F/A-18E/F Nacelle Simulator Input/Output Boundary Condition Flows

Abstract

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Suppression of pool fires with HRC-125 in a simulated engine nacelle.

“…Air leaves the nacelle to balance inflow through several vents and openings. The relative flow through the various paths was measured and found to be independent of air-flow rate [6,20] m from the nacelle front. The remaining 25% of the air leaves through four openings in the nacelle front simulating connections to the AMAD bay and other parts of the aircraft.…”

“…The remaining 25% of the air leaves through four openings in the nacelle front simulating connections to the AMAD bay and other parts of the aircraft. In the ground simulator, the flow out the lower diamond vent, located directly below the upper diamond vent, is effectively zero; this may be because the fine mesh screen covering the vent was clogged with soot, rust and other particulate [6,20]. The flow rate out of the various openings was matched to the measured flow rates [6,20] by varying the porosity of the opening, given the known area of the opening.…”

Transport of High Boiling Point Fire Suppressants in a Droplet-Laden Homogeneous Turbulent Flow Past a Cylinder

“…The nominal water flow rate was 3.0 kg/h ± 0.35 kg/h at a line pressure immediately upstream of the atomizer of 791 kPa ± 65 kPa. 2 The pressure was held constant for the two HFE agents so that liquid atomization would be comparable (thus the flow rates varied according to the change in liquid density; see Table 1). Characterization of the atomizer was only carried out to the extent of providing initial conditions for the modeling effort; data are reported in Appendix A.…”

“…A high-resolution digital camera provided still images and movies (at 9 frames/s) of the spray. A high-speed digital camera (at 1000 frames/s) [23,24] was used to record the 2 Estimation of the measurement uncertainty is determined from statistical analysis of a series of replicated measurements (referred to as a type A evaluation of uncertainty) and from other means other than statistical analysis (referred to as a type B evaluation of uncertainty) [33], calculated as 2u c (representing a level of confidence of 95 %), where u c is the combined standard uncertainty. The value for u c was estimated statistically by sn -1/2 , where s is the standard deviation of the mean and n is the number of samples (type A uncertainty, where n = 11) and from the manufacturer uncertainty (type B uncertainty), if available.…”

“…The common features of the two HFE agents are listed in Table 1. A homogeneous turbulent flow field was used to simulate the turbulence experienced by sprays for a representative fire suppression scenario in an aircraft engine nacelle at reported airflow conditions [2]. The choice of the above conditions was motivated by recent efforts to develop and validate the subgrid droplet impact model of the VULCAN computational fluid dynamics (CFD) fire physics code for spray-clutter interactive environments [3].…”