Effect of Shock Waves Induced by High-Pressure Injection on Spray Characteristics

Shock waves could disturb the surrounding gas. Then the turbulent gas will affect the spray. In this paper, image photography and numerical simulation were used to investigate the effect of shock waves on spray characteristics. The experimental results show that the spray penetration with attached shock waves is shorter than that without shock waves under the same injection pressure and ambient density conditions during the initial injection stage. From simulation results, the shock waves attach the spray tip during the initial stage. The density and pressure of the gas behind the shock waves are higher than that in the front of the shock waves. And the ambient gas with high density behind the shock waves will hinder the spray development. After the shock waves are separated from the spray, however, the spray penetration with shock waves is longer than that without the shock waves. The shock wave can also promote the mixing degree of the fuel and the ambient gas and increase the spray volume. The effect will be more obvious with the increase of the intensity of shock waves, benefit for the mixture formation. The simulation results for the spray under super-high injection pressure condition show that the bow shock wave is generated at the tail of oblique shock wave under the injection pressure of 240MPa and 320 MPa. Furthermore, the shock waves can increase the gas temperature up to 16% at the injection pressure of 320 MPa, improving the atomization and evaporation of spray. © 2019, Editorial Office of the Transaction of CSICE. All right reserved.