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At least 109 records · Page 6

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NASA NTRS2008

Affect of Air Leakage into a Thermal-Vacuum Chamber on Helium Refrigeration Heat Load

NASA s Johnson Space Center (JSC) Building 32 houses two large thermal-vacuum chambers (Chamber A and Chamber B). Within these chambers are liquid nitrogen shrouds to provide a thermal environment and helium panels which operate at 20K to provide cryopumping. Some amount of air leakage into the chambers during tests is inevitable. This causes "air fouling" of the helium panel surfaces due to the components of the air that adhere to the panels. The air fouling causes the emittance of the helium panels to increase during tests. The increase in helium panel emittance increases the heat load on the helium refrigerator that supplies the 20K helium for those panels. Planning for thermal-vacuum tests should account for this increase to make sure that the helium refrigerator capacity will not be exceeded over the duration of a test. During a recent test conducted in Chamber B a known-size air leak was introduced to the chamber. Emittance change of the helium panels and the affect on the helium refrigerator was characterized. A description of the test and the results will be presented.

Garcia, Sam↗

NASA NTRS2008

Chamber for Aerosol Deposition of Bioparticles

Laboratory apparatus is depicted that is a chamber for aerosol deposition of bioparticles on surfaces of test coupons. It is designed for primary use in inoculating both flat and three-dimensional objects with approximately reproducible, uniform dispersions of bacterial spores of the genus Bacillus so that the objects could be used as standards for removal of the spores by quantitative surface sampling and/or cleaning processes. The apparatus is also designed for deposition of particles other than bacterial spores, including fungal spores, viruses, bacteriophages, and standard micron-sized beads. The novelty of the apparatus lies in the combination of a controllable nebulization system with a settling chamber large enough to contain a significant number of test coupons. Several companies market other nebulizer systems, but none are known to include chambers for deposition of bioparticles to mimic the natural fallout of bioparticles. The nebulization system is an expanded and improved version of commercially available aerosol generators that include nebulizers and drying columns. In comparison with a typical commercial aerosol generator, this system includes additional, higher-resolution flowmeters and an additional pressure regulator. Also, unlike a typical commercial aerosol generator, it includes stopcocks for separately controlling flows of gases to the nebulizer and drying column. To maximize the degree of uniformity of dispersion of bioaerosol, the chamber is shaped as an axisymmetrical cylinder and the aerosol generator is positioned centrally within the chamber and aimed upward like a fountain. In order to minimize electric charge associated with the aerosol particles, the drying column is made of aluminum, the drying column is in direct contact with an aluminum base plate, and three equally spaced Po-210 antistatic strips are located at the exit end of the drying column. The sides and top of the chamber are made of an acrylic polymer; to prevent accumulation of electric charge on them, they are spray-coated with an anti-static material. During use, the base plate and the sides and top of the chamber are grounded as a further measure to minimize the buildup of electric charge.

Kern, Roger↗

NASA NTRS2009

Autoignition Chamber for Remote Testing of Pyrotechnic Devices

The autoignition chamber (AIC) performs by remotely heating pyrotechnic devices that can fit the inner diameter of the tube furnace. Two methods, a cold start or a hot start, can be used with this device in autoignition testing of pyrotechnics. A cold start means extending a pyrotechnic device into the cold autoignition chamber and then heating the device until autoignition occurs. A hot start means heating the autoignition chamber to a specified temperature, and then extending the device into a hot autoignition chamber until autoignition occurs. Personnel are remote from the chamber during the extension into the hot chamber. The autoignition chamber, a commercially produced tubular furnace, has a 230-V, single-phase, 60-Hz electrical supply, with a total power output of 2,400 W. It has a 6-in. (15.2-cm) inner diameter, a 12-in. (30.4-cm) outer diameter and a 12-in.- long (30.4-cm), single-zone, solid tubular furnace (element) capable of heating to temperatures up to 2,012 F (1,100 C) in air.

