Effects of Orifice Geometry on Gelled Propellants Sprayed from Impinging-Jet Injectors

摘要

A series of experiments were performed to investigate the spray characteristics of gelled propellants with impinging-jet injectors for which the orifices are in different shapes. The spray photographs shows that the liquid sheet formed by all the injectors demonstrates similar behavior with increased Weber number. Under identical pressure drop, the liquid sheet formed by the impinging of two square jets or two elliptical jets exhibits greater instability than that formed by circular jets. One particular phenomenon is a thick liquid stream in the center of the liquid sheet when the aspect ratio of a rectangular orifice is relatively large. The reason for this phenomenon is the axis-switching feature of the noncircular jets. With respect to the discharge characteristics, the discharge coefficient of a square orifice is larger than that of a circular orifice. The discharge coefficient of an elliptical orifice and a rectangular orifice is much larger than that of a circular orifice. Generally, the discharge coefficient of an elliptical orifice and a rectangular orifice becomes greater as the aspect ratio increases.