Turbine Engine Air Cooling And Sealing Flashcards
Describe the requirement for cooling and sealing of turbine engine components.
Cooling - To control the air temp within the engines components to that which is acceptable to the component heat stress limitations and to also control the amount of metal expansion within the engine to maximize efficiency by minimizing clearances between components.
Sealing - prevent oil leaking from bearing chambers, direct and control airflows for cooling and prevent combustion gas from entering into the turbine disc cavities.
Describe the uses of compressor bleed air for cooling and sealing.
Compressor bleed air is bled and ducted so as to provide pressurized air to seal the components and to provide air for the purposes of cooling much hotter components.
This air is bled form many different points within the compressor section.
Where the bled air is ducted to depends on the temperature needs within the engine, the hotter air going to the hottest parts of the engine and vica versa so as to avoid shock cooling.
Describe how turbine blades, discs and nozzles are cooled using compressor bleed air.
turbine blades will have relatively cooler air passed over them to provide a film of protective insulating air and/or have internally machined passages for air to be ducted from the disc ducting and blown through the blade to maintain a certain temp.
Discs and nozzles have air seals to direct/contain bleed air and passages internally and/or between themselves to pass the bleed air around and through them, maintaining an acceptable temp limit.
