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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Integrated System for Health Management and Autonomous Control (ISHM-AC) for Cryogenic Operations on the Simulated Propellant Loading System

Autonomous control systems represent a technological barrier from manual and automated operated control systems in an industry wide application. An increase in energy-efficient storage, transfer and use of cryogens and cryogenic propellants on Earth and in space has been observed in space related industries between NASA, government and commercial programs. An increase in efficiency of cryogenic systems demands an increase in the capabilities of the control and monitoring system that manages them. As new technologies are developed for cryogenic systems, complexity and capability increases. The increase in complexities are a natural drive to develop better and more capable health monitoring and control system management. Current research and development efforts lead the Cryogenics Test Laboratory at the Kennedy Space Center to improve its automated control and health monitoring system from a Programmable Logic Control (PLC) based-only system to a fully Integrated System for Health Management (ISHM) - Autonomous Control (AC) capable of performing autonomous operations on a cryogenic propellant transfer system. This ISHM-AC system has been developed and tested by controlling a complete simulated propellant transfer operation. The capabilities and test results of this fully integrated autonomous system for cryogenics propellant transfer operation will be presented in this paper.

Toro Medina, Jaime A.↗
NASA NTRS2016

Wave Amplitude Dependent Engineering Model of Propellant Slosh in Spherical Tanks

Liquid propellant slosh is often a concern for the controllability of flight vehicles. Anti-slosh devices are traditionally included in propellant tank designs to limit the amount of sloshing allowed during flight. These devices and any necessary supports can be quite heavy to meet various structural requirements. Some of the burden on anti-slosh devices can be relieved by exploiting the nonlinear behavior of slosh waves in bare smooth wall tanks. A nonlinear regime slosh model for bare spherical tanks was developed through a joint analytical and experimental effort by NASA/MSFC. The developed slosh model accounts for the large damping inherent in nonlinear slosh waves which is more accurate and drives conservatism from vehicle stability analyses that use traditional bare tank slosh models. A more accurate slosh model will result in more realistic predicted slosh forces during flight reducing or removing the need for active controls during a maneuver or baffles in the tank design. Lower control gains and smaller or fewer tank baffles can reduce cost and system complexity while increasing vehicle performance. Both Computational Fluid Dynamics (CFD) simulation and slosh testing of three different spherical tank geometries were performed to develop the proposed slosh model. Several important findings were made during this effort in addition to determining the parameters to the nonlinear regime slosh model. The linear regime slosh damping trend for spherical tanks reported in NASA SP-106 was shown to be inaccurate for certain regions of a tank. Additionally, transition to the nonlinear regime for spherical tanks was only found to occur at very large wave amplitudes in the lower hemisphere and was a strong function of the propellant fill level in the upper hemisphere. The nonlinear regime damping trend was also found to be a function of the propellant fill level.

