Self-regulating back-side pressurization system for thermal insulation blankets

Abstract

High-pressure fan duct bleed air is used to pressurize a cavity between the fan duct inner wall and the inner wall thermal insulation blankets. The cavity is pressurized to prevent hot air from the nacelle core compartment from flowing under the insulation blankets and degrading the fan duct inner wall. Pressure regulating valves (PRV) allow better control of the cavity pressure during different phases of the flight profile and under different levels of insulation blanket seal degradation by passively controlling exit area from the cavity based on an established pressure limit. Moreover, the pressurization system can be implemented as a passive cooling system by increasing the mass flow rate into the cavity and then the core compartment to a level suitable for core compartment cooling. The cooling air can be vented at the forward end of the insulation blanket assembly to provide core compartment ventilation flow, or vented through dedicated ports in the insulation blanket for targeted core compartment component cooling.