Propellant Management Research Articles

Development of a hybrid screen channel liquid acquisition device for reliable microgravity transfer of cryogenic fluids

Refueling spacecraft in orbit offers potential benefits to future extended duration missions including increased spacecraft payload capacity and reduced launch cost. However, a key challenge for refueling cryogenic propellants in microgravity conditions is the acquisition of vapor-free liquid propellants from an in-orbit supply tank. This is especially true when the required liquid flow rate is high but residual liquid in the tank must be minimal. Vane-type Propellant Management Devices (PMDs) excel in stabilizing and distributing liquid, but are more susceptible to gas ingestion, and generally only perform well at lower flow rates and/or under favorable acceleration gradients. Screen channel PMDs do not stabilize and distribute the liquid as well, but are less susceptible to gas ingestion, and perform well at higher flow rates and/or under adverse accelerations. Screened channel LADs appear to hold many advantages for a flight cryogenic system with high demand flow rate, however there are currently no flight cryogenic fluid-based screen channel LADs. To address this need, Creare has been working with NASA Glenn to develop a hybrid Liquid Acquisition Device (LAD) for cryogenic propellants consisting of screened channels with attached guide vanes, and a screened sump. Creare’s design forms the flow channel from screen material itself, allowing much higher acquisition surface area per unit volume as compared to existing designs. The screened channel LAD and screened sump are assembled by Creare’s advanced laser welding processes to reliably maintain the pore structure of the screen adjacent to the bonding joints. After completing a series of fabrication trials to validate the reliability and repeatability of the approach, a prototype screen channel was fabricated, and its performance was characterized in LN2 outflow. Results were found to be consistent with single-phase CFD predictions of this geometry for a partially exposed screen channel. Two-phase CFD analysis was conducted to evaluate the performance of the guide vanes in favorably distributing liquid to enhance expulsion efficiency. Preliminary structural analysis was performed on representative geometry for the LAD assembly to assess stresses of the under 5 g acceleration. Using this screen channel geometry and overall design approach, Creare assembled a laboratory-scale hybrid LAD with four parallel gallery arms, a screened sump, and guide vanes. The assembly has been installed in a large dewar for preliminary evaluation in LN2. This unit is planned for delivery to NASA for follow-on investigations using liquid hydrogen.

Experimental Study on Liquid Sloshing of a Vane-type Surface Tension Tank for Satellite

This study conducts experimental research on the liquid sloshing performance of a vane-type tank used in high orbit satellites. The liquid sloshing tests of the tank without a propellant management device (PMD) were developed under different liquid-filling ratios. Liquid sloshing tests of the tank with PMD were performed in different directions and liquid-filling ratios. The experimental test results agree considerably with the theoretical results, indicating the test system’s reliability. A linear relationship was observed between the sloshing frequency and the liquid-filling ratio of the vertical installation test when the gas–liquid interface was in the hemisphere. The vertical installation test sloshing frequency remains unchanged when the gas–liquid interface is in the cylindrical section. The inverted conical accumulator structure of the PMD can increase the damping in the vertical installation tank. The sloshing mass in the vertical direction is less than that in the horizontal direction. Liquid sloshing results of the vane-type propellant tank will guide the design of spacecraft structures and control systems.

A three-dimensional flow model of screen channel liquid acquisition devices for propellant management in microgravity

Screen channel liquid acquisition devices (LADs) are among the most promising technologies for separating liquid and vapor phases in propellant storage tanks under microgravity conditions and thus ensuring vapor-free propellant supply to spacecraft engines. However, the prediction of the critical flow rate of a screen channel LAD relies on the full understanding of the three dimensional distribution of injection velocity. In this study, the flow characteristics at the entrance region of the LAD were investigated via particle image velocimetry (PIV) technique and numerical simulations under various working conditions. The experimental results illustrated that the velocity component normal to the porous woven mesh is non-uniform in both streamwise and spanwise directions of channel flow and that this phenomenon has a significant influence on the critical flow rate. Hence, a model that accounts for the three-dimensional flow field was proposed to predict the critical flow rate. The average error in the critical flow rate, which was determined by comparing the proposed model’s predictions and the experimental results, was less than 8.4%.

