The Influence of Plain-Orifice Geometry on Pintle Injector Flow Discharge Coefficient

Abstract In this study, an experiment was carried out to understand the behavior of incompressible flow passing through the plain-orifices of pintle injector to characterize the discharge coefficient (Cd) for different orifice geometries. Three types of orifices, including primary, secondary, and film-cooling orifices, were utilized to characterize the discharge coefficient and understand each orifice flow pattern with high-speed imaging. Each of these orifices will be separated and tested in their test article. The impacts of parameters, including shape and size, on discharge coefficient were studied. The discharge coefficient was determined for each test article by subjecting the orifices to a range of flow rates and measuring the pressure differential. The results obtained for the test article F show a good agreement with the choked fit curve obtained from the analytical relation. In contrast, the results of other test articles show an inconsistency due to the cavitation phenomenon as an unstable flow in their trends. However, they show that after the cavitation, they precisely follow the expected trends.