Measurements, Modeling and Control in Nonequilibrium in Shock-Boundary Layer Interaction
Abstract
Shock-boundary layer interactions can induce flow distortion and impair vehicle performance, create flow separation with loss of control authority, and result in severe localized heating rates. In hypersonic flight, the problem is extremely challenging due to the nonlinearity of the thermal-chemical-fluid mechanics coupling and the broad range of length and time scales exhibited. Correct prediction of the peak heat transfer rates is critical to vehicle survival, however a recent NATO workshop revealed severe underprediction of the transient thermal loads by state-of-the-art simulations in high enthalpy, air flows of interest to the Air Force (Knight et al 2012). Shock interactions which respond on the measurable macroscale to changes in the molecular processes also provide valuable diagnostic tools for development and validation of thermochemical models recently developed in response to Air Force needs. Shock wave-boundary layer interaction experiments over double wedge and double cone geometries in hypervelocity flows are reported. Experiments are conducted in two complementary high-stagnation enthalpy impulse facilities which provide the flexibility to access a range of test conditions with undissociated freestream (Hypervelocity Expansion Tube, HET), achieve long test times (T5 Free Piston Shock Tunnel), and examine facility independence of the results. Diagnostics include surface heat transfer measurements, high-speed schlieren and chemiluminescence imaging, and spectroscopic species and temperature measurements. These experimental capabilities permit direct measurements that dissect the anatomy of the shock-boundary layer structure and use this model problem as a diagnostic tool to help resolve the interplay between the fluid mechanics and coupled chemical and thermal processes in the gas.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 28, 2019
- Accession Number
- AD1085968
Entities
People
- Deborah Ann Levin
- Joanna Austin
Organizations
- California Institute of Technology