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  • 1
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    Modeling and Simulation of Radiative Compressible Flows in Aerodynamic Heating Arc-Jet Facility (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Numerical simulations of an arc heated flow inside NASA's 20 [MW] Aerodynamics heating facility (AHF) are performed in order to investigate the three-dimensional swirling flow and the current distribution inside the wind tunnel. The plasma is considered in Local Thermodynamics Equilibrium(LTE) and is composed of Air-Argon gas mixture. The governing equations are the Navier-Stokes equations that include source terms corresponding to Joule heating and radiative cooling. The former is obtained by solving an electric potential equation, while the latter is calculated using an innovative massively parallel ray-tracing algorithm. The fully coupled system is closed by the thermodynamics relations and transport properties which are obtained from Chapman-Enskog method. A novel strategy was developed in order to enable the flow solver and the radiation calculation to be preformed independently and simultaneously using a different number of processors. Drastic reduction in the computational cost was achieved using this strategy. Details on the numerical methods used for space discretization, time integration and ray-tracing algorithm will be presented. The effect of the radiative cooling on the dynamics of the flow will be investigated. The complete set of equations were implemented within the COOLFluiD Framework. Fig. 1 shows the geometry of the Anode and part of the constrictor of the Aerodynamics heating facility (AHF). Fig. 2 shows the velocity field distribution along (x-y) plane and the streamline in (z-y) plane.
    Keywords: Numerical Analysis; Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN29873 , International Conference on Computational Fluid Dynamics (ICCFD9); Jul 11, 2016 - Jul 15, 2016; Istanbul; Turkey
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    NASA TECHNICAL REPORTS
  • 2
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    Computational Modeling for Non-Equilibrium Shock Tube Flows (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-25
    Description: Time accurate simulation of non-equilibrium flows inside shock tube facilities presents several challenges from both physical and mathematical aspects. Furthermore, the large computational cost makes it impractical to support a real-time experimental test campaign. In this work, we explore other methods for modeling the shock tube problem with the main focus on the post-shock region and the absolute radiation emanating from it. The proposed alternative approach is several orders of magnitude less computationally expensive while still accurate enough with regards to the quantities of interest. Excellent agreement is found with the established stagnation-line approach. Comparison with time-accurate simulations shows good agreement close to the peak values and disagreement of the temperatures relaxation and radiance profiles toward equilibrium.
    Keywords: Aircraft Propulsion and Power
    Type: ARC-E-DAA-TN70861 , International Symposium on Shock Waves (ISSW32); Jul 14, 2019 - Jul 19, 2019; Singapore; China
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    NASA TECHNICAL REPORTS
  • 3
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    Time Accurate Simulation of Nonequilibrium Flow Inside the NASA Ames Electric Arc Shock Tube (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Numerical investigations of the flowfield inside NASA Ames' Electric Arc Shock Tube have been performed. The focus is to simulate the experiments designed to reproduce shock layer radiation layer relevant to Earth re-entry conditions. This paper assess the current computational capability in simulating time-accurate unsteady nonequilibrium flows in the presence of strong shock waves with state-of-the-art physical models. The technical approach is described with preliminary results presented for one specific flow condition. It was found that the axisymmetric source term generates a numerical instability that appears as shock bending. This instability is time dependent which greatly affects the shock speed. Post-shock conditions are discussed and compared to CEA equilibrium prediction and good agreement was obtained close to the test-section and just behind the shock.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN64558 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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  • 4
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    Computational Modeling for Non-equilibrium Shock Tube Flows (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-07
    Description: Time accurate simulation of non-equilibrium flows inside shock tube facilities presents several challenges from both physical and mathematical aspects. Furthermore, the drastic computational cost makes it non-practical to support real-time experimental test campaign. In this work, we explore other methods for modeling the shock tube prob- lem with the main focus on the post-shock region and the absolute radiation emanating from it. The proposed alternative approach is several orders of magnitude less computa- tionally expansive while still accurate enough with regards to the quantities of interest. Excellent agreement is found with the well-established stagnation-line approach. Comparison with the time-accurate simulation shows good agreement close to the peak values and disagreement of the temperatures relaxation and radiance profiles toward equilibrium, due to shock speed unsteadiness.
    Keywords: Aircraft Propulsion and Power
    Type: ARC-E-DAA-TN70486 , International Symposium on Shock Waves (ISSW32); Jul 14, 2019 - Jul 19, 2019; Singapore; China
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    NASA TECHNICAL REPORTS
  • 5
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    Time Accurate Simulation of Nonequilibrium Flow inside the NASA Ames Electric Arc Shock Tube (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-06
    Description: Numerical investigations of the ow field inside NASA Ames' Electric Arc Shock Tube have been performed. The focus is to simulate the experiments designed to reproduce shock layer radiation layer relevant to Earth re-entry conditions. This paper assess the current computational capability in simulating unsteady nonequilibrium flows in the presence of strong shock waves with state-of-the-art physical models. The technical approach is described with preliminary results presented for one specific ow condition. The numerical problems encountered during the computation of these flows are detailed, along with the methods used to resolve them. Post-shock conditions are discussed and compared to CEA equilibrium prediction.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN64117 , AIAA SciTech Forum; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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