Interaction Of Chemistry Turbulence And Shock Waves In Hypervelocity Flow

Interaction of Chemistry, Turbulence and Shock Waves in Hypervelocity Flow

Interaction of Chemistry, Turbulence, and Shock Waves in Hypervelocity Flow

Significant contributions were made in a four-year interdisciplinary experimental, numerical and theoretical program to extend the state of knowledge and understanding of the effects of chemical reactions in hypervelocity flows. The program addressed the key problems in aerothermochemistry that arise from the interaction between the three strongly nonlinear effects: Compressibility; vorticity; and chemistry. Results included: (1) Discovery of dramatic damping effects of nonequilibrium vibration and chemistry on transition in hypervelocity flows; (2) Proper formulation of parameters for reacting blunt-body flows. (3) Effects of nonequilibrium chemistry in shock-on-shock interaction; (4) New experiments on, and correlation with theory of high-enthalpy flap-induced separation; (5) Computations of interaction of a shock wave with density interfaces and with compressible Hill's spherical vortex; (6) Extensive clarification of phenomena in supersonic shear flows using new diagnostic and computational tools; (7) New experiments and computations of hypervelocity double-one flow yielded insights into vibration-dissociation coupling; (8) First-principles computations of electron collision cross-sections with diatomic molecules and CO2; and (9) Development of new diagnostic technique LITA for accurate non-intrusive point measurement of gas properties.

Interaction of Chemistry, Turbulence, and Shock Waves in Hypervelocity Flow

Significant progress was made during the second year of an interdisciplinary experimental, numerical and theoretical program to extend the state of knowledge and understanding of the effects of chemical reactions in hypervelocity flows. The program addressed key problems in naerothermochemistry that arise from interactions between the three strongly nonlinear effects: Compressibility; vorticity; and chemistry. Important new results included: Clear understanding of the two important parameters that define hypervelocity flow over spheres. Closed-form solution for stand-off distance. Completion of computation of hollow-core compressible vortex streets. First high-resolution interferograms of shock-shock interaction in hypervelocity flow. Detailed experimental and theoretical study shows that high-enthalpy real-gas effects do not further increase heat flux in type IV Interaction. Interferograms establish flow quality in the hypervelocity shock tunnel T5. Upgrade of the Supersonic Shear Layer facility to higher Mach number. New results on supersonic shear layers and shear-layer/shock-wave interaction. Computational discovery of a flow field that is sensitive to vibration-dissociation coupling. Extension of the equilibrium flux method to a more robust less dissipative form and tests. Computation of collision cross section to electrons of low excited states of OH, NO, and CO2. Establishment of Laser-Induced Thermal Acoustics as an accurate diagnostic for gas properties over large pressure ranges. (AN).