DSMC Study of Shock-Detachment Process in Hypersonic Chemically Reacting Flow PDF Download
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Category :
Languages : en
Pages : 7
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Book Description
Hypersonic chemically reacting flow around a wedge in the near-continuum regime was numerically studied by the DSMC method with the main goal of validation of real gas effect models. The influence of vibration-dissociation coupling on the results of numerical simulations was analyzed. To this end, two models of chemical reactions were used in the computations, the total collisional energy model and a vibrationally favored model. The numerical results were compared with the experimental data of Hornung and Smith on the shock-wave stand-off distance in a hypersonic flow around the wedge. Sensitivity of simulation results to chemical reaction rate constants was also estimated.
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Category :
Languages : en
Pages : 7
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Book Description
Hypersonic chemically reacting flow around a wedge in the near-continuum regime was numerically studied by the DSMC method with the main goal of validation of real gas effect models. The influence of vibration-dissociation coupling on the results of numerical simulations was analyzed. To this end, two models of chemical reactions were used in the computations, the total collisional energy model and a vibrationally favored model. The numerical results were compared with the experimental data of Hornung and Smith on the shock-wave stand-off distance in a hypersonic flow around the wedge. Sensitivity of simulation results to chemical reaction rate constants was also estimated.
Author: Yu-Hang Zhu
Publisher:
ISBN:
Category : Chemical kinetics
Languages : en
Pages : 150
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Author: M. Capitelli
Publisher: American Institute of Physics
ISBN:
Category : Science
Languages : en
Pages : 1386
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Book Description
The book contains papers presented at the 24th International Symposium on Rarefied Gas Dynamics, a conference that is recognized as the principal forum for the presentation of recent advances in the field of rarefied gas dynamics. The topics include fundamental aspects of Boltzmann and related equations, transport theory, Monte Carlo methods, kinetic theory, gas phase molecular collision dynamics, gas surface interaction, state to state kinetics, rarefied plasmas, and non-equilibrium plasma kinetics. Applications in the fields of internal flows, vacuum systems, rarefied jets, plumes, molecular beams, scamjets and hypersonics, microflows, granular gases, electrical thrusters are discussed. Researchers in the fields of mathematics, physics, chemistry and engineering can strongly benefit from the interdisciplinary nature of the book.
Author: Tong Zhu
Publisher:
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Category :
Languages : en
Pages :
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Book Description
The spectra of high-temperature, chemically reacting hypersonic flows provides the most powerful diagnostic available for testing thermochemically nonequilibrium models in re-entry conditions. Several shock tube experiments have revealed that conventional phenomenological approach can not accurately predict the internal temperature of the gas and also the corresponding radiation.In particular, large rotational nonequilibrium in strong shocks has been observed in several experiments with high peak translational temperatures. The Direct Simulation Monte Carlo (DSMC) method is a particle-based simulation method that is capable of properly simulating flows with large nonequilibrium. In the experiments above, one dimensional shocks are most widely studied but they are challenging to simulate using the DSMC method due to the unsteady nature of the flows and especially for hypersonic flows with chemical reactions taking place. Therefore, efficient approaches for simulating one-dimensional shocks are developed for use in DSMC simulations.Both a shock stabilization technique and a modified DSMC unsteady sampling approach are used in simulating one dimensional, unsteady shocks. In the latter approach, a moving sampling region is used to obtain an accurate profile of the reflected shock in air. The shock number density and temperature profiles are obtained and used to calculate excitation and radiation. The Quasi-Steady-State (QSS) assumption is made in the excitation calculation where both electron impact and heavy particle impact excitation for the NO(A) and the N2+(B) states are studied. The calculated NO radiation in the wavelength range of lambda = 235+/-7nm for shock speeds below 7km/s are in good agreement with the experiment, but, the predicted radiation is lower than the experiment for shock speeds above 7km/s. In addition, the N2+ radiation in the wavelength range of lambda = 391.4+/-0.2nm are in good agreement with the experimental data for shock speeds above 9km/s. High fidelity models for simulating both the dissociation and relaxation processes in N+N2 and N2+N2 systems are also investigated. Relaxation cross sections are computed and the 99 bin method shows good agreement between the bin-to-bin and state specific relaxation cross sections for both N-N2 and N2-N2 relaxation. These relaxation cross sections are then implemented separately in 0D DSMC isothermal relaxation cases. For both cases, the rotational and vibrational temperatures relax to the equilibrium heat bath temperature. For N-N2 relaxations, the rotational temperature relaxes faster than the vibrational temperature at relatively low translational temperature and at a very similar rate to the vibrational temperature at relatively high temperature. These are in qualitative agreement with the observation of earlier experiments. The one-dimensional binning method and associated cross sections by Parsons et al. are implemented in DSMC simulations and the results are compared with those using the traditional TCE and LB models. For shock conditions similar to those in the experiments of Gorelov, it is found that the MD-QCT chemical reaction model predicts more dissociation and faster relaxation of the vibrational temperature. In the higher speed shock condition of the experiment by Fujita, the use of MD-QCT databases for both chemical reaction and internal energy predicts more dissociation in the downstream of the shock but slower relaxation of the rotational temperature. Also the rotational temperature in the shock region is in somewhat better agreement with the experiment of Fujita.
