A Comprehensive Investigation of Transitional Shock Boundary Layer Interaction using Controlled Experiments, Direct Numerical Simulations and Stability Theory
Abstract
The potential of maneuverable high-speed/hypersonic flight vehicles for increasing range and reducing transit time while avoiding detection and interception has been recognized for many years, but the challenges are substantial. Two of the most pressing issues are the understandingand prediction of boundary layer transition (BLT) and shock boundary layer interaction (SBLI).Significant advances related to these individual phenomena have been developed over the last few decades. However, the interaction between BLT and SBLI (i.e. transitional SBLI) has received much less attention despite its prevalence on existing and next generation high-speed/hypersonicflight systems. This is a rich scientific and practical problem considering that heat flux, skin friction, control authority and unsteadiness are substantial drivers in the design process and directly stem from BLT and SBLIs, both individually and collectively. A combined research approach encompassing spatially and temporally resolved measurements, high fidelity direct numerical simulations (DNS) as well as local and global stability analyses is proposed for investigating transitional SBLIs produced by compression ramps at boundary layer edge Mach numbers between 4 and 5. An important and unique aspect of theproposed work is to identify, control and quantify the state of the transitional boundary layer entering the SBLI. To do so requires the use of controlled disturbances (i.e. forcing) to excite various stages of BLT in both experiments and simulations. Controlled forcing techniques are lacking in high-speed BLT experimental research and will be developed here using both fluidic and plasma actuators. This is especially significant in the context of transitional SBLIs which are poorly understood in part due the lack of quantification of the precise state of the transitional boundary layer entering the SBLI. This is critically important since the disturbance levels entering the SBLI can have a strong influence on unsteadiness and surface heat flux. It is known that certain stages of the BLT process can match or even exceed the detrimental effects (e.g. heat flux, skinfriction) of fully turbulent boundary layers and it is expected that similar negative consequences occur for transitional SBLIs.Experiments will be performed in a nationally unique combination of conventional and quiet small-scale (15in2) Mach 4 wind tunnels along with a larger scale Mach 5 facility (15in diameter). The experiments shall be seamlessly coupled with DNS and stability theory using highly accurate in-house research codes. Highly-resolved surface and flow-field measurementswill be employed to document the mean and unsteady flow behavior and DNS will be performed for the wind tunnel conditions. Data from DNS and experiments will be analyzed using state-of the art techniques and in the same fashion where possible to bring out beneficial aspects of each.Instability analyses and modal decomposition wility modes. The energy fluxes between the basic flow and the various instability modes will be analyzed. Finally, the effect of selective forcing (steady and unsteady) on the energy fluxes, mean flow topology and unsteadiness will be investigated.The proposed research will provide a fundamental physics-based understanding of the underlying instability mechanisms governing transitional SBLIs which is required for reliable and efficient high-speed/hypersonic flight. This research will ultimately contribute to guidelines for the design of high-speed atmospheric flight vehicles with reduced structural fatigue loading,reduced surface heat fluxes, lower weight and lower drag.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 29, 2020
- Source ID
- N000142012267
Entities
People
- Jesse C. Little
Organizations
- Office of Naval Research
- United States Navy
- University of Arizona