A Fast and Accurate Method to Predict the Impact of a Bump on the N-factor Envelope

Autor(es)

Himeno, Fernando H. T. ; Medeiros, Marcello A. F.

• Tipo de documento: Artigo Científico
• Fonte: AIAA AVIATION FORUM AND ASCEND 2024; v. N/A, p. 18-pg., 2024-01-01.

Resumo

In practical scenarios, it is almost impossible to avoid the presence of surface irregularities. Even for designs that avoid joints, gaps, and rivets, dirt may accumulate in operation. It is widely known that the transition can be drastically advanced in the presence of surface imperfections. Attempts have been conducted to develop more accurate and practical tools to predict the impact of surface imperfections on the transition location, but most do not account for several effects. In this study, we investigated the impact caused by two-dimensional sharp-edged bumps on the evolution of Tollmien-Schlichting waves. We used a high-fidelity simulation code to simulate bumps with heights from 5% to 40% of the local displacement thickness (delta(R)*). The influence of the delta(R)*-based Reynolds number and of the wave frequency are also addressed. From these numerical results, we developed a fast and accurate method to estimate the bump impact on the wave evolution in terms of the N-factor deviation (Delta N) that the bump causes relative to the smooth case. The method accounts for the combined effects of bump height, local Reynolds number, and wave frequency. It provides the Delta N-factor envelope curve at any location downstream of the bump. This information can be readily plugged into prediction methods currently used by the industry, such as PSE. As shown here, the bump impact can be substantially different depending on the distance from the bump where its impact is evaluated. For all cases tested, we show that a maximum Delta N occurs about 90 x delta(R)* downstream of the bump, which encompasses the region of practical interest in a flat plate boundary layer. As the bumps are sharp-edged, this method can be used as a criterion for permissible bumps that provide a threshold value for any bump shape. (AU)

• Processo FAPESP: 19/15366-7 - Estudo experimental do efeito de uma cavidade sobre a transição da camada limite
• Beneficiário: Marcello Augusto Faraco de Medeiros
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 18/02542-9 - Estudo numérico de pacotes de onda sobre placa plana com rugosidade
• Beneficiário: Fernando Henrique Tadashi Himeno
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 13/07375-0 - CeMEAI - Centro de Ciências Matemáticas Aplicadas à Indústria
• Beneficiário: Francisco Louzada Neto
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs