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Indeed, many gas turbine engine seals leak by design. [4] Labyrinth seals are also found on pistons, which use them to store oil and seal against high pressure during compression and power strokes, as well as on non-rotating shafts. In these applications, it is the long and difficult path and the formation of controlled fluid vortices plus some ...
Seals are used to prevent oil leakage, control air for cooling and prevent stray air flows into turbine cavities. A series of (e.g. labyrinth) seals allow a small flow of bleed air to wash the turbine disc to extract heat and, at the same time, pressurize the turbine rim seal, to prevent hot gases entering the inner part of the engine.
The first dry gas seal for a compressor was patented by Kaydon Ring & Seal in 1951 when it was known as Koppers Corporation. Field applications of dry gas seal designs were completed in 1952. The original patent was for Kaydon's "Tapered Ramp" lift geometry, a constant diameter / variable depth dynamic lift design.
A gland is a general type of stuffing box, used to seal a rotating or reciprocating shaft against a fluid. The most common example is in the head of a tap where the gland is usually packed with string which has been soaked in tallow or similar grease.
The design of the seal ring must allow for minimizing distortion and maximizing heat transfer while considering the secondary sealing element, drive mechanism, spring and ease of assembly. Many seal rings contain the seal face diameters, although this is not a requirement of the primary ring. The seal ring always contains the balance diameter.
A seal is a device or material that helps join systems, mechanisms or other materials together by preventing leakage (e.g. in a pumping system), containing pressure, or excluding contamination. The effectiveness of a seal is dependent on adhesion in the case of sealants and compression in the case of gaskets .
Active clearance control (ACC) is a method used in large aircraft gas turbines to improve fuel efficiency during cruise. This is achieved by setting the turbine tip clearance at more than one operating point and contrasts with passive clearance control which sets it for only one condition and is explained below.
Labyrinth seals are also used in the secondary air system between rotating and stationary parts. Example locations for these are shown by Bobo. [112] Tip clearance between compressor and turbine blades [113] and their cases is a significant source of performance loss.