Project Description

The general frame

The “System for Green Operations” (SGO) is one of the six Integrated Technology Demonstrators of the CleanSky program. The main driver of SGO is represented by an eco-compatible design, aiming at reducing CO2 production and at optimizing aircraft energy management.

Work package 2.3.3 “Optimized Electrical Wiring Interconnection System for More Electric Aircraft & More Composite Aircraft”, led by Labinal will address very ambitious challenges for Electrical Wiring Interconnection System (EWIS) for future Aircraft.

The main objectives of this WP will be:

  • To develop tools and methodologies to optimize wiring, taking into account the new constraints related to a More Electrical Aircraft & More Composite Aircraft and new regulation requirements (subpart H from CS25) covering
    • Requirements
    • Route minimization including new  ±270 High Voltage DC routes
    • Current return network
    • Lightning
    • Electromagnetic Compatibility
    • Gauge and noise optimization
  • To develop HV and EMC optimized prototype cables for MEA and MCA consistent with new regulations and to apply WP 2.3.3 results.

In order to develop a global EWIS tool, to optimize EWIS voltage drop and current return network design, LABINAL needs to develop and validate a numerical methodology and a software to model the current return networks (ALEEN, ALmost Equipotential Electrical Network) installed aboard composite aircrafts.

The GENIAL project responds to this need by developing such a numerical methodology and software.

What is the problem GENIAL aims to resolve

The metallic bodies of “standard” aircrafts are commonly used as conductive electrical pathways for the return of direct and alternating currents, fault currents, lightning currents and also have other functions related to voltage differentials, electrostatic charge draining, electromagnetic shielding etc.

This is no longer applicable on aircrafts made of composite materials because of the low conductivity that characterize these materials. A dedicated conductive electrical pathway, usually called “current return network” (which is referred as ALEEN, ALmost Equipotential Electrical Network in the frame of this project) therefore has to be integrated into the aircraft body.

Such networks can be practically realized in several different ways, mainly exploiting both structural metallic parts of the aircraft (beams, seat rails, etc.) and also dedicated paths, but in any case they can never be an ideal ground, and poorer performance than that currently obtained on metal aircraft may be expected.

Aeronautical manufacturers and providers of cable-harness and equipment are interested in having an accurate electrical/electromagnetic characterization of a given ALEEN configuration, in order to be able to correctly design the connected/co-located electrical systems such as EWIS, reducing risks and saving mass.

Further, these main actors and together with certification authorities could be interested in estimating how the selected ALEEN configuration would work with respect to other required functions (e.g. fault currents, lightning currents, electromagnetic shielding,…), optimizing it if needed without requiring expensive (and sometime almost unfeasible) repeated breadbording.

The main concepts of GENIAL

The GENIAL project aims to develop a numerical methodology and a CAE (Computer Aided Engineering) tool to model the current return networks installed aboard aircrafts that include parts made from composite materials. The tool is able to:

  • input aircraft and ALEEN geometries and material properties from CAD;
  • evaluate the equivalent impedance matrix of ALEEN in the DC-MHz frequency range, while also considering the EWIS and the electromagnetic interaction with aircraft body;
  • interface the above mentioned impedance matrix with an electrical database of EWIS to allow correct evaluation of the impedance between any two EWIS interconnection points;
  • visualize induced current and voltage distribution on the aircraft/ALEEN.

Full-wave 3D modeling based on the PEEC (Partial Element Equivalent Circuit) method is applied, in which all the electromagnetic interactions are considered (capacitive and inductive mutual coupling, skin and proximity effects…). This type of method has been selected for its effectiveness in the low frequency region (where the well-known “low-frequency break-down effect” makes the problem ill-conditioned). Due to the tight requirements in terms of accuracy (mΩ range), particular effort has been devoted to pursuing the concept of “high-fidelity modeling”, which doesn’t require the user to simplify the numerical model with respect to the CAD model.

Acceleration methods are coupled to PEEC to allow effective modelling of large structures in a limited amount of time with currently available HW resources (i.e. no expensive HPC resources required).

The procedure will be validated against experimental data measured on a mock-up realized by the SGO WP leader Labinal.