Accession Number : AD1030882


Title :   Energy transformation, transfer, and release dynamics in high speed turbulent flows


Descriptive Note : Technical Report,30 Sep 2012,30 Nov 2016


Corporate Author : California Institute of Technology Pasadena United States


Personal Author(s) : Dimotakis,Paul E ; Candler,Graham V


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/1030882.pdf


Report Date : 01 Mar 2017


Pagination or Media Count : 51


Abstract : Delay length for chemical-reaction initiation downstream of jet-injection was attributed to turbulent mixing and not chemical kinetics, for flows investigated. Inclined-jet injection dramatically decreases freestream-flow disturbances, relative to normal jet injection, but increases ignition distance. This penalty may be acceptable considering the lower total-pressure losses than for normal injection. New experimental techniques developed allowed non-intrusive measurement of convecting velocity fields in supersonic flows and used for validation of LES of jet-injection flow in a supersonic stream. Small-scale experiments revealed 3D behavior of scalar mixing. In DNS, the turbulent fluid-mixing behavior of fluids with variable density revealed new scaling, providing guidance for subgrid-scale modeling of variable-density flows. A new subgrid-scale (SGS) combustion model (EVM) was developed for distributed-reaction zone (DRZ) environments allowing efficient computation of turbulent combustion, extending to hydrocarbon combustion. Integrated in a LES of turbulent combustion of a hydrogen jet in supersonic air crossflow it captured many important flow features. Unphysical scalar excursions in finite-difference LES modeling were traced to dispersion errors of finite-difference operators. Many presentations, conference papers, and publications derived from this effort, as listed and discussed in the report.


Descriptors :   computational fluid dynamics , turbulent mixing , boundary layer , laser induced fluorescence , combustion , chemical reactions , turbulent flow , reynolds number , refractive index , mechanical properties , buoyancy , chemical kinetics , energy transfer


Subject Categories : Fluid Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE