Fraunhofer Institute for Building Physics IBP
Fraunhofer Institute for Building Physics IBP

Clean Sky 2 – Environmentally Friendly Fire Protection System: tests and simulations on environmentally-friendly cargo fire extinguishing agents

Cargo area of aircraft demonstrator
© Fraunhofer IBP
Cargo area of the aircraft demonstrator in the Fraunhofer Flight Laboratory.
Local oxygen concentration
© Fraunhofer IBP
Simulation of the local oxygen concentration during an extinguishing process.

Extinguishing fires with a view to the environment 

Making flying more climate friendly by developing an environmentally-friendly fire protection system - that is the aim of our scientists in the Flight and Vehicle Climate Control working group. In the “Environmentally Friendly Fire Protection” project, the distribution of new, environmentally-friendly fire extinguishing agents for the cargo sector is being tested by way of experiments under various climatic boundary conditions. The scientists want to demonstrate that the desired concentration is reliably maintained throughout the cargo area during the entire flight until landing. To this end, the temperature of the cargo area and extinguishing agent, the way the cargo is loaded, and the extinguishing agent are varied.

Project goals

Alternative to the ozone-depleting gas halon

One goal of the project is to develop an environmentally-friendly fire protection system to replace ozone-depleting halon in the cargo hold of aircraft. With this in mind, the aircraft demonstrator in the low-pressure vessel of the Flight Test Facility (FTF) will be fitted with a halon-free fire extinguishing system. This allows the system to be assessed under realistic pressure conditions and changes. Climatic influences on the system, such as extreme cold or heat, are investigated.

In addition, a zonal simulation model based on the Indoor Environment Simulation Suite has been developed as a design tool to predict the local concentration of the extinguishing agent. The model enables fast transient simulations of the fire extinguishing system in operation. The zonal model can also be used to develop future fire-fighting systems based on models.

Current project status

The Environmentally Friendly Fire Protection project studied nitrogen-based extinguishing systems based not only on pressurized gas cylinders but also on a technology involving the production of inert gas by selective membranes. The latter is currently used as an inerting system for the fuel tank on board. A demonstrator for a 2-phase extinguishing agent was also integrated. The strengths and weaknesses of the systems were identified. It was verified that the systems do not lead to an unacceptable accumulation of the extinguishing agents in the passenger cabin. To verify the absence of leaks in the cargo area, the blower door method commonly used in buildings was adapted to detect leaks in the wall cladding.

Simulation models were generated for different cargo configurations and validated using the test data. Parameters such as room volume, quantity of extinguishing agent, loading state and temperature were varied.

You can find more detailed information on the project in the paper  “Validation of a Simulation Tool for an Environmentally Friendly Aircraft Cargo Fire Protection System".

Project partners

  • Airbus 
  • Safran