At present, the hydraulic oil pipeline system of aero-engine usually has a high pressure range between 21MPa and 28MPa. Due to the operation of the hydraulic pump, it will produce a constant pulse, which will make the pressure in the pipe fluctuate, which will have a great impact on the service life of the engine pipe. At the same time, because the engine pipe is a closed cycle system, the pipe will expand and contract during use due to installation, which will cause stress concentration and eventually lead to pipe rupture.
Modern aero-engines mainly use metal hoses and non-metallic polytetrafluoroethylene hoses in two different systems. Metal hose is a pipe fitting with bellows as the core component, which can play a compensation role between pipes and equipment, and has the advantages of light weight, good flexibility, high pressure bearing, high and low temperature resistance. Non-metallic polytetrafluoroethylene hose is mainly a pipeline fitting with polytetrafluoroethylene as the core component. It has the advantages of small size, corrosion resistance, fatigue resistance, etc., and is widely used in the fields of ships, mines, metallurgy, petroleum, engineering machinery, etc.
Due to the high temperature resistance of the metal hose, but compared with the poor fatigue resistance of the PTFE hose, we are mostly used in the air bleed system of the aeroengine, especially the connection part of the external casing, to solve the leakage problem of the air bleed pipeline due to the different degrees of thermal expansion and contraction of the external casing and the connecting pipeline. Due to the good anti-fatigue performance of non-metallic polytetrafluoroethylene hose, and the number of hydraulic oil pulse shocks inside the pipe can reach more than 250000 times, non-metallic polytetrafluoroethylene hose is mostly used in hydraulic oil pipeline systems such as aviation engine fuel and lubricating oil to solve the thermal compensation problem of hydraulic oil pipeline system. These hoses can fully absorb the installation stress, deformation stress, internal stress and other stresses in the pipeline system, compensate for the position movement of the pipeline and absorb the vibration of the pipeline system, prevent the deformation and leakage of the supporting system caused by uneven foundation settlement, and have a good absorption effect on the changes of the piping system caused by thermal expansion and cold contraction. They are indispensable and important parts of the modern pipeline system. The hose can bend at will when meeting its minimum bending radius. Therefore, it can meet the installation requirements of most of the pipelines and has a certain protection effect on the operation of the engine system. Under some special and severe conditions (vibration, dust, impact, acceleration, acid atmosphere, etc.), using hose to compensate engine pipeline can not only absorb vibration, but also improve the system's ability to resist fatigue damage, corrosion, and even reduce noise, and better improve the performance and service life of aeroengine.