15.6 TURBINE Flashcards
what energy does the turbine transfer
kinetic energy into mechanical
what are the 2 types of turbine on gas turbine engine
radial flow turbine, axial flow turbine
do both types of turbine have the same components and if so what are they
yes, stationary vanes, moving rotor blades
are radial flow turbines single or dual stage turbines
single
what types of gas turbine are radial flow turbines used on
small turbines such as the APU
whats a disadvantage of radial flow turbines
only allow small airflow and are less efficient
where are axial flow turbines used
modern gas turbine engines
how many turbine stages can axial flow turbines have
any amount to operate the compressor
whats an advantage of axial flow turbines
very high airflow
before the gas from the compressor reaches the turbine what must it go through
stationary turbine nozzle guide vanes
whats the name of the turbine that only rotates due to gas flow on the blades
impulse turbine
turbine blades are classified as 3 types
impulse, reaction, reaction-impulse
where does the pressure drop occur in the impulse configuration
fixed nozzle guide vanes
what do the reaction configuration do to the gas flow and pressure
alter gas flow without changing pressure
turbine blades are made by either being
forged or cast
what are the disadvantage of shrouded blades
limits turbine speed and requires more blades
what is the turbine shaft usually made from
alloy steel
whats the most common way of attaching the turbine blade to the disk
fir tree fitting
why are the fir tree fittings not an exact fit
to allow for thermal expansion
what is a good aid to visual inspections of the blades
dye penetrant
stress rupture cracks usually appear as what
minute hairline cracks
what materials creep
metals and plastics
what is creep
slow structural deformation on a molecular level
