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?


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.

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