Harrington, Maureen L.↗

NASA NTRS2012

Prevention of Over-Pressurization During Combustion in a Sealed Chamber

The combustion of flammable material in a sealed chamber invariably leads to an initial pressure rise in the volume. The pressure rise is due to the increase in the total number of gaseous moles (condensed fuel plus chamber oxygen combining to form gaseous carbon dioxide and water vapor) and, most importantly, the temperature rise of the gas in the chamber. Though the rise in temperature and pressure would reduce with time after flame extinguishment due to the absorption of heat by the walls and contents of the sealed spacecraft, the initial pressure rise from a fire, if large enough, could lead to a vehicle over-pressure and the release of gas through the pressure relief valve. This paper presents a simple lumped-parameter model of the pressure rise in a sealed chamber resulting from the heat release during combustion. The transient model considers the increase in gaseous moles due to combustion, and heat transfer to the chamber walls by convection and radiation and to the fuel-sample holder by conduction, as a function of the burning rate of the material. The results of the model are compared to the pressure rise in an experimental chamber during flame spread tests as well as to the pressure falloff after flame extinguishment. The experiments involve flame spread over thin solid fuel samples. Estimates of the heat release rate profiles for input to the model come from the assumed stoichiometric burning of the fuel along with the observed flame spread behavior. The sensitivity of the model to predict maximum chamber pressure is determined with respect to the uncertainties in input parameters. Model predictions are also presented for the pressure profile anticipated in the Fire Safety-1 experiment, a material flammability and fire safety experiment proposed for the European Space Agency (ESA) Automated Transfer Vehicle (ATV). Computations are done for a range of scenarios including various initial pressures and sample sizes. Based on these results, various mitigation approaches are suggested to prevent vehicle over-pressurization and help guide the definition of the space experiment.

Gokoglu, Suleyman A.↗

NASA NTRS2017

Development and Hot-fire Testing of Additively Manufactured Copper Combustion Chambers for Liquid Rocket Engine Applications

NASA and industry partners are working towards fabrication process development to reduce costs and schedules associated with manufacturing liquid rocket engine components with the goal of reducing overall mission costs. One such technique being evaluated is powder-bed fusion or selective laser melting (SLM), commonly referred to as additive manufacturing (AM). The NASA Low Cost Upper Stage Propulsion (LCUSP) program was designed to develop processes and material characterization for GRCop-84 (a NASA Glenn Research Center-developed copper, chrome, niobium alloy) commensurate with powder-bed AM, evaluate bimetallic deposition, and complete testing of a full scale combustion chamber. As part of this development, the process has been transferred to industry partners to enable a long-term supply chain of monolithic copper combustion chambers. To advance the processes further and allow for optimization with multiple materials, NASA is also investigating the feasibility of bimetallic AM chambers. In addition to the LCUSP program, NASA has completed a series of development programs and hot-fire tests to demonstrate SLM GRCop-84 and other AM techniques. NASA's efforts include a 4K lbf thrust liquid oxygen/methane (LOX/CH4) combustion chamber and subscale thrust chambers for 1.2K lbf LOX/hydrogen (H2) applications that have been designed and fabricated with SLM GRCop-84. The same technologies for these lower thrust applications are being applied to 25-35K lbf main combustion chamber (MCC) designs. This paper describes the design, development, manufacturing and testing of these numerous combustion chambers, and the associated lessons learned throughout their design and development processes.

Gradl, Paul R.↗

NASA NTRS2018

Characterizing Performance of Additively Manufacturing Regenerative Cooled Combustion Chambers Through Hot Fire Testing

NASA Marshall Space Flight Center (MSFC) has developed several additive manufactured regenerative cooled combustion chambers from 2014 to present. Chambers have been constructed using the Selective Laser Melting (SLM) powder bed additive manufacturing (AM) technique. The materials used for the chambers has varied from Inconel 718, Inconel 625, GRCop-84, and C18150 metal alloys. The surface finish and build techniques used to successfully manufacture combustion chambers using the SLM AM result in as built surface finish and off nominal geometric features. This paper discusses and reviews the effects of surface roughness, flow area, and hydraulic performance of regenerative cooled combustion chambers. The thrust chambers designs tested ranged from 200 to 1,400 psia producing 1,000 to 35,000 lbf thrust. Empirical data from four test campaigns will be reviewed and related to design modeling parameters such as pressure drop, surface roughness, and actual fluid flow geometry. Correlation results with simple 2-D CFD modeling will also be presented. The goal of the work is to better understand how the finished additive manufactured component characteristics inside internal features can effect regenerative cooling chamber design. Adjustments to design methodology will be discussed and recommended based on the above results.

Garcia, C. P.↗

NASA NTRS2016

Micro Acoustic Resonant Chambers for Heating/Agitating/Mixing (MARCHAM)

A variety of applications require the mixing and/or heating of a slurry made from a powder/fluid mixture. One of these applications, Sub Critical Water Extraction (SCWE), is a process where water and an environmental powder sample (sieved soil, drill cuttings, etc.) are heated in a sealed chamber to temperatures greater than 200 degrees Celsius by allowing the pressure to increase, but without reaching the critical point of water. At these temperatures, the ability of water to extract organics from solid particulate increases drastically. This paper describes the modeling and experimentation on the use of an acoustic resonant chamber which is part of an amino acid detection instrument called Astrobionibbler [Noell et al. 2014, 2015]. In this instrument we use acoustics to excite a fluid- solid fines mixture in different frequency/Amplitude regimes to accomplish a variety of sample processing tasks. Driving the acoustic resonant chamber at lower frequencies can create circulation patterns in the fluid and mixes the liquid and fines, while driving the chamber at higher frequencies one can agitate the fluid and powder and create a suspension. If one then drives the chamber at high amplitude at resonance heating of the slurry occurs. In the mixing and agitating cell the particle levitation force depends on the relative densities and compressibility’s of the particulate and fluid and on the kinetic and potential energy densities associated with the velocity and pressure fields [Glynne-Jones, Boltryk and Hill 2012] in the cell. When heating, the piezoelectric transducer and chamber is driven at high power in resonance where the solid/fines region is modelled as acoustic transmission line with a large loss component. In this regime, heat is pumped into the solution/fines mixture and rapidly heats the sample. We have modeled the piezoelectric transducer/chamber/ sample using Mason’s equivalent circuit. In order to assess the validity of the model we have built and tested a variety of chambers. This paper describes the experimental results which are in general agreement with theory within the limitations of the modeling.

fluid particle interaction↗

NASA NTRS2019

Additive Manufacturing and Hot-Fire Testing of Bimetallic GRCop-84 and C-18150 Channel-Cooled Combustion Chambers Using Powder Bed Fusion and Inconel 625 Hybrid Directed Energy Deposition

Additive manufacturing (AM) is an advanced fabrication technique that is demonstrating tremendous potential to reduce fabrication lead times and costs for liquid rocket engine components. The additive manufacturing technology lends itself to fabricate components with complex features such as internal coolant channels in combustion chambers that would otherwise require complex manufacturing operations. A requirement for high performance engines is to use high conductivity, high strength materials such as copper-alloys for combustion chamber liners to provide adequate wall temperatures and meet subsequent structural margins. A further requirement of this configuration is to minimize weight by defining and fabricating material in discrete locations as required. NASA and Industry partner, Virgin Orbit, have been working to advance these technologies through development of bimetallic additive manufacturing techniques under a public-private partnership through NASA’s Announcement of Collaborative Opportunity (ACO). This partnership is advancing a bimetallic hybrid additively manufactured combustion chamber that integrates Powder Bed Fusion (PBF), specifically Selective Laser Melting (SLM), and Directed Energy Deposition (DED) blown powder techniques to optimize the chamber materials and subsequent assembly. The SLM process is being developed for the combustion chamber liner to use copper-alloys GRCop-84 (Copper-Chrome-Niobium) or C-18150 (Copper-Chrome-Zirconium). The hybrid DED blown powder technology is used to apply an integrated structural jacket and manifolds using an Inconel 625 superalloy on the outer surface of the SLM copper liner. The hybrid DED technology being used on this program is a DMG Mori Seiki AM machining center which integrates the DED blown powder with an integral subtractive (traditional) machining to minimize overall setups. A series of chambers were fabricated using these techniques with GRCop-84/Inconel 625 and C-18150/Inconel and hot-fire tested at NASA Marshall Space Flight Center (MSFC) in LOX/Kerosene (RP-1). This paper describes the process development to integrate these AM technologies into an integrated bimetallic assembly, the design of the chamber, results from hot-fire testing, and further development.

