Optimisation and analysis of injector geometry on a centre-bodiless continuous rotating detonation rocket engine

Hann, Reuben (2021) Optimisation and analysis of injector geometry on a centre-bodiless continuous rotating detonation rocket engine. MSc(R) thesis, University of Glasgow.

Abstract

Rotating Detonation Engines (RDEs) provide a means of improving the efficiency of combustion engines at a time when reducing emissions is paramount. The key to their operation are RDE injectors, the two main injector design methodologies being the Semi-Impinging Injector (SII) method and Pintle injector method. In this thesis, the SII method was modified to add an additional degree of freedom (DOF) perpendicular to the two DOFs present in the SII method to develop the Modified Semi-Impinging Injector (MSII) method. This was done with the goal of improving the optimisation, implementation, and performance of the injector. The MSII and SII methods were compared where it was found that the injector flows could be categorised into two stages, the mixing phase where the mixing efficiency rose rapidly and the dampening phase where the mixing efficiency value stabilise over the length of the flow. The stabilised flow was found to remain relatively constant over the DOF ranges explored. Therefore, to determine the optimal injector, given that the speed of mixing is key to RDE performance, the characteristic length measurement was developed. The characteristic length is defined as the length required to meet 63.2% of the final stabilised value, with the lower the length, the faster the mixing. It was discovered that the mixing efficiency was the most relevant performance characteristic and that applying the characteristic length to the mixing efficiency allowed the mixing speed to be measured. It was found that the MSII injectors outperformed the SII injectors in mixing speed. The MSII method was then applied to a numerically simulated RDE and compared to a comparable Pintle injector method RDE. The two injector designs were simulated using Ansys Fluent by a detailed and simplified simulation method. It was found that the Ansys software had issues simulating RDEs resulting in only short runs of the engines, where the results were inconclusive and often contradictory. It was recommended that the MSII and SII methods be first empirically validated before more numerical simulations are conducted, and that with the information currently available, that the Pintle injector method is the best currently in use.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Grustan Gutierrez, Dr. Enric
• Date of Award: 2021
• Depositing User: Theses Team
• Unique ID: glathesis:2021-82576
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 03 Dec 2021 16:37
• Last Modified: 08 Apr 2022 17:08
• Thesis DOI: 10.5525/gla.thesis.82576
• URI: https://theses.gla.ac.uk/id/eprint/82576