Flow characteristics and structural optimization of multiple heterogeneous self-excited oscillatory pulse structures

To enhance the potential for diversified field applications of self-excited oscillatory pulse structure devices, this paper compares the velocity and pressure fields of the original structure (PSOS) with those of heterogeneous structures (return channels RCOS, diffusion angles ANOS, wall folds WCOS, and rectification blocks RBOS) using the standard k-ε model and large eddy simulation (LES), which reveals the variation rules of vortex structure evolution, perturbation oscillation range, and pulsation pressure value during the dynamic development of the jet. It turns out that the standard k-ε model has limitations in describing the vortex fragmentation and dissipation processes. In contrast, the LES model can capture the flow details more accurately and agrees well with the results of high-speed camera experiments. The different oscillatory structures show significant differences: the PSOS structure has a symmetric velocity field distribution with a large outlet pressure amplitude, the RCOS has a significant wall-attachment effect, the inlet is significantly diverted by the feedback channel, the ANOS has faster velocity decay and the most extensive sweeping range, and the WCOS has a wall folding corner structure that induces wall-vortex generation and less energy dissipation; the RBOS increases the flow resistance in the cavity and generates significant pressure fluctuations. The optimized PSOS-O structure exhibits high-frequency oscillatory flow with both high mean peak pressure and maximum pulsation pressure. This study provides a reference for the optimization of the oscillatory flow field and the design of engineering-assisted efficiency enhancement devices.