Experimental methodology for measuring combustion and injector coupled responses

The objective of this research was to design, build and test a laboratory scale liquid propellant rocket injector stability characterization test facility. The design of the experiment is based on a Russian scaling methodology that employs gaseous propellants to simulate supercritical full scale propellants at atmospheric pressures. The preliminary objective of the experimentation was to determine if the methodology was capable of creating high frequency combustion instability. The maximum fundamental mode pressure fluctuations were 17% peak to peak of the mean chamber pressure. Russian pentad impinging jet injectors with impingement angles of thirty, forty-five, or sixty degree showed significantly different combustion stability characteristics using this methodology. The studies were run with gaseous methane and gaseous oxygen as the propellants. The excited modes of instability were the first radial mode and a combined mode of the first radial and second tangential modes.