The Effect of Pulsed Injection on Supersonic Shear Layer Mixing in a Scramjet Combustor
-
Leslie Smith
and
Saeed Farokhi
Abstract
A novel injector has been designed and cold flow injection tests were performed in a modified supersonic wind tunnel. To complement these experimental studies three dimensional STAR-CCM+CFD simulations were developed. The pulse width may be varied, with options of injecting gas for 33 %, 50 % and 66 % of the injection period. The scramjet combustor environment is simulated in a supersonic wind tunnel through a backward facing step for secondary injection purposes and a 157.5 cm (62-inch) long test section. The gas in secondary injection is carbon dioxide and the primary flow is air. The simulations show a coupled interaction between the forcing from injection and the shear layer. Steady state static pressure measurements on the lower wall of the wind tunnel test section agree well with the simulated static pressure along the lower wall. The pulse width strongly impacts shear layer reattachment on the lower wall and varies between 2.4 and 4.3 step heights. Reduction in duty cycle from 66 % to 33 % at 1 kHz caused ~30 % reduction in the shear layer reattachments distance, which points to large scale mixing enhancement.
Funding statement: This research was funded by the School of Engineering at the University of Kansas and the Department of Aerospace Engineering at the University of Kansas. The first author received the Self Graduate Fellowship Award that provided support for her graduate studies at the University of Kansas for four years.
Acknowledgment
The authors would like to thank Dr. Barrett, Dr. Taghavi, Dr. Keshmiri, Dr. Yimer, Wes Ellison, Robin and Lauren Kerth,, and Lauren Schumacher for their support of this research.
Nomenclature
- a1
speed of sound in flow region 1, m/s, ft/s
- a2
speed of sound in flow region 2, m/s, ft/s
- ea21
approximate error between the medium mesh and the coarse mesh, %
- ea32
approximate error between the fine mesh and the medium mesh, %
- eext21
extrapolated error between the medium mesh and the coarse mesh, %
- eext32
approximate error between the fine mesh and the medium mesh, %
- GCIfine21
grid convergence index, Unitless
- Mc1
convective Mach number in flow region 1, Unitless
- Mc2
convective Mach number in flow region 2, Unitless
- p
apparent order, Unitless
- r21
Grid refinement ratio between the medium and coarse mesh, Unitless
- r32
Grid refinement ratio between the medium and fine mesh, Unitless
- U1
air velocity in region 1, m/s, ft/s
- U2
air velocity in region 2, m/s, ft/s
- Uc
velocity of vortical structures in the shear layer, m/s, ft/s
- ε21
Difference between grid refinement parameters for the medium and coarse meshes, Unitless
- ε32
Difference between grid refinement parameters for the medium and fine meshes, Unitless
- ϕ1
Gird refinement parameter for the coarse mesh, Unitless
- ϕ2
Gird refinement parameter for the medium mesh, Unitless
- ϕ3
Gird refinement parameter for the fine mesh, Unitless
- ϕext21
Extrapolated gird refinement parameter for the coarse mesh to medium mesh, Unitless
- ϕext21
Extrapolated gird refinement parameter for the medium mesh to fine mesh, Unitless
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© 2018 Walter de Gruyter GmbH, Berlin/Boston
Articles in the same Issue
- Frontmatter
- Original Research Articles
- The Effect of Pulsed Injection on Supersonic Shear Layer Mixing in a Scramjet Combustor
- Entropy Generation Calculation of a Turbofan Engine: A Case of CFM56-7B
- Separation Control by Slot Jet in a Critically Loaded Compressor Cascade
- An Impingement Cooling Using Swirling Jets Induced by Helical Rod Swirl Generators
- Studies on Stepped Air Ejector Diffusers incorporating Heat Transfer Effects
- Assessment of Analytical Predictions for Radial Growth of Rotating Labyrinth Seals
- Ground Simulation of High Altitude Test of Turbo-Refrigeration Cycle
- Investigations on the Film Cooling of Counter-Inclined Film-Hole Row Structures for Turbine Vane Leading Edge
Articles in the same Issue
- Frontmatter
- Original Research Articles
- The Effect of Pulsed Injection on Supersonic Shear Layer Mixing in a Scramjet Combustor
- Entropy Generation Calculation of a Turbofan Engine: A Case of CFM56-7B
- Separation Control by Slot Jet in a Critically Loaded Compressor Cascade
- An Impingement Cooling Using Swirling Jets Induced by Helical Rod Swirl Generators
- Studies on Stepped Air Ejector Diffusers incorporating Heat Transfer Effects
- Assessment of Analytical Predictions for Radial Growth of Rotating Labyrinth Seals
- Ground Simulation of High Altitude Test of Turbo-Refrigeration Cycle
- Investigations on the Film Cooling of Counter-Inclined Film-Hole Row Structures for Turbine Vane Leading Edge
