Auxiliary power unit fire enclosure drain seal

摘要

A drain assembly for an auxiliary power unit having a hot zone formed by a combustor case comprises a fire enclosure, a drain fitting, a discharge port and a piston seal. The fire enclosure encapsulates the hot zone of the combustor case. The drain fitting connects to the fire enclosure. The discharge port extends from the combustor case into the drain fitting. The piston seal is positioned between the drain fitting and the discharge port.

主权项

1. An auxiliary power unit comprising:
a gas turbine engine comprising:
a combustor section includinga combustor case a fire enclosure joined to the auxiliary power unit to circumscribe the combustor case; and a drain assembly configured to permit fluid within the combustor case to drain out of the fire enclosure, the drain assembly including:
a piston seal configured to prevent combustor air from leaking into the fire enclosure;a scupper extending outward from the combustor case to form a trough;a drain fitting extending through an opening in the fire enclosure to align with the trough; andan orifice extended from the trough by a cylindrical body penetrating into the drain fitting to form an expansion joint; wherein the piston seal comprises a piston ring positioned around the cylindrical body within the drain fitting; wherein the combustor case includes perforations within a perimeter of the scupper; wherein the drain fitting includes a cup in which the piston ring is positioned; and wherein the cup comprises:
a first collar extending away from the fire enclosure to receive the cylindrical body;a platform extending from the first collar and upon which the piston ring rests;a sidewall extending from the platform alongside the piston ring; anda retaining ring engaged with the sidewall to prevent the piston ring from being displaced from the cup.