Using Burner Exit Temperature in the Control of a Geared Turbofan Engine with NPSS

1. David Shore Using Burner Exit Temperature in the Control of a Geared Turbofan Engine with NPSS

2. Project Summary and Background • Internal Pratt & Whitney engine simulations use the Numerical Propulsion System Simulation (NPSS) for modeling engine performance. • All models supplied to the customer for engine performance modeling use NPSS as well. • Previous customer model was developed for thrust levels of 23k and 21k lbs of thrust, for max takeoff (MTO), max continuous (MCT), and max climb (MCL) power settings. • Customer model target thrusts for a number of flight regimes in the flight envelope were either missing updated targets, or not meeting new requirements. • New simulation needed to be developed using combustor exit temperature (CET or T4) as the rating target.

3. New Customer Requirements • Additional to the 23k base thrust level and the 21k derate, an 18.9k derate was also requested. • New requirements for MTO, MCT, and MCL across all derates was required. Examples follow: • 21k MCT = 0.94 * 23k MCT within the takeoff envelope. Outside the takeoff envelope, 21k MCT = 23k MCT • 18.9k derate = 0.90 * 21k at all flight regimes and bleed configurations • MTO ≥ MCT ≥ MCL • These examples above are additional requirements to the agreed upon thrust targets outlined in the technical requirements document (TRD) agreed upon between the customer and P&W.

4. T4 Ratings Table • Thrust targets were hit by creating a new T4 ratings table. By running the baseline customer simulation, saving the thrust and T4 output, and modifying the T4 values, I created a new T4 table that hits the new thrust targets. • These requirements had to be met for the following conditions: • 23k MTO, MCT, MCL • 21k MTO, MCT, MCL • 18.9k MTO, MCT, MCL • Additional to the thrust levels above, new schedules need to be developed for a number of different bleed configurations. Different schedules were created using the different combinations of ECS, CAI, and WAI bleed off-take.

5. T4 Schedules

6. Modified A/C Flight Envelope • Schedules needed to be defined throughout the entire flight envelope and takeoff envelope of the aircraft. Typically, a “node” was placed at every 2000 feet and 0.05 MN. Ratings file nearly doubled in size (~10k lines of code)‏

7. Contour Plots and Behavior Checks • Ratings design using T4 results in a typical behavior – final ratings file exhibited normal behavior + =

8. Contour Plots and Behavior Checks • Hundreds of contour plots were created to ensure model was correctly targeting T4, and resulting in the required thrust levels. 21k to 18.9k Derate Contour Plot 23k to 21k MCT Bleeds OFF Contour Plot