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At least 739 records · Page 41

Review and test of chilldown methods for space-based cryogenic tanks

The literature for tank chilldown methods applicable to cryogenic tankage in the zero gravity environment of earth orbit is reviewed. One method is selected for demonstration in a ground based test. The method selected for investigation was the charge-hold-vent method which uses repeated injection of liquid slugs, followed by a hold to allow complete vaporization of the liquid and a vent of the tank to space vacuum to cool tankage to the desired temperature. The test was conducted on a 175 cubic foot, 2219 aluminum walled tank weighing 329 pounds, which was previously outfitted with spray systems to test nonvented fill technologies. To minimize hardware changes, a simple control-by-pressure scheme was implemented to control injected liquid quantities. The tank cooled from 440 R sufficiently in six charge-hold-vent cycles to allow a complete nonvented fill of the test tank. Liquid hydrogen consumed in the process is estimated at 32 pounds.

Chato, David J.↗

Effect of orifice length-diameter ratio on the coefficient of discharge of fuel-injection nozzles

The variation of the coefficient of discharge with the length-diameter ratio of the orifice was determined for nozzles having single orifice 0.008 and 0.020 inch in diameter. Ratios from 0.5 to 10 were investigated at injection pressures from 500 to 5,000 pounds per square inch. The tests showed that, within the error of the observation, the coefficients were the same whether the nozzles were assembled at the end of a constant tube or in an automatic injection valve having a plain stem.

Gelalles, A G↗

Evaluation of Impinging Stream Vortex Chamber Concepts for Liquid Rocket Engine Applications

To pursue technology developments for future launch vehicles, NASA/Marshall Space Flight Center (MSFC) is examining vortex chamber concepts for liquid rocket engine applications. Past studies indicated that the vortex chamber schemes potentially have a number of advantages over conventional chamber methods. Due to the nature of the vortex flow, relatively cooler propellant streams tend to flow along the chamber wall. Hence, the thruster chamber can be operated without the need of any cooling techniques. This vortex flow also creates strong turbulence, which promotes the propellant mixing process. Consequently, the subject chamber concepts not only offer the system simplicity, but they also would enhance the combustion performance. The test results showed that the chamber performance was markedly high even at a low chamber length-to-diameter ratio (L/D). This incentive can be translated to a convenience in the thrust chamber packaging. Variations of the vortex chamber concepts have been introduced in the past few decades. These investigations include an ongoing work at Orbital Technologies Corporation (ORBITEC). By injecting the oxidizer tangentially at the chamber convergence and fuel axially at the chamber head end, Knuth et al. were able to keep the wall relatively cold. A recent investigation of the low L/D vortex chamber concept for gel propellants was conducted by Michaels. He used both triplet (two oxidizer and one fuel orifices) and unlike impinging schemes to inject propellants tangentially along the chamber wall. Michaels called the subject injection scheme as Impinging Stream Vortex Chamber (ISVC). His preliminary tests showed that high performance, with an Isp efficiency of 92%, can be obtained. MSFC and the U.S. Army are jointly investigating an application of the ISVC concept for the cryogenic oxygen/hydrocarbon propellant system. This vortex chamber concept is currently tested with gel propellants at AMCOM at Redstone Arsenal, Alabama. A version of this concept for the liquid oxygen (LOX)/hydrocarbon fuel (RPM) system has been derived from the one for the gel propellant.

