Modeling of surface roughness effects on bypass and laminar separation bubble-induced transition for turbomachinery flows

• Main Authors: Bai, J. (Author), Li, Y. (Author), Qiao, L. (Author), Xu, J. (Author), Zhang, Y. (Author)
• Format: Article
• Language: English
• Published: American Institute of Physics Inc. 2022
• Subjects: Amplification factors; Induced transitions; Laminar flow; Laminar separation bubble; Local variables; Modeling of surface roughness; One-equation; Quay walls; Surface roughness; Surface roughness effects; Transition model; Transport equation; Turbomachinery flows
• Online Access: View Fulltext in Publisher

 In a previous study, we developed a one-equation transition model for the bypass and laminar separation bubble (LSB)-induced transition based on local variables. In this paper, distributed surface roughness effects are taken into account by constructing a new transport equation for the roughness amplification factor Ar. Modified criteria taking account of Ar are proposed to describe the roughness effects on the bypass and LSB-induced transitions. Moreover, to predict the flow properties in the laminar-turbulent region more accurately, a modified boundary condition for rough surfaces is employed. The calculations show that, overall, the rough wall promotes the bypass transition and reduces the size, or even causes the disappearance, of the LSBs. Good agreement of the numerical results from the proposed model with the experimental data indicates that the present roughness correction formula is reasonable and accurate. © 2022 Author(s).