Cold Flow Characterization of Triplet Injector Head Realized Through Additive Manufacturing

Abstract

Additive manufacturing is an emerging field in the area of fabrication process and being employed for the realization of rocket engine systems and subsystems. This process is comparatively cheaper and requires less lead time compared to conventional machining process. PSLV, a workhorse launch vehicle of ISRO uses a pressure fed PS4 engine for its upper stage. This engine is realized through conventional machining routes and qualified for flight so far. An attempt has been made to realize the PS4 engine through additive manufacturing route at LPSC. Injector is the major part of the engine which controls the combustion process inside the combustion chamber of rocket engine. It is imperative to realize the injector head first through additive manufacturing and checked for its cold flow performance. The present work investigates the cold flow characteristics of PS4 triplet injector head realized through additive manufacturing. PS4 injector consists of 45 nos of triplet injector elements, injecting oxidizer through the two angular impinging orifices and fuel through the central orifice. There are also 36 nos of fuel film cooling elements placed at the periphery of the injector face angled at 45°. Cold flow characteristics were evaluated for both oxidizer and fuel flow paths at the rated flow rates. Experiments were also conducted at different pressure drops to evaluate the coefficient of discharge for both oxidizer and fuel orifices. Impinging patterns of the oxidizer flow path was also visualized through photographic method.