Abstract
The purpose of this study is to clarify the nonsteady aspects of mixing and ignition of hydrogen jets injected into air heated by rapid compression. A numerical model for hydrogen jets undergoing chemical reaction is developed on the basis of experimental findings. For calculation, the axisymmetric compressible Navier-Stokes equations considering a simplified reaction model and the explicit turbulence effect, which is represented by the k-ε two-equation model, is discretized by the explicit MacCormack method and the Flux-Corrected Transports technique.
General Patterns of the computed density distribution of the jet agree well with the corresponding experimental results deduced from Schliern photographs. When the initial air temperature is between 1200K and 1400K, the ignition time measured by the rapid increasing of the temperature and the amount of water production in the computation are generally consistent with that of hydrogen jets in the experiments. The ignition point and its tendency depend on the initial air temperature; for high air temperature (1400-1300K), the ignition point is near the spurting hole and the ignition tendency is diffusive, and as the temperature goes down lower (1200-1100K), the point moves far from the spurting hole and the tendency is pre-mixed.