Gradl, Paul R.↗

NASA NTRS2019

Additive Manufacturing and Hot-fire Testing of Bimetallic GRCop-84 and C-18150 Channel-Cooled Combustion Chambers using Powder Bed Fusion and Inconel 625 Hybrid Directed Energy Deposition

Gradl, Paul↗

NASA NTRSDate not supplied

Lightweight Thrust Chamber Composite Overwrap Lessons Learned

The manufacturing, design, and analysis of filament wound carbon fiber/polymer composite overwraps for additively manufactured, copper combustion chambers are a critical part of NASA’s Rapid Analysis and Manufacturing Propulsion Technology (RAMPT) project. Ideally, the composite overwrap acts as a light-weight structural jacket and allows significant weight reduction of the high pressure thrust chamber assembly, reduction of overall cost, and reduced fabrication schedules. Chamber assemblies for 2000 lb. (2k) and 7000 lb. (7k) of thrust have been successfully tested at NASA’s Marshall Space Flight Center. Multiple lessons were learned throughout the overwrap process development and manufacturing trials. The lessons learned on small scale hardware, such as the 2k and 7k chambers, will guide further composite manufacturing technologies and enable a progression to larger scale assemblies with greater structural loads. Material performance requirements, manufacturing process development, and surface preparation were evaluated during the small chamber trials, with the broad thermal requirements of the resin being the primary driver for material selection and processing. Both epoxy and bismaleimide (BMI) materials were evaluated with respect to both performance in the hot-fire test and ease of fabrication. Separately, surface preparation procedures were studied with the goal of providing a smooth chamber surface to promote a non-bonded overwrap. Recent testing of the 7k trust chamber has provided data in Non-Destructive Evaluation (NDE) and processing in order to continue to evaluate the performance requirements stated.

Allison Clark↗

NASA NTRSDate not supplied

Operating and Maintaining the JWST Cleanroom attached to JSC's Chamber A during preparations for the OTIS Cryogenic Thermal Vacuum Test

In order to maintain cleanliness during preparations for JWST’s OTIS (Optical Telescope Element-Integrated Science Instrument Module) Cryogenic Thermal Vacuum Test, a cleanroom was built that attached directly to the 60-year-old Chamber A. The cleanroom and chamber were outfitted with independent environmental control systems each providing ISO Class 71 air cleanliness. To maintain balanced, positive pressure in both the cleanroom and chamber volumes, a special control protocol was developed and successfully implemented. Dual back-up environmental control units (one each for the chamber and cleanroom) were installed just outside the building to provide environmental control redundancy due to a single source chilled water supply and weather threats. In addition, lack of a dedicated cleanroom airlock facilitating clean ingress and egress made it necessary to perform additional cleaning and packaging, as well as augment the uncontrolled truck lock space with small clean tents for pre-cleaning. Special procedures were developed to allow ingress of extra-large support equipment required for load testing of the cleanroom crane, installation of optical equipment in Chamber A and accommodation of the OTIS shipping container. A thorough bake-out and cleaning of Chamber A was also necessary to reduce volatiles from the shroud’s black thermal paint and to reduce particle fallout. Acrylic adhesive fracture discovered during early cryo-testing represented a significant challenge that was successfully mitigated prior to OTIS testing. A dedicated team of Contamination Control (CC) Technicians was specifically trained to clean support equipment and screen materials entering the cleanroom and chamber to ensure cleanliness and vacuum compatibility.

