Stability of boundary-layer flow over a skin made of porous compliant wall and micro floating raft arrays

ABSTRACT

To improve the drag reduction performance of underwater vehicles, a skin composed of a porous compliant wall and micro floating raft elements is proposed. A two-dimensional stability model of boundary-layer flow over the compliant skin is established, and the effect of structural parameters on the flow stability is investigated. It is found that enlarging the spacing l attenuates the Tollmien-Schlichting Instability (TSI) mode but promotes the occurrence of the Compliance-Induced Flow Instability (CIFI) mode, while the permeability coefficient a presents an opposite effect on the instability modes. Moreover, the CIFI mode is stabilised by increasing the stiffness ratio β, damping ratio γ and intermediate mass m, within limits. The skin proposed in this paper with specific parameters can better reduce the arising of TSI and CIFI modes in boundary-layer flow compared with the corresponding rigid and compliant walls, leading to a favourable performance for delaying boundary-layer transition.

KEYWORDS:

• Underwater vehicles
• micro floating raft
• flow stability
• boundary-layer transition

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is supported by the National Natural Science Foundation of China [grant numbers 51775123 and 52075111], and the Fundamental Research Funds for the Central Universities [grant number 3072021CF0702].