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Atwell. Matthew J. - One of the best experts on this subject based on the ideXlab platform.
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Cold Helium Gas Pressurization For Spacecraft Cryogenic Propulsion Systems
2017Co-Authors: Hurlbert, Eric A., Morehead, Robert L., Melcher J. C., Atwell. Matthew J.Abstract:To reduce the dry mass of a spacecraft pressurization system, helium pressurant may be stored at low temperature and high pressure to increase mass in a given tank volume. Warming this gas through an engine heat exchanger prior to tank pressurization both increases the system efficiency and simplifies the designs of intermediate hardware such as regulators, valves, etc. since the gas is no longer cryogenic. If this type of cold helium pressurization system is used in conjunction with a cryogenic propellant, though, a loss in overall system efficiency can be expected due to heat transfer from the warm ullage gas to the cryogenic propellant which results in a specific volume loss for the pressurant, interpreted as the Collapse Factor. Future spacecraft with cryogenic propellants will likely have a cold helium system, with increasing collapse factor effects as vehicle sizes decrease. To determine the collapse factor effects and overall implementation strategies for a representative design point, a cold helium system was hotfire Tested on the Integrated Cryogenic Propulsion Test Article (ICPTA) in a thermal vacuum environment at the NASA Glenn Research Center Plum Brook Station. The ICPTA vehicle is a small lander-sized spacecraft prototype built at NASA Johnson Space Center utilizing cryogenic liquid oxygen/liquid methane propellants and cryogenic helium gas as a pressurant to operate one 2,800lbf 5:1 throttling main engine, two 28lbf Reaction Control Engines (RCE), and two 7lbf RCEs (Figure 1). This vehicle was hotfire Tested at a variety of environmental conditions at NASA Plum Brook, ranging from ambient temperature/simulated high altitude, deep thermal/high altitude, and deep thermal/high vacuum conditions. A detailed summary of the vehicle design and Testing campaign may be found in Integrated Cryogenic Propulsion Test Article Thermal Vacuum Hotfire Testing, AIAA JPC 2017
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Characterization of a Pressure-Fed LOX/LCH4 Reaction Control System Under Simulated Altitude and Thermal Vacuum Conditions
2017Co-Authors: Atwell. Matthew J., Hurlbert, Eric A., Melcher, John C., Morehead, Robert L.Abstract:A liquid oxygen, liquid methane (LOX/LCH4) reaction control system (RCS) was Tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under simulated altitude and thermal vacuum conditions. The RCS is a subsystem of the Integrated Cryogenic Propulsion Test Article (ICPTA) and was initially developed under Project Morpheus. Composed of two 28 lbf-thrust and two 7 lbf-thrust engines, the RCS is fed in parallel with the ICPTA main engine from four propellant tanks. 40 Tests consisting of 1,010 individual thruster pulses were performed across 6 different Test days. Major Test objectives were focused on system dynamics, and included characterization of fluid transients, manifold priming, manifold thermal conditioning, thermodynamic vent system (TVS) performance, and main engine/RCS interaction. Peak surge pressures from valve opening and closing events were examined. It was determined that these events were impacted significantly by vapor cavity formation and collapse. In most cases the valve opening transient was more severe than the valve closing. Under thermal vacuum conditions it was shown that TVS operation is unnecessary to maintain liquid conditions at the thruster inlets. However, under higher heat leak environments the RCS can still be operated in a self-conditioning mode without overboard TVS venting, contingent upon the engines managing a range of potentially severe thermal transients. Lastly, during Testing under cold thermal conditions the engines experienced significant ignition problems. Only after warming the thruster bodies with a gaseous nitrogen purge to an intermediate temperature was successful ignition demonstrated
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Pressure-Fed LOX/LCH4 Reaction Control System for Spacecraft: Transient Modeling and Thermal Vacuum Hotfire Test Results
2017Co-Authors: Melcher, John C., Hurlbert, Eric A., Morehead, Robe L., Atwell. Matthew J.Abstract:An integrated cryogenic liquid oxygen, liquid methane (LOX/LCH4) reaction control system (RCS) was Tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. The RCS is a subsystem of the Integrated Cryogenic Propulsion Test Article (ICPTA), a pressure-fed LOX/LCH4 Propulsion system composed of a single 2,800 lbf main engine, two 28 lbf RCS engines, and two 7 lbf RCS engines. Propellants are stored in four 48 inch diameter 5083 aluminum tanks that feed both the main engine and RCS engines in parallel. Helium stored cryogenically in a composite overwrapped pressure vessel (COPV) flows through a heat exchanger on the main engine before being used to pressurize the propellant tanks to a design operating pressure of 325 psi. The ICPTA is capable of simultaneous main engine and RCS operation. The RCS engines utilize a coil-on-plug (COP) ignition system designed for operation in a vacuum environment, eliminating corona discharge issues associated with a high voltage lead. There are two RCS pods on the ICPTA, with two engines on each pod. One of these two engines is a heritage flight engine from Project Morpheus. Its sea level nozzle was