Laboratory Scale Survey of Pentad Injector Stability Characteristics

• Published in: Journal of propulsion and power 2008-05, Vol.24 (3), p.534-540
• Main Authors: Cavitt, Ryan C, Frederick, Robert A, Bazarov, Vladimir G
• Format: Article
• Language: English
• ISSN: 0748-4658; 1533-3876
• DOI: 10.2514/1.32618

This work provides an assessment of an experimental method for characterizing combustion stability of liquid rocket injectors. The research has shown that the single-element laboratory scale methodology is capable of creating high-frequency combustion instability with gaseous methane and oxygen. Modified pentad impinging jet injectors were selected for the stability survey. The maximum peak-to-peak dynamic pressure recorded in the chamber was 27% of the mean chamber pressure. Other factors indicating instability include injector manifold pressure pulsations as well as twofold chamber temperature increases from steady operation. The testing evidenced that the flame structure varies with the onset of unstable combustion as well as mode transition. Moreover, a bifurcation process was seen as the dominant frequency shifted. The results also showed that there were significant differences in stability characteristics which were a function of fuel impingement angle. Correlation with chamber natural frequency predictions suggest that the injectors excited the first radial mode and the first radial, second tangential combined mode. [PUBLISHER ABSTRACT]