Evaluation of ultra-high bypass ratio engines for an over-wing aircraft configuration

Abstract

Today, main hub airports are already at their capacity limit and hence, smaller airports have become more interesting for providing point-to-point connections. Unfortunately, the use of regional airports induces an increased environmental footprint for the population living around it. In an attempt to solve the related problems, the research project Coordinated Research Centre 880 aims to examine the fundamentals of a single-aisle aircraft with active high-lift configuration powered by two geared ultra-high bypass turbofan engines mounted over the wing. Low direct operating costs, noise shielding due to the over-wing configuration, and short runway lengths are the main advantages. Highlighting the performance, economical and noise benefits of a geared ultra-high bypass engine is the key aim of this paper. This assessment includes a correspondingly adjusted aircraft. Open literature values are applied to design the two investigated bypass ratios; a reference engine with a bypass ratio of 5 and 17 respectively. This study shows that a careful selection of engine mass flow, turbine entry temperature and overall pressure ratio determines the desirable bypass ratio. The aircraft direct operating costs drop by 5.7% when comparing the designed conventional with a future ultra-high bypass ratio engine. Furthermore, the sound at source for a selected mission and operating condition can be reduced by 7 dB. A variable bypass nozzle area for the ultra-high bypass ratio engine is analysed in terms of performance and operability. An increase of safety margin is shown for the turbofan engine with a variable bypass nozzle. It is concluded that this unconventional aircraft configuration with ultra-high bypass ratio engines mounted over the wing has the potential to relieve main hub airports and reduce the environmental impact.

Multi-Fidelity Design Optimization of a Long-Range Blended Wing Body Aircraft with New Airframe Technologies

“…It has to be noted that, for the initial design of SE²A-LR, hybrid laminar flow control (80% of the blended wing area is laminarised), boundary layer ingestion (5% improvement in propulsive efficiency due to boundary layer ingestion), advanced structure design with composite materials (20% structure weight reduction as compared to baseline), as well as active load alleviation technologies (load factor is reduced to 1.5 g) were included [2]. Table 2 gives a summary of the new airframe technologies applied to the reference long-range aircraft SE²A-LR [10,12,22,23]. It has to be noted that, for the initial design of SE 2 A-LR, hybrid laminar flow control (80% of the blended wing area is laminarised), boundary layer ingestion (5% improvement in propulsive efficiency due to boundary layer ingestion), advanced structure design with composite materials (20% structure weight reduction as compared to baseline), as well as active load alleviation technologies (load factor is reduced to 1.5 g) were included [2].…”

“…It has to be noted that, for the initial design of SE 2 A-LR, hybrid laminar flow control (80% of the blended wing area is laminarised), boundary layer ingestion (5% improvement in propulsive efficiency due to boundary layer ingestion), advanced structure design with composite materials (20% structure weight reduction as compared to baseline), as well as active load alleviation technologies (load factor is reduced to 1.5 g) were included [2]. Table 2 gives a summary of the new airframe technologies applied to the reference long-range aircraft SE 2 A-LR [10,12,22,23]. Lateral-Directional stability and control are carried by two winglets that feature rudders.…”

“…Extensive information about the current state of the BLI modeling, analysis, and its benefits from the aircraft design standpoint are provided in [17][18][19][20][21]. In addition to BLI, ultra-high bypass ratio turbofan engines that further improve fuel consumption [22] are assumed in this project. 4.…”

Aerodynamic and Aeroelastic Effects of Design-Based Geometry Variations on a Low-Pressure Compressor

“…As the fan configuration was solely used to generate the specific inflow for the LPC parameter studies, the fan will not further be investigated in this paper. Detailed information can be found in the work of Giesecke et al [34] as well as Eggers and Friedrichs [4].…”

10 years of joint research at DLR and TU Braunschweig toward low-noise aircraft design-what did we achieve?

“…It included additional updates and upgrades to the process toward its current status with the focus on noise immission in early 2018, see Refs. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]…”