removed and replaced by an 85:1 nozzle machined using Inconel 718, resulting in a maximum thrust of 28 lbf under altitude conditions. The other engine is a scaled down version of the 28 lbf engine, designed to match the core and overall mixture ratios as well as other injector characteristics. This engine can produce a maximum thrust of 7 lbf with an 85:1 nozzle that was additively manufactured using Inconel 718. Both engines are film-cooled and capable of limited duration gas-gas and gas-liquid operation, as well as steady-state liquid-liquid operation. Each pod contains one of each version, such that two engines of the same thrust level can be fired as a couple on opposite pods. The RCS feed system is composed of symmetrical 3/8 inch lines that tap off of the main propellant manifold to send LOX and LCH4 outboard to the RCS pods. A Thermodynamic Vent System (TVS) is used to condition propellants at each pod by venting through an orifice and then routing the cold expansion products back through tubing that is welded along a large portion of the main RCS feed lines. Prior to final installation on the ICPTA, the RCS engines were Tested in a small vacuum chamber at the Johnson Space Center (JSC) Energy Systems Test Area (ESTA) to verify functionality of the new COP ignition system and check out operation of the vacuum nozzles. After engine-level Testing, the RCS engines were installed on the vehicle and a series of integrated hot-fire Tests were performed at JSC consisting of various pulsing and steady-state firings as well as integrated main engine/RCS operation. The ICPTA was then integrated into the Plum Brook B-2 facility for vacuum and thermal/vacuum Testing. Testing in the B-2 facility was composed of multiple thermal and pressure environments. The first set of Tests were performed under ambient temperature and altitude pressure conditions. These Tests consisted of a range of minimum impulse bit (MIB) pulsing sequences with low duty cycle, analogous to a coast phase in which the RCS is primarily used for station keeping. The primary goal of this sequence is to understand how propellant conditions were effected without an active TVS. In this scenario, consistent gas-gas operation is desirable since it results in a smaller MIB and more efficient propellant consumption. Multiple skin thermocouples are mounted on the feedlines, in addition to a submerged thermocouple on each commodity, in order to gather thermal data on the system. Higher duty cycle pulsing Tests were then performed, analogous to an ascent or landing mission phase. The primary goal of this sequence was to examine how well the engines self-conditioned without active TVS when starting from a quiescent state. The TVS was then activated during some Tests to demonstrate the capability to quickly condition the engines for higher pulsing demand scenarios. A thermocouple at the TVS outlet allows for the calculation of energy absorbed by the vented propellant. Lastly, Tests with longer pulses and multiple engines firing either in sequence or simultaneously were run in order to gather transient system response data on waterhammer. Six total high-speed pressure transducers are installed on the RCS system, one sensor at the end of each propellant manifold line on the pods, and one at the tap-off location for each commodity. This will allow for the accurate characterization of waterhammer in the system under various propellant conditions and firing sequences. Other instrumentation for this Test series includes nozzle throat thermocouples, chamber pressure measurement, heat soakback measurement, and tank wall plume impingement temperature measurement. The next set of Tests were performed to demonstrate simultaneous main engine and RCS operation. Data from this Test will be used to examine if there is any change to nominal operation of the RCS as a result of feed system interaction or other phenomenon. Some of these Tests began under high vacuum conditions (target ambient pressure less than 1x10(exp -3) torr) and others began at altitude conditions. The last set of Tests were performed with the B-2 cold wall active. Under these Tests, many of the same low duty cycle MIB Tests were repeated in order to characterize how propellant conditions changed with the lower heat leak. In this scenario the RCS manifold experiences much less heat leak, resulting in a change to how well the engines self-condition. As a result, an increase in maximum waterhammer pressures and a change in natural frequency of the system was expected due to higher density propellants. The lower heat leak should also result in a change to the MIB pulse profile, and data will be examined to understand how MIB repeatability is affected in the different operating environments. Parallel to the Test efforts, a set of transient model development efforts were made to predict RCS performance. The primary effort was aimed at producing a SINDA/FLUINT model to predict propellant conditioning up to the engine inlet as a function of different environmental and operating parameters, with the goal of predicting chamber pressure, TVS performance, and propellant consumption over time. Preliminary results for this effort will be presented in comparison with Test data. Additional modeling efforts were made using SINDA/FLUINT to predict waterhammer in the system since the software is capable of handling multiphase transient fluid dynamics. These results will be compared with the high-speed pressure transducer Test data for validation purposes
Dany H Gagnon - One of the best experts on this subject based on the ideXlab platform.
