Dynamics of a High-Frequency Fuel Actuator and its Applications for Combustion Instability Control

The present paper performs complementary experimental and theoretical investigations of a pump-style, high-frequency, magnetostrictive fuel actuator, which achieves fuel modulations by periodically “pushing” fuel out of a piston-cylinder unit instead of by modulating the flow area. The low-order models are developed to identify relevant parameters and investigate their influences on fuel modulations. This fuel actuator is proprietary, its detailed internal structure and dimension are not available, so only qualitative comparisons between the model predictions and experiments are made. Experiments validate the trend of the model predictions. A system-identification-based LQG controller is designed to quickly suppress strong interferences of fuel modulations with the mean fuel flow rate. Improvements to the fuel setup have been made according to the model predictions, which have been experimentally shown to be beneficial to combustion instability control.