AIAA Scitech 2021 Forum最新文献

{"title":"Numerical analysis and prediction of Aero-optical effects","authors":"Daniel W. Hartman, T. Dzanic, F. Witherden, A. Tropina, R. Miles","doi":"10.2514/6.2021-0335","DOIUrl":"https://doi.org/10.2514/6.2021-0335","url":null,"abstract":"Shell models of turbulence were used to study the effect of isotropic turbulence on the refractive index spectrum for the case of a plane wave beam propagation through turbulent flow. Existing theories of the 1D and 3D temperature spectra were shown to be inaccurate in the dissipative range of the spectrum due to unresolved scales at high Reynolds numbers. The shell model explaining the buoyancy driven turbulence was chosen as a tool to consider density changes with temperature and resolve all the range of wavenumbers up to the Kolmogorov’s scale. The physical nature of the Hill bump (increase of the slope of the energy spectrum), observed in the transition region between inertial-convective and viscous–diffusive parts of the cascade was explored. It was shown that no Hill bump is formed if the sufficient number of shells is chosen to resolve all of the spectrum, but the Hill bump will appear at the additional non-compensated forcing at large wavenumbers. The calculated shell-averaged temperature spectrum was used to determine the refractive index power spectral density and to create 2D phase-screens for modeling the laser beam propagation in the formed turbulent flow. Verification and validation of the combined shell and aero-optics problem were done by the comparison of the irradiance profiles with the laboratory experimental data and Direct Numerical Simulations for the case of a 532 nm laser beam propagation in grid generated turbulence and for the case of the buoyancy driven turbulence. The turbulent velocity and temperature spectra generated by the shell model were shown to be comparable to the Modified Von-Karman theory. Good quantitative agreement with the experimental data confirmed that the main source of the laser beam distortion at considered conditions relates to the thermal distortions.","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"332 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115976185","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":"Study of Separation of Three-Dimensional Boundary Layer using Critical Point Theory","authors":"Vasanth Kumar, R. Mukherjee","doi":"10.2514/6.2021-1995","DOIUrl":"https://doi.org/10.2514/6.2021-1995","url":null,"abstract":"","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115271905","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":"Direct numerical simulation of single-species and binary-species boundary layers at high pressure","authors":"Takahiko Toki, J. Bellan","doi":"10.2514/6.2021-0682","DOIUrl":"https://doi.org/10.2514/6.2021-0682","url":null,"abstract":"","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115135188","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":"Numerical Simulations of Multiple Shock Wave Boundary Layer Interactions","authors":"K. Boychev, G. Barakos, R. Steijl","doi":"10.2514/6.2021-1762","DOIUrl":"https://doi.org/10.2514/6.2021-1762","url":null,"abstract":"Shock wave boundary layer interactions occur in many aerospace applications, and of particular interest are the interactions occurring in high-speed intakes. The high-speed intakes aim to decelerate the flow with minimum losses using a series of oblique shocks followed by a weak normal shock. Depending on the state of the boundary layer and on the upstream Mach number, multiple shocks can form in the throat of the intake. Often, they are referred to as shock trains, or pseudo-shocks and can have a significant impact on the inake performance. The in-house CFD solver of the Unversity of Glasgow is used here, to investigate an isolated multiple shock interaction and quantify the effect of different non-linear turbulence models. The non-linear models, and their ability to account for the Reynolds stress anisotropy, resolve the corner flows and give favourable agreement with experiments. As a second step, shock train simulations in a geometry more representative of a high-speed intake are performed. Three different pitot intakes are considered and performance metrics based on the total pressure recovery and flow distortion are evaluated at different free-stream conditions. The predicted shock trains are highly asymmetric and the strong sensitivity of the total pressure recovery and flow distortion to the intake geometry is observed which reduces at higher incidence angles.","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127014489","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":"3D-Printed