Optics↗

DOE OSTI2024

Scintillating Bubble Chambers for Direct Dark Matter Detection, and an Update on SBC-LAr10

The Scintillating Bubble Chamber (SBC) Collaboration aims to use the liquid-noble bubble chamber technology as a low-threshold detector for dark matter particles of 1-10 GeV/c2. The detector combines the remarkable electron recoil (ER) discrimination of the bubble chamber with the event-by-event energy resolution provided by liquid argon (LAr) scintillation, with the crucial added benefit that ER discrimination in liquid-noble bubble chambers extends to much lower thresholds than in past freon-filled bubble chambers, with the potential for quasi-background-free operation at thresholds of 100 eV in nuclear recoil (NR) energy. SBC has developed two functionally identical 10 kg detectors: SBC-LAr10 at Fermilab will calibrate low-threshold performance, while the radio-pure SBC-SNOLAB chamber will execute SBC s first deep-underground dark matter search. SBC-LAr10 at Fermilab was recently installed in the MINOS tunnel 100 meters underground, and the first bubbles are expected this fall. I will present the current status of SBC-LAr10 and describe the suite of gamma and neutron calibrations we will execute. The calibrations will confirm the physics reach of this new technology, motivating not just the SBC-SNOLAB chamber now being assembled but also future searches into the solar neutrino fog at 1 GeV/c2.

Sheng, Zhiheng↗

DOE OSTI2025

Enhancing Turbulent Mixing and Microphysical Uniformity in a Tall Convection‐Cloud Chamber Through Idealized Heterogeneity of Boundaries

A large convection cloud chamber has been proposed for exploring aerosol–cloud–drizzle interactions under well‐controlled turbulent conditions. Recent theoretical and numerical studies suggest that a convection cloud chamber with two heated and two cooled sidewalls can significantly enhance the liquid water content and thus benefit drizzle initiation. However, a chamber with such a sidewall configuration develops stable stratification and extremely weak turbulence therein. In this study, we conduct large‐eddy simulations of a tall convection chamber with five different sidewall configurations consisting of alternating warm and cold patches. For each configuration, the total surface area of warm patches equals that of cold patches, resulting in the same expected cloud‐free supersaturation based on a flux budget model. Results show that changing the sidewall configuration, while keeping all other factors constant, can substantially enhance turbulent mixing and improve the uniformity of thermodynamic and cloud microphysical properties in the bulk region of the chamber. In addition, turbulence strength is positively correlated with liquid water content and negatively correlated with cloud droplet number concentration, consistent with theoretical predictions. Our results highlight the advantage of building a large cloud chamber using modular patches with individually controllable temperature and humidity to achieve well‐mixed conditions.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2025

Benchmark study of the DTU OWC chamber with both two-way and one-way absorption

This paper reports on a benchmark study based on small-scale (1:50) measurements of a single, oscillating water column chamber mounted sideways in a long flume. The geometry of the OWC chamber is extracted from a barge-like, attenuator-type floating concept “KNSwing” with 40 chambers targeted for deployment in the Danish part of the North Sea. In addition to traditional two-way energy extraction we also consider one-way energy extraction with passive venting and compare chamber response, pressures and total absorbed energy between the two methods. A blind study was established for the numerical modeling, with participants applying several implementations of weakly nonlinear potential flow theory and commercial Navier–Stokes solvers (CFD). Both compressible and incompressible models were used for the air phase. Potential flow calculations predict more energy absorption near the chamber resonance for one-way absorption than for two-way absorption, but the opposite is found from the experimental measurements. This outcome is mainly attributed to energy losses in the experimental passive valve system, but this conclusion must be confirmed by better experimental measurements. Modeling the one-way valve in CFD proved to be very challenging and only one team was able to provide results which were generally closer to the experiments. The study illustrates the challenges associated with both numerical and experimental analysis of OWC chambers. Air compressibility effects were not found to be important at this scale, even with the large volume of additional air used for the one-way case.

