What is it about?
High-speed propulsive systems of future vehicles are envisaged to allow routine space access and fast intercontinental travel. Development of such systems still requires extensive numerical and experimental analyses. This paper investigates numerically the base and jet flow distortion as a result of wind-tunnel installation effects, for a sub-scale, high-speed exhaust system.
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Why is it important?
Our findings suggest that wingtip-mounted engines, typically incorporated in future, high-speed vehicles, could exhibit a jet deflection effect as a result of the wing, which could lead to loss of thrust and side loads. Additionally, we introduce a base flow similarity methodology that allows comparison of the base flow between the tunnel-constrained model and equivalent unbounded flow. Our results show that through application of this similarity method, locally the flow at the base can be representative of free-stream flow, even if the overall flow differs notably in the wind-tunnel. This means that experimental base drag reduction studies for high-speed systems, can be performed under high blockage ratios or even choked tunnel conditions. This is critical if one considers the relatively small size of most closed transonic tunnels found in academic facilities, which guarantees high blockage and choking effects.
Perspectives
I hope this article helps researchers to answer some of the questions I had myself when it comes to what is the impact of integrating a sub-scale model in the wind-tunnel and how is blockage and mounting device going to affect the flow I am interested in analyzing. These questions are hard to answer without actually performing numerical studies but are critical. In the context of base drag reduction of high-speed systems, I think that our method demonstrates that we can perform experiments with some confidence under high blockage ratios and/or choked tunnel conditions, when our interest is only the flow at the base. I think blockage is a common issue among experimenters and a problem that they always come across, and I hope our work can help in that direction.
Spyros Tsentis
Cranfield University
Read the Original
This page is a summary of: Wind Tunnel Installation Effects on the Base Flow for a High-Speed Exhaust System, January 2024, American Institute of Aeronautics and Astronautics (AIAA),
DOI: 10.2514/6.2024-1774.
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