Invertible Model of Jet Noise Source for Mid-to-Near Field

This study is motivated by the need to evaluate the jet noise experimentally in the mid-to-near field. Source inversion and sound field reconstruction offer a promising approach. The key lies in appropriately modeling the jet noise sources to ensure the invertibility, as well as the compatibility with the jet mid-to-near field. A hybrid equivalent source model and the inversion method are developed in this paper for source identification via acoustic array measurements. The model consists of two submodels corresponding to the large-scale structures and fine-scale turbulence. For the large-scale component, the wavepacket submodel is employed. An improved parameter determination algorithm, combined with an analytical criterion for determining the wavepacket equivalent radius, is proposed. For the fine-scale component, the multipole submodel and the coefficients inversion algorithm are proposed following a detailed comparison with the monopole model, which provide improved accuracy in representing the acoustic radiation in the jet mid-to-near field. The hybrid model is validated against reference measurements, and excellent agreement is achieved in both the sideline and downstream regions of the jet. This work presents a new method for efficient evaluation of the jet mid-to-near-field noise through experimental approaches.