What happens to a steam turbine when it reaches critical speed?

When a steam turbine reaches critical speed, it can start to vibrate violently due to resonance. Critical speed is a specific rotational speed at which the natural frequency of the turbine components aligns with the operational frequency, leading to excessive vibrations. This phenomenon occurs because the mechanical system becomes unstable at those speeds, causing it to oscillate uncontrollably.

Monitoring and managing these vibrations is crucial as they can lead to structural damage, reduced efficiency, and potential failure of the components over time. Proper design and operational protocols typically include measures to avoid operating at critical speeds to maintain the overall integrity and performance of the turbine. The other outcomes, such as increased power generation, improved efficiency, or a drop in temperature, are not directly associated with the condition of reaching critical speed and can be attributed to different operational parameters.