Numerical Analysis for Propellant Management in Rocket Tanks

TLDR

The study develops a level‑set numerical scheme to track the three‑dimensional behavior of liquid surfaces in orbiting storage tanks, emphasizing the dynamic surface and contact‑line displacement. The level‑set scheme was verified against drop‑tower experiments of liquid surface deformations and then applied to simulate draining flowfields in a liquid oxygen tank of an H‑IIA launch vehicle under low‑gravity. The simulations showed good agreement with experiments, validated a surface‑tension boundary condition and wetting model, and revealed that slight buoyancy prevents dip growth, increasing usable propellant in the launch‑vehicle tank.

Abstract

To track the three-dimensional behavior of liquid surfaces in storage tanks on orbit, a numerical scheme based on the level set method was developed. For the verification of the numerical methods, experimental data were acquired through the observation of the unsteady deformations of liquid surfaces in cylindrical containers under low-gravity conditions in a drop tower. Primary emphasis was placed on the dynamic behavior of the liquid surface and the displacement of the contact line on the solid wall. Based on the results, the boundary condition for surface tension was discussed and the model of wetting phenomena was adequately introduced into the computation. Compared with the experimental data, the corresponding numerical results showed good agreement. With the developed code, the flowfields at the draining process in the liquid oxygen (LO X ) tank for the upper-stage propulsion system of an H-IIA launch vehicle under low-gravity conditions were also investigated. It was found that the buoyancy induced by a slight acceleration was efficient to prevent dip growth and that the serviceable propellant in the launch-vehicle tank could thereby be increased in a realistic situation.