Trinh, Huu P.↗

Computational Fluid Dynamics Simulation of Dual Bell Nozzle Film Cooling

Marshall Space Flight Center (MSFC) and Armstrong Flight Research Center (AFRC) are working together to advance the technology readiness level (TRL) of the dual bell nozzle concept. Dual bell nozzles are a form of altitude compensating nozzle that consists of two connecting bell contours. At low altitude the nozzle flows fully in the first, relatively lower area ratio, nozzle. The nozzle flow separates from the wall at the inflection point which joins the two bell contours. This relatively low expansion results in higher nozzle efficiency during the low altitude portion of the launch. As ambient pressure decreases with increasing altitude, the nozzle flow will expand to fill the relatively large area ratio second nozzle. The larger area ratio of the second bell enables higher Isp during the high altitude and vacuum portions of the launch. Despite a long history of theoretical consideration and promise towards improving rocket performance, dual bell nozzles have yet to be developed for practical use and have seen only limited testing. One barrier to use of dual bell nozzles is the lack of control over the nozzle flow transition from the first bell to the second bell during operation. A method that this team is pursuing to enhance the controllability of the nozzle flow transition is manipulation of the film coolant that is injected near the inflection between the two bell contours. Computational fluid dynamics (CFD) analysis is being run to assess the degree of control over nozzle flow transition generated via manipulation of the film injection. A cold flow dual bell nozzle, without film coolant, was tested over a range of simulated altitudes in 2004 in MSFC's nozzle test facility. Both NASA centers have performed a series of simulations of that dual bell to validate their computational models. Those CFD results are compared to the experimental results within this paper. MSFC then proceeded to add film injection to the CFD grid of the dual bell nozzle. A series of nozzle pressure ratios and film coolant flow rates are investigated to determine the effect of the film injection on the nozzle flow transition behavior. The results of this CFD study of a dual bell with film injection are presented in this paper.

Braman, Kalen↗

Effects of unsteady shock impingement on high-speed gaseous mixing

Tests are performed to determine the effects of impinging oscillating shocks of different frequencies on a 15 deg downstream angled, underexpanded, sonic helium jet injected into a supersonic airflow. Information on mixing, penetration, total pressure loss, and turbulence structure from these tests is employed to estimate mixing control achieved by adding an oscillating shock to the helium injection flow field. The principal result of this study is that impingement of an oscillating shock on a high-speed shear layer can be utilized to control the rate of mixing.

Wood, C. W.↗

Impact of Flight Enthalpy, Fuel Simulant, and Chemical Reactions on the Mixing Characteristics of Several Injectors at Hypervelocity Flow Conditions

The high total temperatures or total enthalpies required to duplicate the high-speed flight conditions in ground experiments often place stringent requirements on the material selection and cooling needs for the test articles and intrusive flow diagnostic equipment. Furthermore, for internal flows, these conditions often complicate the use of nonintrusive diagnostics that need optical access to the test section and interior portions of the flowpath. Because of the technical challenges and increased costs associated with experimentation at high values of total enthalpy, an attempt is often made to reduce it. This is the case for the Enhanced Injection and Mixing Project (EIMP) currently underway in the Arc-Heated Scramjet Test Facility at the NASA Langley Research Center. The EIMP aims to investigate supersonic combustion ramjet (scramjet) fuel injection and mixing physics, improve the understanding of underlying physical processes, and develop enhancement strategies and functional relationships between mixing performance and losses relevant to flight Mach numbers greater than 8. The experiments will consider a "direct-connect" approach and utilize a Mach 6 nozzle to simulate the combustor entrance flow of a scramjet engine. However, while the value of the Mach number is matched to that expected at the combustor entrance in flight, the maximum value of the total enthalpy for these experiments is limited by the thermal-structural limits of the uncooled experimental hardware. Furthermore, the fuel simulant is helium, not hydrogen. The use of "cold" flows and non-reacting mixtures of fuel simulants for mixing experiments is not new and has been extensively utilized as a screening technique for scramjet fuel injectors. In this study, Reynolds-averaged simulations are utilized (RAS) to systematically verify the implicit assumptions used by the EIMP. This is accomplished by first performing RAS of mixing for two injector configurations at planned nominal experimental conditions. The mixing parameters of interest, such as mixing efficiency and total pressure recovery, are then computed and compared to the values obtained from RAS under the true enthalpy conditions and using helium and hydrogen. Finally, the impact of combustion on mixing, often deemed small enough to neglect at hypervelocity conditions, is assessed by comparing the results obtained from the hydrogen-fueled reacting and non-reacting RAS. For reacting flows, in addition to mixing efficiency and total pressure recovery, the combustion efficiency and thrust potential are also considered. In all of the simulations, the incoming air Mach number and the fuel-to-air ratio are the same, while the total pressure, total enthalpy, and the fuel simulant vary depending on the case considered. It is found that under some conditions the "cold" flow experiments are a good approximation of the flight.

