Multi-Disciplinary Survey of Engine Parameters and its Impact on Performance and Energy Maneuverability

Abstract

An Energy Maneuverability (E-M) point-performance approach is used to study the effects of changing engine parameters upon a baseline airframe. This work considers, as independent variables, the effects of overall engine scale factor (sea level static thrust), power extraction, bleed air extraction, bypass ratio, turbine inlet temperature, fan pressure ratio, and overall pressure ratio against a reference aerodynamic database. This design study integrates propulsion analyses developed using NASA's NPSS propulsion modelling language. The E-M "skymap" grids demonstrate relations between the independent variables and their resulting impact on overall aircraft performance across the flight envelope. The results show the negative impact of bleed air extraction and shaft power extraction and the positive effect of high bypass ratio engines on cruise performance and sustained turning fuel burn but the negative effects on the maximum thrust of the engine. Overall the methods and data capture the relationships between several engine designs and the resulting impact on aircraft performance using a grid contour display. Nomenclature AR= wing aspect ratio BPR = engine bypass ratio C D = dimensionless drag coefficient C L = dimensionless lift coefficient FPR = engine fan pressure ratio L/D = aerodynamic efficiency M = Mach number M(L/D) = aerodynamic performance efficiency OPR = overall pressure ratio PLA = power lever angle Ps = specific excess power ROC = rate-of-climb (ft/min) S ref = reference planform area of a wing surface (ft 2 ) SE = specific endurance (hr/lbm) SR = specific range (nM/lbm) T = thrust (lbf) TIT = turbine inlet temperature ( º R) TSFC = thrust specific fuel consumption (lbm/lbf-hr) T/W = thrust loading (thrust-to-weight ratio) W = aircraft flight weight (lbm)