An impulse turbine has fixed nozzles that orient the steam flow into high speed jets.
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The resulting impulse spins the turbine and leaves the fluid flow with diminished kinetic energy.
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New impulse geared turbine engines, coupled with very heavy anti-aircraft protection, gave the class a very high speed and protection.
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In practice, modern turbine designs use both reaction and impulse concepts to varying degrees whenever possible.
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The design of this water turbine takes advantage of a mechanics principle known as impulse, a force defined as the product of the force and the time during which it acts.