Surface Tension Propellant Management Device Research Articles

Experiment Investigation on Fluid Transportation Performance of Propellant Acquisition Vanes in Microgravity Environment

The propellant acquisition vane (PAV) is a key part of a vane type surface tension propellant management device (PMD), which can manage the propellant effectively. In the present paper, the fluid transportation behaviors for five PAVs with different sections were investigated by using microgravity drop tower test. Further, numerical simulation for the propellant flow in a PMD under microgravity condition was also carried out based on VOF model, and showed the similar flow pattern for PAVs to the experiment. It is noted that the section geometry of PAVs is one of the main factors affecting the fluid transportation behavior of PMD. PAVs with bottom length ratio of 5/6 and 1/2 have larger propellant transportation velocity. Based on the experiments, there were two stages during the process of propellant transportation under microgravity environment: liquid relocation and steady transportation stage. It is also recognized that there is a linear correlation between liquid transportation velocity and relative time`s square root. Those results can not only provide a guideline for optimization of new vane type PMDs, but also are helpful for fluid control applications in space environment.

Experiment Investigation on Fluid Storage Characteristic and Transportation Performance of Propellant Refillable Reservoir in Microgravity Environment

Satellites store and manage propellant by surface tension. A surface tension propellant management device (PMD) consists of a propellant refillable reservoir (PRR) for propellant storage and propellant acquisition vanes (PAVs) for propellant transportation. PRR is a key part of vane type surface tension tank (STT), and its storage performance determines the fluid management of vane type STT. In the present paper, a model test system was established and microgravity drop tower tests conducted based on experimental study of fluid storage and transportation behavior of PRR. Laws of fluid storage and transportation of PRR in microgravity environment were obtained. The test results show that two types of PRR both have good liquid storage capacity, and the double cone PRR exhibits good liquid storage capacity in lateral acceleration. A rational design of PRR can effectively store liquid and control liquid transportation velocity. The test results offer a guideline for optimization of new-style vane type PMD, and also provide a new method for fluid control in space environment.

Studies of the Wetting of Gaps in Weightlessness

The geometry of a thin sheet metal vane terminating near a wall in a surface tension propellant management device (PMD) is common in devices designed by various people. A research program into the capillary fluid physics of the common vane-wall gap began in 1998 with the arrival of the second author at the School of Aeronautics and Astronautics at Purdue University. Drop tower experiments, Surface Evolver computations, and analysis were combined to explore the details of the fluid behavior in the vane-wall gap geometry. Results of four vane-wall gap experiment topics: critical wetting, advance rates, sensitivity to vane orientation, and effect of imperfect initial conditions, are discussed here. This work led to a desire by Weislogel to incorporate this type of geometry into his “Capillary Fluids Experiment” (CFE) that operated flawlessly on the International Space Station in 2006 and 2007. It is found that the wetting of vane-wall gaps is predicted correctly through use of the critical wetting analysis of Concus and Finn. Furthermore, the dynamics of the wetting flows are found to have scaling of flow rates versus time similar to those known for capillary advances in solid corners. In some cases, a seemingly misaligned vane is found to have more rapid capillary advance than for the same vane and gap but with the vane normal to the tank wall. An initial drop tower study of sensitivity to imperfect initial conditions shows that a critical wetting flow is largely immune to small tilts in the initial test orientation but that larger errors can be seen in cases that lack critical wetting and in the measurements of the time history of the meniscus minimum point.

Investigation of the Symmetric Wetting of Vane-Wall Gaps in Propellant Tanks

Symmetric wetting of a liquid in a vane-wall intersection with a gap is investigated. The geometry is common in surface tension propellant management devices (PMDs) in spacecraft liquid propellant tanks. A theoretical method is applied to determine a critical contact angle in the geometry for a range of parameters. The critical contact angle marks a division between the existence and nonexistence of a single-valued finite height equilibrium capillary surface spanning the entire cross section. When the contact angle is below the critical value, the capillary surface wicks up the gap, which is necessary for proper function of the PMD. The problem and results can also be viewed as determination of a critical gap size for a given contact angle. In addition to analysis, Surface Evolver simulations and drop tower experiments provide results in agreement with the analytical results. Drop tower results also demonstrate that the evolution of the wicking rate mimics that for a solid corner.

Estimating zero‐g flow rates in open channels having capillary pumping vanes

AbstractIn vane‐type surface tension propellant management devices (PMD) commonly used in satellite fuel tanks, the propellant is transported along guiding vanes from a reservoir at the inlet of the device to a sump at the outlet from where it is pumped to the satellite engine. The pressure gradient driving this free‐surface flow under zero‐gravity (zero‐g) conditions is generated by surface tension and is related to the differential curvatures of the propellant‐gas interface at the inlet and outlet of the PMD. A new semi‐analytical procedure is prescribed for accurately calculating the extremely small fuel flow rates under reasonably idealized conditions. Convergence of the algorithm is demonstrated by detailed numerical calculations. Owing to the substantial cost and the technical hurdles involved in accurately estimating these minuscule flow rates by either direct numerical simulation or by experimental methods which simulate zero‐g conditions in the lab, it is expected that the proposed method will be an indispensable tool in the design and operation of satellite fuel tanks. Copyright © 2003 John Wiley & Sons, Ltd.

Application of etched disk stacks in surface tension propellant management devices

Application of etched disk stacks in surface tension propellant management devices