| Author: | Fan, Jianhui |
| Title: | Numerical study on aerodynamics interactions around a supersonic parachute using high fidelity detached eddy simulation |
| Advisors: | Wen, Chih-yung (ME) |
| Degree: | M.Sc. |
| Year: | 2020 |
| Subject: | Parachutes -- Aerodynamics Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Mechanical Engineering |
| Pages: | 79 pages : color illustrations |
| Language: | English |
| Abstract: | In the present study, our works are related to Entry, Descent, and Landing (EDL) technologies of Mars mission, specifically, technologies regarding supersonic parachute decelerators. In our works, a history of the development of supersonic parachutes was introduced base on relevant Mars programs, which cover critical experiments, tests, and numerical studies. According to reviews on the history, we found that a state of the art code for supersonic parachute problems is characterized by numerical technologies as adaptive mesh refinement, turbulent models, and the capacity to deal with FSI problems. To develop our in-house code to such a remarkable Code. We start from the development of turbulent models and high order numerical schemes. With efforts are taken, three main achievements are completed in present works, those achievements are summarized and presented as follows: First, a high-order inviscid numerical scheme is coded for our in-house code. The numerical scheme is the TENO (Target Essential Non-Oscillation). It is found out that the scheme shows its computational unstability on simulations that the flow structures are complex as a supersonic parachute problem, which is characterized by a supersonic, turbulent, rich aerodynamics, and unsteady flow. To settle such unstability, then, a hybrid numerical scheme was achieved by combining low order numerical schemes with the TENO method. The key idea of the hybrid scheme is to sacrifice numerical accuracy to make the calculations stable. Unfortunately, our simulations on the supersonic parachute problem tell that the hybrid method only shows slightly higher accuracy, but more computational cost than pure lower numerical schemes. Second, two turbulent models are added into our in-house code, which is the RANS and DES. Notably, these two turbulent models are all based on SST (shear stress transport) model. Validations on such models are conducted by two cases, which are supersonic flat-plate and supersonic reattach shear layer flow. All results of simulations have good agreements on DNS results or experimental results. Last, by using the in-house code, a turbulent-based study on aerodynamics interactions around a supersonic parachute was conduct. From the study, we found that although turbulent models have a small impact on shock evolution, they make an apparent influence on vortex dynamics. Besides, turbulence simulations show higher numerical accuracy than the laminar one, and also show variations on the low-frequency energy in pressure fluctuation and turbulent kinetic energy fluctuation. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 5229.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 3.61 MB | Adobe PDF | View/Open |
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