Exchange Rate Analysis for Ultra High Bypass Ratio Geared Turbofan Engines

Abstract

This paper investigates the impact of thermal management methods on the design point and synthesis exchange rates of an ultra-high bypass ratio geared turbofan engine. In a typical thermal management system, where heat is managed by means of heat exchangers that transfer engine waste heat into oil, air, or fuel. However, the utilization of air–oil and fuel–oil heat exchangers has an adverse impact on engine performance. This paper investigates the impact on and engine’s specific fuel consumption and summarizes it into common exchange rates for different thermal management configurations. The results show that any pressure loss in the bypass duct results in a severe specific fuel consumption penalty (an increase of 1% pressure loss in the bypass duct causes a 2% specific fuel consumption increase at cruise conditions). In addition, quite severe is the impact of extracting air from the gas path, particularly when the bleed location is in the bypass duct or the high-pressure compressor. It is also found that the utilization of a fuel–oil heat exchanger improves the specific fuel consumption at a higher rate than an air–oil heat exchanger. For the performance characteristics of the examined engine, the specific fuel consumption benefit with the former is 1.33%, while for the latter it is 0.38%.

Application of Probabilistic Set-Based Design Exploration on the Energy Management of a Hybrid-Electric Aircraft

“…Required fuel, instead, is calculated by estimating the fuel flow from table of gas turbine data with a radial-basis function interpolation and multiplying it by the step time. These data have been previously computed with the in-house gas turbine performance tool TURBOMATCH [73], with a span of all possible combinations of altitude, Mach and required shaft power from the selected mission. The step adopted for altitude, Mach number and power are 300 m, 0.1 and 100 kW, respectively.…”

Aircraft thermal management: Practices, technology, system architectures, future challenges, and opportunities

“…In another study using the UHBR GTF engine models [18], several parameters were investigated to determine how TMS solutions may affect the engine performance. In this study, it was shown that there is a strong linear relationship between bypass duct pressure losses and increases in SFC.…”

“…• The waste heat produced in UHBR GTFs is projected to be significant (up to 275 kW per engine for an Airbus A320-sized UHBR GTF aircraft [18]). This heat is not expelled along with the exhaust gases and require dedicated cooling.…”

“…For civil transport aircraft, the increase of electrically powered subsystems, the imminent implementation of ultra-high bypass geared turbofan engines, as well as the possible advent of electrified propulsion, are also expected to bring forth significant increases in on board waste heat loads [14]- [18]. As with military aircraft, this increase in heat loads also coincides with a growing use of composite materials for airframe structures and subsequent diminished heat sink capacity.…”