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changes to biceps and supraspinatus tendons in response to a progressive maximal treadmill based Propulsion aerobic fitness Test in manual wheelchair users a quantitative musculoskeletal ultrasound study
Rehabilitation Research and Practice, 2021Co-Authors: Mylene Leclerc, Cindy Gauthier, Rachel Brosseau, Francois Desmeules, Dany H GagnonAbstract:Objective To investigate if the completion of a recently developed treadmill-based wheelchair Propulsion maximal progressive workload incremental Test alters the integrity of the long head of the biceps and supraspinatus tendons using musculoskeletal ultrasound imaging biomarkers. Method Fifteen manual wheelchair users completed the incremental Test. Ultrasound images of the long head of the biceps and supraspinatus tendons were recorded before, immediately after, and 48 hours after the completion of the Test using a standardized protocol. Geometric, composition, and texture-related ultrasound biomarkers characterized tendon integrity. Results Participants propelled during 10.2 ± 2.9 minutes with the majority (N = 13/15) having reached at least the eighth stage of the Test (speed = 0.8 m/s; slope = 3.6°). All ultrasound biomarkers characterizing tendon integrity, measured in the longitudinal and transversal planes for both tendons, were similar (p = 0.063 to 1.000) across measurement times. Conclusion The performance of the motorized treadmill wheelchair Propulsion Test to assess aerobic fitness produced no changes to ultrasound biomarkers of the biceps or supraspinatus tendons. Hence, there was no ultrasound imaging evidence of a maladaptive response due to overstimulation in these tendons immediately after and 48 hours after the performance of the Test.
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comparison of the 6 min Propulsion and arm crank ergometer Tests to assess aerobic fitness in manual wheelchair users with a spinal cord injury
American Journal of Physical Medicine & Rehabilitation, 2020Co-Authors: Alec Bass, Cindy Gauthier, Rachel Brosseau, Simon Decary, Dany H GagnonAbstract:OBJECTIVE The 6-Min Manual Wheelchair Propulsion Test is proposed to easily and rapidly assess aerobic fitness among long-term (≥3 mos) manual wheelchair users with spinal cord injury. However, aerobic responses to this Test have not been established. This study aimed (1) to characterize aerobic responses during the 6-Min Manual Wheelchair Propulsion Test, (2) to establish parallel reliability between the 6-Min Manual Wheelchair Propulsion Test and the Maximal Arm Crank Ergometer Test, and (3) to quantify the strength of association between the total distance traveled during the 6-Min Manual Wheelchair Propulsion Test and peak oxygen consumption. DESIGN Twenty manual wheelchair users with a spinal cord injury completed both Tests. Aerobic parameters were measured before, during, and after the Tests. Main outcome measures were peak oxygen consumption and total distance traveled. RESULTS Progressive cardiorespiratory responses, consistent with guidelines for exercise Testing, were observed during both Tests. Similar peak oxygen consumption values were obtained during both Tests (6-Min Manual Wheelchair Propulsion Test: 20.2 ± 4.9 ml/kg·min; Maximal Arm Crank Ergometer Test: 20.4 ± 5.0 ml/kg·min), were highly correlated (r = 0.92, P < 0.001), and had a good agreement (mean absolute difference = 0.21, 95% confidence interval = -0.70 to 1.11, P = 0.639). The peak oxygen consumption and total distance traveled (mean = 636.6 ± 56.9 m) during the 6-Min Manual Wheelchair Propulsion Test were highly correlated (r = 0.74, P < 0.001). CONCLUSIONS The 6-Min Manual Wheelchair Propulsion Test induces progressive aerobic responses consistent with guidelines for exercise Testing and can be used to efficiently estimate aerobic fitness in manual wheelchair users with a spinal cord injury. TO CLAIM CME CREDITS Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Explain how to administer the Six-Minute Manual Wheelchair Propulsion Test in long-term manual wheelchair users with a spinal cord injury; (2) Contrast how the workload is developed between the Six-Minute Manual Wheelchair Propulsion Test and the Maximal Arm Crank Ergometry Test and recognize how these differences may affect physiological responses; and (3) Explain why caution is advised regarding the use of the Six-Minute Manual Wheelchair Propulsion Test if aiming to estimate aerobic fitness. LEVEL Advanced ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.