Drozda, Tomasz G.↗

Liquid Transfer Cryogenic Test Facility: Initial hydrogen and nitrogen no-vent fill data

The Liquid Transfer Cryogenic Test Facility is a versatile testbed for ground-based cryogenic fluid storage, handling, and transfer experimentation. The test rig contains two well instrumented tanks, and a third interchangeable tank, designed to accommodate liquid nitrogen or liquid hydrogen testing. The internal tank volumes are approx. 18, 5, and 1.2 cu. ft. Tank pressures can be varied from 2 to 30 psia. Preliminary no vent fill tests with nitrogen and hydrogen were successfully completed with the test rig. Initial results indicate that no vent fills of nitrogen above 90 percent full are achievable using this test configuration, in a 1-g environment, and with inlet liquid temperatures as high as 143 R, and an average tank wall temperature of nearly 300 R. This inlet temperature corresponds to a saturation pressure of 19 psia for nitrogen. Hydrogen proved considerably more difficult to transfer between tanks without venting. The highest temperature conditions resulting in a fill level greater than 90 percent were with an inlet liquid temperature of 34 R, and an estimated tank wall temperature of slightly more than 100 R. Saturation pressure for hydrogen at this inlet temperature is 10 psia. All preliminary no vent fill tests were performed with a top mounted full cone nozzle for liquid injection. The nozzle produces a 120 degree conical droplet spray at a differential pressure of 10 psi. Pressure in the receiving tank was held to less than 30 psia for all tests.

Moran, Matthew E.↗

Shock Tunnel Studies of Scramjet Phenomena

Work focussed on a large number of preliminary studies of supersonic combustion in a simple combustion duct - thrust nozzle combination, investigating effects of Mach number, equivalence ratio, combustor divergence, fuel injecting angle and other parameters with an influence on the combustion process. This phase lasted for some three or four years, during which strongest emphasis was placed on responding to the request for preliminary experimental information on high enthalpy effects, to support the technology maturation activities of the NASP program. As the need for preliminary data became less urgent, it was possible to conduct more systematic studies of high enthalpy combustion phenomena, and to initiate other projects aimed at improving the facilities and instrumentation used for studying scramjet phenomena at high enthalpies. The combustion studies were particularly directed towards hypersonic combustion, and to the effects of injecting fuel along the combustion chamber wall. A substantial effort was directed towards a study of the effect of scale on the supersonic combustion process. The influence of wave phenomena (both compression waves and expansion waves) on the realization of thrust from a supersonic combustion process was also investigated. The effect of chemical kinetics was looked into, particularly as it affected the composition of the test flow provided by a ground facility. The effect of injection of the fuel through wall orifices was compared with injection from a strut spanning the stream, and the effect of heating the fuel prior to injection was investigated. Studies of fuel-air mixing by shock impingement were also done, as well as mass spectrometer surveys of a combustion wake. The use of hypersonic nozzles with an expansion tube was investigated. A new method was developed for measuring the forces acting of a model in less than one millisecond. Also included in this report are listings of published journal papers and conference presentations.

Stalker, R. J.↗

Assessment of Carbonated Brine Injection as Low-risk Strategy for Geologic Carbon Storage

The main objective of this early-phase research was to evaluate the techno-economic feasibility and risk associated with combined brine and CO 2 storage in SWD wells using brine dissolution in the North Dakota portion of the Williston Basin. Three simulation studies were conducted to investigate: (1) CO 2 phases at different conditions, (2) wellbore compatibility, and (3) long-term storage fate in reservoir. (1) A simple reservoir model and injection simulations were created using data to represent the BEST (brine extraction and storage test) site, an operational SWD facility located near Watford City, North Dakota. The pressure evolution caused by CO 2 comingled in produced water injectate in a layer cake reservoir was then modeled while tracking aqueous CO 2 throughout the project. The salinity of the injection water, the salinity of the reservoir brine, and the amount of dissolved CO 2 comingled in the injection water were varied. (2) A wellbore corrosion model was performed using the CO 2 concentrations selected based on the reservoir modeling to examine the carbonated produced water impact on wellbore. (3) Reactive transport modeling was conducted with the optimal CO 2 concentration for this injection site to study the rock-fluid interactions and CO 2 fate in the reservoir. Results suggest that CO 2 dissolved in produced water can be injected without appreciably increasing subsurface pressure or leakage risks. Pressure buildup was found to vary with salinity but not with CO 2 mass fraction. Simulation results show that lower CO 2 percent mass fraction leads to a higher amount of CO 2 that can be dissolved at a higher injection salinity. Furthermore, the long-term goal of dissolution trapping in a traditional carbon storage project is accomplished from the start, mitigating risks associated with potential migration of buoyant CO 2 , so long as the reservoir pressure and temperature are used to determine the maximum mass fraction of the dissolved CO 2 .

