Analysis of Internal Hydrodynamic Behavior of Pressure Swirl Atomizer for Liquid Rocket Engines

Abstract

AbstractThe combustion performance and instability behavior of liquid rocket engines are inaudibly related to the effective performance of an injector, thus understanding its internal and external flow characteristics are decisive to enhance its efficiency. The single element pressure swirl injector model is fabricated through a transparent acrylic for enhanced visualization in the internal segment of an injector. The cold flow method is performed for a fixed duration of sixteen seconds to reveal the nature of the formation of an air-core and spray during a transient as well as steady-state operation of an injector. The injector performance parameters like discharge coefficient, injection velocity, volume flow rate, and differential pressures are observed and tabulated for the fluid injection pressure range of 0.5 to 3 bar. In the same manner, air-core and spray formations are also recorded for the entire test duration. Results of image processing show that the complete formation of air-core possesses three phases of transformation. In the first phase, the tornado-like structure is formed, in the second phase it transformed into a twisted water sheet-like shape, and finally in the third phase air-core settles down with the nearly constant cylindrical shape of minimal disturbances around its perimeter. Once the air-core reaches the end of the third stage, spray formation also reaches its nearly steady-state cone angle.KeywordsPressure swirl injectorUnsteady stateCold flowAir-coreSpray pattern