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reliability and minimal detectable change of a new treadmill based progressive workload incremental Test to measure cardiorespiratory fitness in manual wheelchair users
Journal of Spinal Cord Medicine, 2017Co-Authors: Cindy Gauthier, Jasmine Arel, Rachel Brosseau, Audrey L Hicks, Dany H GagnonAbstract:Background: Cardiorespiratory fitness training is commonly provided to manual wheelchair users (MWUs) in rehabilitation and physical activity programs, emphasizing the need for a reliable task-specific incremental wheelchair Propulsion Test.Objective: Quantifying Test-reTest reliability and minimal detectable change (MDC) of key cardiorespiratory fitness measures following performance of a newly developed continuous treadmill-based wheelchair Propulsion Test (WPTTreadmill).Methods: Twenty-five MWUs completed the WPTTreadmill on two separate occasions within one week. During these Tests, participants continuously propelled their wheelchair on a motorized treadmill while the exercise intensity was gradually increased every minute until exhaustion by changing the slope and/or speed according to a standardized protocol. Peak oxygen consumption (VO2peak), carbon dioxide production (VCO2peak), respiratory exchange ratio (RERpeak), minute ventilation (VEpeak) and heart rate (HRpeak) were computed. Time to exhaus...
Mitchell M. A. - One of the best experts on this subject based on the ideXlab platform.
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Solvent Replacement for Hydrochlorofluorocarbon-225 for Cleaning Oxygen System Components
2017Co-Authors: Lowrey N. M., Mitchell M. A.Abstract:This Technical Memorandum is the result of a 2-year project funded by the Defense Logistics Agency-Aviation, Hazardous Minimization and Green Products Branch, to identify and Test two candidate solvents to replace hydrochlorofluorocarbon-225 (HCFC-225) for cleaning oxygen systems. The solvents were also compared to a second solvent composed predominantly of perfluorobutyl iodide (PFBI), which had received limited approval by the United States Air Force (USAF) for hand wipe cleaning of components for aviators breathing oxygen systems. The Tests performed for this study were based on those reported in AFRL-ML-WP-TR-2003-4040, The Wipe Solvent Program, the Test program used to qualify Ikon Solvent P for USAF applications.The study was completed in August 2014, prior to the completion of a more extensive study funded by the NASA Rocket Propulsion Test (RPT) program. The results of the RPT project are reported in NASA/TP-2015-18207, Replacement of Hydrochlorofluorocarbon225 Solvent for Cleaning and Verification Sampling of NASA Propulsion Oxygen Systems Hardware, Ground Support Equipment, and Associated Test Systems. The Test methods used in this study for nonvolatile residue (NVR) background, materials compatibility, and cleaning effectiveness were different than those used for the RPT project; a smaller set of materials and contaminants were Tested. The Tests for this study were complementary to and provided supplementary information for the down-selection process during the course of the Test program reported in NASA/TP-2015-218207
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Results of the Test Program for Replacement of AK-225G Solvent for Cleaning NASA Propulsion Oxygen Systems
2016Co-Authors: Mitchell M. A., Lowrey N. M.Abstract:Since the 1990's, when the Class I Ozone Depleting Substance (ODS) chlorofluorocarbon-113 (CFC-113) was banned, NASA's Propulsion Test facilities at Marshall Space Flight Center (MSFC) and Stennis Space Center (SSC) have relied upon the solvent AsahiKlin AK-225 (hydrochlorofluorocarbon-225ca/cb or HCFC-225ca/cb) and, more recently AK-225G (the single isomer form, HCFC-225cb) to safely clean and verify the cleanliness of large scale Propulsion oxygen systems. Effective January 1, 2015, the production, import, export, and new use of Class II Ozone Depleting Substances, including AK-225G, was prohibited in the United States by the Clean Air Act. In 2012 through 2014, NASA Test labs at MSFC, SSC, and Johnson Space Center's White Sands Test Facility (WSTF) collaborated to seek out, Test, and qualify a solvent replacement for AK-225G that is both an effective cleaner and safe for use with oxygen systems. This paper summarizes the Tests performed, results, and lessons learned
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Replacement of HCFC-225 Solvent for Cleaning NASA Propulsion Oxygen Systems
