2008

Simulating Operation of a Large Turbofan Engine

The Commercial Modular Aero- Propulsion System Simulation (CMAPSS) is a computer program for simulating transient operation of a commercial turbofan engine that can generate as much as 90,000 lb (≈0.4 MN) of thrust. It includes a power-management system that enables simulation of openor closed-loop engine operation over a wide range of thrust levels throughout the full range of flight conditions.

C-MAPSS runs in the Simulink (The Mathworks, Inc.) block-diagram language, providing a graphical simulation environment in which advanced control and diagnostics algorithms can be implemented and tested. The software has a graphical user interface (GUI) that makes engine “health” data and control and engine parameters easily accessible. It can run user-specified transient simulations and generate state-space linear models of a nonlinear engine model at an operating point.

C-MAPSS produces GUI screens that enable point-and-click operation and include editable fields for user-specified input. The software includes an atmospheric model for simulating operation at altitudes from sea level to 40,000 ft (≈12 km), Mach numbers from 0 to 0.90, and sea-level ambient temperatures from –60 to +103 °F (≈–51 to +39 °C). CMAPSS has a comprehensive control system consisting of a gain-scheduled fan-speed controller and several limit regulators, integrated in a manner similar to that used in real engine controllers to avoid integrator windup. The simulation code itself operates several times faster than real time, giving it the potential to be deployed (all or in part) as machine code for hardware-in-the-loop applications such as flight simulators and realtime controller/diagnostic system validation.

Overall, C-MAPSS provides the user with a set of tools for performing openand closed-loop transient simulations and comparison of linear and non-linear models throughout its operating envelope, in an easy-to-use graphical environment.

This program was written by Jonathan S. Litt of Glenn Research Center; Dean K. Frederick of Saratoga Control Systems, Inc.; and Jonathan A. DeCastro of ASRC Aerospace Corp.

Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steve Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW- 18315-1.

This Brief includes a Technical Support Package (TSP).

Simulating Operation of a Large Turbofan Engine (reference LEW-18315-1) is currently available for download from the TSP library.

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