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DANIELA
Demonstration of ANemometry InstrumEnt based on Laser

Tags: Air

State of the Art - Background

The aim of the DANIELA project is to prepare the operational use of a flush-mounted air data system (ADS) built around a three-axis Doppler LiDAR function as a primary air data channel on civil aircraft.

A typical air data system is composed of probes and pressure sensors and delivers parameters during flight such as air speed, angle of attack and altitude.

Such systems need de-icing, leading to high power consumption (typically 4kW for the three channels) and require maintenance as the externally mounted probes are exposed to corrosion. A laser-based anemometry instrument will avoid these drawbacks and feature enhanced reliability and an extended lifetime.

Air data parameters are inputs for the flight systems. Therefore the main issue to address before implementing a change of sensor technology in future airliner programmes is to make sure that the new system will perform as expected in all flight phases.

Objectives

The use of LiDAR, for one of the three channels, is seen as an appropriate solution to improve performance. An implementation using a three-axis velocity is envisioned in the next airliner programmes, enabling the removal of the most exposed external probes: Pitot and AOA/SSA. Furthermore, the introduction of a new measurement principle allows for a dissymmetric system, resulting in an improved configuration.

Based on the NESLIE results, DANIELA aims to provide a further step via two parallel objectives:

- To demonstrate data availability in adverse conditions;

- To explore the promising technologies leading to a full Optical Air Data System.

The main expected result is to improve the laser-based anemometer developed in the frame of NESLIE in order to make it affordable and to verify that the system will be available over the full flight envelope, particularly in areas where particles are supposed to be rare. This second objective is very important for the certification aspects of the LiDAR.

This system, as a replacement for conventional air data probes, will increase system availability and robustness (dissymmetric technologies, improved maintenance).

Description of Work

The project has been organised into four work packages which will run in parallel:

- The development of Infrared Doppler LiDAR technology, focused on a smart heterodyne detector and glass-integrated optical components;

- The development of a LiDAR mock-up suitable for ground and flight-test performance assessment;

- The validation of optical temperature measurement concepts;

- The consortium management.

The consortium is made up of skilled partners, and benefits from the results of the NESLIE project. The main tasks are:

- Integration of the passive and active optical functions through monolithic and hybrid technologies in order to reduce the weight, size and cost;

- Development of a self-sufficient balanced heterodyne photo-detector device;

- Studying the occurrence and microphysical properties of aerosol;

- Optimising signal processing specification and implementation;

- R&D on optical window and related aircraft-installation issues;

- LiDAR mock-up realisation, flight-testing and records analysis;

- Assessing UV and IR temperature-measurement concept;

- Management of the consortium.

Expected Results

The main expected result is the demonstration of accuracy and availability of a laser-based anemometry system. Based on further enhancement applied to the NESLIE mock-up demonstrator, it will be assessed by ground and flight tests, in worst-case scenarios.

The developed technologies will then pave the way for LiDAR anemometry full-scale development for next-generation transport aircraft.

The second result is the availability of optical temperature-measurement concept, enabling the development of a fully optical air data system.

Other expected results are:

- Integrated passive and active optical components;

- Self-sufficient balanced heterodyne photo-detector device;

- LiDAR window installations and coatings;

- Enhanced signal processing;

- Recording flight-test results;

- LiDAR sufficiently ready to start early-stage certification process;

- Technologies enabling a dissymmetrical air data system.

DANIELA

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