A introduction to Campbell diagram

Campbell diagram

This article is from Wikipedia
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 interference diagram.

In rotordynamics

In rotordynamical system, the eigefrequencies(本征频率) often depend on the rotation rates due to the induced gyrosopic(回旋效应) effects or variable hydrodynamic conditions in fluid bearings. It might represent the following cases:

• Analytically computed values of eigenfrequencies as a function of the shaft’s speed. This case is also called "whirl speed map(旋转速度图)’. Such chart can be used in turbine design as shown in the numerically calculated Campbell diagram example illustrated by the image: analysis shows that
  • There are well-damped critical speed(阻尼良好的临界转速) at lower speed range.
  • Another critical speed at mode 4 is observed at 7810 rpm(130Hz) in dangerous vicinity of nominal shaft speed, but it has 30% damping -enough to safety ignore it.

• Exoermentally measured vibration response spectrum as a function of the shaft’s ratation speed(waterfall plot ), the peak locations for each slice usually corresponding to the eigenfrequencies .

In acoustical engineering

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

campbell diagrams