Brodnick, Jacob↗
NASA NTRS2011

The Effects of Propellant Slosh Dynamics on the Solar Dynamics Observatory

The Solar Dynamics Observatory (SDO) mission, which is part of the Living With a Star program, was successfully launched and deployed from its Atlas V launch vehicle on February 11, 2010. SDO is an Explorer-class mission now operating in a geosynchronous orbit (GEO). The basic mission is to observe the Sun for a very high percentage of the 5-year mission (10-year goal) with long stretches of uninterrupted observations and with constant, high-data-rate transmission to a dedicated ground station located in White Sands, New Mexico. A significant portion of SDO's launch mass was propellant, contained in two large tanks. To ensure performance with this level of propellant, a slosh analysis was performed. This paper provides an overview of the SDO slosh analysis, the on-orbit experience, and the lessons learned. SDO is a three-axis controlled, single fault tolerant spacecraft. The attitude sensor complement includes sixteen coarse Sun sensors, a digital Sun sensor, three two-axis inertial reference units, two star trackers, and four guide telescopes. Attitude actuation is performed either using four reaction wheels or eight thrusters, depending on the control mode, along with single main engine which nominally provides velocity-change thrust. The attitude control software has five nominal control modes: three wheel-based modes and two thruster-based modes. A wheel-based Safehold running in the Attitude Control Electronics (ACE) box improves the robustness of the system as a whole. All six modes are designed on the same basic proportional-integral-derivative attitude error structure, with more robust modes setting their integral gains to zero. To achieve and maintain a geosynchronous orbit for a 2974-kilogram spacecraft in a cost effective manner, the SDO team designed a high-efficiency propulsive system. This bi-propellant design includes a 100-pound-force main engine and eight 5-pound-force attitude control thrusters. The main engine provides high specific impulse for the maneuvers to attain GEO, while the smaller Attitude Control System (ACS) thrusters manage the disturbance torques of the larger main engine and provide the capability for much smaller orbit adjustment burns. SDO's large solar profile produces a large solar torque disturbance and momentum buildup. This buildup drives the frequency of momentum unloads via ACS thrusters. SDO requires 1409 kilograms (which is approximately half the launch mass) of propellant to achieve and maintain the GEO orbit while performing the momentum unloads for 10 years.

Mason, Paul↗
NASA NTRS2019

Simulations of the Mars Helicopter Test Propeller in Hover Configuration at Martian Pressure and Air Density

In order to properly validate experimental data, a theoretical model must be generated and converge with the results. Providing possible results for future testing can help experimenters better understand the results they are getting. Certain effects cannot be shown during experimentation, and must therefore be quantified through another means. The Mars Helicopter is currently being tested in the N242 wind tunnel at NASA Ames Research Center, which can reach a density and pressure similar to Mars. A test propeller was analyzed in a computational fluid dynamics solver. The propeller blades were previously modeled, and were simulated in the full experimental setup, which includes the blast shields, rotor stand and tunnel walls, to thoroughly generate the effects of the true testing conditions. Simulations were run using both an isolated hover condition and with the full setup, and results for thrust and total power were quantified. The data generated was used to quantify the impact of the facility on the propeller. These calculations will ultimately be used to help separate these effects from the actual thrust the propeller will generate, this making the data more accurate.

Wagner, Lauren N.↗
NASA NTRS2019

Gradient-Based Propeller Optimization with Acoustic Constraints

Urban Air Mobility vehicles are intended to operate near or within large cities, where a significant portion of the public will be exposed to the noise they create. If these vehicles are to become acceptable to the public, designers must be able to manage the amount of noise they generate, and understand the relationship between traditional performance metrics (thrust, efficiency, etc.) and noise. As a first step to addressing this need, this work combines a blade element momentum theory tool (OpenBEMT) with an acoustic prediction tool (ANOPP2) to optimize a propeller subject to both aerodynamic and acoustic constraints. These tools are developed within a optimization framework (OpenMDAO) that allows analytic derivatives to be propagated through the models and passed to a gradient-based optimizer. This tool chain is exercised on the cruise propellers from the X-57 Maxwell, and yields propeller designs that reduced the overall sound pressure level by about 5 dB for a cost of 1% propeller efficiency.

Ingraham, Daniel↗
NASA NTRS2019

Assessment of MON-25/MMH Propellant System for Deep-Space Engines

Hypergolic propellant system of oxidizer MON-25 and fuel MMH has been considered in propulsion trade studies for NASA science mission concepts. A propulsion system using this bi-propellant combination will be capable of operating at a lower temperature as compared to traditional MON-3/MMH for heater power reduction. Operation robustness can also be realized since such a propellant system is utilized under a wide range of temperatures. Propulsion system designs and engine test programs for MON-25/MMH have been carried out since 2008. Several engine development programs have been conducted. The thrust classes of 22-Newton [5-lb(sub f)] and 445-Newton [100-lb(sub f)] were tested with the capability of a pulse mode operation for a wide range of duty cycles. Additional engine development tests are followed. Outcomes of the development efforts suggest that there is a balance of mission benefits and potential engine design and operation challenges, although the propellants can handle a low temperature. This paper will report an assessment of using the MON-25/MMH system for deep- space application.

