Identifying optimal fan compressor pressure ratios for the mixed-stream turbofan engine

This paper describes a heuristic approach for determining the optimal fan c ompressor pressure ratio for a fixed set of mixed-stream turbofan engine pa rameters. During the aircraft design process, it is important to select an engine design that minimizes fuel consumption while producing the thrust re quired by the various aircraft mission Eight conditions. Although the most fuel-efficient values of such parameters as bypass ratio and high-pressure compressor (core) pressure ratio depend on the integrated effects of the va rious flight altitudes, Mach numbers, and thrusts required throughout the m ission, it is possible to heuristically locate the most efficient fan compr essor pressure ratio to complement other engine parameters independent of t he mission, At this optimal value, thrust specific fuel consumption is appr oximately minimized and specific thrust is approximately maximized at all f light conditions. Exploiting the observed engine performance characteristic s, optimal fan compressor pressure ratios were successfully located for a w ide range of bypass ratios and core compressor pressure ratios across a var iety of on- and off design flight conditions.