A probabilistic transition model for hypersonic boundary layers
Abstract
The objective of this project is to enable drastically improved predictions of laminar-to-turbulent transition for hypersonic boundary layers by developing a new class of probabilistic models that predict the likelihood that a flow will transition at each downstream position. Predicting boundary layer transition and the associated impact on heat transfer and aerodynamic performance is a fundamental challenge in hypersonic vehicle design, and the inability of current models to quantify the sensitivity of the transition process to freestream and surface conditions creates large uncertainties that necessitate conservative designs that increase weight and degrade vehicle performance. This project will fill the urgent need for reliable hypersonic transition models by approaching the problem from a novel probabilistic perspective. Rather than seeking a definite transition point, which is inconsistent with the sensitivity and intermittent nature of transitional flow, the proposed model will take a statistical description of environmental disturbances as input and predict the expected (mean) transition point and the probability of observing transition at each downstream position along the boundary layer. The input statistics are spatially propagated using linear and nonlinear one-way Navier-Stokes equations. The model includes the receptivity process and captures modal (exponential) and nonmodal (transient) growth mechanisms, making it applicable to both natural and bypass transition. The models also capture the global flow structures that cause the predictedgrowth, providing insight into the transition physics. The models will be used to study the sensitivity of transition probabilities to leading-edge bluntness, freestream disturbances, and surface roughness for a series of blunt and finned cones. We envision that the probabilistic description and quantification of transition uncertainty provided by our models will enable principled design choices, tighter design margins, and, ultimately, robust and optimized hypersonic flight.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 15, 2023
- Source ID
- N000142412033
Entities
People
- Aaron Towne
Organizations
- Board of Regents of the University of Michigan
- Office of Naval Research
- United States Navy