Hydrogen is regarded as a promising solution to fulfill the energy demand of Mars human base in the future. Through in-situ resource utilization (ISRU) on Mars, the composite of metal-organic frameworks (MOFs) and magnesium hydride which demonstrates synergistic effect of physi- and chemisorption has been proposed to be an attractive approach for long-term hydrogen storage. MOFs may act either as scaffolds to confine Mg nanoparticles or as catalysts/precursors to lower the energy barrier for hydrogen dissociation on Mg surfaces. The corresponding mechanisms for faster hydrogenation/dehydrogenation kinetics and lower operation temperature were further discussed and analyzed.
This study numerically investigates fluid dynamics of a jet flow at supersonic speed. The meshless method and the overlapping point cloud method are used to handle the moving boundary problems. The interaction between the jet flow and a moving ball-shaped plug is numerically solved, which has been rarely done in the published literature. The switching mechanism of a novel designed jet valve in an attitude and orbit control system (AOCS) is analyzed. It is found out that applied pressure to the control inlets of the jet valve must be high enough in order to successfully drive the plug to move and subsequently change the force direction acting on the jet valve. Then the switching mechanism of AOCS can be triggered. The initial fluid condition also plays a vital role and it significantly influences the response time of the switch. This study explores the underlying physics of the jet flow on its deflection, wall attachment, and interaction with the ball-shaped plug. It contributes to the optimization design of the jet valve in the AOCS with a fast and efficient response.
The meshless method does not need the mesh cells to divide the computational domain, but use the 'clouds of points' to replace the function of mesh cells. For this reason, the meshfree method can bring the advantage of flexible point distribution to divide the computational domain. In the present paper, an efficient and accurate 3D least square meshless algorithm is shown to solve the Euler equations based on the AUSM+-up and MUSCL scheme. The explicit three-stage Strong Stability Preserving (SSP) Runge-Kutta method is chosen to advance the time evolution. The spatial derivatives are fitted by the least square method based on the cloud of point. The explicit expressions of the spatial derivatives are given in the present work. In order to investigate the robustness and accuracy of the present 3D meshless method, both transonic flow and supersonic flow are simulated. The results obtained show a good agreement with the exact solution or the experiment results.
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