{"title":"A Flight Study of Unsteady Aerodynamic Loading Induced by Wake Vortex Encounter","authors":"Anthony P. Brown","doi":"10.2514/6.2018-3023","DOIUrl":"https://doi.org/10.2514/6.2018-3023","url":null,"abstract":"","PeriodicalId":419456,"journal":{"name":"2018 Atmospheric and Space Environments Conference","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128151551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
During an Extravehicular Activity (EVA), if the Extravehicular Mobility Unit (EMU) makes galvanic contact with the International Space Station (ISS), a negative Floating Potential (FP) can lead to an arcing hazard when it exceeds -45.5 V, and a positive FP can produce a DC current high enough to stimulate the astronaut’s muscles (5 mA), and also cause a hazard. The Boeing Space Environments team developed and utilizes a Plasma Interaction Model (PIM) in order to calculate the ISS FP based on the plasma environment, ISS velocity, geomagnetic field, solar array and ISS orientation, and solar array regulation to support EVA planning operations. Presently, the model excludes the sheath capacitance, resulting in the total potential drop being across the dielectric surface of the vehicle. Data from the Floating Potential Measurement Unit (FPMU) show this assumption to be generally true. However, Rapid Charging Events (RCE) are often observed in the FPMU data at eclipse exit when the electron number density, Ne, is low (less than 5(sub e)10 m (exp-3)). During these events, the FP can rise more than 40 V in one to five seconds. There is then a relaxation phase where the FP drops back to the normal FP values. The PIM model is not capable of producing these RCEs. It was thought that the inclusion of the sheath in PIM could improve the charging predictions, particularly as related to RCEs. A parametric study was performed to determine what portion of the measured FP is across the sheath for a range of Ne experienced by the ISS, and if the inclusion of the sheath in PIM is necessary. Results show that the potential drop across the sheath is negligible at times when the N(sub e) is greater than 1(sub e)11 m-3. However, there appears to be a transitional region between 1(sub e)10 m(exp -3) and 1(sub e)11 m(exp -3) where the sheath capacitance becomes more significant. During those conditions the potential drop across the sheath can be larger than the potential drop across the dielectric for short periods (1-5 seconds). These results agree remarkably well with measurements made by the FPMU. The inclusion of the sheath explains why high charging measurements occur when the Ne is low at eclipse exit and even times when the solar arrays are not a significant driver (i.e., potentials often rise as the ISS flies through spread-F). Results also show that the RCEs are not a safety concern because the potential drop across the dielectric surface does not exceed -45.5 V. In that case, the EMU would not arc. This gives high confidence in the low probability of an arcing hazard occurring.
{"title":"Characterization of Rapid Charging Events due to Sheath Capacitance and Impact on the International Space Station Plasma Hazard Process","authors":"W. Schmidl, W. A. Hartman, R. Mikatarian","doi":"10.2514/6.2018-3652","DOIUrl":"https://doi.org/10.2514/6.2018-3652","url":null,"abstract":"During an Extravehicular Activity (EVA), if the Extravehicular Mobility Unit (EMU) makes galvanic contact with the International Space Station (ISS), a negative Floating Potential (FP) can lead to an arcing hazard when it exceeds -45.5 V, and a positive FP can produce a DC current high enough to stimulate the astronaut’s muscles (5 mA), and also cause a hazard. The Boeing Space Environments team developed and utilizes a Plasma Interaction Model (PIM) in order to calculate the ISS FP based on the plasma environment, ISS velocity, geomagnetic field, solar array and ISS orientation, and solar array regulation to support EVA planning operations. Presently, the model excludes the sheath capacitance, resulting in the total potential drop being across the dielectric surface of the vehicle. Data from the Floating Potential Measurement Unit (FPMU) show this assumption to be generally true. However, Rapid Charging Events (RCE) are often observed in the FPMU data at eclipse exit when the electron number density, Ne, is low (less than 5(sub e)10 m (exp-3)). During these events, the FP can rise more than 40 V in one to five seconds. There is then a relaxation phase where the FP drops back to the normal FP values. The PIM model is not capable of producing these RCEs. It was thought that the inclusion of the sheath in PIM could improve the charging predictions, particularly as related to RCEs. A parametric study was performed to determine what portion of the measured FP is across the sheath for a range of Ne experienced by the ISS, and if the inclusion of the sheath in PIM is necessary. Results show that the potential drop across the sheath is negligible at times when the N(sub e) is greater than 1(sub e)11 m-3. However, there appears to be a transitional region between 1(sub e)10 m(exp -3) and 1(sub e)11 m(exp -3) where the sheath capacitance becomes more significant. During those conditions the potential drop across the sheath can be larger than the potential drop across the dielectric for short periods (1-5 seconds). These results agree remarkably well with measurements made by the FPMU. The inclusion of the sheath explains why high charging measurements occur when the Ne is low at eclipse exit and even times when the solar arrays are not a significant driver (i.e., potentials often rise as the ISS flies through spread-F). Results also show that the RCEs are not a safety concern because the potential drop across the dielectric surface does not exceed -45.5 V. In that case, the EMU would not arc. This gives high confidence in the low probability of an arcing hazard occurring.","PeriodicalId":419456,"journal":{"name":"2018 Atmospheric and Space Environments Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128652016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Wake Turbulence Mitigation in High Altitude Airspace Using Lateral Offset Procedures","authors":"L. Davenport, Shannon W. Murphy, E. Johnson","doi":"10.2514/6.2018-3190","DOIUrl":"https://doi.org/10.2514/6.2018-3190","url":null,"abstract":"","PeriodicalId":419456,"journal":{"name":"2018 Atmospheric and Space Environments Conference","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127477662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Explorative Study to Use Thermal Effects of Duty-Cycled Plasma Actuation for Aircraft Icing Mitigation","authors":"Yang Liu, Cem Kolbakir, Haiyang Hu, Hui Hu","doi":"10.2514/6.2018-3653","DOIUrl":"https://doi.org/10.2514/6.2018-3653","url":null,"abstract":"","PeriodicalId":419456,"journal":{"name":"2018 Atmospheric and Space Environments Conference","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133089716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. King, J. Manin, J. V. Zante, Emily N. Timko, P. Struk
The particle size characterization portion of the 2017 Propulsion Systems Laboratory Cloud Calibration is described. The work focuses on characterizing the particle size distribution of the icing cloud as a function of simulated atmospheric conditions. These results will aid in upcoming ice crystal and supercooled liquid icing tests in PSL. Measurements acquired with the Phase Doppler Interferometer and High Speed Imaging instruments are presented. Experimental results indicate that the particle size distribution is primarily a function nozzle air and water pressures, and that air speed is not a significant effect for ice crystal clouds in PSL and both thermodynamic conditions and air speed are not significant effects for supercooled liquid water clouds in PSL.
{"title":"Particle Size Calibration Testing in the NASA Propulsion System Laboratory","authors":"M. King, J. Manin, J. V. Zante, Emily N. Timko, P. Struk","doi":"10.2514/6.2018-3971","DOIUrl":"https://doi.org/10.2514/6.2018-3971","url":null,"abstract":"The particle size characterization portion of the 2017 Propulsion Systems Laboratory Cloud Calibration is described. The work focuses on characterizing the particle size distribution of the icing cloud as a function of simulated atmospheric conditions. These results will aid in upcoming ice crystal and supercooled liquid icing tests in PSL. Measurements acquired with the Phase Doppler Interferometer and High Speed Imaging instruments are presented. Experimental results indicate that the particle size distribution is primarily a function nozzle air and water pressures, and that air speed is not a significant effect for ice crystal clouds in PSL and both thermodynamic conditions and air speed are not significant effects for supercooled liquid water clouds in PSL.","PeriodicalId":419456,"journal":{"name":"2018 Atmospheric and Space Environments Conference","volume":"208 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132471312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Aouizerate, V. Charton, M. Balland, J. Senoner, P. Trontin, C. Laurent, Ghislain Blanchard, P. Villedieu
{"title":"Ice Crystals Trajectory Calculations in a Turbofan Engine","authors":"G. Aouizerate, V. Charton, M. Balland, J. Senoner, P. Trontin, C. Laurent, Ghislain Blanchard, P. Villedieu","doi":"10.2514/6.2018-4130","DOIUrl":"https://doi.org/10.2514/6.2018-4130","url":null,"abstract":"","PeriodicalId":419456,"journal":{"name":"2018 Atmospheric and Space Environments Conference","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129566331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Design, Fabrication, Calibration, and Testing of a Centrifugal Ice Adhesion Test Rig with Strain Rate Control Capability","authors":"R. Douglass, J. Palacios, Grant M. Schneeberger","doi":"10.2514/6.2018-3342","DOIUrl":"https://doi.org/10.2514/6.2018-3342","url":null,"abstract":"","PeriodicalId":419456,"journal":{"name":"2018 Atmospheric and Space Environments Conference","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130046568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effects of Aerodynamic Blockage on Stagnation Collection Efficiency in a Wind Tunnel Icing Environment","authors":"C. Clark","doi":"10.2514/6.2018-3832","DOIUrl":"https://doi.org/10.2514/6.2018-3832","url":null,"abstract":"","PeriodicalId":419456,"journal":{"name":"2018 Atmospheric and Space Environments Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130512134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An ice shape database has been created to document ice accretions on a 72-inch chord NACA 23012 airfoil model resulting from an exposure to a Supercooled Large Drop (SLD) icing cloud with a bimodal drop size distribution. The ice shapes created were documented with photographs, laser scanned surface measurements over a section of the model span, and measurement of the ice mass over the same section of each accretion. The icing conditions used in the test matrix were based upon previously measured ice shapes on the same model to connect the current database to previously measured information. Ice shapes resulting from the bimodal distribution as well as from equivalent mono-modal drop size distributions were obtained and compared. Results indicate that the ice shapes resulting from the bimodal drop size distributions had higher mass and volume values than their mono-modal distribution equivalents as well as having icing limits that extended further back on the chord of the model.
