Morphing nacelle inlet lip with pneumatic actuators and a flexible nano composite sandwich panel

Abstract

We present a hybrid pneumatic/flexible sandwich structure with thermoplastic (TP) nanocomposite skins to enable the morphing of a nacelle inlet lip. The design consists of pneumatic inflatables as actuators and a flexible sandwich panel that morphs under variable pressure combinations to adapt different flight conditions and save fuel. The sandwich panel forms the outer layer of the nacelle inlet lip. It is lightweight, compliant and impact resistant with no discontinuities, and consists of graphene-doped thermoplastic polyurethane (G/TPU) skins that are supported by an aluminium Flex-core honeycomb in the middle, with near zero in-plane Poisson's ratio behaviour. A test rig for a reduced-scale demonstrator was designed and built to test the prototype of morphing nacelle with custom-made pneumatic actuators. The output force and the deflections of the experimental demonstrator are verified with the internal pressures of the actuators varying from 0 to 0.41 MPa. The results show the feasibility and promise of the hybrid inflatable/nanocomposite sandwich panel for morphing nacelle airframes.

Review of variable leading-edge patents for aircraft wings and engine inlets and their relevance for variable pitot inlets in future supersonic transport

“…Due to their considerable potential benefits, variable inlets have been investigated in previous studies, compare Within the MorphElle project (morphing enabling technologies for propulsion system nacelles), different concepts for subsonic variable pitot inlets [3,[18][19][20] have been elaborated. In cooperation with the NASA, Kondor et al…”

Parametric Design Study on Aerodynamic Characteristics of Variable Pitot Inlets for Transonic and Supersonic Civil Aviation

“…Subsonic variable inlets that adjust the ideal inlet geometry for each flight condition have been investigated [2], [3] and [18], but did not yet find their way in service in commercial aviation. A potential reason is that the expectable limited aerodynamic benefit at subsonic conditions is eliminated or even negated by the additional weight and the higher complexity of the design.…”

“…Using variable pitot inlets, which provide the ideal geometry for different flight and operating conditions, instead of rigid inlets can decrease aerodynamic drag, allowing for increased efficiency and flight speed. Although research studies concerning subsonic circular variable inlets with adjustable lip and duct geometry have been carried out [2], [3], this technology has not yet made its way into service, as the aerodynamic benefit of subsonic variable inlets may not compensate for the increased complexity and weight.…”

A Variable Pitot-Inlet Concept for Supersonic Aviation

“…Furthermore, they can support the prevention of engine surge during operation at high angles of incidence or crosswind. Hence, variable inlets have been investigated in a number of subsonic studies (Ozdemir et al, 2015), (Kling et al, 2016), (Kondor et al, 2003). As subsonic variable inlets are currently not in use, potential reasons for this absence of application are that their limitations concerning complexity, reliability and costs outweigh their provided aerodynamic benefits.…”