Rotationsfrequenz

Rotationsfrequenz, in physics and engineering often called the frequency of rotation, is the number of complete turns a rotating body makes per unit of time. The standard unit is the hertz (Hz), which means cycles per second; in many practical contexts rotations per minute (rpm) are used. For a constant rotation speed, the rotation frequency f and the angular velocity ω are related by ω = 2π f, with ω expressed in radians per second. The inverse relation is f = ω/(2π). The time for one full rotation, the period, is T = 1/f.

If the rotation speed is not constant, the rotation frequency can be defined as an instantaneous quantity f(t), representing how many rotations occur per unit time at a given moment. In such cases, the frequency may vary due to acceleration or deceleration, and may be described in terms of average over a time interval.

Measurement methods include tachometers, optical encoders, and Hall-effect sensors, which detect passing features or pulses and convert them into a rotation frequency, rpm, or angular velocity. Data acquisition may integrate multiple pulses to improve accuracy, especially at low speeds or high dynamics.

Applications of rotation frequency are widespread. It is a key parameter in electric motors, fans, turbines, and combustion engines, affecting performance, efficiency, and vibrations. In data storage devices like hard drives, the spindle rotation frequency influences access times and throughput. Engineers specify allowable speed ranges, start-up transients, and bearing life considerations, recognizing that changes in rotation frequency impact thermal behavior and mechanical stability.