A Novel Method for Estimating Natural Frequencies of Rotating Machinery

A novel method is proposed for Operational Modal Analysis (OMA) of linear rotating machinery. This method is explained for applications where Experimental Modal Analysis (EMA) methods cannot be used and there is not rich environmental excitations to use simple methods of OMA. In the OMA method, the system is excited by the environment in operating conditions, and it is assumed that the excitation is white noise. In practice, this may not happen or the excitation may not be large enough to be recorded and processed. This paper considers adding noise to the rotational speed to provide excitations for the OMA method. Simulations of rotors with four and multi degrees of freedom show that this method is effective in estimating the natural frequencies of a rotating system. The estimation error of this method is found to be close to zero compared to actual natural frequencies