Abstract
Concentration measurements of a high-speed unsteady gaseous jet were carried out using a Mie scattering method. Helium is injected through an automotive gaseous fuel injector into a pressure vessel. The injection pressure is set at 4.0 and 9.0 MPa(g), and the ambient pressure is varied from 0.1 to 1.0 MPa(a). The pressure vessel is filled with 1.2 μm-diameter scattering particles, and a pulse laser sheet is projected along the jet axis. Due to the displacement of the scattering particles, the Mie scattered light intensity decreases with the increase in the helium concentration. It is observed that the helium concentration along the jet axis decreases gradually with the downstream distance, and that it decreases rapidly near the jet tip. With the increase in the ambient pressure, the helium concentration inside the jet decreases. It is observed that the helium concentration in the jet has a self-similarity in the radial direction, which indicates that the intermittent gaseous jet can be treated as a steady jet except for the jet tip region.
