Rate-based model predictive control of turbofan engine clearance

Original publisher: Cleveland, Ohio : National Aeronautics and Space Administration, Glenn Research Center, [2006] OCLC Number: (OCoLC)687734760 Subject: Airplanes -- Turbofan engines. Excerpt: ... Takeoff Thrust reversal Aircraft stall pwr ) 1 0.7 0.9 max 0.8 0.6 N2 to 0.6 0.5 0.85 ( normalized X 0.4 0.4 0.3 0.2 0.8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 0 0 ( in ) input-0.005-0.005-0.005-0.01 load-0.01-0.01 flight-0.015-0.015-0.015-0.02 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 1 1 0.8 ( normalized ) 0.8 0.6 0.6 0.5 0.4 UACT 0.4 0.2 0.2 0 0 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8-4-3-4 x 10 x 10 x 10 ( in ) 10 1 5 constraint ointinactive constraint setpactive 5 0 0 CLR 0-1-5-CLR-5-2-10 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 time ( sec ) time ( sec ) time ( sec ) Figure 9. R-LPV responses for fast thermal actuator. p was increased to 50 samples power-increase event. To extend the anticipation capability, the prediction horizon and control horizon to 5 samples. From the figure, the MPC response to a thrust reversal transient produces the m most benefit over an unconstrained controller, eliminating the 2-mil excursion below the constraint. It is encouraging that enforcement of the clearance constraint is a result of very smooth actuator command signals rather than abrupt or highly oscillatory control actions. Although unconstrained responses in the remaining two events have milder constraint violations, it is important to note that the constrained controller satisfies the blade rub objective in both cases. One may interpret these results from a systems point-of-view. If the clearance setpoint using this LQG-like controller must be 2 mils greater than the MPC setpoint to accommodate the possibility of the worst-case event, then this would detract from exploiting the benefits of a tip clearance control system. Based upon 5 past studies, the penalty on efficiency would be 0.2 % and the penalty on EGT overshoot would be 2ºC. Figure 10 shows the response with a thermal actuator with, a rate 60 % slower ...