Crushing Law of Cavitation Jets on Natural Gas Hydrate

As a clean and efficient energy source, natural gas hydrate has the advantages of high energy density and low combustion pollution. Further, solid-state fluidization is a widely used approach for natural gas hydrate exploitation, and the fragmentation performance of high-pressure water jets directly determines its production efficiency. Herein, a coupled DEM-CFD method was adapted to investigate the fragmentation effect of organ-pipe nozzles on natural gas hydrate-bearing sediments. The model was validated against experimental results. The effects of throat diameter, expansion angle, expansion length, and standoff distance on fragmentation performance were investigated. Results indicate that a throat diameter of ۳ mm yields the largest cavity volume and optimal performance. Fragmentation efficiency initially increases and then decreases with the expansion angle, peaking at ۵۰º. An expansion length of L۴ = ۴.۵ mm promotes jet stability. A standoff distance of ۱۵ mm facilitates the most concentrated cavitation cloud collapse, generating the strongest impact and largest fragmentation area. Based on point and arc elasticity theories, the sensitivity of structural parameters to fragmentation performance was evaluated, ranked as follows: throat diameter > standoff distance > expansion angle > expansion length. This study provides a theoretical foundation for the application and optimization of cavitating jets in natural gas hydrate extraction.

کلیدواژه ها:

Cavitation jets ، Hydrates ، Numerical simulation ، Organ-pipe nozzle ، Sensitivity coefficients