G-300, the first French Getaway Special microgravity measurements of fluid thermal conductivity

On Earth thermal conductivity measurements on liquids are difficult to perform because thermal motions due to convection. In microgravity the convection due to buoyancy is evanescent and we expect a strong lowering of Rayleigh and Nusselt numbers. Three low viscosity liquids are selected to carry out the measurements: distilled water (standard) and two silicone oils. We use a modified “hot plate” method with a simplified guard ring, the lowering of convective motions let us to use in the experimental cells larger interplate distances and/or temperature differences than in earth measurements so the accuracy must be improved. Comparisons between Earth and orbit results may help to understand the convection occurrence in our cells. G-300 payload is cantilevered from the experiment mounting plate (EMP) and it includes: four struts, an intermediate plate, a bottom plate with four bumpers, a battery box, an electronic rack and six experimental cells assembled in twin-packs thermally coupled with the EMP. Thermal, vibration and EMI tests have proved that the design satisfies the Nasa requirements and acceptance is in progress.