Patent Application
20130001892
Gas turbine engine exhaust ducts include a liner disposed between an exhaust gas path and an engine casing. Cooling air flows between the liner and casing and is then discharged over nozzle seals and flaps located at the rear end of the exhaust duct to minimize damage that might be caused by high temperatures of the exhaust gas. In order to improve engine operation and performance, duct cooling air is carefully rationed. Since cooling air extracted from the engine may not be utilized to produce thrust, this cooling air may be a penalty to overall engine performance.
To control the quantity of cooling air flow while the engine is subjected to core pressure gradients at various operating conditions, a rotational flow balance system includes a member that is rotated to meter the flow cooling air flow through the duct. The member opens and closes a plurality of flow paths for the cooling air.
According to an embodiment disclosed herein, a seal assembly for a fan duct metering valve disposed within a casing of a gas turbine engine includes a tab for extending through an opening in the casing and attaching to the valve, a carrier for extending into the opening and engaging the valve such that fluid does not leak between the valve and the carrier.
According to a further embodiment disclosed herein, a seal assembly for a rotational fluid metering valve disposed within a casing includes a tab for extending through an opening in the casing and attaching to the valve, a carrier for extending into the opening and engaging the valve such that fluid does not leak between the valve and the carrier.
Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:
An engine outer case 22 and an inner cooling liner structure 24 define an annular secondary fan bypass flow path 26. It should be understood that various structures within the engine may be defined as the outer engine case 22 and inner cooling liner structure 24 to define various cooling fluid (e.g., air) flow paths such as disclosed fan bypass flow path 26. The fan bypass flow path 26 guides a cooling air flow (illustrated schematically by arrow C in
Referring to
Referring now to
The linkage 36 includes a vertically extending tab 38 that attaches integrally with the fan duct blocker ring 30 and has a central opening therein 40 for receiving a bearing 42 that attaches to a rod 44 that fixedly, but removeably, attaches to the actuator 35 so that the actuator 35 and the rod 44 move as one. Motion of the actuator 35 rotates the fan duct blocker ring 30 to partially open, open or close openings 39 thereby metering the flow of cooling air into the duct (e.g., bypass flow path 26). Because the actuator is connected directly to the tab 38 via bearing 42, slop in the actuator system is minimized to provide accurate metering thereby. Other drives that are not directly connected to actuator 35, are not able to meet positioning requirements of the fan duct blocker to provide adequate cooling because of slop in the system.
Because, however, use of the cooling air still must be controlled, leakage about the tab 38 is controlled as shown herein. Referring now to
An oval slot 90 is cut into fan duct 70 to allow the tab 38 to extend therethrough. The slot 90 has a length corresponding to an operating range of the fan blocker 30.
Referring now to
The top base 110 has four angularly disposed surfaces 130 which extend outwardly from the top surface 110. The top surface 110 provides a base for the seal 60 that fits over the lip 100. The angular extensions 130 permit the seal carrier 65 to extend into the oval slot 90 without falling therethrough.
Referring now to
Referring to
Referring now to
To assemble the seal assembly 50, the housing 55 is torqued down into the machined area 75 as nuts 85 are tightened over bolts 80. Because the legs 170, 171 of the seal 60 are springy, torquing the housing down to the seal carrier 65 creates an effective seal because leg 170 tends to flatten against surface 157 and leg 171 tends to flatten against top surface 110. The width W of the cutout 155 provides area for the legs 170, 171 of the seal 60 to extend outwardly with room to spare (see
The seal carrier 65 and the housing 55 are made of machined titanium or other hard metal that can survive in the rigorous gas turbine engine environment. The rounded base 115 is designed to ride upon the seal blocker 30 and the fabroid material 120 reduces drag to add accuracy of the system. The surface 157 of the housing is nickel plated 195 (see
The seal 60 is compressed between the seal housing 55 and seal carrier 65. Its function is to load the seal carrier 65 against the fan duct blocker ring 30 in order to create a seal at the sliding interface between those parts and to create a seal between the seal carrier 65 and the seal housing 55. Because the seal carrier 65 floats on the fan duct blocker ring 30 and the housing 55 is mounted to the duct 70, there is a large accumulation of radial tolerance between the parts. The sum of these tolerances sets the range of deflection for the seal.
Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.
The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.
