Steam Turbines Flashcards
What is a sentinel valve?
A high pressure warning device on small turbines
What is Newton’s third law?
For every action, there is an equal and opposite reaction
What is Bernoulli’s principle?
When a gas or liquid passes through a restriction the pressure drops and the velocity increases. When the fluid or gas leaves the restriction the velocity drops and the pressure increases.
What are the two turbine blades and what shape is each?
Reaction blades, they look like a airplane wing
Impulse blades, that are symmetrical
What is the purpose of an impulse nozzle?
To change the pressure to velocity in one step.
Is there a change in steam pressure across an impulse blade?
No there is zero change in steam pressure across the blade when the steam passes through it. The blade spacing is the same between entry and exit.
What happens to the velocity on the impulse stationary blade?
It stays a constant because it is just redirecting the steam into the next moveable blade
How does a reaction blade work?
The steam pressure drops across both the fixed and the moving blades while the absolute velocity rises in the fixed blades and drops in the moving blades.
The velocity drop in the moving blades are because they are imparting energy to the moving wheel.
Do impulse blades require sealing between the blades?
No because there is no pressure difference
What are the most common ways of turbine blade attachment?
Dovetail and fir tree method
What happens when steam goes through any reaction type nozzle?
Steam pressure decreases
Steam velocity increases
Steam volume increases
How can staging of a turbine be determined?
By the number of rotating rows of blades in the turbine or by the number of pressure drops across the turbine
What is a combination impulse/reaction
turbine best for?
Good for varying loads
Using high pressure steam and
Using all the energy in the steam
What area of a turbine has the highest pressure?
The steam chest
How are carbon rings installed?
With the dots towards the pressure