Study on Propellant Supply System for a Small-scale Supersonic Flight Experiment Vehicle (Study on a Propellant Management Device)

Study on Propellant Supply System for a Small-scale Supersonic Flight Experiment Vehicle (Study on a Propellant Management Device)

Asymmetric Propellant Positioning in Symmetric Tanks and Propellant Management Devices

Dangers of assuming symmetric liquid and gas positioning in symmetric tanks with symmetric propellant management device vanes are identified. Examples from spaceflight history plus modeling of proposed designs illustrate the issue in numerous geometries. Spaceflight hardware and research geometries present the same behavior: that the minimum-energy state for static positioning of liquid and gas in a partially filled vessel with axial symmetry or with, for example, fourfold symmetry of propellant management device vanes need not be symmetric. Because it is simple to assume a symmetric solution, the reality of the nonsymmetric solution may surface as a potentially crippling anomaly in spaceflight or in 0 research operations. Altered mass properties and thermal response of tanks to heaters are two important changes that nonsymmetric liquid positioning can produce. The surprises are avoidable by ground-based analysis and modeling that consider the possibility of such solutions.

Study on propellant management device in plate surface tension tanks

Surface tension tanks exploit the liquid surface tension in liquid transport and gas–liquid separation to provide gas-free propellant for the thruster. High transport efficiency of deflectors can ensure liquid relocation in the microgravity environment within a short period of time, which is helpful for providing gas-free propellant. This paper explores transport efficiency of deflectors through drop tower experiments and numerical simulations with the volume of fluid method. The experimental and numerical results show that both the liquid flow speed and the mass flow rate along deflectors increase as the widths of deflectors increase. Besides, a new type of propellant management device, which consists of four deflectors and four anti-sloshing baffles, is verified with numerical simulations and drop tower experiments. Moreover, long-term conditions are predicted by using similarity theories. These results can provide important references for the design of plate tanks.

Magnetic Positive Positioning: Toward the application in space propulsion

The sloshing of liquids in low-gravity entails several technical challenges for spacecraft designers and operators. Those include the generation of significant attitude disturbances, the uncontrolled displacement of the center of mass of the vehicle or the production of gas bubbles, among others. Magnetic fields can be used to induce the reorientation of magnetically susceptible propellants and improve the controllability of a fluid system. Despite being proposed in the early 1960s, this approach remains largely unexplored. This paper provides new insight into the prospects and challenges of using magnetic control of space propellants. Key unanswered theoretical and technical questions are identified, highlighting the importance of developing appropriate analytical tools and fluid-magnetic simulation frameworks. New results associated with the reachability, scaling, long-term thermal and radiation stability, and efficiency of paramagnetic and ferromagnetic propellants are presented. Magnetic settling forces are shown to enhance the stability and speed up the oscillatory response of the liquid, leading to more predictable propellant management systems for different scales and filling ratios. These effects are particularly relevant for ferrofluids, whose enhanced magnetic properties make them excellent candidates for active sloshing control applications in space.

A Conjoint Analysis of Propellant Budget and Maneuver Life for a Communication Satellite

