Numerical and Experimental Investigation of Hypersonic Fin Junction Flows - Tracking No: 22-000003275
Abstract
Fins provide stability and control to hypersonic flight vehicles. Depending on the state of the vehicle boundary layer and the fin geometry (leading edge bluntness, sweep angle), boundary layer fin interactions can exhibit a low-frequency unsteadiness. The associated large unsteady pressure and heat loads are a structural concern, are detrimental to precision flight path control, and have an overall negative effect on mission success. The existing data on hypersonic fin interactions is mostly experimental and concerned with turbulent interactions. To address these challenges, we propose to obtain new experimentally validated large-eddy simulation datasets for both laminar and turbulent hypersonic boundary layer fin interactions for a wide range of fin sweep angles and leading-edge diameters. Turbulent and laminar boundary layer interactions for six different fin geometries (leading edge diameter and sweep angle) will be investigated in the New Mexico State University Mach 5 shock tunnel. High-speed pressure transducers and thin-film heat flux sensors as well as a new stereoscopic femtosecond laser electronic excitation and tagging system will be employed to obtain time-resolved measurements of the upstream boundary layer and junction region. In addition, schlieren flow visualizations will be obtained. The experimental conditions will be matched in the large-eddy simulations to allow for a one-on-one comparison and detailed validation of the simulations. The simulations will reveal details of the flow fields that cannot be obtained with the tunnel instrumentation. Depending on the progress of the research, simulations will also be carried out for Mach numbers other than 5 (e.g., 2.5 or 10).The data obtained from the experiments and simulations will be analyzed with correlations, Fourier transforms, modal decomposition and data-driven techniques, as well as linear stability theory analysis. Based on the analyses, the physical mechanisms that #drive# the low-frequency unsteadiness will be investigated and revealed and the critical parameters that govern its onset will be identified. The research findings will be presented at conferences and disseminated in journal publications. The project will support two graduate and several undergraduate students. The students will be trained in hypersonics, which is an area with significant workforce development need. Equally qualified students from underrepresented groups will be given preference. One of the graduate students will focus on the experimental side of the project while the other graduate student will focus on the simulations. The analysis of the data will be performed by both graduate students. The undergraduate students will support the graduate students. The anticipated outcomes are a wealth of new validated data for laminar and turbulent hypersonic fin interactions and new physical understanding of the origin of the low-frequency unsteadiness and the critical parameters that determine its onset. The proposed research will also provide insight into the mean flow topology and the unsteady flow physics of the resulting oblique shockwave boundary layer interactions. The research outcomes will be of immediate value to engineers and designers engaged in the simulation and modeling of the flow over hypersonic vehicles and to structural and flight control system designers. An improved understanding of the flow physics will support the development of strategies for controlling the unsteadiness. A passive strategy, filleting, will be investigated as part of the proposed research. The research contributes to the development of morphing vehicles, where the fin sweep angle is adjusted as the flight Mach number changes during flight. The potential benefits are reduced drag and aero-heating and increased range and target precision. Overall, the proposed research is of direct relevance for the development of reliable and accurate high-performance (payload, range, etc) hypersonic vehicles.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 24, 2023
- Source ID
- N000142312713
Entities
People
- Andreas Gross
Organizations
- New Mexico State University
- Office of Naval Research
- United States Navy