Advanced Open Rotor Performance Modelling for Multidisciplinary Optimization Assessments

Abstract

As a consequence of increased stringent engine emission regulations, in a highly competitive market, it has become necessary to explore innovative, economic and environmentally friendly cycles to sustain competitive advantages. Among these innovative cycles, both the geared and the direct drive counter-rotating open rotors, due to their relatively higher propulsive efficiency, have the potential to significantly reduce fuel consumption and emissions relative to conventional high bypass ratio turbofans. A detailed TERA (Technoeconomic Environmental Risk Analysis), multidisciplinary optimisation framework, can be used to optimise both engines and thereby assess their potential as well as quantify their risks on a formal and consistent basis. This technique is based on detailed and rigorous engine performance, aircraft performance, engine geometry, engine weight, noise, gaseous emissions and environmental impact simulation models. No specific performance simulation methodology for counter rotating open rotors is available in the public domain. An innovative technique is introduced, comprising novel models of: • Counter-rotating propellers (including their interaction); • Counter-rotating turbines; • Planetary differential gearboxes. A thorough description of the modelling methodology (with a justification of the main assumptions) of each of these three components is presented and an indication of work in progress is provided. These components are then used to develop direct drive and geared open rotor performance models. The results of steady state design point and off design performance simulations of these two engine models are subsequently presented via two case studies. Some of the differences in the performance of the low pressure system of geared and direct drive open rotors are highlighted. It was observed that the impact of the key OR performance DP parameters is different for the two engines. Consequently the optimal design and control strategies of theses two configurations will differ. The flexibility of the new simulation technique makes it a suitable candidate to perform multi-disciplinary TERA design space exploration and optimisation studies assess and optimise open rotor designs and control strategies in a multidisciplinary framework.

Development of an Open Rotor Propulsion System Model and Power Management Strategy

“…Station B030 also supplies any required customer bleed air (i.e., for other aircraft subsystems). Note that this configuration is different from prior open rotor models that were modeled after the GE36, which had pusher-type rotors connected to a counter-rotating FPT on a separate shaft [30,31].…”

Modeling Contra-Rotating Turbomachinery Components for Engine Performance Simulations: The Geared Turbofan With Contra-Rotating Core Case

“…Since these early attempts, the technological improvements achieved with respect to design and hardware implementation have resulted in a revival of the contra-rotating propeller concept (see, e.g., Refs. [3,4,[9][10][11][12]). …”

“…Regarding performance modeling of engine eonfigtirations containing contra-rotating turbomachinery components, there are only a few studies available in the public domain for contra-rotating open rotors and ducted contra-rotating fans for high bypass turbofan engines [10][11][12][29][30][31]. In these studies, though, either:…”

Robust Gas Turbine and Airframe System Design in Light of Uncertain Fuel and CO2 Prices

“…The two propeller rows can either be installed at the front or the rear of the engine, respectively known as the tractor and the pusher conguration [31]. A further option is whether the propellers are driven directly by a counter-rotating turbine or through a reduction gearbox which requires cooling and increases mechanical complexity [47].…”

“…Of the ve system options, the open rotor presents the most technological and operational chal-lenges, however, including open rotor blade integration, control and reliability, engine installation and noise [32,46,47]. The two propeller rows can either be installed at the front or the rear of the engine, respectively known as the tractor and the pusher conguration [31].…”