Investigation of Laminar-Turbulent Transition for Transonic Boundary Layers using Advanced Computational Tools
Abstract
Presently a large gap exists in the understanding of laminar-turbulent boundary-layer transition in the transonic flow regime. In the open literature a significant body of research is available for low-subsonic, (predominantly incompressible) boundary layers and to a lesser degree for supersonic and hypersonic boundary layers. In contrast, relatively little has been published for the transonic regime, and the few publications that tangentially deal with it are very dated. This gap is indeed surprising as the transonic flow regime is highly relevant for both military and civilian applications (transport aircraft, helicopters, munitions, rockets, etc.). On the experimental side this gap may be due to the fact that experiments in transonic facilities that have the flow quality needed for transition are very expensive and inherently difficult. This lack of quality experimental research may have also caused the relative lack of theoretical and/or computational investigations that focus on the transonic regime and/or because of unexpected difficulties in theory and computations, which may have been caused by the assumptions required for these tools that may not be justified in this flow regime. For these reasons, a comprehensive investigation of laminar-turbulent transition for in boundary-layers for the transonic flow regime using state-of-the-art investigative tools is proposed. Towards this end, an approach will be employed for the linear (primary) instability regime that is based on the Linearized Navier-Stokes Equations (LNSE) that does not require any additional assumptions (as for LST and/or PSE).Towards this end, in the proposed research, for the linear (primary) instability regime, an approach will be employed that is based on the Linearized Navier-Stokes Equations (LNSE) that does not require any additional assumptions (as for LST and/or PSE). The nonlinear transition regime (including the breakdown to turbulence) will be attacked by Direct Numerical Simulations (DNS) using high-fidelity simulation codes that we have developed over many years with funding from AFOSR and NASA. This approach promises to lead to a breakthrough in the understanding of stability and transition for transonic boundary layers, and thus fill the glaring gap that exists today. This research is highly relevant for a broad range of military and civilian applications. For example, for in for the design and safe operation of future efficient aircraft where major parts of the flow field are transonic, improved transition prediction tools are required that account for the effects of compressibility and nonlinearity. Furthermore, understanding of the relevant transition physics will aid in the development of novel flow control concepts, both passive and active, to either delay (for decreasing drag) or accelerate (for preventing separation/stall) transition.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 29, 2019
- Source ID
- W911NF1910100
Entities
People
- Hermann Fasel
Organizations
- Army Contracting Command
- United States Army
- University of Arizona