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AME Seminar
Wed, Apr 09, 2025 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Pedro Paredes, NASA Langley Research Center
Talk Title: Hypersonic Boundary Layer Transition over Blunt Cones
Abstract: The linear amplification of modal Mack-mode disturbances that lead to boundary-layer transition in two-dimensional/axisymmetric hypersonic configurations is strongly reduced by the presence of a blunt nosetip. The mechanisms underlying the low Mack-mode N-factor values at the observed onset of transition over the cone frustum are currently unknown. As the nose bluntness is increased beyond the critical nose Reynolds number for transition reversal, the transition location rapidly moves upstream, and transition appears to depend on uncontrolled disturbances due to nosetip roughness. Linear nonmodal analysis has shown that both planar and oblique traveling disturbances that peak within the entropy layer experience appreciable energy amplification for moderate to large nosetip bluntness. Nonlinear nonmodal analysis shows that planar entropy-layer disturbances excited near the nose tip can excite the high frequency Mack-mode disturbances and hence, can lead to a reduction in the transition N-factor. Digital wind-tunnel simulations are conducted via direct numerical simulations (DNS) to understand the effects of freestream acoustic disturbances in transition over blunt cones during a conventional tunnel experiment. The results confirm the appearance of entropy-layer disturbances predicted by linear nonmodal analysis and the numerical schlieren contours show the inclined structures predicted by nonlinear nonmodal analysis and observed in experiments.
Biography: Pedro Paredes is a Research Scientist at the Computational AeroSciences Branch of the NASA Langley Research Center. Dr. Paredes earned his Ph.D. and M.Sc. in Aerospace Engineering from the Polytechnic University of Madrid, Spain. He was one of the recipients of the Air Force Office of Scientific Research Young Investigator Award in 2020 and has been awarded with two Office of Naval Research grants as the principal investigator. Dr. Paredes was honored with the American Institute of Aeronautics and Astronautics (AIAA) Associate Fellow distinction in 2024. The research activities of Dr. Paredes are related to boundary layer transition (BLT) prediction and physics-based development of technology concepts for BLT control across the flight speed regimes. He has developed and applied advanced, multidimensional stability-analysis methods for BLT prediction of high-speed flow configurations. With a prolific academic record, he has authored over 50 journal articles and 80 conference papers.
Host: AME Department
More Info: https://ame.usc.edu/seminars/
Location: James H. Zumberge Hall Of Science (ZHS) - 252
Audiences: Everyone Is Invited
Contact: Tessa Yao
Event Link: https://ame.usc.edu/seminars/
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor.
