gMETAL

The microgravity effects on metal particles dynamics in fluids (gMETAL) project from TÜBİTAK UZAY will investigate how the lack of gravity impacts the mixing of solid particles in a gas (two-phase mixture formation) within a contained environment. This mixing is important to understand how metal particles and an oxidizing gas can react in a combustion chamber for efficient combustion and maximum heat release. Applications for this research include the development of zero-carbon energy generation technologies on Earth by burning metal particles in air; or for development of propulsion systems or energy generation on Mars, for example, by reacting metal particles with CO2 collected from the Martian atmosphere.

The objective of the GMETAL (Ax-3) investigation is to study the effect of gravity on the dynamics of two-phase mixing between solid particles and a gaseous fluid medium in a stationary volume. The ultimate long-term goal is to gather validated knowledge on the formation of a homogeneous mixture between metal particles and an oxidant medium in a combustion chamber or a reactor to insure efficient combustion and maximum heat release rate. GMETAL (Ax-3) only investigates the mixture formation phase so that no reactive mixtures are explored. Metal particles are simulated by silica (SiO₂) particles. Experiments are conducted using pre-filled and sealed quartz tubes (12.5 × 12.5mm²; length: 45mm), transported from the Earth by the Axiom-3 crew. Three different particle sizes from 10 to 100 micrometers and 4 particle volume densities (gr/cm³) are explored on board the International Space Station using the Life Sciences Glovebox (LSG) Facility. Time- and space-resolved visualizations of the particle dynamics are recorded for post-processing and for comparison with normal Earth gravity (1g) experiments and numerical computations.

The mixing of two-phase flows is an actively researched topic for various applications. The experiments are expected to contribute to two major areas by providing information on the mixing properties of solid particles and a fluid under reduced gravity and normal gravity conditions. One area concerns the ‘in situ propellant production’ approach on Mars for propulsion and energy generation purposes based on the burning of metal particles (aluminum or magnesium transported from the Earth) in carbon dioxide (CO₂) collected from the Martian atmosphere. The second area concerns the development of zero-carbon energy generation options by combustion of metal particles in air for terrestrial applications.

For both areas, the investigation of two-phase mixture formation between solid particles and a fluid and the role of gravitational acceleration in this process is crucial for the design of the appropriate operational systems under various gravity levels.

‍