This SAE Aerospace Information Report (AIR) provides a review of real-time modeling methodologies for gas turbine engine performance. The application of real-time models and modeling methodologies are discussed. The modeling methodologies addressed in this AIR concentrate on the aerothermal portion of the gas turbine propulsion system. Characteristics of the models, the various algorithms used in them, and system integration issues are also reviewed. In addition, example cases of digital models in source code are provided for several methodologies.

Purpose:

The purpose of this document is to provide a source of information on current practices and procedures for developing real-time turbine engine models, not models of controls or other installation subsystems. This document is intended to be a basis for communication between supplier and customer.

Overview:

Current applications of real-time engine models include development and testing of control systems, embedded software for control systems, flight simulators, and engine/airframe integration. The implementation of these models must balance the constraints of cost, execution time, consistency with the system being modeled and the capability to be scaled to match new information. Common engine model types are: aerothermodynamic (aerothermo), piece-wise linear, and transfer function. The real-time models require supporting mathematical utilities such as integrators, optimizers, transfer function algorithms, and data handlers. A real-time model of a turbine engine powerplant often requires models of the control system, lubrication system, engine starting system, ignition system, and others.