63. What is critical speed?
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63. What is critical speed?
If the rotational speed of the rotor happens to be equal to or close to the rotor’s natural frequency, the rotor system will experience severe vibrations, a phenomenon known as resonance. The critical speed refers to the speed at which a rotating rotor begins to vibrate during operation. The amplitude of these vibrations increases as the speed rises, reaching its maximum value at a certain speed (this is what is commonly referred to as resonance). Beyond this speed, the amplitude decreases gradually as the speed continues to increase, and stabilizes within a certain range. This speed at which the rotor’s amplitude is at its maximum is known as the rotor’s critical speed.
:When the rotor is rotating at a certain speed, resonance occurs if the frequency that causes forced vibration in the rotor is identical to or proportional to the frequency of the rotor’s natural vibration; this speed is then referred to as the rotor’s critical speed.