In this study, FLUENT v.16.1 was used to investigate the compressible flow generated by the supersonic jet spewed from a high pressure tube. As the boundary condition for CFD (Computational Fluid Dynamics) analysis, the inlet temperature of air was constantly 300 K and the variation of JPR (Jet Pressure Ratio) were 5, 50, 100, 150 and the variation of tube diameter were 10, 20, 30 cm. As a result, it was confirmed that the effective range was increased as the JPR was higher, but it was confirmed that the effective range was lower than the JPR rise, and that the effective range was increased as the diameter was larger. Therefore, it is found that the tube diameter is more sensitive than the JPR among the influence factors of jet, and if the result of this study were reflected in the design of high pressure system, it will contribute to the design of the system for preventing the second accident.

Our goal is to present a simple volume-of-fluid type interface-tracking algorithm to compressible two-phase flow in two space dimensions. The algorithm uses a uniform underlying Cartesian grid with some cells cut by the tracked interfaces into two subcells. A volume-moving procedure that consists of two basic steps: (1) the update of volume fractions in each grid cell at the end of the time step, and (2) the reconstruction of interfaces from discrete set of volume fractions, is employed to follow the dynamical behavior of the interface motion. As in the previous work with a surface-tracking procedure for general front tracking (LeVeque & Shyue 1995, 1996), a high resolution finite volume method is then applied on the resulting slightly nonuniform grid to update all the cell values, while the stability of the method is maintained by using a large time step wave propagation approach even in the presence of small cells and the use of a time step with respect to the uniform grid cells. A sample preliminary numerical result for an underwater explosion problem is shown to demonstrate the feasibility of the algorithm for practical problems.

The behavior of the flow about gas atomizers with a supersonic nozzle containing an under-expanded or over-expanded jet is very important with respect to performance and stability characteristics. Since detailed experiments are expensive, computational fluid mechanics have been applied recently to various relating flow field. In this study, a higher order upwind method with the 3rd order MUSCL type TVD scheme is used to solve the full Reynolds Wavier-Stokes equations. To delineate the purely exhaust jet effects, the melt flow is not considered. Comparison is made with some experimental data in terms of density fields. The influence of the exhaust-jet-to freestream pressure ratio and the effect of the protrusion length of the melt orifice are studied. The present study leads us to believe that the computational fluid mechanics should be considered as powerful tool in predicting the gas atomizer flows.