than 100 μs from the beginning of the expiration process.
numerical study,
sonicFoam solver of package OpenFOAM,
high-pressure chamber,
thin nozzle,
supercritical state of water vapor
Problem: The study of the unsteady process of formation of a cavity inside the jet at the sudden outflow of water vapor through a thin nozzle from a high-pressure vessel, initially being in a supercritical state for a long time interval.
Methods: The numerical study was carried out by using the solver for differential equations of gas dynamics for the viscous gas sonicFoam of the OpenFOAM library in a two-dimensional axisymmetric approximation with the Peng-Robinson equation of state. for this purpose, in the original code of the sonicFoam solver for calculating the pressure and internal energy, changes were made to the thermophysicalProperties file to connect the selected equation of state of water vapor. The solution method is based on an implicit PISO algorithm that calculates the pressure with a two-step corrector. The formation of the calculated grid area in the Cartesian coordinate system is carried out and the initial and boundary conditions of the problem are set using the utilities blockMesh, setFieldsDict and blockMeshDict.
As a result of numerical studies of the supercritical regime of water vapor outflow through a thin nozzle, it is shown that the interaction of the high-speed flow with the adjacent weakly disturbed zone leads to the curvature of the gas trajectory, which is accompanied by the formation and development of vortex zones. Due to the formation of an external toroidal vortex, a supersonic flow velocity is maintained in the outer section of the jet. A weaker vortex, the direction of rotation of which is opposite to the main external vortex, is formed near the axis of symmetry in the surrounding gas stream and due to the direction of the gas flow towards the movement of the jet in its center, moves the Mach disk to the expiration zone, which leads to the development of a hollow jet. The hollow jet mode is maintained for a process time of up to 100 µs.