2015Co-Authors: Mitchell M. A., Lowrey N. M.Abstract:Since the 1990's, when the Class I Ozone Depleting Substance (ODS) chlorofluorocarbon113 (CFC113) was banned, NASA's rocket Propulsion Test facilities at Marshall Space Flight Center (MSFC) and Stennis Space Center (SSC) have relied upon hydrochlorofluorocarbon225 (HCFC225) to safely clean and verify the cleanliness of large scale Propulsion oxygen systems. Effective January 1, 2015, the production, import, export, and new use of HCFC225, a Class II ODS, was prohibited by the Clean Air Act. In 2012 through 2014, leveraging resources from both the NASA Rocket Propulsion Test Program and the Defense Logistics Agency Aviation Hazardous Minimization and Green Products Branch, Test labs at MSFC, SSC, and Johnson Space Center's White Sands Test Facility (WSTF) collaborated to seek out, Test, and qualify a replacement for HCFC225 that is both an effective cleaner and safe for use with oxygen systems. Candidate solvents were selected and a Test plan was developed following the guidelines of ASTM G127, Standard Guide for the Selection of Cleaning Agents for Oxygen Systems. Solvents were evaluated for materials compatibility, oxygen compatibility, cleaning effectiveness, and suitability for use in cleanliness verification and field cleaning operations. Two solvents were determined to be acceptable for cleaning oxygen systems and one was chosen for implementation at NASA's rocket Propulsion Test facilities. The Test program and results are summarized. This project also demonstrated the benefits of crossagency collaboration in a time of limited resources
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Replacement of HCFC-225 Solvent for Cleaning NASA Propulsion Oxygen Systems
2015Co-Authors: Lowrey N. M., Mitchell M. A.Abstract:Since the 1990's, when the Class I Ozone Depleting Substance (ODS) chlorofluorocarbon113 (CFC113) was banned, NASA's Propulsion Test facilities at Marshall Space Flight Center (MSFC) and Stennis Space Center (SSC) have relied upon hydrochlorofluorocarbon225 (HCFC225) to safely clean and verify the cleanliness of large scale Propulsion oxygen systems. Effective January 1, 2015, the production, import, export, and new use of HCFC225, a Class II ODS, was prohibited by the Clean Air Act. In 2012 through 2014, leveraging resources from both NASA and the Defense Logistics Agency Aviation Hazardous Minimization and Green Products Branch, Test labs at MSFC, SSC, and Johnson Space Center's White Sands Test Facility (WSTF) collaborated to seek out, Test, and qualify a replacement for HCFC225 that is both an effective cleaner and safe for use with oxygen systems. This presentation summarizes the Tests performed, results, and lessons learned. It also demonstrates the benefits of crossagency collaboration in a time of limited resources
Lowrey N. M. - One of the best experts on this subject based on the ideXlab platform.
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Solvent Replacement for Hydrochlorofluorocarbon-225 for Cleaning Oxygen System Components
2017Co-Authors: Lowrey N. M., Mitchell M. A.Abstract:This Technical Memorandum is the result of a 2-year project funded by the Defense Logistics Agency-Aviation, Hazardous Minimization and Green Products Branch, to identify and Test two candidate solvents to replace hydrochlorofluorocarbon-225 (HCFC-225) for cleaning oxygen systems. The solvents were also compared to a second solvent composed predominantly of perfluorobutyl iodide (PFBI), which had received limited approval by the United States Air Force (USAF) for hand wipe cleaning of components for aviators breathing oxygen systems. The Tests performed for this study were based on those reported in AFRL-ML-WP-TR-2003-4040, The Wipe Solvent Program, the Test program used to qualify Ikon Solvent P for USAF applications.The study was completed in August 2014, prior to the completion of a more extensive study funded by the NASA Rocket Propulsion Test (RPT) program. The results of the RPT project are reported in NASA/TP-2015-18207, Replacement of Hydrochlorofluorocarbon225 Solvent for Cleaning and Verification Sampling of NASA Propulsion Oxygen Systems Hardware, Ground Support Equipment, and Associated Test Systems. The Test methods used in this study for nonvolatile residue (NVR) background, materials compatibility, and cleaning effectiveness were different than those used for the RPT project; a smaller set of materials and contaminants were Tested. The Tests for this study were complementary to and provided supplementary information for the down-selection process during the course of the Test program reported in NASA/TP-2015-218207
