Engineering topics
Journell, Christopher L.
Publications and source records attributed to Journell, Christopher L..
Operability of a Natural Gas–Air Rotating Detonation Engine
A combustor was developed to operate with natural gas and air as the primary propellants at elevated chamber pressures and air preheat temperatures representative of land-based power generation gas turbine engines. Detonation dynamics were studied to characterize the operability of rotating detonation-based pressure gain combustion systems for this application. Measurements of chamber wave dynamics were performed using high-frequency pressure transducers and high-speed imaging of broadband combustion chemiluminescence. The rotating detonation engine was tested with two injector configurations across a broad range of mass flux (200–500 kg/m 2 /s), equivalence ratio (0.85–1.2), and oxygen mass fraction (23.2–35%) conditions to determine the effect of operating parameters on the propagation of detonation waves in the combustor. Wave propagation speeds of up to 70% of the mixture Chapman–Jouguet detonation velocity and chamber pressure fluctuations greater than 4 times the mean chamber pressure were observed. Supplementing the air with additional oxygen, varying the equivalence ratio, and enriching the fuel with hydrogen revealed that combustor operability is sensitive to the chemical kinetics of the propellant mixture. Comparing the operational trends of the two injector configurations suggests that one design mixes the incoming propellants more effectively. Although most test conditions exhibited counter-rotating detonation waves within the chamber, the injector design with superior mixing characteristics was able to support single-wave propagation.
Parametric Survey of a Natural Gas-Air Rotating Detonation Engine at Elevated Pressure
Detonation dynamics in a rotating detonation engine were studied to characterize the operability and performance of rotating detonation based pressure gain combustion systems at application-relevant conditions. The combustor was developed to operate with natural gas and air as the primary propellants at elevated chamber pressures and high air pre-heat temperatures representative of land based power generation systems. Measurements of chamber wave dynamics were performed using high-frequency pressure transducers and high speed imaging of broadband combustion luminescence. The rotating detonation engine was tested across a broad range of flow conditions to determine how operating parameters affect the propagation of detonation waves in the combustor. Enriching the air with additional oxygen was shown to broaden the range of conditions that allowed detonation fronts to stably propagate within the chamber, though all tested conditions exhibited counter-rotating waves. This range was shifted to lower oxygen content by increasing the oxidizer preheat temperature, which suggests a dependence on the chemical kinetics of the reactant mixture. Some conditions exhibited modulations in pressure fluctuation amplitude and frequency measured by chamber pressure probes. Analysis of high speed images identified the source of the modulation as the intersection point of the counter-propagating detonation waves rotating to align with different pressure measurement ports throughout the test duration.