An impulse turbine is a type of rotatary machine for converting kinetic energy of some flow into rotational energy to be used for
grinding corn,
generating electricity,
compressing air or getting me to the store to buy beer.
Yes, i just described just about any turbine. So what makes an impulse turbine different and/or special?
IT'S ALL ABOUT THE MOTION, BABYCAKES!
Just like the name implies, the impulse turbine is driven by an
impulse. That is, whatever is going to power this turbine (usually water, high pressure steam or exhaust gases, herein after called the "working fluid") comes in as a
high pressure, low velocity stream. Got it? Lotsa pressure, slow flow. This goes through a stationary
nozzle (or more accurately, many many nozzles in
parallel) which makes it into a
low pressure, high velocity flow through this here impulse turbine. This nozzle is pointed right at the blades of said turbine.
Now the fluid is just
cruising along real nice and fast and
WHAM it ran into a turbine blade, which slows it down a bit. Just like a speeding
cement mixer careening into a
concrete abutment, the working fluid runs into the blades of the
rotor. This transfers some of the
kinetic energy of the fluid into
rotational energy of the turbine rotor. Congratulations, you now have rotary motion. Go forth and make useful stuff.
Examples of impulse turbines are
Pelton Wheel,
Turgo,
crossflow &
Kaplan hydroelectric turbines. Impulse turbines are best suited for high
head hydroelectric power stations.
Most turbines operate as a combination of
impulse and
reaction modes. The distinction between the two is used to show how it primarily receives power from the working fluid.
node your work