Phase Separation in Porous Media Integrated Capillary Channels

Abstract

Phase separation in space is critical for gas-free propellant supply, life support systems, refueling of spacecraft in low earth orbit (LEO), and for deep space exploration missions. In the absence of gravity, the stability of the liquid-gas interface depends on capillary forces. High liquid flow rates, sudden accelerations, and vibrational disturbances can cause the free surface of the liquid to collapse, which results in the ingestion of gas. Propellant tanks may have screen channel liquid acquisition devices (SCLADs) to position and maintain a gas-free propellant supply to the outlet. A saturated porous screen permits liquid to pass through but acts as a barrier to the gas. We investigated phase separation in porous media integrated capillary channels during parabolic flights (33rd DLR parabolic flight campaign in March 2019). An open side of a rectangular channel was covered with a dutch twill weave 200×1400. The liquid was ingested into the channel from its surroundings by establishing a differential pressure across the screen section. The gas-phase was blocked during the liquid withdrawal. We could show that the gas breakthrough occurs when the pressure difference across the screen exceeds the bubble point pressure. The experimental results showed good agreement with correlations from literature.

Effects of the Fluid Flow Front Instability as It Passes through a Porous Medium under Reduced Gravity and with Chemical Interactions between the Phases

“…Многофазные течения через пористую среду рассматриваются во многих исследованиях. Течение жидкости и поведение границы раздела фаз в небольших каналах различной формы изучались на борту международной космической станции [9][10][11]. Движение пузырьковой структуры в условиях микрогравитации рассмотрено в [12].…”

“…величину ξ конкретизируем впоследствии так, чтобы по возможности убрать «лишние» члены в уравнении неразрывности (7), которые появятся там после подстановки уравнений импульса. Заметим, что при выполнении (11) автоматически соблюдается (10), давления же фаз p α ниже заменим на комбинацию (p,ξ). Назовем эти значения средним давлением и поправкой к нему.…”

SiOC Screens with Aligned and Adjustable Pore Structure for Screen Channel Liquid Acquisition Device

“…The knowledge of the geometry of the metallic screen is sufficient to calculate geometric properties such as the pore diameter, porosity, thickness of the screen, and surface-to-volume ratio using the proper equations [ 11 , 12 ]. Numerous experimental and simulated data can be found in the literature where metallic screens have been tested under Earth gravity conditions and in microgravity environments [ 13 , 14 , 15 , 16 , 17 ]. After two initial papers dealing with the applicability of porous SiOC monoliths for isothermal/cryogenic wicking [ 18 , 19 ], there are, to the authors’ knowledge, no data reported on the further development of these materials into crack-free SiOC as SC-LADs, the correlation of experimental results with the pore structure, or an analytical solution.…”

Pressure-Driven Phase Separation Based on Modified Porous Mesh for Liquid Management in Microgravity

“…The liquid phase tends to attach on the walls and surround the gas phase, resulting in a mixture of gas and liquid at the outlet of the tank . Passive phase separation based on porous material, which takes full advantage of the capillary force, is an important technique in liquid management and advanced life support systems for spacecraft, including gas-free water acquisition from water tanks, orbital propellant acquisition devices, and gas port phase separators. − For example, a screen channel liquid acquisition device (LAD) is a successful application of porous material in phase separation. Screen channel is a hollow duct composed of three walls and a porous wall made from metal wire mesh.…”