Spectrally and spatially resolved radiance has been measured in the Electric Arc Shock Tube (EAST) facility, with the aim of improving fundamental understanding of high en-thalpy flows in pure nitrogen. These tests provide data to inform models used for simulations of high speed flight in nitrogen rich atmospheres, such as Earth or Titan. The experiments presented in this paper cover conditions from approximately 6 km/s to 11 km/s at an initial pressure of 0.2 Torr. A wide range of physics, with different degrees of non-equilibrium and nitrogen dissociation, are covered. The EAST data are presented in different formats for analysis and comparisons. These formats include the spectral radiance at equilibrium (where appropriate), the spatial dependence of radiance over defined wavelength ranges and the mean non-equilibrium spectral radiance (the so-called “spec-tral non-equilibrium metric”). All the information needed to simulate each experimental trace, including free-stream conditions, shock time of arrival (i.e. x-t) relation, and the spectral and spatial resolution functions, are provided. Equilibrium radiation calculations are shown as a reference. It is the intention of this paper to motivate code comparisons benchmarked against this data set.
{"title":"Shock Tube Radiation Measurements in Nitrogen","authors":"A. Brandis, B. Cruden","doi":"10.2514/6.2018-3437","DOIUrl":"https://doi.org/10.2514/6.2018-3437","url":null,"abstract":"Spectrally and spatially resolved radiance has been measured in the Electric Arc Shock Tube (EAST) facility, with the aim of improving fundamental understanding of high en-thalpy flows in pure nitrogen. These tests provide data to inform models used for simulations of high speed flight in nitrogen rich atmospheres, such as Earth or Titan. The experiments presented in this paper cover conditions from approximately 6 km/s to 11 km/s at an initial pressure of 0.2 Torr. A wide range of physics, with different degrees of non-equilibrium and nitrogen dissociation, are covered. The EAST data are presented in different formats for analysis and comparisons. These formats include the spectral radiance at equilibrium (where appropriate), the spatial dependence of radiance over defined wavelength ranges and the mean non-equilibrium spectral radiance (the so-called “spec-tral non-equilibrium metric”). All the information needed to simulate each experimental trace, including free-stream conditions, shock time of arrival (i.e. x-t) relation, and the spectral and spatial resolution functions, are provided. Equilibrium radiation calculations are shown as a reference. It is the intention of this paper to motivate code comparisons benchmarked against this data set.","PeriodicalId":423948,"journal":{"name":"2018 Joint Thermophysics and Heat Transfer Conference","volume":"10 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":"131107417","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}
A. Wagner, J. Schramm, C. Dittert, Victor C. B. Sousa, D. Patel, C. Scalo
The paper addresses the experimental and numerical acoustic characterization of ultrasonically absorptive porous materials with random microstructure such as carbon fiber reinforced carbon ceramic C/C or C/C-SiC. The present study builds upon previous efforts by the authors, improving and extending the established experimental method, complemented by a numerical analysis based on linear acoustics. The latter includes a blind-hole porosity approximation, only accounting for the larger cracks in the C/C with complex acoustic impedance given by the inverse Helmholtz Solver approach, and a highly parametrized homogeneous acoustic Absorber model, accounting for the complete volumetric structure of the porous absorber albeit with lower fidelity. The experimental approach is complemented by high-speed Schlieren visualization and Mach-Zehnder Interferometer measurements to qualitatively and quantitatively assess the interaction between an ultrasonic wave packet and a porous surface. It is found that neglecting the smaller pores and only accounting for the surface porosity, as done in the blind-hole porosity approximation, leads to the underestimation of the acoustic energy absorption coefficient. Phase shifts were found to be experimentally assessable, but remain to be corroborated by a numerical analysis. The comparisons carried out in this paper will pave the way for accurate determination of impedance boundary conditions to be applied in direct numerical simulations of hypersonic transition delay over C/C. The main emphasis of the paper is to assess the potential and the limitations of the experimental methods and the comparison of the experimental results to the numerically obtained absorption characteristics.
