Directional adaptive kernel distribution and its application

The directional adaptive kernel distribution as a new time‐frequency analysis method is proposed to analyse the vibration signal of rotor‐bearing system. This method extends the adaptive kernel distribution to process the constructed complex‐valued signal by defining directional ambiguity function (DAF). Based on the cyclic autocorrelation analysis and the complex‐valued signal decomposition, the DAF is proposed, which is the product of the adaptive optimal kernel function and directional cyclic autocorrelation function. The kernel function taken as a two‐dimension filter is optimised and used to suppress the cross‐terms in the DAF. Then, the directional adaptive kernel distribution is obtained through the positive and inverse Fourier transform on the DAF. The new time‐frequency transform is used to analyse the lateral vibration signals of the rotor and the bearing pedestal operating at oil whirling and whipping speeds. The experimental results verified that the proposed method is effective in the characterisation of the fault instantaneous characteristic frequency, rub‐impact information, instantaneous planar motion and modulation information etc. in oil‐film instability states of rotor‐bearing system.