Effects of the fluidization modes on conveying characteristics in the powder fueled ramjets via a multiple state model of the dense powder flows

As the core component of powder fueled ramjets, accurately characterizing the dense powder conveying behaviors is crucial for the design of powder feeding system and for achieving the ramjet's energy control and multi-mode operations. Limited by the testing approaches for dense powders, a modified two-fluid model (TFM), integrating μ(I) rheology theory and Hooke's law, has been constructed in this paper to depict the multiple states and nonlinear evolutions of dense granular flows within the powder feeding systems. And a piston dynamic mesh boundary, consistent with the actual process, was constructed. By using the modified TFM, the effects of fluidization modes on conveying characteristics were explored, revealing the nonlinear correlation between the powder rheological properties and the fluctuation of output flow rate. Furthermore, the impacts of fluidizing gas injection direction and the contraction angle of the storage tank on the conveying performance were investigated. The findings have indicated that the gas cavitation instability led to flow rate fluctuations, while reducing the contraction angle of the storage tank enhanced the output flow rate and solid-gas ratio. This study provides a novel approach and valuable insights for the designing propellant feeding systems, contributing significantly to the development of stable and controllable powdered fuel feeding technology for powder fueled ramjets.