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You searched for subject:(Supersonic combustion modeling). Showing records 1 – 2 of 2 total matches.

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University of Washington

1. Daneshvaran, Navid. Transient Computational Fluid Dynamic Modeling of Baffled Tube Ram Accelerator.

Degree: 2017, University of Washington

Transient computational fluid dynamic modeling in laboratory frame of reference was used to investigate baffled tube ram accelerator operating characteristics in inert and reactive mixtures. The minimum entrance Mach number that allowed supersonic projectile transit through a baffled tube filled with inert gas and the thrust generated in reactive flow were examined. The primary parameters considered were chamber-to-projectile diameter ratio, projectile geometry, baffle thickness, baffle spacing and baffle geometry. Axisymmetric and three-dimensional simulations used a dynamic mesh for a projectile moving at constant Mach (ranging from 1.8 to 5.1) through stationary baffles. The maximum baffle thickness and minimum baffle spacing at velocities near the minimum allowable entrance Mach number were both found to be ~53% of the projectile diameter. Further reducing the baffle spacing resulted in the projectile pushing a normal shockwave ahead of it like in a jet engine unstart. It was also found that thicker baffles and closer baffle spacing increased the projectile drag coefficient. Reactive flow phenomena were investigated by first establishing the combustion on the projectile in a smooth bore tube before it entered the baffled-tube section. A key finding from premixed methane and oxygen propellant simulations was that aftward-slanted baffles generated higher thrust than when the baffles were normal to the projectile or forward-slanted. This increase in thrust was associated with more complete propellant combustion in the annular baffle chambers around the tail and base sections of the axisymmetric projectile, as well as immediately behind it. It was also determined that residence time of the propellant during combustion process in the vicinity of the projectile at any given baffle, influences the overall thrust production. As the projectile Mach increases, both the propellant residence time and overall thrust level decrease. Advisors/Committee Members: Knowlen, Carl (advisor).

Subjects/Keywords: Baffled Tube Ram Accelerator; Combustion; Inert and Reactive Flow; Ram Accelerator; Supersonic Flow; Transient Computational Fluid Dynamic Modeling; Aerospace engineering; Aeronautics and astronautics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Daneshvaran, N. (2017). Transient Computational Fluid Dynamic Modeling of Baffled Tube Ram Accelerator. (Thesis). University of Washington. Retrieved from http://hdl.handle.net/1773/39913

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Daneshvaran, Navid. “Transient Computational Fluid Dynamic Modeling of Baffled Tube Ram Accelerator.” 2017. Thesis, University of Washington. Accessed January 23, 2021. http://hdl.handle.net/1773/39913.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Daneshvaran, Navid. “Transient Computational Fluid Dynamic Modeling of Baffled Tube Ram Accelerator.” 2017. Web. 23 Jan 2021.

Vancouver:

Daneshvaran N. Transient Computational Fluid Dynamic Modeling of Baffled Tube Ram Accelerator. [Internet] [Thesis]. University of Washington; 2017. [cited 2021 Jan 23]. Available from: http://hdl.handle.net/1773/39913.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Daneshvaran N. Transient Computational Fluid Dynamic Modeling of Baffled Tube Ram Accelerator. [Thesis]. University of Washington; 2017. Available from: http://hdl.handle.net/1773/39913

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Donde, Pratik Prakash. LES/PDF approach for turbulent reacting flows.

Degree: PhD, Aerospace Engineering, 2012, University of Texas – Austin

The probability density function (PDF) approach is a powerful technique for large eddy simulation (LES) based modeling of turbulent reacting flows. In this approach, the joint-PDF of all reacting scalars is estimated by solving a PDF transport equation, thus providing detailed information about small-scale correlations between these quantities. The objective of this work is to further develop the LES/PDF approach for studying flame stabilization in supersonic combustors, and for soot modeling in turbulent flames. Supersonic combustors are characterized by strong shock-turbulence interactions which preclude the application of conventional Lagrangian stochastic methods for solving the PDF transport equation. A viable alternative is provided by quadrature based methods which are deterministic and Eulerian. In this work, it is first demonstrated that the numerical errors associated with LES require special care in the development of PDF solution algorithms. The direct quadrature method of moments (DQMOM) is one quadrature-based approach developed for supersonic combustion modeling. This approach is shown to generate inconsistent evolution of the scalar moments. Further, gradient-based source terms that appear in the DQMOM transport equations are severely underpredicted in LES leading to artificial mixing of fuel and oxidizer. To overcome these numerical issues, a new approach called semi-discrete quadrature method of moments (SeQMOM) is formulated. The performance of the new technique is compared with the DQMOM approach in canonical flow configurations as well as a three-dimensional supersonic cavity stabilized flame configuration. The SeQMOM approach is shown to predict subfilter statistics accurately compared to the DQMOM approach. For soot modeling in turbulent flows, an LES/PDF approach is integrated with detailed models for soot formation and growth. The PDF approach directly evolves the joint statistics of the gas-phase scalars and a set of moments of the soot number density function. This LES/PDF approach is then used to simulate a turbulent natural gas flame. A Lagrangian method formulated in cylindrical coordinates solves the high dimensional PDF transport equation and is coupled to an Eulerian LES solver. The LES/PDF simulations show that soot formation is highly intermittent and is always restricted to the fuel-rich region of the flow. The PDF of soot moments has a wide spread leading to a large subfilter variance. Further, the conditional statistics of soot moments conditioned on mixture fraction and reaction progress variable show strong correlation between the gas phase composition and soot moments. Advisors/Committee Members: Raman, Venkat (advisor), Clemens, Noel (committee member), Ezekoye, Ofodike (committee member), Goldstein, David (committee member), Moser, Robert (committee member).

Subjects/Keywords: Probability density function approach; Large eddy simulation; Supersonic combustion modeling; Soot modeling; Turbulent reacting flows; Direct quadrature method of moments; Semi-discrete quadrature method of moments; Quadrature based methods; Lagrangian Monte Carlo methods; Supersonic combustors; Flame stabilization; Polycyclic aromatic hydrocarbons; Soot-turbulence-chemistry interactions; Shock-turbulence-chemistry interactions

…Chapter 7. Conclusion and future direction 7.1 Supersonic combustion modeling studies… …for the LES/PDF approach. The PDF approach for supersonic combustion modeling is reviewed in… …modeling. 17 Chapter 3 PDF approach for supersonic combustion modeling The flow-field inside… …xii Chapter 1. Introduction 1.1 Supersonic combustion . . . . . . 1.2 Soot formation… …reacting flows . . . . . . . . . . . . . . 2.3 PDF approach for combustion modeling . . . . 2.3.1… 

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Donde, P. P. (2012). LES/PDF approach for turbulent reacting flows. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/19481

Chicago Manual of Style (16th Edition):

Donde, Pratik Prakash. “LES/PDF approach for turbulent reacting flows.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed January 23, 2021. http://hdl.handle.net/2152/19481.

MLA Handbook (7th Edition):

Donde, Pratik Prakash. “LES/PDF approach for turbulent reacting flows.” 2012. Web. 23 Jan 2021.

Vancouver:

Donde PP. LES/PDF approach for turbulent reacting flows. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Jan 23]. Available from: http://hdl.handle.net/2152/19481.

Council of Science Editors:

Donde PP. LES/PDF approach for turbulent reacting flows. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/19481

.