Trinh, Huu P.↗
NASA NTRSDate not supplied

How the Allocation of Lander Functions Impacts Human Lunar Exploration Architecture Propellant Demands

As NASA looks to the moon as a proving ground for the technologies required to conduct the first human exploration campaign of Mars, this study assesses the potential propellant demands that a sustained human lunar presence would require. In particular, this study evaluates how the allocation and distribution of vehicle functions to a different number of vehicles can impact the propellant required to conduct a human lunar exploration mission. Four different transportation architectures for human lunar exploration and three different refueling assumptions were defined. The impact on the propellant required for a mission was assessed for all architectures and refueling assumptions for ranges of crew payload mass, vehicle inert mass fraction, and a sensitivity to the mission maneuver velocity magnitudes. The results of this analysis show that aggregating vehicle functions to a single-stage lander vehicle can have a positive impact on the architecture's level of vehicle reusability and that an increase in the number of refueling opportunities reduces the mass of the vehicles and of the propellant required per mission.

Matteo A. Clark↗
NASA NTRS2019

SPARROW: A Steam Propelled Autonomous Retrieval Robot for Ocean Worlds

This paper presents the results of a NIAC Phase I study into the use of a propulsively hopping robot for the exploration of Europa’s rugged, icy surface. Named the“Steam Propelled Retrieval Robot for Ocean Worlds,” SPARROW is a multi-thruster robot passively gimballed within a protective, spherical shell, which enables it to freely rotate, self-right, and tumble over chaotic terrains. SPARROW is envisioned as a soccerball-sized payload to a primary lander mission. Europa’s abundant surface ice would be harvested as an in situ propellant source. The principal objective of SPARROW would be to increase the science return of a Europa landed asset by enabling access to distal, spatially distributed geologic units. The design of mobility systems for Europa is challenging, due in part to its almost entirely unconstrained surface topography and strength. Images returned by Voyager and Galileo yielded resolutions on the order of hundreds of meters per pixel, with localized regions reaching 6 meters per pixel—still far larger than a typical rover. A key benefit of SPARROW’s hopping, impact-tolerant design, is that it eliminates the need for a piori information on the terrain topography and surface strength; no surface reaction forces are required for motion. In this context, SPARROW is entirely terrain agnostic. In this paper we detail the results of three study objectives: i) to quantify the energy required to collect surface ice, change its phase, and maintain propellant temperature, ii) to identify control and estimation strategies that enable SPARROW to successfully reach, and return from, regions of scientific interest, and iii) to characterize the impact of SPARROW’s range on likely science return. Five water-based propellant architectures are presented alongside their mass, power, and volume requirements. Monte Carlo simulations of SPARROW hopping and tumbling over 1 km of glacial ice are summarized, characterizing SPARROW’s sensitivity to uncertainty in: initial conditions, thrust control, and cage-terrain interaction. Finally, a science traceability matrix is presented, which details the effect of sortie range on three science goals: constraining Europa’s evolutionary morphology, assessing sub-surface ocean habitability, and searching for life and/or biosignatures.

