Next-generation aircraft: Design integration as a key enabler

While we often hear of technological advances being made in many areas of aerospace design, aircraft performance improvement will continue to remain focused on three key areas: economic efficiency, environmental impact, and improved passenger experience. While these factors have always been important considerations, recent trends in fuel price volatility, noise and emissions commitments, and fierce competition for passengers – particularly in emerging markets – have heightened the sense of urgency.

The European Clean Sky initiative and the NASA-led Environmentally Responsible Aviation (ERA) Program have been established to stimulate academic, industry, and government partnerships to accelerate the implementation of next-generation aircraft designs. Boeing, Airbus, Lockheed Martin, Northrop Grumman, and others continue to develop concepts.

The priority aircraft technology areas that will see the largest improvement will include the propulsion system and its integration within the airframe, aerodynamics, advanced materials, and electronic and aircraft systems.
 

Propulsion system and integration

Possibly the largest single impact on the efficiency and environmental footprint of the aircraft relies in the design of the propulsion system. Important areas for next-generation aircraft propulsion will include:

• More advanced materials that reduce weight while withstanding higher operating temperatures and pressures
• New configurations that free the engine from the under-wing constraint to enable much larger bypass and open rotor designs
• Alternative fuels, such as already demonstrated biofuels, and an increasing shift to a more electric aircraft
• Increasingly sophisticated engine management and control software and systems that will improve operational performance and optimize maintenance frequency and costs

Through these four areas, engineers will work to develop a new propulsion system that will meet regulatory standards. In turn, this will ensure greater cost efficiencies throughout the entire supply and operational chain.
 

Airframe and structural components

Composite materials have significantly improved the performance of the latest aircraft such as the Boeing 787 and Airbus A350, and next-generation aircraft will benefit even more.For example, composites that are infused with carbon nanotubes (CNTs) promise not only light weight and high strength, but also an ability to manipulate the electrical and thermal properties of the material. This opens up new vistas as systems that have traditionally been separate become an integral part of the aircraft, making the materials truly multifunctional.

Consider a layer of CNT-infused composite that can act as part of the wing structure and perform de-icing at the same time, eliminating the need for a metal-based heating system. Industry leaders are already talking about using aircraft structural materials as electrical networks for systems communication and structural health monitoring. Next-generation aircraft will leverage multifunctional materials extensively, and not only will the materials themselves change, but so will the way they are manufactured.

Today we are on the cusp of the additive manufacturing revolution. Airframe components of radically different shapes that have leveraged topology optimization and spatially dependent material properties during the design process will be an integral part of next-generation aircraft, providing a bio-inspired look and feel.
 

Aerodynamics

Even very small improvements in an aircraft’s aerodynamics can significantly improve its life cycle efficiency and operational cost performance. Many potential improvements have been known for some time and now that the commercial drivers are becoming sufficiently acute, next-generation aircraft will likely implement many of them, such as a more pervasive use of laminar flow technology, the introduction of active flow control devices, and a shift to blended-wing designs. With developments in advanced multifunctional materials, adaptive aerodynamic surfaces will be standard.
 

Electrification and safety systems

Electrical and hybrid power sources will be used extensively to deliver an enhanced passenger experience while reducing power demands from engine systems. This, coupled with the control systems and logic required to manage multifunctional materials, adaptive structures, and advanced engine performance, will mean that one of the biggest design challenges facing next-generation aircraft will be the certification of the millions of lines of safety-critical embedded software lines of code. As much as we look at the hardware within an aircraft, the software is becoming a vital part not to overlook.
 

The Internet of Things

The next generation of aircraft will not be alone. It will be a tightly integrated and a connected component to a much larger system, of which elements are already being put in place today. For example, engine telemetry helps optimize maintenance schedules and track the overall health of the aircraft. The Single European Sky (SESAR) and the U.S.-based NextGen initiatives promise to use satellite-based connectivity to improve flight operations to reduce fuel burn and environmental impact. However, this is just the tip of the iceberg.

Logistics for goods and passengers for whom the aircraft journey is only one stage will become much more integrated and optimized. As the aircraft system communicates with the rest of the transportation chain in real-time, it can make adjustments as needed. Advanced materials throughout the aircraft will be their own sensors – automatically detecting damage, performing self-healing, and scheduling maintenance.
 

Design integration

The compelling factors driving the development of next-generation aircraft promise to create a platform that merges known but yet-to-be-used technology with rapidly emerging capabilities. Whether this is a new propulsion system and airframe aerodynamics integration, multi-functional composites materials, adaptive structures, new manufacturing processes, higher dependence on safety-critical embedded software and controls, or integrating the aircraft into a completely connected system, the common thread is a critical dependence on a tighter design discipline integration than ever before.

Multi-disciplinary design and optimization is not new, but is unlikely to meet the needs of next-generation aircraft in its current form due to requirements for a truly robust design evaluation of these tightly integrated technologies very early in the conceptual design stages. The digital design backbone to support the required level of multi-disciplinary design optimization at all stages of the process, including virtual hardware, is being investigated in multiple research projects around the world.

No matter what form next-generation aircraft will take and how all the technologies will be integrated to create a better consumer experience, one thing is for certain – the aircraft will demand a suitably next-generation digital design process that is yet to be fully realized.

ANSYS Inc.
www.ansys.com

About the author: Robert Harwood is the director of aerospace and defense industry at ANSYS, an engineering simulation software company based in Canonsburg, Pennsylvania. Harwood obtained his engineering Ph.D. in 1998 from the University of Sheffield, one of the top five engineering schools in the U.K. During and since that time Harwood has focused on the industrial use of physics-based simulation in a broad range of sectors including environmental engineering, healthcare, chemical process, energy, aerospace and defense. Harwood has been with ANSYS for 12 years and has focused on the aerospace and defense sector since 2006. He can be reached at 724.746.3304.