Carrier-phase direct numerical simulations (CP-DNS) of a three-dimensional turbulent shear- and mixing-layer are presented. DNS enables detailed investigation of complex multiphase turbulent reacting systems that are difficult to study experimentally; however, the reliability and reproducibility of such simulations remain uncertain and are potentially sensitive to the underlying numerical treatment. Given this, the simulations are cross-validated against DNS data by Luu et al. (Flow Turbul. Combust. 2024), first in a statistical sense and then, for the first time, by direct comparison of the instantaneous realizations of the two DNS. A further DNS is then presented for a higher Reynolds number at twice the grid resolution. This represents the most resolved carrier-phase DNS of such systems to date and enables higher turbulence conditions that better represent realistic burner operating conditions. The new simulations confirm the previously observed overall system behavior and further demonstrate the influence of Reynolds number on the combustion process. Higher turbulence intensity leads to a broader ignition zone, enhanced oxygen entrainment, and increased ignition and conversion rates, while the particle-scale oxidation behavior remains largely unchanged, indicating weak coupling between gas-phase turbulence and individual particle combustion.

Although negative pressure crystallization of ammonium sulfate can mitigate low yield and long processing time in atmospheric pressure crystallization, it still faces challenges in enhancing crystallization efficiency and achieving a uniform crystal size distribution. To address these issues, this study proposed an ultrasound-assisted negative pressure crystallization technique. Under optimized conditions (pH = 7, 300 rpm, 80 ℃, 45 min, 180 W, 0.03 MPa), the yield increased by 27.64 g and the direct yield improved by 36.80% compared with negative pressure crystallization. XRD and FTIR confirmed that this process maintained the crystal structure of ammonium sulfate while enhancing crystallinity. Mechanistic studies revealed that, compared with negative pressure crystallization, the synergistic effect of ultrasound narrowed the metastable zone width (MSZW) by approximately 33%, lowering the nucleation energy barrier. Ultrasound cavitation generated numerous bubbles, providing heterogeneous nucleation sites and localized supersaturation driving forces, which jointly accelerated nucleation and reduced the solid-liquid transition time by 35.7%. Furthermore, compared with the negative pressure crystallization system, the ultrasonic negative pressure crystallization reduced the solution viscosity by 5.7%, enhancing mass transfer and crystal growth. Ultimately, ultrasound-assisted negative pressure crystallization produced crystals with more uniform size and more regular morphology, offering important theoretical insights for improving ammonium sulfate crystallization processes.