Maneuvers require velocity augmentation to control a satellite at the defined orbit. The velocity augmentation provides achieving geostationary orbit, compensating orbital perturbation, orbit dispersion correction, and any other maneuver's operations for a communication satellite. All maneuvers and propellant consumption must be taken into account in the propellant budget for successful mission management. In this study, a straightforward method was proposed to calculate satellite maneuver life or associated propellant budget for general purposes. The method provides enough accuracy for general mission planning. However, communication satellite accurate end of life estimation, especially in the last three months is vitally important and depends on many factors. According to the performance requirement of procurement's standard, the propellant budget and associated satellite maneuver's life are calculated based on the worst-case or adverse three-sigma. The worst-case calculations include allocations for inefficiencies, velocity uncertainties, dispersions resulting from thruster firings, propellant residuals, the selected thrusting, and maneuver strategies' performance. High accuracy remaining propellant estimation is necessary for a successful end of life operation and decommissioning. The cost of early deorbit because of propellant misestimation is millions of dollars. Accurate remaining propellant and associated maneuver life analysis can be performed in different methods.The most common three methods are pressure, volume, temperature (PVT), bookkeeping (BK), and thermal propellant gauging (TPG). The propellant accuracy analysis shows that the propagation of uncertainties is related to system design, tank fill ratio, propellant load accuracy, orbital maneuver's inefficiency, pressure and temperature sensors, transducers, telemetry resolution, and error in equipment test data. Comparing the methods, PVT provides accuracy between ±27.81 kg to ±38.93 kg, depending on equipment size and accuracy. BK currently provides the best estimation and the highest gauging accuracy between ±9.83 kg to ±13.76 kg. TPG provides accuracy between ±10.52 to ±14.73 kg for some cases. However, the satellite operators request ±1 kg estimation of the remaining propellant to extend the lifetime and reduce costs. The satellite manufacturers should optimize propulsiıon and attitude control subsystem design and manufacturing, including propellant management device performance, applied sensors reliability and accuracy, and tank expansion performance over a mission life.

Capillary-flow dynamics in open rectangular microchannels

Abstract

Testing Liquid Distribution in a Vane-Type Propellant Tank under Conditions of Microgravity Using a Drop Tower Test

Propellant management devices (PMDs) are a key component used to manage liquid propellant in a propellant tank under zero gravity conditions. A microgravity drop tower test system was established to investigate the performance of a PMD. A single module was used for the experiments, and the microgravity level was less than 3 × 10 − 3 g . Anhydrous ethanol was used as the simulate liquid. Different volume fractions of liquid were used to study the influence of the PMD on performance management. Experiments were conducted with the position of the container oriented in different directions. Changes in the gas-liquid interface were studied during the test. This kind of vane transports liquid through the rectangular area between the vane and the wall. The velocity flows along the vane of different liquid volume fractions in the tank were different at the beginning ( t < 0.8 s ) compared with the end of the test. The liquid relocation time was less than 0.8 s while the liquid volume fraction was larger than 25%. The liquid relocation time was prolonged when the liquid volume fraction was less than 25%. The liquid climbing height along the vane under microgravity increased as the volume fraction of liquid reduced. The climbing velocity of the liquid is half reduction when the liquid volume fraction is small. The time for the liquid transferred from the top of the tank to the liquid outlet can be obtained by climbing velocity. It shows that the maneuverability of the satellite decreases at the end of its life. The above results are applicable to all propellant tank with vertical vanes. These results provide a favorable reference for further optimized design of vertical vane-type propellant tanks.

Experimental investigation of liquid transport in a vane type tank of satellite with microgravity

Propellant tank is used to store the propellant in propulsion system of satellite. Propellant management device (PMD) is the key component in propellant tank to manage the liquid propellant under zero gravity. In this paper, a microgravity drop tower test system was established to investigate the performance of vanes and refillable reservoir separately. Single module is used for experiment tests, and the microgravity level is between 10−2 g0 and 10−3 g0. Vane is fixed in a plexiglas container which provide a visual windows for the inner flow distribution. The anhydrous ethanol is used as analogue liquid. Different kinds of vanes were used to study influence of the geometry on the transport performance. Experiment tests of refillable reservoir were performed with different direction of gravity. Changes of liquid-gas interface during the test are studied. The width of the vane is related to the velocity of the liquid flow along the vane. The liquid climbing height along vane under microgravity is proportional to the time t1/2. Experiment results show that the direction of microgravity has great effect on the expulsion efficiency of a vane type tank. Experimental results provide a favorable reference for further optimization design of vanes and refillable reservoir.

