Coupling mechanism between rear chamber volume and surge frequency in axial compressors: An integrated experimental and numerical study

This study systematically investigates the coupling mechanism between rear chamber volume and surge frequency in axial compressors through combined experimental and numerical approaches. Utilizing a high-precision axial compressor test rig, surge characteristic tests were conducted for three rear chamber volumes (1.5, 1.954, and 2.343 m³). Fast Fourier Transform analysis of pressure signals revealed that increased chamber volume significantly reduces surge frequency. Experimental results demonstrate a 37.4% frequency reduction from 4.71 to 2.95 Hz when chamber volume expands by 56.2%, confirming the volume's suppression effect on flow oscillations. A three-dimensional numerical model incorporating rear chamber geometry was developed, with computational fluid dynamics (CFD) simulations showing strong agreement with experimental data at critical operating conditions (near-stall and peak efficiency points), validating model reliability. Numerical analysis indicates that small chambers induce intense leakage vortex breakdown due to spatial constraints, exacerbating pressure fluctuations and flow instability. Conversely, large chambers dampen pressure fluctuations through volumetric buffering, retard vortex core expansion, and reduce energy dissipation by 18.7%, thereby enhancing system stability. CFD simulations further elucidate the mechanism of axial velocity (W_z) circumferential inhomogeneity amplification under zero-mass-flow conditions with increasing chamber volume, attributed to the inertial energy storage effect and delayed pressure wave propagation, providing theoretical explanations for surge inception. Through multidimensional experimental-numerical cross-validation, this research establishes for the first time the quantitative correlation between the rear chamber volume and the surge frequency, revealing the coupled mechanisms of pressure pulsation, vortex dynamics, and energy dissipation. These findings provide critical theoretical support for optimizing aerodynamic stability in axial compressors and ensuring safe operation of aeroengines.