54 ENVIRONMENTAL SCIENCES↗

Some injector element detail effects on screech in hydrogen-oxygen rockets

An experimental investigation was conducted to learn more about how the specific details of a concentric tube injection element affect the screech characteristics of a hydrogen-oxygen rocket engine. The four variables investigated were (1) impingement angle, (2) oxidizer tube blunt base thickness, (3) oxidizer tube recess and extension, and (4) oxidizer tube-annulus concentricity. Tests were made using a 27.34-cm (10.77-in.) diameter heat sink combustor at nominally 300-psia chamber pressure. All of the test variables were investigated using a 157 element circular pattern injector. Additional oxidizer tube recess tests were made with a 421 element hexagonal pattern injector. Tests were conducted over the oxidant-fuel ratio range of 4 to 6. Stability evaluation for each configuration was made using the hydrogen temperature rating technique. Several element configurations were also cold flow tested using nitrogen and water as simulants. The element detail changes resulted in changes in hydrogen injector pressure drop even though the physical injection area was constant for all similar tests in both hot firing and cold flow tests. These changes in injector pressure drop produced changes in combustion stability. The data were correlated with a modified version of a previously reported injection area ratio correlation. By interpreting changes in injector pressure drop as changes in injector hydrogen flow resistance, the data were compared with a hydrogen flow response stability model and were found to be in agreement.

Hannum, N. P.↗

Cast Aluminum Alloys for High Temperature Applications Using Nanoparticles Al2O3 and Al3-X Compounds (X = Ti, V, Zr)

In this paper, the effect of nanoparticles Al2O3 and Al3-X compounds (X = Ti, V, Zr) on the improvement of mechanical properties of aluminum alloys for elevated temperature applications is presented. These nanoparticles were selected based on their low cost, chemical stability and low diffusions rates in aluminum at high temperatures. The strengthening mechanism at high temperature for aluminum alloy is based on the mechanical blocking of dislocation movements by these nanoparticles. For Al2O3 nanoparticles, the test samples were prepared from special Al2O3 preforms, which were produced using ceramic injection molding process and then pressure infiltrated by molten aluminum. In another method, Al2O3 nanoparticles can also be homogeneously mixed with fine aluminum powder and consolidated into test samples through hot pressing and sintering. With the Al3-X nanoparticles, the test samples are produced as precipitates from in-situ reactions with molten aluminum using conventional permanent mold or die casting techniques. It is found that cast aluminum alloy using nanoparticles Al3-X is the most cost effective method to produce high strength aluminum alloys for high temperature applications in comparison to nanoparticles Al2O3. Furthermore, significant mechanical properties retention in high temperature environment could be achieved with Al3-X nanoparticles, resulting in tensile strength of nearly 3 times higher than most 300- series conventional cast aluminum alloys tested at 600 F.

