Analysis the dynamics formation of a vapor supersonic jet under outflow from thin nozzle

The dynamics formation of a vapor jet with near-critical state parameters outflowing from a high-pressure vessel through a thin nozzle is studied. The numerical modeling of this process, by using a system of model equations for gas-vapor-liquid mixture, which include conservation laws of mass, momentum, and energy of phases in accordance with one-pressure, one-velocity and two-temperature approximations, was conducted, taking into account heat and mass transfer processes of evaporation and condensation under conditions of equilibrium state with modified reactingTwoPhaseEulerFoam solver of open package OpenFOAM. The process of barrel shock formation in supersonic boiling jet with shaping Mach disk is shown. It was found that the process of boiling fluid outflow is accompanied by formation of vortex zones near axis of symmetry and leads to generation of acoustic wave pulses series preceding the main jet flow, which are the source of pulsations, observed in experiments. The justification of applied numerical method reliability is shown by comparing the computational and analytical solutions for Sedov’s problem of a point explosion in gas-water mixture at the plane case.

Study the dynamics of hollow jet formation under vapor outflow from the supercritical state

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.

The study of the process of evolution of the jet under outflow of water from the supercritical state through a thin nozzle

The dynamics of the water outflow from the initial supercritical state through a thin nozzle is studied. To describe the initial stage of non-stationary process outflow the system of differential equations of conservation of mass, momentum and energy in a two-dimensional cylindrical coordinates with axial symmetry is used. The spatial distribution of pressure and velocity of jet formation was received. It was established that a supersonic regime of outflow at supercritical temperature of 650 K is formed, which have a qualitative agreement for the velocity compared with the Bernoulli analytical solution and the experimental data.

Air barriers used for separating smoke free zones in case of fire in tunnel

The aim of this paper is to take the advantage of CFD application in calculating, optimising, and designing air curtains used to separate smoke free zones in case of fire in tunnel. Air curtains can be a good solution in case when the usage of solid obstructions is not feasible(for example in a big tunnel). A properly designed air curtain produces a pressure drop which prevents transversal flow through the opening. An accurate CFD calculation of an air curtain is challenging because of the high air velocity and relatively thin nozzle. Most air curtains are tested on scaled down models which are difficult to extrapolate. Tests in a real scale model are performed and the tests results are used to verify the chosen turbulence model. The intention of this paper is to present the comparison between the CFD calculations and tests results.

Verification of computational calculations based on physical tests of plane jet used to separate zones full of smoke

The aim of this paper is to take advantage of CFD application in calculating, optimizing, and designing air barriers used to separate smoke free zones in the case of fire. Properly designed air curtain produces a pressure drop which forbides transversal flow through the opening. It is hard to make a good quality CFD calculation of that kind of air curtain because of high velocity and relatively thin nozzle. Most air curtains are tested on scaled down models which are difficult to extrapolate. The author of this article performed tests in a real scale model. Tests results were used to verify chosen turbulence model. The intention of this paper is to present the comparison between CFD calculations and tests results.