Numerical simulation of the flow in a vertical vane type tank with micro downward acceleration

Vane type propellant tank is widely used in propellant system of satellite at present for that it can be refuelled in space. The performance of a vertical vane type tank is determined by propellant management device (PMD). The VOF model with commercial code (Fluent) was used to simulate the gas-liquid distribution with micro downward acceleration. Two kinds of volume fractions of liquid were chosen for the simulation. The flow rate of the liquid can reach 1300 ml/s. The potential energy caused by gravity for the initial conditions would be released in three seconds. The liquid in the tank would keep steady state in 28 seconds. These results could provide a reference for high acceleration maneuvers of a satellite.

Modeling and Characterization of a Thermally Controlled Iodine Feeding System for Electric Propulsion Applications

Iodine is considered as a feasible alternative to xenon as a propellant for electric propulsion systems, thanks to its good propulsive performance, high availability, and high storage density. However, as iodine is stored in solid state at ambient temperature, current state-of-the-art propellant management systems are not suitable to be used with it. Moreover, due to its high reactivity, iodine imposes requirements on material-compatibility, hindering the use of mass flow measurement and control systems typically used with other propellants. The architecture of a controlled iodine feeding system for low power (200 W class) ion and Hall effect thrusters is presented and the resulting prototype is described. It consists of a sublimation assembly whose temperature is used to control the tank pressure, a normally-closed ON-OFF valve, and a thermal throttle to perform the fine control of the mass flow rate. A 1D thermal-fluid model concerning the vapor generation in the tank, and its evolution along the different components is detailed. The thermal throttle model has been experimentally verified using air as a working fluid. The model results agree with the measurements of the verification tests in the hypothesis of the presence of an extended region at the entrance of the pipe where the laminar flow velocity and temperature profiles are not fully developed (known as entry flow region). Finally, the system is experimentally characterized and the model of the full system is calibrated using experimental measurements. The calibration shows that the thermal throttle flow presents an entry flow region, that the viscosity is correctly modeled, and that there is a difference between the measured tank temperature and the effective sublimation temperature.

Experimental study on liquid distribution in a vane type propellant tank

Propellant tank is used to store the propellant in propulsion system. Propellant management device (PMD) is the key component in propellant tank to manage the liquid propellant under zero gravity. A microgravity drop tower test system was established to investigate the performance of PMD. A kind of vane type propellant tank was used for the drop tower test. Single module was used for experiment tests, and the microgravity level wass between 10-2g0 and 10-3g0. The anhydrous ethanol is used as analogue liquid. Different volume fraction of liquid were used to study influence of the PMD on the management performance. Changes of gas-liquid interface during the test are studied. Velocities flow along the vane of different liquid volume fraction in the tank are different at the beginning (t<0.8s). The liquid reorientation time is 0.8s when the liquid volume fraction is larger than 10%. The liquid reorientation time is prolong when the liquid volume fraction is less than 10%. The liquid climbing height along vane under microgravity increases as the volume fraction of liquid reduces. Experimental results provide a favorable reference for further optimization design of vane type propellant tank.

Research on Sinking Movement of Liquid Propellant in Space Vehicle

Considering the requirement of rocket engine restart on the liquid propellant location, this paper dedicates to the simulation research on sinking movement of liquid propellant in space vehicle. The extrusion, thrust and structural types of liquid propellant management for space vehicle are summarized. The numerical simulation and drop tower test are compared to study how the liquid propellant moves in the gravity environment, and the relationship between the sinking time and flight acceleration for a new-type space vehicle are provided. These results have considerable significance for the liquid propellant management and acceleration design of space vehicle.