Lee, Jonathan A.↗

Automated Generation and Assessment of Autonomous Systems Test Cases

This slide presentation reviews some of the issues concerning verification and validation testing of autonomous spacecraft routinely culminates in the exploration of anomalous or faulted mission-like scenarios using the work involved during the Dawn mission's tests as examples. Prioritizing which scenarios to develop usually comes down to focusing on the most vulnerable areas and ensuring the best return on investment of test time. Rules-of-thumb strategies often come into play, such as injecting applicable anomalies prior to, during, and after system state changes; or, creating cases that ensure good safety-net algorithm coverage. Although experience and judgment in test selection can lead to high levels of confidence about the majority of a system's autonomy, it's likely that important test cases are overlooked. One method to fill in potential test coverage gaps is to automatically generate and execute test cases using algorithms that ensure desirable properties about the coverage. For example, generate cases for all possible fault monitors, and across all state change boundaries. Of course, the scope of coverage is determined by the test environment capabilities, where a faster-than-real-time, high-fidelity, software-only simulation would allow the broadest coverage. Even real-time systems that can be replicated and run in parallel, and that have reliable set-up and operations features provide an excellent resource for automated testing. Making detailed predictions for the outcome of such tests can be difficult, and when algorithmic means are employed to produce hundreds or even thousands of cases, generating predicts individually is impractical, and generating predicts with tools requires executable models of the design and environment that themselves require a complete test program. Therefore, evaluating the results of large number of mission scenario tests poses special challenges. A good approach to address this problem is to automatically score the results based on a range of metrics. Although the specific means of scoring depends highly on the application, the use of formal scoring - metrics has high value in identifying and prioritizing anomalies, and in presenting an overall picture of the state of the test program. In this paper we present a case study based on automatic generation and assessment of faulted test runs for the Dawn mission, and discuss its role in optimizing the allocation of resources for completing the test program.

Testing challenges↗

Progress of Gas Injection EOR Surveillance in the Bakken Unconventional Play—Technical Review and Machine Learning Study

Although considerable laboratory and modeling activities were performed to investigate the enhanced oil recovery (EOR) mechanisms and potential in unconventional reservoirs, only limited research has been reported to investigate actual EOR implementations and their surveillance in fields. Eleven EOR pilot tests that used CO2, rich gas, surfactant, water, etc., have been conducted in the Bakken unconventional play since 2008. Gas injection was involved in eight of these pilots with huff ‘n’ puff, flooding, and injectivity operations. Surveillance data, including daily production/injection rates, bottomhole injection pressure, gas composition, well logs, and tracer testing, were collected from these tests to generate time-series plots or analytics that can inform operators of downhole conditions. A technical review showed that pressure buildup, conformance issues, and timely gas breakthrough detection were some of the main challenges because of the interconnected fractures between injection and offset wells. The latest operation of co-injecting gas, water, and surfactant through the same injection well showed that these challenges could be mitigated by careful EOR design and continuous reservoir monitoring. Reservoir simulation and machine learning were then conducted for operators to rapidly predict EOR performance and take control actions to improve EOR outcomes in unconventional reservoirs.

Energy & Fuels↗

Langley 8-foot high-temperature tunnel oxygen measurement system

In order to ensure that there is a proper amount of oxygen necessary for sustaining test engine operation for hypersonic propulsion systems testing at the NASA Langley 8-foot high-temperature tunnel, a quickly responding real-time measurement system of test section oxygen concentration has been designed and tested at Langley. It is built around a zirconium oxide-based sensor which develops a voltage proportional to the oxygen partial pressure of the test gas. The voltage signal is used to control the amount of oxygen being injected into the combustor air. The physical operation of the oxygen sensor is described, as well as the sampling system used to extract the test gas from the tunnel test section. Results of laboratory tests conducted to verify sensor accuracy and response time performance are discussed, as well as the final configuration of the system to be installed in the tunnel.

