Nuclear rocket propulsion.
Nuclear rocket propulsion development, noting nuclear rocket engine test program
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Nuclear rocket propulsion development, noting nuclear rocket engine test program
Procedures recommended by the JANNAF Performance Standardization Working Group for acquisition and Interpretation of performance test data are presented. Included with the description of these procedures are recommended procedures covering the required measurements, associated instrumentation, calibration methods, and data uncertainties. In addition, criteria for the applicability of existing test data, the selection of test models, and analytical performance prediction improvement based on test results are outlined. Three sample cases using the recommended procedures are presented as an addendum under separate cover. Author
A set of PC-based computational Dynamic Fluid Flow Simulation models is presented for modeling facility gas and cryogenic systems. Data obtained provide important information regarding performance envelope parameters for the facility using different engine components; time-dependent valve setting for controlling steady-state, quasi-steady state, and transient profiles; optimum facility pipe and pipe component sizes and parameters; momentum transfer loads; and fluid conditions at critical points. A set of COSMIC NASTRAN-based finite element models is also presented to evaluate the loads and stresses on test facility piping systems from fluid and gaseous effects, thermal chill down, and occasional wind loads. The models are based on Apple Macintosh software which makes it possible to change numerous parameters.
This viewgraph presentation reviews computational fluid dynamics as a tool for modelling the dispersion of carbon monoxide at the Stennis Space Center's A3 Test Stand. The contents include: 1) Constellation Program; 2) Constellation Launch Vehicles; 3) J2X Engine; 4) A-3 Test Stand; 5) Chemical Steam Generators; 6) Emission Estimates; 7) Located in Existing Test Complex; 8) Computational Fluid Dynamics; 9) Computational Tools; 10) CO Modeling; 11) CO Model results; and 12) Next steps.
This paper describes work accomplished to predict the service life of a flexure joint design which is a component of a diffuser duct in the A3 Test Stand, an altitude simulation rocket engine test facility at NASA's Stennis Space Center. The duct has two pressure shells separated by cooling water passages and connected by stiffening ribs and flexure joints. Rocket exhaust flows within the duct and heats the inner pressure shell while the outer pressure shell remains at ambient temperature. The flexure joints allow for differential thermal expansion of the inner and outer pressure shells and are subject to in-service loading by this thermal expansion along with water pressure in the cooling water passage, atmospheric pressure outside the duct, near vacuum conditions within the duct, and vibrational loads from operation of the facility and rocket engine. Figure 1 shows a schematic axisymmetric cross section of the diffuser pressure shells and flexure joints with a zoomed in view of the flexure joint. The flexure joints are expected to eventually fail by fatigue cracking leading to leaks from the cooling water passages to the outside. The zoomed in view in Figure 1 indicates where cracking is expected to occur, namely through a weld bead between two plates of SA-516 Grade 70 steel. This weld bead acts as the fulcrum of the flexure joint and it is clear from inspection of the geometry and loading represented in the zoomed in portion of Figure 1 that inherent in the design there is a severe notch formed between the flexure plate, weld bead, and stiffening ring that will be the site of crack initiation and location from which the crack grows to the outer surface of the weld bead.
Rocket engine testing is important throughout a program s life and is essential to the overall success of the program. Space Shuttle Main Engine (SSME) testing can be divided into three phases: development, certification, and operational. Development tests are conducted on the basic design and are used to develop safe start and shutdown transients and to demonstrate mainstage operation. This phase helps form the foundation of the program, demands navigation of a very steep learning curve, and yields results that shape the final engine design. Certification testing involves multiple engine samples and more aggressive test profiles that explore the boundaries of the engine to vehicle interface requirements. The hardware being tested may have evolved slightly from that in the development phase. Operational testing is conducted with mature hardware and includes acceptance testing of flight assets, resolving anomalies that occur in flight, continuing to expand the performance envelope, and implementing design upgrades. This paper will examine these phases of testing and their importance to the SSME program. Examples of tests conducted in each phase will also be presented.
Computational Fluid Dynamics (CFD) technology has been used to assess the exhaust plume pollutant environment of the RD-170 engine hot-firing on the F1 Test Stand at Marshall Space Flight Center. Researchers know that rocket engine hot-firing has the potential for forming thermal nitric oxides (NOx), as well as producing carbon monoxide (CO) when hydrocarbon fuels are used. Because of the complicated physics involved, however, little attempt has been made to predict the pollutant emissions from ground-based engine testing, except for simplified methods which can grossly underpredict and/or overpredict the pollutant formations in a test environment. The objective of this work, therefore, has been to develop a technology using CFD to describe the underlying pollutant emission physics from ground-based rocket engine testing. This resultant technology is based on a three-dimensional, viscous flow, pressure-based CFD formulation, where wet CO and thermal NOx finite-rate chemistry mechanisms are solved with a Penalty function method.
Computational Fluid Dynamics (CFD) technology has been used to assess the exhaust plume pollutant environment of the RD-170 engine hot-firing on the F1 Test Stand at Marshall Space Flight Center. Researchers know that rocket engine hot-firing has the potential for forming thermal nitric oxides (NO(x)), as well as producing carbon monoxide (CO) when hydrocarbon fuels are used. Because of the complicated physics involved, however, little attempt has been made to predict the pollutant emissions from ground-based engine testing, except for simplified methods which can grossly underpredict and/or overpredict the pollutant formations in a test environment. The objective of this work, therefore, has been to develop a technology using CFD to describe the underlying pollutant emission physics from ground-based rocket engine testing. This resultant technology is based on a three-dimensional (3D), viscous flow, pressure-based CFD formulation, where wet CO and thermal NO finite-rate chemistry mechanisms are solved with a Penalty Function method. A nominal hot-firing of a RD-170 engine on the F1 stand has been computed. Pertinent test stand flow physics such as the multiple-nozzle clustered engine plume interaction, air aspiration from base and aspirator, plume mixing with entrained air that resulted in contaminant dilution and afterburning, counter-afterburning due to flame bucket water-quenching, plume impingement on the flame bucket, and restricted multiple-plume expansion and turning have been captured. The predicted total emission rates compared reasonably well with those of the existing hydrocarbon engine hot-firing test data.