{"title":"Experimental and numerical acoustic characterization of ultrasonically absorptive porous materials","authors":"A. Wagner, J. Schramm, C. Dittert, Victor C. B. Sousa, D. Patel, C. Scalo","doi":"10.2514/6.2018-2948","DOIUrl":"https://doi.org/10.2514/6.2018-2948","url":null,"abstract":"The paper addresses the experimental and numerical acoustic characterization of ultrasonically absorptive porous materials with random microstructure such as carbon fiber reinforced carbon ceramic C/C or C/C-SiC. The present study builds upon previous efforts by the authors, \u0000improving and extending the established experimental method, complemented by a numerical analysis based on linear acoustics. The latter includes a blind-hole porosity approximation, only accounting for the larger cracks in the C/C with complex acoustic impedance given by the \u0000inverse Helmholtz Solver approach, and a highly parametrized homogeneous acoustic Absorber model, accounting for the complete volumetric structure of the porous absorber albeit with lower fidelity. The experimental approach is complemented by high-speed Schlieren visualization and Mach-Zehnder Interferometer measurements to qualitatively and quantitatively \u0000assess the interaction between an ultrasonic wave packet and a porous surface. It is found that neglecting the smaller pores and only accounting for the surface porosity, as done in the blind-hole porosity approximation, leads to the underestimation of the acoustic energy absorption coefficient. Phase shifts were found to be experimentally assessable, but remain to be corroborated by a numerical analysis. The comparisons carried out in this paper will pave \u0000the way for accurate determination of impedance boundary conditions to be applied in direct numerical simulations of hypersonic transition delay over C/C. The main emphasis of the paper is to assess the potential and the limitations of the experimental methods and the comparison of the experimental results to the numerically obtained absorption characteristics.","PeriodicalId":423948,"journal":{"name":"2018 Joint Thermophysics and Heat Transfer Conference","volume":"48 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":"134484917","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 Test Box Pressure on Arc-Jet Flowfields and Implications for Testing","authors":"T. Gokcen","doi":"10.2514/6.2018-3771","DOIUrl":"https://doi.org/10.2514/6.2018-3771","url":null,"abstract":"","PeriodicalId":423948,"journal":{"name":"2018 Joint Thermophysics and Heat Transfer Conference","volume":"2013 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":"114510968","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":"A Numerical Study of Bayesian Inference of Surface Catalycity in Low Speed Reacting Flow using Laser Absorption Spectroscopy","authors":"Timothy R. Adowski, P. Bauman","doi":"10.2514/6.2018-4290","DOIUrl":"https://doi.org/10.2514/6.2018-4290","url":null,"abstract":"","PeriodicalId":423948,"journal":{"name":"2018 Joint Thermophysics and Heat Transfer Conference","volume":"16 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":"116904033","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}
Ross S. Chaudhry, Narendra Singh, Maninder S. Grover, T. Schwartzentruber, G. Candler
{"title":"Implementation of a Nitrogen Chemical Kinetics Model Based on ab-Initio Data for Hypersonic CFD","authors":"Ross S. Chaudhry, Narendra Singh, Maninder S. Grover, T. Schwartzentruber, G. Candler","doi":"10.2514/6.2018-3439","DOIUrl":"https://doi.org/10.2514/6.2018-3439","url":null,"abstract":"","PeriodicalId":423948,"journal":{"name":"2018 Joint Thermophysics and Heat Transfer Conference","volume":"59 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":"129188484","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}
Aerothermal optimization is a powerful technique for the design of internal cooling passages because it maximizes heat transfer and simultaneously minimizes pressure loss. Moreover, the optimization is fully automatic, which reduces the duration of design process compared with a human-supervised design approach. Existing optimization studies commonly rely on gradient-free methods, which can only handle a small number of design variables. However, cooling passage designs use complex geometry configurations (e.g., serpentine channels with rib-roughened surfaces) to enhance heat transfer; what is needed is to parameterize the passage using a large number of design variables. To address this need, we perform aerothermal optimization using a gradient-based optimization algorithm along with the discrete adjoint method to compute derivatives. The benefit of using the adjoint method is that its computational cost is independent of the number of design variables. In this paper, we focus on optimizing a U-bend duct, which is representative of a simplified, rib-free turbine internal cooling passage. The duct geometry is parameterized using 135 design variables, which gives us sufficient design freedom for geometric modification. We construct a Pareto front for heat transfer enhancement and total pressure loss reduction by running multi-objective optimizations. We also compare our optimization results with those from the gradient-free methods and demonstrate that we achieve better pressure loss reduction and heat transfer enhancement. The above results show that our gradient-based optimization framework functions as desired and has the potential to be a useful tool for turbine aerothermal designs with full internal cooling configurations.
