Variable Cycle Engine Control System Definition Study. Turbine Engine Technology Demonstrator Component Development Program, Project 668A. Controls Development Program
Final technical rept. Jul 1973-Mar 1976
GENERAL MOTORS CORP INDIANAPOLIS IN ALLISON GAS TURBINE DIV
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The primary objective of this Air Force funded program was the development of a control mode for a Joint Technology Demonstrator JTD engine that achieves optimal steady state performance minimum sfc and maximum thrust with rapid transient performance over the entire flight envelope of a hypothetical transonicsupersonic aircraft. A flexible digital computer simulation of the JTD turbofan engine with a control system was developed along with computerized optimization and constraint procedures to establish optimal engine operating conditions and variable geometry positions to achieve minimum sfc and maximum thrust. Speed and turbine temperature fuel governors along with a compressor Mach Number delta PP surge control loop in the fuel control were evaluated. A control mode that positioned the geometry to scheduled optimal geometry settings was unable to achieve steady state maximum thrust over the entire flight envelope. However, a control mode developed to force engine parameters to scheduled optimal parametric relationships successfully attained minimum sfc and maximum thrust at all the selected test points in the flight envelope. Since certain parametric relationships are true for minimum sfc i.e., maximum airflow and minimum temperature for a given thrust and maximum thrust i.e., maximum speed, temperature, and pressure within engine limits, the control based upon parametric relationships will yield maximum thrust and near minimum sfc for a resonable range of engine variation. Therefore, it is not necessary to tune each new engine for maximum thrust or adjust the control for engine aging.
- Jet and Gas Turbine Engines