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Results of the Test Program for Replacement of AK-225G Solvent for Cleaning NASA Propulsion Oxygen Systems
2016Co-Authors: Mitchell M. A., Lowrey N. M.Abstract:Since the 1990's, when the Class I Ozone Depleting Substance (ODS) chlorofluorocarbon-113 (CFC-113) was banned, NASA's Propulsion Test facilities at Marshall Space Flight Center (MSFC) and Stennis Space Center (SSC) have relied upon the solvent AsahiKlin AK-225 (hydrochlorofluorocarbon-225ca/cb or HCFC-225ca/cb) and, more recently AK-225G (the single isomer form, HCFC-225cb) to safely clean and verify the cleanliness of large scale Propulsion oxygen systems. Effective January 1, 2015, the production, import, export, and new use of Class II Ozone Depleting Substances, including AK-225G, was prohibited in the United States by the Clean Air Act. In 2012 through 2014, NASA Test labs at MSFC, SSC, and Johnson Space Center's White Sands Test Facility (WSTF) collaborated to seek out, Test, and qualify a solvent replacement for AK-225G that is both an effective cleaner and safe for use with oxygen systems. This paper summarizes the Tests performed, results, and lessons learned
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Replacement of HCFC-225 Solvent for Cleaning NASA Propulsion Oxygen Systems
2015Co-Authors: Mitchell M. A., Lowrey N. M.Abstract:Since the 1990's, when the Class I Ozone Depleting Substance (ODS) chlorofluorocarbon113 (CFC113) was banned, NASA's rocket Propulsion Test facilities at Marshall Space Flight Center (MSFC) and Stennis Space Center (SSC) have relied upon hydrochlorofluorocarbon225 (HCFC225) to safely clean and verify the cleanliness of large scale Propulsion oxygen systems. Effective January 1, 2015, the production, import, export, and new use of HCFC225, a Class II ODS, was prohibited by the Clean Air Act. In 2012 through 2014, leveraging resources from both the NASA Rocket Propulsion Test Program and the Defense Logistics Agency Aviation Hazardous Minimization and Green Products Branch, Test labs at MSFC, SSC, and Johnson Space Center's White Sands Test Facility (WSTF) collaborated to seek out, Test, and qualify a replacement for HCFC225 that is both an effective cleaner and safe for use with oxygen systems. Candidate solvents were selected and a Test plan was developed following the guidelines of ASTM G127, Standard Guide for the Selection of Cleaning Agents for Oxygen Systems. Solvents were evaluated for materials compatibility, oxygen compatibility, cleaning effectiveness, and suitability for use in cleanliness verification and field cleaning operations. Two solvents were determined to be acceptable for cleaning oxygen systems and one was chosen for implementation at NASA's rocket Propulsion Test facilities. The Test program and results are summarized. This project also demonstrated the benefits of crossagency collaboration in a time of limited resources
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Replacement of HCFC-225 Solvent for Cleaning NASA Propulsion Oxygen Systems
2015Co-Authors: Lowrey N. M., Mitchell M. A.Abstract:Since the 1990's, when the Class I Ozone Depleting Substance (ODS) chlorofluorocarbon113 (CFC113) was banned, NASA's Propulsion Test facilities at Marshall Space Flight Center (MSFC) and Stennis Space Center (SSC) have relied upon hydrochlorofluorocarbon225 (HCFC225) to safely clean and verify the cleanliness of large scale Propulsion oxygen systems. Effective January 1, 2015, the production, import, export, and new use of HCFC225, a Class II ODS, was prohibited by the Clean Air Act. In 2012 through 2014, leveraging resources from both NASA and the Defense Logistics Agency Aviation Hazardous Minimization and Green Products Branch, Test labs at MSFC, SSC, and Johnson Space Center's White Sands Test Facility (WSTF) collaborated to seek out, Test, and qualify a replacement for HCFC225 that is both an effective cleaner and safe for use with oxygen systems. This presentation summarizes the Tests performed, results, and lessons learned. It also demonstrates the benefits of crossagency collaboration in a time of limited resources
Hurlbert, Eric A. - One of the best experts on this subject based on the ideXlab platform.
