基于 TBOS 的超声速喷流模态诊断与非线性交互机制

To address the challenges of unclear identification of dominant disturbance structures，ambiguous far-field radiation mechanisms of sound sources， and the lack of quantification for nonlinear interaction paths in high-Mach-number jet flows， a multiphysics modal identification framework integrating tomography-integrated background-oriented schlieren (TBOS) experiments， density-pressure tomographic inversion， proper orthogonal decomposition (POD)， complex mode construction， and nonlinear interaction tensor analysis was proposed. Taking Mach number of 1.26 and 1.53 screeching jet conditions as typical cases， the framework tomographically reconstructed the axisymmetric flow field’s density and pressure structures via TBOS， revealing the coupling evolution process between shear layers and shock cells. By constructing the complex mode fields and quantifying the dominant wavelength，it was found that at higher Mach numbers， the dominant wavelength increased by 17%， which explicitly characterized the ordering of far-field acoustic radiation structures induced by shear-shock coupling. The dominant frequencies extracted from POD spectra matched theoretical models with 99.7% accuracy，validating the existence of acoustic feedback paths. Furthermore， Hilbert transform and triadic modal energy transfer tensors revealed that as the Mach number increased， the phase-locking structure of dominant modes transitted from Mode 1-2 coordination to strong Mode 1-3 coupling， accompanied by a shift in energy transport from concentrated single-path feedback to multi-modal distributed interaction. This revealed the reconstruction of dominant modal systems and multi-scale energy cooperative modulation mechanisms in high-Mach-number jets. Utilizing single-camera projection combined with TBOS visualization technology， a three-layer coupling path “structural identification-propagation extraction-nonlinear interaction analysis” was establishes which overcame the limitation of conventional POD to some extent in resolving the evolution of main-lobe acoustic sources. This framework can provide a paradigm and technical support for screech mode identification， jet modulation， and far-field acoustic modeling in supersonic flows.