The Woodruff School

SUMMARY

Swirl injectors has been broadly used in contemporary liquid-propellant rocket engines to achieve efficient mixing and combustion, but the understanding of flow dynamics and combustion at supercritical conditions is still very limited and not sufficient to support design optimization. The existing axisymmetric studies failed to include the flow variations in the azimuthal direction and vortex-stretching mechanism which is responsible for the energy transfer from large- to small- scale structures in the flowfield. The objective of this work is to enhance the understanding of the liquid-swirling flow dynamics by carrying out a systematic three-dimensional numerical study using large eddy simulation. The numerical scheme is based on full-conservation laws and accommodates real-fluid thermodynamics and transport theory over entire range of fluid states. The first part of the work is to investigate the flow dynamics of liquid oxygen injecting into the injector initially with gaseous oxygen. The complex three-dimensional flow structures will first be identified and explored using the spectral analysis and proper orthogonal decomposition technique. Various underlying mechanisms dictating the flow evolution, including Kelvin-Helmholtz instability, Rayleigh-Taylor instability, centrifugal instability, vortex breakdown, acoustic instability, and their interactions will be studied. In addition, a parametric study will be made to examine the pressure and temperature effects on the injector design attributes, such as liquid film thickness and spray cone angle. The second part of the work is to study the combustion dynamics of bi-swirl coaxial injector with liquid oxygen and kerosene. The injector near-field flow and flame structures will be examined. The possible instability modes dictating combustion oscillatory field and their feedback coupling with injecting process will also be explored. The proposed work will provide the important information for the future injector design and combustion stabilization in liquid rocket engines.

SUBJECT:	Ph.D. Proposal Presentation

BY:	Xingjian Wang

TIME:	Thursday, January 22, 2015, 3:45 p.m.

PLACE:	Knight Bldg, 317

TITLE:	Swirling Fluid Mixing and Combustion Dynamics at Supercritical Conditions

COMMITTEE:	Dr. Vigor Yang, Co-Chair (AE) Dr. Tim Lieuwen, Co-Chair (ME) Dr. Suresh Menon (AE) Dr. Devesh Ranjan (ME) Dr. Wenting Sun (ME)

SUMMARY Swirl injectors has been broadly used in contemporary liquid-propellant rocket engines to achieve efficient mixing and combustion, but the understanding of flow dynamics and combustion at supercritical conditions is still very limited and not sufficient to support design optimization. The existing axisymmetric studies failed to include the flow variations in the azimuthal direction and vortex-stretching mechanism which is responsible for the energy transfer from large- to small- scale structures in the flowfield. The objective of this work is to enhance the understanding of the liquid-swirling flow dynamics by carrying out a systematic three-dimensional numerical study using large eddy simulation. The numerical scheme is based on full-conservation laws and accommodates real-fluid thermodynamics and transport theory over entire range of fluid states. The first part of the work is to investigate the flow dynamics of liquid oxygen injecting into the injector initially with gaseous oxygen. The complex three-dimensional flow structures will first be identified and explored using the spectral analysis and proper orthogonal decomposition technique. Various underlying mechanisms dictating the flow evolution, including Kelvin-Helmholtz instability, Rayleigh-Taylor instability, centrifugal instability, vortex breakdown, acoustic instability, and their interactions will be studied. In addition, a parametric study will be made to examine the pressure and temperature effects on the injector design attributes, such as liquid film thickness and spray cone angle. The second part of the work is to study the combustion dynamics of bi-swirl coaxial injector with liquid oxygen and kerosene. The injector near-field flow and flame structures will be examined. The possible instability modes dictating combustion oscillatory field and their feedback coupling with injecting process will also be explored. The proposed work will provide the important information for the future injector design and combustion stabilization in liquid rocket engines.