Fire Suppressant Transport Modeling

ABSTRACT: Fires initiating in engine nacelles and dry bays are the most common causes of loss of aircraft. However, since the Montreal Protocol restricting the production of Halons, a replacement has not yet been accepted by the aircraft survivability community despite numerous testing programs. The costs and limitations of designing new systems based primarily on live testing can be mitigated by modeling. ADA Technologies is partnering with ARA to propose the development and preliminary validation of a fast-running, physics-based, computational fluid dynamics (CFD) code for mapping the concentration of clean agent fire suppressants in obstructed environments such as dry bays. At the core of the simplified approach is the focus on the low-Mach number equations, describing phenomenon happening in the subsonic regime. This is appropriate for dispersion of fire suppressant exiting nozzles at velocities smaller than Mach 0.2. Our approach contains three steps: acquisition of relevant experimental data in our lab, modeling of the experiment with a fast code on a PC, and comparison of the results with the output from a comprehensive CFD code running on a computer cluster. As a result, the product of this project will be an experimentally validated code. BENEFIT: A fast-running CFD code modeling the dispersion of Halon replacements, also known as clean agents, would allow optimization of new fire suppression designs by minimizing the amount of suppressant to be carried on-board an aircraft while ensuring satisfactory extinguishment performance. Limiting weight is always a primary concern in aircraft applications. Finding an effective and environmentally friendly replacement for Halon 1301 in dry bay systems would be greatly aided by such a validated CFD code. This code would be applicable to a variety of fire suppression applications looking for optimized Halon replacement systems. Beyond military aircraft, commercial aircraft is a natural fit for the code, as the FAA is struggling with the same issue. Outside aerospace markets, weight and cost optimization of the protection of other obstructed volumes is another commercialization opportunity. For examples, light armored vehicles in the DOD market and server rooms in the commercial sector represent promising business prospects for the future code.