Phillips, Cynthia↗
NASA NTRSDate not supplied

Validation of Cryogenic Propellant Tank Self-Pressurization

NASA’s near-future long-term space missions necessitate advancements in cryogenic fluid management (CFM), which includes safe and reliable long-term propellant storage. Consequently, NASA STMD (Space Technology Mission Directorate) has established the CFM Portfolio Project to improve CFM technologies for upcoming missions. As a part of CFM Modeling Portfolio, NASA Marshall Space Flight Center’s (MSFC) Fluid Dynamics branch within the Propulsion Systems Department is tasked with assessing and improving computational tools used to support flight projects such as Human Lander System and Commercial Lunar Payload Services. One of the challenging modeling problems is that of self-pressurization of propellant tank due to heat leakage over long time periods. Reduced order and nodal tools find it extremely difficult to accurately predict self-pressurization under transient conditions or where complex flow patterns or thermal gradients exist, and application of 3-D CFD (computational fluid dynamics) simulations is necessary to characterize these problems. Until recently, CFD simulations for these long-term processes (order of hours or days) have been too impractical to conduct due to prohibitive wall time and computational resource requirements. The requisite CFD tool need to be efficient, computationally scalable, modular with ability to incorporate various physics models, and robust enough to not accumulate conservation errors over several hours of simulated time. NASA MSFC’s Loci-Stream CFD tool along with the VOF module is a great candidate to fit this mold. In this paper, we validate Loci-Stream for predicting self-pressurization of a flight scale propellant tank so it can serve as a reliable design and analysis tool for NASA’s CFM application needs. Liquid hydrogen tank pressurization tests carried out at the K-site testing facility provide a reliable data set for this purpose. These tests were simulated using Loci-Stream solver with VOF module as well as a hybrid approach which uses a lumped model for the ullage gas domain and CFD simulation of the liquid propellant. Both are shown to have very good predictive capabilities over multiple K-site experiments.

Hong Q. Yang↗
NASA NTRSDate not supplied

Validation of Cryogenic Propellant Tank Self-Pressurization

NASA's near-future long-term space missions necessitate advancements in cryogenic fluid management (CFM), which includes safe and reliable long-term propellant storage. Consequently, NASA STMD (Space Technology Mission Directorate) has established the CFM Portfolio Project to improve CFM technologies for upcoming missions. As a part of CFM Modeling Portfolio, NASA Marshall Space Flight Center's (MSFC) Fluid Dynamics branch within the Propulsion Systems Department is tasked with assessing and improving computational tools used to support flight projects such as Human Lander System and Commercial Lunar Payload Services. One of the challenging modeling problems is that of self-pressurization of propellant tank due to heat leakage over long time periods. Reduced order and nodal tools find it extremely difficult to accurately predict self-pressurization under transient conditions or where complex flow patterns or thermal gradients exist, and application of 3-D CFD (computational fluid dynamics) simulations is necessary to characterize these problems. Until recently, CFD simulations for these long-term processes (order of hours or days) have been too impractical to conduct due to prohibitive wall time and computational resource requirements. The requisite CFD tool need to be efficient, computationally scalable, modular with ability to incorporate various physics models, and robust enough to not accumulate conservation errors over several hours of simulated time. NASA MSFC's Loci-Stream CFD tool along with the VOF module is a great candidate to fit this mold. In this paper, we validate Loci-Stream for predicting self-pressurization of a flight scale propellant tank so it can serve as a reliable design and analysis tool for NASA's CFM application needs. Liquid hydrogen tank pressurization tests carried out at the K-site testing facility provide a reliable data set for this purpose. These tests were simulated using Loci-Stream solver with VOF module as well as a hybrid approach which uses a lumped model for the ullage gas domain and CFD simulation of the liquid propellant. Both are shown to have very good predictive capabilities over multiple K-site experiments.

cryogenic fluid management↗
NASA NTRSDate not supplied

Modeling of A Large-Scale Liquid Oxygen Propellant Transfer Test

Current planned NASA missions to the Moon and Mars involve the transfer of cryogenic propellants in orbit. Correctly predicting the flow rate during the propellant transfer operation could help with planning these operations. In lieu of expensive tests conducted on-orbit, accurate predictive computational models of these propellant transfer processes can be used to predict the propellant transfer flow rate. To gain confidence in these computational models, appropriate anchoring and validation to experimental data can be performed. Ground tests conducted at SpaceX involving the transfer of liquid oxygen were carried out to investigate the effect of the thermodynamic conditions including inlet pressure and temperature and downstream pressure on the flow rate. The results from the test were compared against flow rate predictions from a commercially available two-phase flow software. On average the model predicted the flow rates within 10% of the experimentally observed flow rates for the full range of thermodynamic inlet and outlet conditions.

