Visualization and Analysis of Gaseous Jet Process for an Outward-Opening Nozzle

In this article, the effects on the jet process of natural gas through an outward-opening nozzle were analyzed at different pressure ratios (PR). The visualization and analysis of the jet process was based on Schlieren methods. High-speed Schlieren imaging was used to capture the growth of the transient gas jet in a constant volume vessel (CVV) under atmospheric conditions. The experimental results revealed an increase in the radial and axial penetrations in accordance with an increase in the PR. The jet process of the outward-opening nozzle can be divided into two stages, according to the ratio of the radial penetration to the axial penetration. The spread angle increased with the advancement of the gas jet at the initial phase of the jet process. After this phase, the spread angle decreased to a constant value. The appearance of the constant value is directly related to the PR. The peak velocity increased with an increase in the PR. Moreover, the difference between the velocities of the jet and surrounding air was large, which was conducive to the formation of a high-quality mixture. The jet area and volume exhibited similar increase trends with different PRs. Both quantities increased with an increase in the PRs. However, the excessive PR had only a slight influence on the jet area.