Modeling and characteristic analysis of unsteady broadband excitation spectrum of thruster based on OU-Gaussian process

Objectives To solve the problem of obtaining propeller excitation information in the prediction and control of ship acoustic vibration, a generalized characterization model of the unsteady broadband excitation of a propeller induced by turbulence based on the Ornstein-Uhlenbeck (OU)- Gaussian process is proposed.

Method By using the OU stochastic process theory and blade element theory, an approximate analytical model of the broadband excitation power spectrum of a pump-jet rotor is derived. The operating frequency ranges and influence patterns of the model parameters are obtained through Sobol global sensitivity analysis, and the rationality and generality of the model are verified by the computational fluid dynamics (CFD) calculation results.

Results The results show that the model can accurately capture the broadband attenuation characteristics and hump features in the non-stationary excitation power spectrum. The parameters have strong frequency dependence. Among them, some parameters characterizing the OU process operate in a wide frequency range, while parameters determining the Gaussian function are focused on the frequency band near the hump. In the description of the thrust power spectrum of the pump-jet propeller, the generalized characterization model is consistent with the CFD results, and is verified from the perspective of the statistical confidence interval.

Conclusion The proposed explicit parametric model has high computational accuracy and speed. It can provide a simple and reliable empirical spectral input condition for the acoustic vibration control of naval vessels. It can also provide prior information constraints for the inversion and identification of the non-stationary excitation of the propeller, mitigating the ill-posedness of inverse problems and improving the identification accuracy.