Modeling of turbulent mixing and combustion at transcritical conditions
Abstract/Contents
- Abstract
- The simulation of transcritical real-fluid effects is crucial for many engineering applications, such as fuel injection and combustion in internal-combustion engines, rocket motors and gas turbines. In these systems, the liquid fuel is injected into the ambient gas at a pressure that exceeds its critical value, and the fuel jet will be heated to a supercritical temperature before combustion takes place. At elevated pressures, the mixture properties exhibit liquid-like densities and gas-like diffusivities, and the surface tension and enthalpy of vaporization approach zero. In this thesis, algorithms and modeling tools are developed for the prediction of supercritical and transcritical mixing and combustion. A diffuse-interface method is developed for simulating turbulent flows at transcritical conditions. Real-fluid thermodynamics is described efficiently using the cubic equation of state. Spurious pressure oscillations associated with fully conservative (FC) formulations are addressed by a double-flux model. An entropy-stable scheme that combines high-order non-dissipative and low-order dissipative finite-volume schemes is proposed to preserve the physical realizability of numerical solutions across large density gradients. The resulting algorithms are applied to a series of test cases to demonstrate the capability in simulations of problems that are relevant for multi-species transcritical turbulent flows. The developed quasi-conservative (QC) scheme is subsequently analyzed with the traditional FC scheme for multi-species mixing problems. Through numerical analysis, it is shown that mixing processes for isobaric systems follow the limiting cases of adiabatic and isochoric mixing models for FC and QC schemes, respectively, which is confirmed by several numerical test cases. An extension to the classical flamelet/progress variable approach is developed for transcritical combustion simulations. The novelty of the proposed approach lies in the ability to account for pressure and temperature variations from the baseline tabulated values in a thermodynamically consistent fashion. Application cases relevant to rocket combustors are performed to demonstrate the capability of the proposed approach in multidimensional transcritical combustion simulations. Finally, a finite-rate chemistry model is employed in conjunction with the developed diffuse-interface method for the prediction of diesel fuel injection and auto-ignition processes. Simulations of an ECN-relevant diesel-fuel injector are performed for both inert and reacting cases at multiple operating points. The performance of the presented numerical framework is demonstrated through comparisons with available experimental data.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2018 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Ma, Peter C |
|---|---|
| Associated with | Stanford University, Department of Mechanical Engineering. |
| Primary advisor | Ihme, Matthias |
| Thesis advisor | Ihme, Matthias |
| Thesis advisor | Iaccarino, Gianluca |
| Thesis advisor | Lele, Sanjiva K. (Sanjiva Keshava), 1958- |
| Advisor | Iaccarino, Gianluca |
| Advisor | Lele, Sanjiva K. (Sanjiva Keshava), 1958- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Peter C. Ma. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2018. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2018 by Chao Ma
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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