6 - Turbine Section Flashcards
What are two types of turbines
- Radial flow
- Axial Flow
What shape are impulse turbine blades
Bucket/curved
How much energy is absorbed by the turbine
60% - 70%
Where are radial flow turbines installed
Small gas turbines such as APUs
What are the advantages of axial turbines
They allow much higher airflow and can be built up with any number of stages
What are the types of turbine blades
- Impulse
- Reaction
- Reaction-impulse
What happens in an impulse configurtion
Velocity increases but pressure decreases
What are reaction configuration designed for
Redirecting the airflow without pressure change
What is the most common type of turbine blade configuration
Reaction-impulse
Briefly explain the material used for turbine blades and why
Single crystal for better strength and heat properties
What is the turbine disc
The component that attaches the blades to the power shaft
How is the turbine disc cooled
Series of grooves/notches bleeds cool air onto the disc
What is the most common turbine blade attachment
Fir tree
How do stress rupture cracks appear
On or across the leading edge
What causes creep
Prolonged exposure to high stress
