Aerodynamic characteristics of sonic injection through diamond-shaped orifices in supersonic flow field

Three-dimensional supersonic flow field with sonic injector was numerically investigated, the characteristics of diamond-shaped orifice which were compared with that of the circular injector were analyzed, and at last the effect of the diamond-shaped orifice on the flow field with different injection angles was explored. It is found that the plume from diamond-shaped orifice can weaken the strength of the bow shock and reduce total pressure loss, and the fuel penetration height of diamond-shaped orifice is higher than that of the circular injector, however, the diffusivity is almost the same in spanwise direction regardless of the structure type of injector. With the increase of the injection angle, the penetration height of the fuel firstly increases and then decreases; the model with 60 degree injection angle has the best characteristics. The change of total pressure loss is not obvious when the injection angle changes within a certain range, whereas an injection angle which is too large would lead to a rapid increase in the total pressure loss. This investigation provides insight into the characteristics of flow field with diamond-shaped orifice, which is crucial for optimization of injector.