Daniel Hauser↗
NASA NTRSDate not supplied

Validation of a Computational Fluid Dynamics Model of Axial Jet Mixing for Cryogenic Propellant Tank Pressure Control

The Fluid Dynamics Branch at the NASA Marshall Space Flight Center is preparing to support flight programs through analysis of a variety of cryogenic fluid management (CFM) applications. Many vehicles being considered for future manned missions to the moon and beyond use chemical or nuclear thermal propulsion systems that rely on cryogenic propellants. Storing cryogenic propellants for later use is a challenge, though. Many areas of active CFM research, testing, and design involve propellant conditioning to ensure propellant remains a usable liquid for propulsion. Multiple technologies may be used to achieve adequate conditioning including the subject of this paper, a jet-based mixer. Mixing serves to homogenize fluid temperatures and decrease ullage pressure. Development and validation of a modeling methodology for jet-based mixing was conducted to prepare for in-line design work.

Jacob M Brodnick↗
NASA NTRSDate not supplied

Validation of a Computational Fluid Dynamics Model of Axial Jet Mixing for Cryogenic Propellant Tank Pressure Control

The Fluid Dynamics Branch at the NASA Marshall Space Flight Center is preparing to support flight programs through analysis of a variety of cryogenic fluid management (CFM) applications. Many vehicles being considered for future manned missions to the moon and beyond use chemical or nuclear thermal propulsion systems that rely on cryogenic propellants. Storing cryogenic propellants for later use is a challenge, though. Many areas of active CFM research, testing, and design involve propellant conditioning to ensure propellant remains a usable liquid for propulsion. Multiple technologies may be used to achieve adequate conditioning including the subject of this paper, a jet-based mixer. Mixing serves to homogenize fluid temperatures and decrease ullage pressure. Development and validation of a modeling methodology for jet-based mixing was conducted to prepare for in-line design work.

Jacob M. Brodnick↗
NASA NTRS2024

Solid-State Thermodynamic Vent System (STVS) for Control of Cryogenic Propellants

A Solid-State Thermodynamic Vent System (STVS) is a novel Cryogenic Fluid Management (CFM) technology for spacecraft cryogenic propellant tanks that may reduce boiloff while providing greater control over the propellant condition. By exploiting the vacuum-induced cryocooling (VIC) potential of cryogen-saturated silica aerogel material, an internal STVS heat exchanger (HX) can expel some sacrificial cryogenic propellant to the vacuum of space to produce cooling within the storage tank. This cooling is transferred directly to the stored fluid, thereby reducing boiloff and increasing hold times. Testing proved the effectiveness of the concept by reducing the liquid nitrogen (LN 2 ) boiloff rate and tank pressure by roughly 70% and 77%, respectively, during a single pump-down cycle, which sacrificed around 1.8 kg of propellant.

Cryogenic Fluid↗
NASA NTRS2024

Nodal Modeling of Liquid Propellant Feed and Pressurization System

Nodal or network flow modeling plays an important role in the design and operation of the feed and pressurization system of a liquid rocket engine. Model development and execution time is relatively short for nodal codes in comparison to the Navier-Stokes based CFD codes. Nodal models also allow the inclusion of several components into one model to predict the behavior of a larger system. Unlike CFD models, the nodal models do not need very fine discretization of the flow field because they use empirical correlations to model fluid friction and heat transfer. This paper presents several applications of nodal modeling of liquid propellant feed and pressurization systems using the Generalized Fluid System Simulation Program (GFSSP), a nodal code developed at NASA/ Marshall Space Flight Center. GFSSP discretizes the flow field into nodes which are connected by branches. The mass and energy conservation equations and the equation of state are solved to calculate pressure, temperature, and resident mass at the nodes. The momentum equations are solved at the branches to calculate flow rates. Applications include a) tank pressurization by inert gas as well as autogenous pressurization by gaseous propellant, b) submerged pressurization by helium, c) self-pressurization due to boil-off of cryogenic propellant, d) chilldown of a transfer line of a cryogenic propellant feed system, and e) chilldown and filling of a cryogenic tank. Each of the above-mentioned models was verified and validated by comparing with test data.