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Cold Helium Gas Pressurization For Spacecraft Cryogenic Propulsion Systems
2017Co-Authors: Hurlbert, Eric A., Morehead, Robert L., Melcher J. C., Atwell. Matthew J.Abstract:To reduce the dry mass of a spacecraft pressurization system, helium pressurant may be stored at low temperature and high pressure to increase mass in a given tank volume. Warming this gas through an engine heat exchanger prior to tank pressurization both increases the system efficiency and simplifies the designs of intermediate hardware such as regulators, valves, etc. since the gas is no longer cryogenic. If this type of cold helium pressurization system is used in conjunction with a cryogenic propellant, though, a loss in overall system efficiency can be expected due to heat transfer from the warm ullage gas to the cryogenic propellant which results in a specific volume loss for the pressurant, interpreted as the Collapse Factor. Future spacecraft with cryogenic propellants will likely have a cold helium system, with increasing collapse factor effects as vehicle sizes decrease. To determine the collapse factor effects and overall implementation strategies for a representative design point, a cold helium system was hotfire Tested on the Integrated Cryogenic Propulsion Test Article (ICPTA) in a thermal vacuum environment at the NASA Glenn Research Center Plum Brook Station. The ICPTA vehicle is a small lander-sized spacecraft prototype built at NASA Johnson Space Center utilizing cryogenic liquid oxygen/liquid methane propellants and cryogenic helium gas as a pressurant to operate one 2,800lbf 5:1 throttling main engine, two 28lbf Reaction Control Engines (RCE), and two 7lbf RCEs (Figure 1). This vehicle was hotfire Tested at a variety of environmental conditions at NASA Plum Brook, ranging from ambient temperature/simulated high altitude, deep thermal/high altitude, and deep thermal/high vacuum conditions. A detailed summary of the vehicle design and Testing campaign may be found in Integrated Cryogenic Propulsion Test Article Thermal Vacuum Hotfire Testing, AIAA JPC 2017
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Characterization of a Pressure-Fed LOX/LCH4 Reaction Control System Under Simulated Altitude and Thermal Vacuum Conditions
2017Co-Authors: Atwell. Matthew J., Hurlbert, Eric A., Melcher, John C., Morehead, Robert L.Abstract:A liquid oxygen, liquid methane (LOX/LCH4) reaction control system (RCS) was Tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under simulated altitude and thermal vacuum conditions. The RCS is a subsystem of the Integrated Cryogenic Propulsion Test Article (ICPTA) and was initially developed under Project Morpheus. Composed of two 28 lbf-thrust and two 7 lbf-thrust engines, the RCS is fed in parallel with the ICPTA main engine from four propellant tanks. 40 Tests consisting of 1,010 individual thruster pulses were performed across 6 different Test days. Major Test objectives were focused on system dynamics, and included characterization of fluid transients, manifold priming, manifold thermal conditioning, thermodynamic vent system (TVS) performance, and main engine/RCS interaction. Peak surge pressures from valve opening and closing events were examined. It was determined that these events were impacted significantly by vapor cavity formation and collapse. In most cases the valve opening transient was more severe than the valve closing. Under thermal vacuum conditions it was shown that TVS operation is unnecessary to maintain liquid conditions at the thruster inlets. However, under higher heat leak environments the RCS can still be operated in a self-conditioning mode without overboard TVS venting, contingent upon the engines managing a range of potentially severe thermal transients. Lastly, during Testing under cold thermal conditions the engines experienced significant ignition problems. Only after warming the thruster bodies with a gaseous nitrogen purge to an intermediate temperature was successful ignition demonstrated
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Pressure-Fed LOX/LCH4 Reaction Control System for Spacecraft: Transient Modeling and Thermal Vacuum Hotfire Test Results
2017Co-Authors: Melcher, John C., Hurlbert, Eric A., Morehead, Robe L., Atwell. Matthew J.Abstract:An integrated cryogenic liquid oxygen, liquid methane (LOX/LCH4) reaction control system (RCS) was Tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. The RCS is a subsystem of the Integrated Cryogenic Propulsion Test Article (ICPTA), a pressure-fed LOX/LCH4 Propulsion system composed of a single 2,800 lbf main engine, two 28 lbf RCS engines, and two 7 lbf RCS engines. Propellants are stored in four 48 inch diameter 5083 aluminum tanks that feed both the main engine and RCS engines in parallel. Helium stored cryogenically in a composite overwrapped pressure vessel (COPV) flows through a heat exchanger on the main engine before being used to pressurize the propellant tanks to a design operating pressure of 325 psi. The ICPTA is capable of simultaneous main engine and RCS operation. The RCS engines utilize a coil-on-plug (COP) ignition system designed for operation in a vacuum environment, eliminating corona discharge issues associated with a high voltage lead. There are two RCS pods on the ICPTA, with two engines on each pod. One of these two engines is a heritage flight engine from Project Morpheus. Its sea level nozzle was removed and replaced by an 