Spatio-temporal linear stability analysis of stratified planar wakes: Velocity and density asymmetry effects

Emerson, Benjamin; Jagtap, Swapnil S.; Quinlan, J. Mathew; Renfro, Michael W.; Cetegen, Baki M.; Lieuwen, Tim

doi:10.1063/1.4943238

Cited by 15 publications

(4 citation statements)

References 29 publications

(49 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several distinct flame modes of symmetric and asymmetric vortex shedding were observed as inflow velocity approaches blow-off limit in the overall laminar flow range. It was found that the flame modes were noticeably changed due to the enhanced fluid dynamic effects of density ratio, consistent with the observations from earlier experimental studies [5,[13][14][15][16]. The fluid dynamic effects were found to be an important factor in determining the ultimate blow-off limit, and the mode was properly described by the Strouhal number scaling.…”

Section: Introductionsupporting

confidence: 86%

Effects of Differential Diffusion on the Stabilization of Unsteady Lean Premixed Flames Behind a Bluff-Body

Kim

Lee

2020

Flow Turbulence Combust

View full text Add to dashboard Cite

Two-dimensional direct numerical simulations were conducted to investigate the effects of differential diffusion on flame stabilization and blow-off dynamics of lean premixed hydrogen-air and syngas-air flames stabilized on a meso-scale bluff-body in a square channel. The unity Lewis number for all species was imposed to isolate the effects of differential diffusion. Four sets of simulation cases were conducted. Two different inflow temperature with unity Lewis number were applied to examine distinct levels of hydrodynamic instability. Each unity Lewis number case was compared with the non-unity Lewis number case to investigate how differential diffusion affects the overall flame responses, instabilities, and blow-off mechanism. For all cases, the overall flame dynamics were observed in several distinct modes as the inflow velocity approaches blow-off limit. One of the primary effects of unity Lewis number was an increased level of hydrodynamic instability due to the lower flame temperature and thus a lower density ratio. The lower gas temperature also led to a weakening of the re-ignition of the quenched local mixture by the product gas entrainment. The combined effects were manifested as suppression of the re-ignition events, leading to a revised conclusion that the ultimate blow-off behavior at high velocity conditions are mainly controlled by the onset of local extinction.

show abstract

Section: Introductionsupporting

confidence: 86%

Effects of Differential Diffusion on the Stabilization of Unsteady Lean Premixed Flames Behind a Bluff-Body

Kim

Lee

2020

Flow Turbulence Combust

View full text Add to dashboard Cite

show abstract

“…In terms of propulsion, there are advanced technologies like ultra-high bypass ratio turbofan engines, hybrid-electric and full-electric concepts [12]. The future aircraft engines will have cleaner/lowemissions and improved combustors [13], [14]. Such combustors will control combustion instabilities, a phenomenon observed in present-day aircraft combustors [13], [14].…”

Section: Future Aviation Technologiesmentioning

confidence: 99%

“…The future aircraft engines will have cleaner/lowemissions and improved combustors [13], [14]. Such combustors will control combustion instabilities, a phenomenon observed in present-day aircraft combustors [13], [14]. These next generation of improved combustors further increase the safety aspect of an aircraft [13], [14].…”

Section: Future Aviation Technologiesmentioning

confidence: 99%

See 1 more Smart Citation

Systems Evaluation of Subsonic Hybrid-Electric Propulsion Concepts for NASA N+3 Goals and Conceptual Aircraft Sizing

Jagtap

2019

IJAME

View full text Add to dashboard Cite

The air-travel demand is anticipated to grow in future and therefore the worldwide airtraffic is forecast to increase significantly. This growth in demand further increases the concerns pertaining to environmental and human health, which results in stringent aviation policies. Emission regulations have been set for the aviation sector to reduce its climate change impacts, and these support the efforts to meet the goals of the UN’s Paris treaty on climate change. The aviation sector is exploring sustainable and improved technologies to become more energy and cost efficient. Along these lines, NASA has developed the concept of ‘N+i’ goals to decrease fuel consumption, noise, and landing and take-off (LTO) oxides of nitrogen (NOx) emissions, and to enhance aircraft performance. The ‘N+3’ represents three technology generations into the future, where ‘N’ represents the current aircraft generation, with a forecasted technology readiness level 4-6, in year 2025 timeframe which will enable year 2035 service-entry. To meet NASA’s N+3 goals, significant improvements must be made in the air transportation system, airframe, mission design, and propulsion systems. A pivotal element to achieve these goals, is the propulsion system. This is because the role of propulsion system can be crucial in reducing emissions, noise, and fuel burn. This work evaluates the N+3 concepts in detail, based on the systems engineering approaches and selects the best of those concepts. A detailed analysis is presented for phase one of such a project using Georgia Institute of Technology’s Integrated Product-Process Development (IPPD) method. This work finds that the NASA N3-X turbo-electric distributed propulsion (TeDP) is the best concept for meeting the NASA N+3 goals, based on the systems engineering approach.

show abstract

CET-4 score analysis based on data mining technology

Liu

2018

Cluster Comput

View full text Add to dashboard Cite

Spatio-temporal linear stability analysis of stratified planar wakes: Velocity and density asymmetry effects

Abstract: Right click to open a feedback form in a new tab to let us know how this document benefits you.

Cited by 15 publications

References 29 publications

Effects of Differential Diffusion on the Stabilization of Unsteady Lean Premixed Flames Behind a Bluff-Body

Effects of Differential Diffusion on the Stabilization of Unsteady Lean Premixed Flames Behind a Bluff-Body

Systems Evaluation of Subsonic Hybrid-Electric Propulsion Concepts for NASA N+3 Goals and Conceptual Aircraft Sizing

CET-4 score analysis based on data mining technology

Contact Info

Product

Resources

About