MOTIVATION

Precise propellant positioning under microgravity conditions is essential for satellites. In the absence of gravity, liquid and vapour phases can redistribute freely within the tank, forming complex and difficult-to-predict phase interfaces. For green propellants, this challenge has not yet been fully resolved.

GATE Space is developing a novel concept for the precise management of green propellants that uses temperature gradients to actively control the positioning of fluids inside the tank.

REQUIREMENTS

Ground-based experiments are distorted by gravity, while experiments in space or under microgravity conditions are expensive. Therefore, the assessment of this novel concept can only be carried out effectively through numerical simulations.

A 3D CFD simulation of the flow inside a satellite tank under microgravity conditions is required, based on the Volume of Fluid method. The simulation shall account for surface tension, wettability, thermocapillary effects, as well as evaporation and condensation using the Lee model.

Thermophysical properties shall be implemented through user-defined functions, ensuring that specific heat capacity, latent heat of vaporization, thermal conductivity, viscosity, and density are represented as temperature- and pressure-dependent quantities.

Capillary forces shall be modelled using a Continuum Surface Stress formulation, while thermocapillary stresses shall be implemented through a temperature-dependent user-defined function.

OBJECTIVE

The objective is to accurately predict the steady-state geometry of the liquid-vapour phase interface under realistic initial and boundary conditions, including a locally imposed temperature gradient.