Conference item
Gas injection into second mode instability on a 7 degree cone at Mach 7
- Abstract:
- The influence of injection gas type on second mode instabilities is researched on a 7 degree half-angle cone at Mach 7. The wind tunnel model of 594.5 mm length with a sharp nosetip is fitted with a porous aluminium patch that spans 60 degree in azimuth and 25 mm in axial length. Four different gases are injected into the boundary layer flow, namely nitrogen, carbon dioxide, helium and argon. Three different tunnel test conditions with different unit Reynolds numbers provide a variety of amplification levels of the second mode instability at the injection location. Frequency data is obtained using PCB sensors and the density boundary layer thickness is inferred from high speed z-type schlieren images. Early analysis of initial data shows a drop in second mode frequency and second mode power behind the injector. If transition is not caused the effect weakens further downstream. Higher blowing ratios caused a stronger decrease in frequency and also reduced the power in the frequency band more. Larger blowing ratios are required at lower unit Reynolds numbers to achieve the same effect. The observed boundary layer thickness, as inferred from schlieren images, followed comparable dynamics. A larger blowing ratio of the same coolant gas lead to more thickening, while Helium had a significantly stronger total effect than carbon dioxide. Preliminary results suggest that helium injection at a moderate rate causes the second mode peak to be disproportionally damped and its bandpower to be significantly reduced. A strongly simplified analytical model suggest that the mechanical increase in boundary layer thickness alone may not be sufficient to explain all observed outcomes.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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Access Document
- Files:
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(Preview, Accepted manuscript, pdf, 9.6MB, Terms of use)
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- Publisher copy:
- 10.2514/6.2022-3856
Authors
- Publisher:
- Aerospace Research Central
- Host title:
- Proceedings of the AIAA AVIATION 2022 Forum
- Publication date:
- 2022-06-20
- Event title:
- AIAA AVIATION 2022 Forum
- Event location:
- Chicago
- Event start date:
- 2022-06-27
- Event end date:
- 2022-07-01
- DOI:
- ISBN:
- 9781624106354
- Language:
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English
- Keywords:
- Pubs id:
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1273060
- Local pid:
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pubs:1273060
- Deposit date:
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2023-06-01
Terms of use
- Copyright holder:
- American Institute of Aeronautics and Astronautics, Inc.
- Copyright date:
- 2022
- Rights statement:
- Copyright © 2022 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
- Notes:
-
This is the accepted manuscript version of the article. The final version is available from Aerospace Research Central at https://doi.org/10.2514/6.2022-3856
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