Experimental Study on the Transition Process in the Restabilization Regime of the Rossiter Mode in Cavities

• Grant number: 25/22419-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2026
• End date: October 31, 2026
• Field of knowledge: Engineering - Aerospace Engineering - Aerodynamics
• Principal Investigator: Marcello Augusto Faraco de Medeiros
• Grantee: Thiago Duarte Lehmann
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

The drag generated by viscous friction in the boundary layer contributes significantly to fuel consumption, operating costs, and reduced aircraft performance. Moreover, the wing surfaces, empennage, nacelles, and others often feature surface gaps, which are modeled as cavities. The presence of these gaps affects the laminar-to-turbulent transition of the boundary layer and, depending on the geometry and flow conditions, can trigger abrupt (bypass) transition over the cavity. The mechanism responsible for this type of transition is caused by an instability of the shear layer over the cavity, known as the Rossiter instability. However, this instability mode tends to restabilize for deep cavities, making it necessary to further investigate how the transition process occurs under these conditions. In this context, the present research proposal has the objective of experimentally study the transition in this scenario of Rossiter mode restabilization. The experiments will be conducted in the low-turbulence wind tunnel at EESC-USP, LANT. A flat plate model containing a cavity with a remotely actuated retractable depth will be used for the experiments. Hot-wire anemometry will be employed for velocity measurements, and a Preston tube will be used to determine the transition location. The expected results aim to identify the mechanism triggering the transition through spectral analysis of the velocity signals collected near the cavity. (AU)