Numerical simulation and microgravity experiment of fluid flow in the vane type tank

Propellant tank is an important component of spacecraft, which determines the life of spacecraft. As a key unit for storage and management fluid on the spacecraft, the vane type tank can provide liquid without gas for thrusters. And the propellant management device(PMD) is the core component in the tank. In the paper, numerical simulation and microgravity experiment have been carried out to study the performance of propellant management. By using a VOF two-phase flow model, the fluid behaviour in tank is numerically simulated. By microgravity drop tower tests, the fluid distribution is obtained actually. The results from numerical simulation are in good agreement with ones from the microgravity drop tower tests. It shows that the PMD of the vane type tank can availably achieve the separation between liquid and gas interface and providing liquid without gas in microgravity environment.

Simultaneous interface position and bulk velocity measurements in cryogenic sloshing

Cryogenic sloshing is of primary importance in aerospace propulsion since it can affect the dynamic stability and the propellant management during each phase of spacecraft missions. We show in this work, for the first time, that cryogenic sloshing can be investigated by means of tracer-based laser techniques, such as Particle Image Velocimetry (PIV), to obtain the liquid/gas interface and the bulk velocity both in the unsteady and steady regime. The fluid heating due to the laser interaction with the tracer particles and the possible effect on the particle-fluid slip velocity is evaluated. An experimental campaign is conducted, and both the liquid/gas interface position and the velocity maps of the bulk are obtained in time-resolved conditions. Finally, the logarithmic damping at the liquid/gas interface and in the bulk are evaluated and compared with satisfactory results to the models available in the literature.

PPU for a small, low power and low cost EPS

The objective of this paper is to present the design of the Power Processing Unit (PPU) of the Microsatellite Electric Propulsion System (MEPS) program currently being developed at Elegant Bread Board (EBB). High efficiency, small size and weight and high reliability are the main parameters that special focus is given. The propulsion system of MEPS consists of two small size and low power (up to 300W) Thruster Units (TUs) each one composed of a Hall Effect Thruster and a Cathode, a single Propellant Management and Tank Assembly (PMA/PTA) and a single PPU. The PPU designed for the EBB phase has no redundancy, is fully flexible and capable of driving two different TU types (Rafael’s CAM-200 coupled with Rafael’s Heaterless Hollow Cathode (RHHC) and SITAEL’s HT100 coupled with SITAEL’s Heated Hollow Cathode (HC1)). This paper illustrates the core design requirements and important aspects on which the design was based. Preliminary results obtained from the coupling tests on the critical parts developed at Bread Board (BB), which contributed to the current design are also briefly depicted. Last but not least, the future development steps of the program that can become the driving factor for the successful implementation of an easily adjustable PPU compatible with a wide range of low power Electric Propulsion Systems (EPSs) are demonstrated.

Numerical simulation of the vane type tank and system on-orbit refueling process

The orbital propellant management achieved by the vane type propellant tank is presented in this paper. Focusing on the research of the vane type tank of on-orbit refueling, by using a VOF (volume of fluid) two-phase flow model, the fluid behavior in microgravity environment and the flow characteristic of the refueling process in tank is numerically simulated. The fluid distributing rule is obtained. By using the system simulation software AMESim, a simulation system for orbital refueling is designed, and the refueling process is simulated on the system. The results of numerical simulation of the vane type tank and system indicate that the orbital refueling is feasible.

Numerical simulation of fluid flow in the vane type tank on orbital refuelling process

On-orbit refuelling of spacecraft is one of the main on-orbit service modes, which is the main technical means to increase the working life and improve the economic efficiency of the spacecraft. The vane type tank is one of the most advanced tanks, which can manage all of the propellant. The vane device is the form of propellant management for the low-gravity expulsion of propellant form spacecraft. The orbital propellant management is achieved by the vane type propellant tank. The fluid reorientation and refilling in space environment is the key technology of on-orbit refuelling. However, the experiment verification of the vane type in microgravity environment couldn’t be given for a long time. Therefore, numerical simulation is necessary for the study of on-orbit refueling. Focusing on the research of the vane type tank of on-orbit refueling, by using a VOF two-phase flow model, the fluid behavior in microgravity environment and the flow characteristic of the refueling process in tank is numerically simulated to research the performance of the van type tank.