Computational flame propagation studies in support of launch vehicle risk assessment
Abstract/Contents
- Abstract
- Understanding how flames propagate in a failure scenario and the associated risk is important to many different fields, including hydrogen storage facilities, mines, and other relatively confined industrial settings, but the focus here is launch vehicles. Large, uncontained, explosive failures occurring in the engine bay of space launch vehicles and resulting from the unwanted release, mixture, and ignition of a fuel source, pose a significant risk to the crew, surrounding personnel, and equipment. Explosions in these failures involve complex physical phenomena and the flame propagation can be extremely sensitive to specific conditions at the time of ignition, for example, confinement and congestion. The combination of complex physics, potentially complicated geometries, and flame sensitivities make blast environments very difficult to characterize. There are three main options for characterizing the environment for use in risk assessments, including physical experiments, computational fluid dynamics (CFD) simulations, and engineering-level blast models. Low cost (time, money, resources) engineering models are the most practical option for a probabilistic approach, but insight from experiments and CFD studies are needed to inform and develop the models. The goal of this work is to use CFD simulations to better understand various flame propagation mechanisms and sensitivities to different parameters. The results will be used to support the development of physics-based probabilistic risk assessment models leading to guidelines for designing safer launch vehicles. The work was broken into two main computational studies, each with several substudies analyzing the effects of varying different parameters. The first study focused on mechanisms of deflagration to detonation transition in confined, obstructed flows, and found that scenarios with limited non-bluff obstacles, limited points of ignition, and lower initial pressure, density, and temperature reduced the risk of detonation initiation because these factors all reduced the potential for large flame accelerations. The second study focused on the influence of underlying flow parameters on deflagration flame propagation, and found that characterizing the underlying flow is important because scenarios with features in the flow tend to cause local flame deformations and acceleration, increasing flame speed and overpressure and changing the potential risk. Parameters like vorticity magnitude and invariants of the velocity gradient tensor may be effective indicators in the model for when local acceleration is likely to take place. All of the approximately 35 cases considered between the two studies were chosen to represent possible scenarios in rocket engine bays, and the insight developed will lead to improved launch vehicle risk assessments
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2020; ©2020 |
| Publication date | 2020; 2020 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Coates, Ashley Michelle |
|---|---|
| Degree supervisor | Cantwell, Brian |
| Thesis advisor | Cantwell, Brian |
| Thesis advisor | Bowman, Craig T. (Craig Thomas), 1939- |
| Thesis advisor | Farhat, Charbel |
| Thesis advisor | Mathias, Donovan L |
| Degree committee member | Bowman, Craig T. (Craig Thomas), 1939- |
| Degree committee member | Farhat, Charbel |
| Degree committee member | Mathias, Donovan L |
| Associated with | Stanford University, Department of Aeronautics & Astronautics. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Ashley Michelle Coates |
|---|---|
| Note | Submitted to the Department of Aeronautics & Astronautics |
| Thesis | Thesis Ph.D. Stanford University 2020 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2020 by Ashley Michelle Coates
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
Also listed in
Loading usage metrics...