Integrated Aircraft Thermal Management & Power Generation: Reconfiguration of a Closed Loop Air Cycle System as a Brayton Cycle Gas Generator to Support Auxiliary Electric Power Generation

The optimal integration of vehicle subsystems is of critical importance in the design of future energy efficient fighter aircraft. The INVENT (INtegrated Vehicle ENergy Technology) program has been dedicated to this endeavor through modeling/simulation of thermal management, power generation & distribution, & actuation subsystems. Achieving dual cooling & power generation capability from a single subsystem would be consistent with current efforts in system integration optimization.

In this paper, we present a reconfiguration of an archetypal closed-loop air cycle system for a modern fighter as an open-loop gas generator cycle operating interchangeably between refrigeration and auxiliary power modes. A numerical model was developed within NPSS to assess maximum power extraction capabilities of a system originally designed for cooling purposes under different operating conditions. Presented results demonstrate variations in maximum power extraction, flow rates, and turbomachinery performance parameters over a range of flight altitudes and Mach numbers. Finally, the effect of variable area nozzle operation for the power turbine was explored at sea level static conditions and was found to improve system power extraction capability.

This document has been cleared for release under case number: 88ABW-2014-2722.