Radiographic, ultrasonic, thermographic and leak test quality control for brazed liquid propellant rocket engine components
Safety program for nuclear rocket engine testing, discussing role of cryogenics
An asymptotic plume growth method based on a time-accurate three-dimensional computational fluid dynamics formulation has been developed to assess the exhaust-plume pollutant environment from a simulated RD-170 engine hot-fire test on the F1 Test Stand at Marshall Space Flight Center. Researchers have long known that rocket-engine hot firing has the potential for forming thermal nitric oxides, as well as producing carbon monoxide when hydrocarbon fuels are used. Because of the complex physics involved, most attempts to predict the pollutant emissions from ground-based engine testing have used simplified methods, which may grossly underpredict and/or overpredict the pollutant formations in a test environment. The objective of this work has been to develop a computational fluid dynamics-based methodology that replicates the underlying test-stand flow physics to accurately and efficiently assess pollutant emissions from ground-based rocket-engine testing. A nominal RD-170 engine hot-fire test was computed, and pertinent test-stand flow physics was captured. The predicted total emission rates compared reasonably well with those of the existing hydrocarbon engine hot-firing test data.
A test facility modification to enable small scale altitude propulsion testing at the NASA Glenn Research Center's In-Space Propulsion (ISP) Facility was verified with a hot fire test campaign. As the facility's primary steam supply system undergoes refurbishment, the alternate facility configuration, known as the "vacuum accumulator" mode, would enable rocket engine testing up to 10,000 lbf thrust. The NASA Johnson Space Center developed the vehicle for the verification test campaign: the Integrated Cryogenic Propulsion Test Article (ICPTA). Constructed primarily from assets of the former Morpheus Project, the ICPTA provided an integrated liquid oxygen (LOX) / liquid methane (LCH4) propulsion system including a 2,800 lbf thrust main engine. The ISP Facility's vacuum accumulator configuration leveraged the large test volume of the facility and a diffuser insert to maintain altitude conditions. During hot fire, the ICPTA main engine "started" the diffuser insert constructed for the test campaign. As a result, the test chamber upstream of the diffuser insert remained at altitude conditions throughout the hot fire. Upon engine shut down, a backflow deflector mitigated blow back into the test chamber by restricting the mass flow and redirecting it away from the test article. The test campaign successfully characterized the performance of the vacuum accumulator configuration. In addition, it provided an opportunity to collect data for an integrated LOX / LCH4 propulsion system in an altitude and thermal vacuum environment.
Protective coating systems for refractory metal used in rocket engine nozzles - rocket engine test firing
Development and testing of ablative rocket engine with selected 7.62 cm /3.0 in./ diameter throat inserts, and testing of zirconia reinforced with tungsten-rhenium wire for throat insert material
The unique space shuttle vehicle size, weight, and configuration gave rise to problems in determining vibration requirements and in verifying structural integrity for anticipated mission environments. The applications of large-scale vibration testing played a prominent part in qualifying the shuttle for its intended missions. Severe vibration excitation from rocket engines, aerodynamic noise, and onboard equipment are expected on each shuttle flight. Scale-model wind tunnel and rocket firing tests, as well as full-size rocket engine tests were relied on to define the random forcing functions. The determination of structural response to these environments is described as well as evaluations of measured flight data and comparison with predicted design and test criteria.
Results from tests of rocket engine for spacecraft reaction control and maneuvering systems
In order to validate the benefits of high aspect ratio cooling channels in a large scale rocket combustion chamber, a high pressure, 89 kN (20,000 lbf) thrust, contoured combustion chamber was tested in the NASA Lewis Research Center Rocket Engine Test Facility. The combustion chamber was tested at chamber pressures from 5.5 to 11.0 MPa (800-1600 psia). The propellants were gaseous hydrogen and liquid oxygen at a nominal mixture ratio of six, and liquid hydrogen was used as the coolant. The combustion chamber was extensively instrumented with 30 backside skin thermocouples, 9 coolant channel rib thermocouples, and 10 coolant channel pressure taps. A total of 29 thermal cycles, each with one second of steady state combustion, were completed on the chamber. For 25 thermal cycles, the coolant mass flow rate was equal to the fuel mass flow rate. During the remaining four thermal cycles, the coolant mass flow rate was progressively reduced by 5, 6, 11, and 20 percent. Computer analysis agreed with coolant channel rib thermocouples within an average of 9 percent and with coolant channel pressure drops within an average of 20 percent. Hot-gas-side wall temperatures of the chamber showed up to 25 percent reduction, in the throat region, over that of a conventionally cooled combustion chamber. Reducing coolant mass flow yielded a reduction of up to 27 percent of the coolant pressure drop from that of a full flow case, while still maintaining up to a 13 percent reduction in a hot-gas-side wall temperature from that of a conventionally cooled combustion chamber.
Third 260-inch diameter solid propellant rocket engine test firing