Symplectic methods in space mission design
Abstract
Riblets are two-dimensional streamwise-aligned surface protrusions with the potential to reduce turbulent drag. They are among the few drag-reducing techniques with successful application to an aircraft. There have been invaluable advances in studying turbulent drag change by riblets. These advancements mainly focus on canonical turbulent flows (e.g., channel flow), hence focusing on the application of riblets to control turbulent skin-friction drag. However, little is known about the application of riblets in the presence of flow deceleration or separation. Decelerating and separating turbulent flows by inducing pressure drag can unfavorably affect the performance of many devices, e.g., diffusers, low-pressure turbines. This project aims to explore the interaction between riblets and flow deceleration-separation in unprecedented detail using high-fidelity numerical simulations. Computational configuration consists of an attached turbulent boundary layer over riblets followed by the boundary layer deceleration-separation downstream of the riblets. We carefully choose the riblet shapes to trigger the flow mechanisms that are conjectured to favorably attenuate the boundary layer separation size. We systematically change the riblet size, riblet-to-separation distance, and the intensity of the boundary layer deceleration or separation. We aim to arrive at the optimal design parameters (riblet size and placement) for minimizing the flow separation, hence mitigating the pressure drag. Such an outcome has a favorable impact on the fuel consumption of aircrafts. Thus, it is aligned with the United States Aviation Climate Action Plan towards 2050 Net Zero Emissions pathway, by introducing new technologies for more energy efficient aircrafts. The acquired knowledge from the high-fidelity simulations of separating flows is aligned with one of the objectives of NASA Computational Fluid Dynamics vision by 2030, towards more robust computational models for separating flows.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 05, 2025
- Source ID
- FA86552417012
Entities
People
- Agustin Moreno
Organizations
- Air Force Office of Scientific Research
- United States Air Force