Sprinkle, Danny R.↗

Utah FORGE: Well 58-32 Stimulation Conference Paper and Data

The U.S. Department of Energy’s (U.S. DOE) Frontier Observatory for Research in Geothermal Energy (FORGE) is a field laboratory that provides a unique opportunity to develop and test new technologies for characterizing, creating and sustaining Enhanced Geothermal Systems (EGS) in a controlled environment. In 2018, the U.S. DOE selected a site in south-central Utah for the FORGE laboratory. Numerous geoscientific studies have been conducted in the region since the 1970s in support of geothermal development at Roosevelt Hot Springs. A vertical scientific well, 58-32, was drilled and tested to a depth of 2290 m (7515 ft) GL in 2017 on the FORGE site to provide additional characterization of the reservoir rocks. The well encountered a conductive thermal regime and a bottom hole temperature of 199degC (390degF). More than 2000 natural fractures were identified, but measured permeabilities are low, less than 30 micro-darcies. Induced fractures indicate that the maximum horizontal stress trends NNE-SSW, consistent with geologic and well observations from the surrounding area. Approximately 45 m (147 ft) at the base of the well was left uncased. A maximum wellhead pressure of 27.6 MPa (4000 psig) at an injection rate of ~1431 L/min (~9 bpm) was measured during stimulation testing in September 2017. Conventional diagnostic evaluations of the data suggest that hydraulic fracturing and shearing occurred. Estimates of the stress gradient for delta_h_min range from of 16.7 to 17.6 kPa/m (0.74 to 0.78 psi/ft). A gradient of 25.6 kPa/m (1.13psi/ft) was calculated for delta_V. In 2019, the 2017 open-hole stimulation in well 58-32 was repeated with injection rates up to 2385 L/min (15 bpm). Two additional stimulations were conducted in the cased portion of the well; one to stimulate critically stressed fractures and the second to test noncritically stressed fractures. Breakdown of the zone spanning critically-stressed fractures occurred at a surface pressure of approximately 29.0 MPa (4200 psig). Although stimulation of the noncritically stressed fractures was interrupted by failure of the bridge plug beneath the perforated interval, micro-seismic data suggests stimulation of the fractures may have been initiated at a surface pressure of 45.5 MPa (6600 psig). These stimulation results support the conclusion the Mineral Mountains granitoid is an appropriate host for EGS development. Micro-seismicity was monitored during the stimulations using surface and downhole instrumentation. Five seismometers and a nodal array of 150 seismic sensors were deployed on the surface. A Distributed Acoustic Sensing (DAS) cable and a string of 12 geophones were deployed in well 78-32, drilled to a depth of 998 m (3274 ft) GL. A broadband sensor and a high-temperature geophone were deployed in well 68-32, drilled to a depth of 303 m (994 ft) GL. More than 420 micro-seismic events were detected by the geophone string. Other instruments detected fewer events.

15 GEOTHERMAL ENERGY↗

Effects of fuel nozzle design on performance of an experimental annular combustor using natural gas fuel

Tests of various fuel nozzles were conducted with natural gas fuel in a full-annulus combustor. The nozzles were designed to provide either axial, angled, or radial fuel injection. Each fuel nozzle was evaluated by measuring combustion efficiency at relatively severe combustor operating conditions. Combustor blowout and altitude ignition tests were also used to evaluate nozzle designs. Results indicate that angled injection gave higher combustion efficiency, less tendency toward combustion instability, and altitude relight characteristics equal to or superior to those of the other fuel nozzles that were tested.

Wear, J. D.↗

Evaluation of Chemistry-Climate Model Results using Long-Term Satellite and Ground-Based Data

Chemistry-climate models attempt to bring together our best knowledge of the key processes that govern the composition of the atmosphere and its response to changes in forcing. We test these models on a process by process basis by comparing model results to data from many sources. A more difficult task is testing the model response to changes. One way to do this is to use the natural and anthropogenic experiments that have been done on the atmosphere and are continuing to be done. These include the volcanic eruptions of El Chichon and Pinatubo, the solar cycle, and the injection of chlorine and bromine from CFCs and methyl bromide. The test of the model's response to these experiments is their ability to produce the long-term variations in ozone and the trace gases that affect ozone. We now have more than 25 years of satellite ozone data. We have more than 15 years of satellite and ground-based data of HC1, HN03, and many other gases. I will discuss the testing of models using long-term satellite data sets, long-term measurements from the Network for Detection of Stratospheric Change (NDSC) , long-term ground-based measurements of ozone.

Stolarski, Richard S.↗

S-2 stage 1/25 scale model base region thermal environment test. Volume 1: Test results, comparison with theory and flight data

A 1/25 scale model S-2 stage base region thermal environment test is presented. Analytical results are included which reflect the effect of engine operating conditions, model scale, turbo-pump exhaust gas injection on base region thermal environment. Comparisons are made between full scale flight data, model test data, and analytical results. The report is prepared in two volumes. The description of analytical predictions and comparisons with flight data are presented. Tabulation of the test data is provided.

Sadunas, J. A.↗