The Northrop Grumman MQ-4C Triton is an unmanned aerial vehicle (UAV) under development for the United States Navy as a surveillance aircraft. Developed under the Broad Area Maritime Surveillance (BAMS) program, the system is intended to provide continuous maritime surveillance for the US Navy, and to complement the Boeing P-8 Poseidon, the Boeing 737-based Multimission Maritime Aircraft (MMA).
Hot air is bled from the turbine and routed to the inlet nacelle for de-iceing.
The bleed air duct is comprised of several duct runs with attach points with different base excitations. The duct is modeled with shell elements while the machined attach points are modeled with solid elements. The ball joints provide moment relief but they also have different rotational stiffnesses when pressurized. Additionally, the ball joints exhibit a nonlinear moment in which the moment must exceed a threshold before articulating.
The base excitation and acoustic vibration spectrums are different for each section of the duct.
In flight, the duct is either fully pressurized when de-iceing or partially pressurized up to the shut-off valve. Thus for each flight load case, there are two sub-cases which must be considered.