{"title":"Aerothermal Optimization of Internal Cooling Passages Using a Discrete Adjoint Method","authors":"P. He, C. Mader, J. Martins, K. Maki","doi":"10.2514/6.2018-4080","DOIUrl":"https://doi.org/10.2514/6.2018-4080","url":null,"abstract":"Aerothermal optimization is a powerful technique for the design of internal cooling passages because it maximizes heat transfer and simultaneously minimizes pressure loss. Moreover, the optimization is fully automatic, which reduces the duration of design process compared with a human-supervised design approach. Existing optimization studies commonly rely on gradient-free methods, which can only handle a small number of design variables. However, cooling passage designs use complex geometry configurations (e.g., serpentine channels with rib-roughened surfaces) to enhance heat transfer; what is needed is to parameterize the passage using a large number of design variables. To address this need, we perform aerothermal optimization using a gradient-based optimization algorithm along with the discrete adjoint method to compute derivatives. The benefit of using the adjoint method is that its computational cost is independent of the number of design variables. In this paper, we focus on optimizing a U-bend duct, which is representative of a simplified, rib-free turbine internal cooling passage. The duct geometry is parameterized using 135 design variables, which gives us sufficient design freedom for geometric modification. We construct a Pareto front for heat transfer enhancement and total pressure loss reduction by running multi-objective optimizations. We also compare our optimization results with those from the gradient-free methods and demonstrate that we achieve better pressure loss reduction and heat transfer enhancement. The above results show that our gradient-based optimization framework functions as desired and has the potential to be a useful tool for turbine aerothermal designs with full internal cooling configurations.","PeriodicalId":423948,"journal":{"name":"2018 Joint Thermophysics and Heat Transfer Conference","volume":"47 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":"116544903","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":"Generalized Solution for Two-Dimensional Transient Heat Conduction Problems with Partial Heating","authors":"R. McMasters, F. Monte, J. Beck","doi":"10.2514/6.2018-4073","DOIUrl":"https://doi.org/10.2514/6.2018-4073","url":null,"abstract":"","PeriodicalId":423948,"journal":{"name":"2018 Joint Thermophysics and Heat Transfer 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":"122405990","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":"Modeling of Excited Oxygen in Post Normal Shock Waves","authors":"Kyle M. Hanquist, I. Boyd","doi":"10.2514/6.2018-3769","DOIUrl":"https://doi.org/10.2514/6.2018-3769","url":null,"abstract":"","PeriodicalId":423948,"journal":{"name":"2018 Joint Thermophysics and Heat Transfer Conference","volume":"15 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":"133563463","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}
Hesham E. Metwally, E. Khalil, Taher E. Abou Dief, Ahmed Abouzeid
{"title":"Air Quality and Flow Regimes at Clean Rooms","authors":"Hesham E. Metwally, E. Khalil, Taher E. Abou Dief, Ahmed Abouzeid","doi":"10.2514/6.2018-3908","DOIUrl":"https://doi.org/10.2514/6.2018-3908","url":null,"abstract":"","PeriodicalId":423948,"journal":{"name":"2018 Joint Thermophysics and Heat Transfer 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":"114056107","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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