Adaptive Control in an Axial Turbofan: Model-Free Implementation with Short Response Time

An adaptive control strategy is implemented in a single-input/single-output experiment to improve the aerodynamic performance of an axial turbofan. Pulsed blowing into the blade tip region is used to prevent flow separation. A slope-seeking control approach is shown to be able to extend the operating region of the engine without an explicit process model. By this, flow separation can be mitigated for smaller flow coefficients. The proposed closed-loop control strategy is capable of both driving the system back to stable operating conditions automatically and stabilizing operation in the presence of large-amplitude disturbances. Moreover, it is possible to accelerate the closed-loop control performance by one order of magnitude, compared with classical extremum-seeking control. By this, an extended Kalman filter is applied that enables a rapid determination of gradients of the corresponding characteristic diagram.