Fundamentals of Parallel Hybrid Turbofan Mission Analysis with Application to the Electrically Variable Engine

This paper describes a basic analysis for mission performance of parallel hybrid turbofan systems. A series of equations is derived to illustrate the concept of parallel hybrid performance showing that there is an optimum range for a given battery size that corresponds to the exact usage of the battery capacity stored on the aircraft. The fundamental concepts were then demonstrated on a more detailed problem using a performance model of the Electrically Variable Engine developed by Rolls-Royce on a high aspect ratio vehicle. Trends from this study again demonstrate the concepts derived in the preliminary theoretical analysis. Finally, a standard method for presenting hybrid data is proposed called the “money chart” which is a means for showing all of the required performance parameters of a parallel hybrid system to compute other metrics of interest as desired.