Campbell diagram

A Campbell diagram plot represents a system's response spectrum as a function of its oscillation regime. It is named for Wilfred Campbell, who introduced the concept. It is also called an interference diagram.

In rotordynamics
In rotordynamical systems, the eigenfrequencies often depend on the rotation rates due to the induced gyroscopic effects or variable hydrodynamic conditions in fluid bearings. It might represent the following cases:




 * 1) Analytically computed values of eigenfrequencies as a function of the shaft's rotation speed. This case is also called "whirl speed map". Such a chart can be used in turbine design.
 * 2) Experimentally measured vibration response spectrum as a function of the shaft's rotation speed (waterfall plot), the peak locations for each slice usually corresponding to the eigenfrequencies.

In acoustical engineering
In acoustical engineering, the Campbell diagram would represent the pressure spectrum waterfall plot vs the machine's shaft rotation speed (sometimes also called 3D noise map).