{"title":"Further Examinations of Bimodal SLD Ice Accretion in the NASA Icing Research Tunnel","authors":"M. Potapczuk, J. Tsao","doi":"10.2514/6.2018-3182","DOIUrl":"https://doi.org/10.2514/6.2018-3182","url":null,"abstract":"An ice shape database has been created to document ice accretions on a 72-inch chord NACA 23012 airfoil model resulting from an exposure to a Supercooled Large Drop (SLD) icing cloud with a bimodal drop size distribution. The ice shapes created were documented with photographs, laser scanned surface measurements over a section of the model span, and measurement of the ice mass over the same section of each accretion. The icing conditions used in the test matrix were based upon previously measured ice shapes on the same model to connect the current database to previously measured information. Ice shapes resulting from the bimodal distribution as well as from equivalent mono-modal drop size distributions were obtained and compared. Results indicate that the ice shapes resulting from the bimodal drop size distributions had higher mass and volume values than their mono-modal distribution equivalents as well as having icing limits that extended further back on the chord of the model.","PeriodicalId":419456,"journal":{"name":"2018 Atmospheric and Space Environments Conference","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129598260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexander Bucknell, M. McGilvray, D. Gillespie, Geoffrey Jones, Alasdair Reed, Benjamin Collier
It has been recognised in recent years that high altitude atmospheric ice crystals pose a threat to aircraft engines in flight. Instances of damage, surge and shutdown have been recorded at altitudes significantly greater than those associated with supercooled water icing. It is believed that ice particles can accrete inside the core compressor, although the exact mechanism by which this occurs remains poorly understood. In order to model ice crystal accretion, an estimate of the proportion of the impinging ice and water that sticks to a surface (the ‘sticking efficiency’) is required. This is believed to be dependent upon a number of parameters including particle melt ratio and diameter, and surface condition (rough or smooth, dry or wetted, warm or cold). This paper presents data from experiments undertaken in the National Research Council of Canada’s (NRC) Research Altitude Test Facility (RATFac). An axisymmetric test article, which featured three interchangeable cone ‘noses’ of varying half-angle, was used over a period of two weeks. A 35° half-angle nose was used for a parametric study of Mach number, Total Water Content (TWC), wet bulb temperature and particle size distribution (PSD). At selected test conditions, 20° and 45° half-angle noses were also tested. An assessment of the response of the Science Engineering Associates WCM-2000 multiwire probe in glaciated condition is presented, as a function of TWC, particle size and Mach number. A shadowgraphy technique was used to measure the ice accretion growth rate on the nose, with isometric camera views for qualitative assessments of spatial uniformity and build/shed events. The results show that sticking efficiency has a strong dependency on particle melt ratio, with maximum values attained when melt is typically between 9-13%. Erosion is shown to be correlated with particle size, Mach number and surface angle. New semi-empirical models are presented for sticking probability and erosion.
{"title":"Experimental Studies of Ice Crystal Accretion on an Axisymmetric Body at Engine-Realistic Conditions","authors":"Alexander Bucknell, M. McGilvray, D. Gillespie, Geoffrey Jones, Alasdair Reed, Benjamin Collier","doi":"10.2514/6.2018-4223","DOIUrl":"https://doi.org/10.2514/6.2018-4223","url":null,"abstract":"It has been recognised in recent years that high altitude atmospheric ice crystals pose a threat to aircraft engines in flight. Instances of damage, surge and shutdown have been recorded at altitudes significantly greater than those associated with supercooled water icing. It is believed that ice particles can accrete inside the core compressor, although the exact mechanism by which this occurs remains poorly understood. In order to model ice crystal accretion, an estimate of the proportion of the impinging ice and water that sticks to a surface (the ‘sticking efficiency’) is required. This is believed to be dependent upon a number of parameters including particle melt ratio and diameter, and surface condition (rough or smooth, dry or wetted, warm or cold). This paper presents data from experiments undertaken in the National Research Council of Canada’s (NRC) Research Altitude Test Facility (RATFac). An axisymmetric test article, which featured three interchangeable cone ‘noses’ of varying half-angle, was used over a period of two weeks. A 35° half-angle nose was used for a parametric study of Mach number, Total Water Content (TWC), wet bulb temperature and particle size distribution (PSD). At selected test conditions, 20° and 45° half-angle noses were also tested. An assessment of the response of the Science Engineering Associates WCM-2000 multiwire probe in glaciated condition is presented, as a function of TWC, particle size and Mach number. A shadowgraphy technique was used to measure the ice accretion growth rate on the nose, with isometric camera views for qualitative assessments of spatial uniformity and build/shed events. The results show that sticking efficiency has a strong dependency on particle melt ratio, with maximum values attained when melt is typically between 9-13%. Erosion is shown to be correlated with particle size, Mach number and surface angle. New semi-empirical models are presented for sticking probability and erosion.","PeriodicalId":419456,"journal":{"name":"2018 Atmospheric and Space Environments Conference","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128738741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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