A labyrinth seal is a type of

mechanical seal A mechanical seal is a device that helps join systems and mechanisms 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 ...

that provides a tortuous path to help prevent leakage. An example of such a seal is sometimes found within an

axle An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, beari ...

's bearing to help prevent the leakage of the oil

lubricating Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology. Lubrication mechanisms such as fluid-lubrica ...

the bearing. A labyrinth seal may be composed of many

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s that press tightly inside another axle, or inside a hole, so that the fluid has to pass through a long and difficult path to escape. Sometimes

screw thread A screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called ...

s exist on the outer and inner portion. These interlock, to produce the long characteristic path which slows leakage. For labyrinth seals on a rotating shaft, a very small clearance must exist between the tips of the labyrinth threads and the running surface. The "teeth" of the labyrinth seal may be on the rotating shaft (Teeth On Rotor - TOR) or on the stator (TOS), or both, in an interlocking configuration.Thermoplastic Labyrinth Seals for Centrifugal Compressors; ''Proceedings of the Thirty-Third Turbomachinery Symposium''
/ref> Labyrinth seals on rotating shafts provide non-contact sealing action by controlling the passage of fluid through a variety of chambers by centrifugal motion, as well as by the formation of controlled fluid vortices. At higher speeds, centrifugal motion forces the liquid towards the outside and therefore away from any passages. Similarly, if the labyrinth chambers are correctly designed, any liquid that has escaped the main chamber becomes entrapped in a labyrinth chamber, where it is forced into a vortex-like motion. This acts to prevent its escape, and also acts to repel any other fluid. Because these labyrinth seals are non-contact, they do not wear out. Many

gas turbine A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directio ...

engines, having high rotational speeds, use labyrinth seals due to their lack of friction and long life. Because liquid-filled labyrinth seals still generate heat due to the viscosity of the seal oil, and because seal oil can contaminate the process fluids, modern high-performance gas turbines use

dry gas seal Dry gas seals are non-contacting, dry-running mechanical face seals that consist of a mating (rotating) ring and a primary (stationary) ring. When operating, lifting geometry in the rotating ring generates a fluid-dynamic lifting force causing the s ...

s which use spring-loaded rings with an inert gas in between the faces of the rings to provide the seal. This creates even lower friction and provides a liquid-free seal. However, such engines often have detectable oil leakage into the compression chamber. Indeed, many gas turbine engine seals leak by design.{{cite speech, last=Scholz, first=Dieter, title=Aircraft Cabin Air and Engine Oil - An Engineering View, event=International Aircraft Cabin Air Conference 2017, date=September 19, 2017, location=

Imperial College London Imperial College London (legally Imperial College of Science, Technology and Medicine) is a public research university in London, United Kingdom. Its history began with Prince Albert, consort of Queen Victoria, who developed his vision for a cu ...

, url=http://www.fzt.haw-hamburg.de/pers/Scholz/Aero/AERO_PRE_GCAQE2017_CabinAirAndEngineOil_17-09-19.pdf Labyrinth seals are also found on pistons, which use them to store oil and seal against high pressure during compression and power

stroke A stroke is a disease, medical condition in which poor cerebral circulation, blood flow to the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemorr ...

s, as well as on other non-rotating shafts. In these applications, it is the long and difficult path and the formation of controlled fluid vortices plus some limited contact-sealing action that creates the seal.

References

Seals (mechanical)

See also

References