16 TIDAL AND WAVE POWER↗

DOE OSTI2024

A dynamic solvent chamber propagation estimation framework using RNN for warm solvent injection in heterogeneous reservoirs

Warm solvent injection (WSI), injecting low-temperature solvent into formations to reduce the viscosity of heavy oil, is a clean technology for heavy oil production through reducing greenhouse gas emissions and water usage. The success of WSI operation depends on the uniform development and propagation of solvent chambers in reservoirs. However, reservoir heterogeneity stemming from shale barriers plays a detrimental role in the conformance of solvent chamber development and oil production rate. In this work, we developed a novel recurrent neural network (RNN)-based framework with the capability of efficiently tracking and estimating the solvent chamber positions in heterogeneous reservoirs based on only production time-series data. The developed estimation model utilizes the “sequence-to-sequence" mapping methodology to correlate observed production time-series sequence and solvent chamber edge sequence via a long short-term memory (LSTM) algorithm. The trained RNN models exhibit high accuracy, evidenced by the predicted dynamic solvent chamber locations match the corresponding true locations from numerical simulation, with a high coefficient of determination (R 2 ) and a low mean squared error. Specifically, the achieved R 2 values exceed 0.98 on both the training and testing data. The developed RNN-based workflow was tested via several cases from both regularly- and irregularly-shaped shale barriers, and the results were promising. The predicted solvent chambers showed strong agreement with those obtained from numerical simulations. The major benefits of this workflow include reducing computational time and saving overall monitoring and tracking costs for conventional techniques. In conclusion, the present work would provide a good demonstration of the capability of practical integration of machine learning methods in solving engineering problems.

58 GEOSCIENCES↗

NASA NTRS1972

Preparation, verification, and operational control of a large space-environment-simulation chamber for contamination sensitive tests

A 2-year program to prepare chamber A at the NASA Manned Spacecraft Center for Apollo telescope mount thermal-vacuum tests is discussed. This program covers modification to existing chamber systems, the development of facility and chamber operating procedures, the selection of chamber cleaning and control methods, and the development and evaluation of diagnostic instrumentation. Extensive efforts to ensure a minimum contamination environment for the Apollo telescope mount test series are illustrated. Recent thermal-vacuum tests of this chamber at progressive stages of cleanliness have demonstrated the success achieved in reducing the particulate and molecular contamination levels of the basic chamber interior.

Visentine, J. T.↗

NASA NTRS1972

Development of boron epoxy rocket motor chambers.

A 71 cm diameter 74 cm length boron/epoxy composite rocket motor chamber was designed based on the geometric configuration of the JPL Applications Technology Satellite titanium alloy apogee motor chamber. Because analyses showed large stress concentrations in the domes, the configuration was modified using the same basic constraints for openings and attachments. The rocket motor chamber was then fabricated by filament winding with boron/epoxy tape and hydrostatically tested to failure at 264 N/sq cm, 57.2 N/sq cm above the design value. Two more rocket motor chambers were fabricated with the same basic constraints, but shortened to 57.6 cm for a smaller propellant load. The first of these short chambers failed in proof because of filament winding fabrication difficulties. The second chamber was successfully fabricated and passed the hydrostatic proof test.

Jensen, W. M.↗

NASA NTRS1973

Development of advanced composite rocket motor chambers using boron and graphite fibers.

Four 71-cm-diameter rocket motor chambers were designed and fabricated with advanced composite materials. The first three chambers were filament wound from boron/epoxy tape, and the fourth from graphite/epoxy tape. The first boron/epoxy chamber was 74 cm in length and was successfully hydroburst tested. The other three chambers were 57.6 cm in length for a smaller propellant load. The first shortened boron/epoxy chamber failed in proof test as a result of fabrication deficiencies. The last boron/epoxy and the graphite/epoxy chambers were successfully proof tested.

Jensen, W. M.↗