Aircraft fire suppression system design is multidisciplinary in many areas (e.g., fluid dynamics, heat transfer, combustion, chemistry, and materials). Of particular interest to the Test and Evaluation community is aircraft engine nacelles which contain a large number of obstructions within a confined space. Due to the high cost of producing aircraft engines much of the fire suppression systems on aircraft engine nacelles has been performed using ground-based simulators that are geometric approximations to the actual components but fabricated for fire testing and their cost can be directly related to the size and material of the test article, with the level of geometric detail needed to ensure an accurate representation. Such detail is only given to salient geometric features, such as large ribs or spars, main fuel lines, wire bundles, etc., which are commonly referred to as clutter elements.
The flow modifications which occur when the airflow is obstructed by protruding clutter elements will generate additional flow unsteadiness, as well as alter the turbulence level and scales. It is therefore necessary to develop a better understanding of the effects of clutter on fire propagation and suppression in highly turbulent flows.
This work investigates the effect of surface-mounted circular-cylindrical obstructions immersed within a turbulent wall boundary layer typically found in aircraft engine nacelles in the vicinity of a pool fire. The flame stability of a liquid pool fire downstream of various obstructions was documented together with the velocity, turbulence, vorticity, shear layer and spread rate of the fire.