85:1 nozzle machined using Inconel 718, resulting in a maximum thrust of 28 lbf under altitude conditions. The other engine is a scaled down version of the 28 lbf engine, designed to match the core and overall mixture ratios as well as other injector characteristics. This engine can produce a maximum thrust of 7 lbf with an 85:1 nozzle that was additively manufactured using Inconel 718. Both engines are film-cooled and capable of limited duration gas-gas and gas-liquid operation, as well as steady-state liquid-liquid operation. Each pod contains one of each version, such that two engines of the same thrust level can be fired as a couple on opposite pods. The RCS feed system is composed of symmetrical 3/8 inch lines that tap off of the main propellant manifold to send LOX and LCH4 outboard to the RCS pods. A Thermodynamic Vent System (TVS) is used to condition propellants at each pod by venting through an orifice and then routing the cold expansion products back through tubing that is welded along a large portion of the main RCS feed lines. Prior to final installation on the ICPTA, the RCS engines were Tested in a small vacuum chamber at the Johnson Space Center (JSC) Energy Systems Test Area (ESTA) to verify functionality of the new COP ignition system and check out operation of the vacuum nozzles. After engine-level Testing, the RCS engines were installed on the vehicle and a series of integrated hot-fire Tests were performed at JSC consisting of various pulsing and steady-state firings as well as integrated main engine/RCS operation. The ICPTA was then integrated into the Plum Brook B-2 facility for vacuum and thermal/vacuum Testing. Testing in the B-2 facility was composed of multiple thermal and pressure environments. The first set of Tests were performed under ambient temperature and altitude pressure conditions. These Tests consisted of a range of minimum impulse bit (MIB) pulsing sequences with low duty cycle, analogous to a coast phase in which the RCS is primarily used for station keeping. The primary goal of this sequence is to understand how propellant conditions were effected without an active TVS. In this scenario, consistent gas-gas operation is desirable since it results in a smaller MIB and more efficient propellant consumption. Multiple skin thermocouples are mounted on the feedlines, in addition to a submerged thermocouple on each commodity, in order to gather thermal data on the system. Higher duty cycle pulsing Tests were then performed, analogous to an ascent or landing mission phase. The primary goal of this sequence was to examine how well the engines self-conditioned without active TVS when starting from a quiescent state. The TVS was then activated during some Tests to demonstrate the capability to quickly condition the engines for higher pulsing demand scenarios. A thermocouple at the TVS outlet allows for the calculation of energy absorbed by the vented propellant. Lastly, Tests with longer pulses and multiple engines firing either in sequence or simultaneously were run in order to gather transient system response data on waterhammer. Six total high-speed pressure transducers are installed on the RCS system, one sensor at the end of each propellant manifold line on the pods, and one at the tap-off location for each commodity. This will allow for the accurate characterization of waterhammer in the system under various propellant conditions and firing sequences. Other instrumentation for this Test series includes nozzle throat thermocouples, chamber pressure measurement, heat soakback measurement, and tank wall plume impingement temperature measurement. The next set of Tests were performed to demonstrate simultaneous main engine and RCS operation. Data from this Test will be used to examine if there is any change to nominal operation of the RCS as a result of feed system interaction or other phenomenon. Some of these Tests began under high vacuum conditions (target ambient pressure less than 1x10(exp -3) torr) and others began at altitude conditions. The last set of Tests were performed with the B-2 cold wall active. Under these Tests, many of the same low duty cycle MIB Tests were repeated in order to characterize how propellant conditions changed with the lower heat leak. In this scenario the RCS manifold experiences much less heat leak, resulting in a change to how well the engines self-condition. As a result, an increase in maximum waterhammer pressures and a change in natural frequency of the system was expected due to higher density propellants. The lower heat leak should also result in a change to the MIB pulse profile, and data will be examined to understand how MIB repeatability is affected in the different operating environments. Parallel to the Test efforts, a set of transient model development efforts were made to predict RCS performance. The primary effort was aimed at producing a SINDA/FLUINT model to predict propellant conditioning up to the engine inlet as a function of different environmental and operating parameters, with the goal of predicting chamber pressure, TVS performance, and propellant consumption over time. Preliminary results for this effort will be presented in comparison with Test data. Additional modeling efforts were made using SINDA/FLUINT to predict waterhammer in the system since the software is capable of handling multiphase transient fluid dynamics. These results will be compared with the high-speed pressure transducer Test data for validation purposes
