THE CHARACTERISTICS OF FLOW DISCHARGE COEFFICIENT OF PLAIN ORIFICE GEOMETRIES ON PINTLE INJECTOR DESIGN

In this study, an experiment was carried out to understand the behavior of incompressible flow passing through the plain orifices of a pintle injector to characterize the discharge coefficient (C-d) for different orifice geometries. Three various 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 was separated and tested in their test article. The impacts of parameters, including shape and size, on discharge coefficient, were studied. The discharge coefficient of each test article was determined 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 flow instability as an unstable flow in their trends.