Wings with Morphing Trailing-Edge Technology","authors":"Benjamin C. Moulton, D. Hunsaker","doi":"10.2514/6.2021-0351","DOIUrl":"https://doi.org/10.2514/6.2021-0351","url":null,"abstract":"In recent years","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120949254","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":"Inlet Performance of the NFAC 1/50th-Scale 80- by 120-Foot Wind Tunnel","authors":"Hannah T. Dromiack, Lauren N. Wagner","doi":"10.2514/6.2021-0510","DOIUrl":"https://doi.org/10.2514/6.2021-0510","url":null,"abstract":"The National Full-Scale Aerodynamics Complex 80by 120-FootWind Tunnel (80x120) was dedicated in 1987 and rated at 100 knots for full-scale aircraft testing at NASA Ames Research Center. The 80x120 is the world’s largest wind tunnel, designed as an open circuit tunnel with a large aerodynamically treated inlet open to the ambient atmospheric air. In 2017, damage was sustained within the wind tunnel drive system, opening a window to do testing using the existing 1/50th-scale model of the 80by 120-Foot Wind Tunnel within the full-scale 80by 120-FootWind tunnel test section. The objective of the research was to quantify the turbulence levels within the 1/50th-scale test section as a function of onset atmospheric wind direction (± 90 deg from tunnel center-line), variable test section speed (5 – 50 m/s) and purposeful obtrusion of wind flow into the inlet. The model wind tunnel inlet, contraction, and test section are geometrically identical to that of the full-scale wind tunnel and model testing provides aerodynamic performance characteristics under controlled test conditions allowing for insight into the full-scale test section flow quality. The test section turbulence levels are minimally affected by the onset direction of the ambient atmospheric wind, but are dramatically affected by the speed in the tunnelwhile operated in the presence ofwinds. Original design specifications were axial/vertical/lateral turbulence ≤ 0.5% at maximum test section speed, though early fullscale tunnel testing determined that lateral turbulence would be ≤ 0.6%. For test section speeds ≥ 30 m/s the tunnel is within the design specification limits. Between 5 m/s and 30 m/s, the test section turbulence levels are dependent on the onset wind direction and test section speed where test section turbulence in the axial, vertical and lateral directions was seen to be between 0.5% and 1% and, at times, greater than 1%. Finally, testing was performed with blockage designs at the inlet to disrupt the wind flow quality entering the tunnel contraction zone in an attempt to create higher levels of turbulence for high turbulent test conditions simulating the earth’s boundary layer. The highest turbulence levels measured were 6% in the axial direction by use of large spires designed to obstruct ≈ 50% of the inlet area.","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125789561","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":"Scoreboard: Management and Creation of In Situ and In Transit Data Extractions via Computational Steering","authors":"B. Whitlock, Christopher Laganella, E. Duque","doi":"10.2514/6.2021-1599","DOIUrl":"https://doi.org/10.2514/6.2021-1599","url":null,"abstract":"","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134219885","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":"Towards Automated Scheduling of NASA's Deep Space Network: A Mixed Integer Linear Programming Approach","authors":"Jonathan A. Sabol, R. Alimo, Mark Hoffmann, Edwin Goh, Brian Wilson, M. Johnston","doi":"10.2514/6.2021-0667","DOIUrl":"https://doi.org/10.2514/6.2021-0667","url":null,"abstract":"","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134609627","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":"Entropically Damped Artificial Compressibility Solver Using Higher Order Finite Difference Schemes on Curvilinear and Deforming Meshes","authors":"Shankar Achu, N. R. Vadlamani","doi":"10.2514/6.2021-0634","DOIUrl":"https://doi.org/10.2514/6.2021-0634","url":null,"abstract":"","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"49-50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133684402","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":"Nuclear Thermal Propulsion Spacecraft Integrated System Model","authors":"Diana Nikitaeva, L. Thomas, Alexander L. Aueron, Saroj Kumar, Dennis Nikitaev","doi":"10.2514/6.2021-1922","DOIUrl":"https://doi.org/10.2514/6.2021-1922","url":null,"abstract":"","PeriodicalId":165313,"journal":{"name":"AIAA Scitech 2021 Forum","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134084126","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}