Author: Shaye Yungster
Publisher:
ISBN:
Category : Chemical reaction, Conditions and laws of
Languages : en
Pages : 24
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Book Description
Author: Raymond Brun
Publisher: Springer Science & Business Media
ISBN: 3642788297
Category : Science
Languages : en
Pages : 497
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Book Description
Recently, there have been significant advances in the fields of high-enthalpy hypersonic flows, high-temperature gas physics, and chemistry shock propagation in various media, industrial and medical applications of shock waves, and shock-tube technology. This series contains all the papers and lectures of the 19th International Symposium on Shock Waves held in Marseille in 1993. They are published in four topical volumes, each containing papers on related topics, and preceded by an overview written by a leading international expert. The volumes may be purchased independently.
Author: Konstantinos Kontis
Publisher: Springer Science & Business Media
ISBN: 3642256856
Category : Science
Languages : en
Pages : 1122
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Book Description
The University of Manchester hosted the 28th International Symposium on Shock Waves between 17 and 22 July 2011. The International Symposium on Shock Waves first took place in 1957 in Boston and has since become an internationally acclaimed series of meetings for the wider Shock Wave Community. The ISSW28 focused on the following areas: Blast Waves, Chemically Reacting Flows, Dense Gases and Rarefied Flows, Detonation and Combustion, Diagnostics, Facilities, Flow Visualisation, Hypersonic Flow, Ignition, Impact and Compaction, Multiphase Flow, Nozzle Flow, Numerical Methods, Propulsion, Richtmyer-Meshkov, Shockwave Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shockwave Phenomena and Applications, as well as Medical and Biological Applications. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 28 and individuals interested in these fields.
Author: Klaus Hannemann
Publisher: Springer Science & Business Media
ISBN: 354085181X
Category : Science
Languages : en
Pages : 786
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Book Description
The 26th International Symposium on Shock Waves in Göttingen, Germany was jointly organised by the German Aerospace Centre DLR and the French-German Research Institute of Saint Louis ISL. The year 2007 marked the 50th anniversary of the Symposium, which first took place in 1957 in Boston and has since become an internationally acclaimed series of meetings for the wider Shock Wave Community. The ISSW26 focused on the following areas: Shock Propagation and Reflection, Detonation and Combustion, Hypersonic Flow, Shock Boundary Layer Interaction, Numerical Methods, Medical, Biological and Industrial Applications, Richtmyer Meshkov Instability, Blast Waves, Chemically Reacting Flows, Diagnostics, Facilities, Flow Visualisation, Ignition, Impact and Compaction, Multiphase Flow, Nozzles Flows, Plasmas and Propulsion. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 26 and individuals interested in these fields.
Author: F. McNeil Cheatwood
Publisher:
ISBN:
Category :
Languages : en
Pages : 200
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Author: James Stephen Strand
Publisher:
ISBN:
Category :
Languages : en
Pages : 376
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Book Description
In this work, statistical techniques were employed to study the modeling of a hypersonic shock with the Direct Simulation Monte Carlo (DSMC) method, and to gain insight into how the model interacts with a set of physical parameters. Direct Simulation Monte Carlo (DSMC) is a particle based method which is useful for simulating gas dynamics in rarefied and/or highly non-equilibrium flowfields. A DSMC code was written and optimized for use in this research. The code was developed with shock tube simulations in mind, and it includes a number of improvements which allow for the efficient simulation of 1D, hypersonic shocks. Most importantly, a moving sampling region is used to obtain an accurate steady shock profile from an unsteady, moving shock wave. The code is MPI parallel and an adaptive load balancing scheme ensures that the workload is distributed properly between processors over the course of a simulation. Global, Monte Carlo based sensitivity analyses were performed in order to determine which of the parameters examined in this work most strongly affect the simulation results for two scenarios: a 0D relaxation from an initial high temperature state and a hypersonic shock. The 0D relaxation scenario was included in order to examine whether, with appropriate initial conditions, it can be viewed in some regards as a substitute for the 1D shock in a statistica sensitivity analysis. In both analyses sensitivities were calculated based on both the square of the Pearson correlation coefficient and the mutual information. The quantity of interest (QoI) chosen for these analyses was the NO density profile. This vector QoI was broken into a set of scalar QoIs, each representing the density of NO at a specific point in time (for the relaxation) or a specific streamwise location (for the shock), and sensitivities were calculated for each scalar QoI based on both measures of sensitivity. The sensitivities were then integrated over the set of scalar QoIs to determine an overall sensitivity for each parameter. A weighting function was used in the integration in order to emphasize sensitivities in the region of greatest thermal and chemical non-equilibrium. The six parameters which most strongly affect the NO density profile were found to be the same for both scenarios, which provides justification for the claim that a 0D relaxation can in some situations be used as a substitute model for a hypersonic shock. These six parameters are the pre-exponential constants in the Arrhenius rate equations for the N2 dissociation reaction N2 + N [reaction in both directions] 3N, the O2 dissociation reaction O2 + O [reaction in both directions] 3O, the NO dissociation reactions NO + N [reaction in both directions] 2N + O and NO + O [reaction in both directions] N + 2O, and the exchange reactions N2 + O [reaction in both directions] NO + N and NO + O [reaction in both directions] O2 + N. After identification of the most sensitive parameters, a synthetic data calibration was performed to demonstrate that the statistical inverse problem could be solved for the 0D relaxation scenario. The calibration was performed using the QUESO code, developed at the PECOS center at UT Austin, which employs the Delayed Rejection Adaptive Metropolis (DRAM) algorithm. The six parameters identified by the sensitivity analysis were calibrated successfully with respect to a group of synthetic datasets.