Nodal Model↗
NASA NTRSDate not supplied

Identification and Computation of Individual Propeller Acoustics of the Joby Aviation Aircraft

The individual propeller sources of the Joby Aviation aircraft are separated using an order tracking filter on measurement data and computed using high- fidelity computational fluid dynamics (CFD) to quantify the relative contributions to the total noise. Computational results are verified against experimental data for hover and steady level flight at 60 knots and demonstrate very good agreement of both overall sound pressure level magnitude and directivity. The propeller source separation for hover shows good agreement between the methods except for the inboard propellers, and it is expected that the assumptions in the CFD model do not accurately capture the flight test condition. Both methods are able to separate the higher tonal levels generated by the tail propellers due to the aerodynamic interaction. Overall, considering the discrepancies between the CFD model and flight test, the agreement in Vold-Kalman-filtered results and prediction yields confidence that the separation method is successful.

eVTOL↗
NASA NTRSDate not supplied

Propeller Source Noise Separation from Flight Test Measurements of the Joby Aviation Aircraft

The Vold-Kalman order-tracking filter is applied to full-scale acoustic flight test measurements of the Joby Aviation eVTOL aircraft. Using synchronized acquisition of the aircraft position, time-varying rotation rates of each propeller, and any given single-channel acoustic signal, harmonic and nonharmonic acoustic content can be separated. Furthermore, this time-domain technique can also separate harmonic content amongst individual propellers, providing additional physical insight into the total acoustic field. A 60 kt level flyover and hover are used to exemplify the effectiveness of the method. Results clearly demonstrate the ability to rank propulsors in terms of their relative importance without the use of phased arrays. Frequency- and order-domain results are provided, as well as noise hemispheres to illustrate directivity and individual propeller contributions. Differences can be associated with interactional or installation effects due to the similarities in propeller states for each condition. Simulated signals that track the measured time-varying shaft rates were used to assess the proper filter pole count and bandwidth.

evtol↗
NASA NTRS2024

Nodal Modeling of Liquid Propellant Feed and Pressurization System

Nodal or network flow modeling plays an important role in the design and operation of the feed and pressurization system of a liquid rocket engine. Model development and execution time is relatively short for nodal codes in comparison to the Navier-Stokes based CFD codes. Nodal models also allow the inclusion of several components into one model to predict the behavior of a larger system. Unlike CFD models, the nodal models do not need very fine discretization of the flow field because they use empirical correlations to model fluid friction and heat transfer. This paper presents several applications of nodal modeling of liquid propellant feed and pressurization systems using the Generalized Fluid System Simulation Program (GFSSP), a nodal code developed at NASA/ Marshall Space Flight Center. GFSSP discretizes the flow field into nodes which are connected by branches. The mass and energy conservation equations and the equation of state are solved to calculate pressure, temperature, and resident mass at the nodes. The momentum equations are solved at the branches to calculate flow rates. Applications include a) tank pressurization by inert gas as well as autogenous pressurization by gaseous propellant, b) submerged pressurization by helium, c) self-pressurization due to boil-off of cryogenic propellant, d) chilldown of a transfer line of a cryogenic propellant feed system, and e) chilldown and filling of a cryogenic tank. Each of the above-mentioned models was verified and validated by comparing with test data.

Nodal Model↗