Mixing enhancement and penetration improvement induced by pulsed gaseous jet and a vortex generator in supersonic flows

Li, Lang-quan; Huang, Wei; Yan, Li; Zhao, Zhentao; Liao, Lei

doi:10.1016/j.ijhydene.2017.06.014

Cited by 55 publications

(11 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ramps have shown improvement in penetration and mixing by producing vortical structures that interact with the injected fuel. Delta wing ramps of a size similar to the boundary layer showed improved mixing, reducing distance to 95% mixing efficienty by more than halve, only inducing total pressure losses of about 34%, albeit at Mach 3.75 (10,11) . The mixing improvement generated by these elements is linked to the generation of streamwise vorticity, with the ramps producing higher losses as mixing enhancement is improved (12) .…”

Section: Introductionmentioning

confidence: 97%

Effect of scramjet inlet vortices on fuel plume elongation and mixing rate

2019

View full text Add to dashboard Cite

Hypersonic air-breathing propulsion can improve cost and flexibility of Low Earth Orbit (LEO) satellite launch missions. However, at the high flight Mach numbers required for access-to-space, performance margins are extremely tight. Techniques to improve mixing efficiency can push this technology forward. However, these are required to produce a minimal increase in losses and heat loads to be viable. The use of inlet-generated vortices in scramjets for mixing enhancement was previously studied. These vortices interact with the injected fuel plume, stretching it and increasing its effective surface for mixing. Moreover, these vortices are intrinsic to the flowfield. Therefore, contrary to other methods, when using inlet vortices mixing is enhanced without producing additional heat loads or losses. This work studies the vortex-injection interaction through numerical RANS simulations. A non-dimensional variable defining the quality of the plume shape for mixing purposes is proposed. This parameter is used to assess the effect of vortex intensity and injector location on fuel plume shape. The results show the ability of inlet vortices to modify fuel plume shape significantly increasing fuel mixing rate with minimal impact on losses.

show abstract

Section: Introductionmentioning

confidence: 97%

Effect of scramjet inlet vortices on fuel plume elongation and mixing rate

2019

View full text Add to dashboard Cite

show abstract

“…The specific heat constant (Cp) is estimated using mixing law and the gas constant by kinetic theory. A second-order upwind scheme (SOU) is employed for spatial discretization along with a flux vector splitting scheme called the advection upstream splitting method (AUSM) employed to quicken the convergence speed [25,50]. The Courant-Friedrichs-Levy (CFL) number is chosen as 0.5 under a suitable relation factor to ensure stability [51].…”

Section: Methodsmentioning

confidence: 99%

The Combustion Characteristics of Double Ramps in a Strut-Based Scramjet Combustor

et al. 2021

View full text Add to dashboard Cite

This paper focuses on the influence of ramp locations upstream of a strut-based scramjet combustor under reacting flow conditions that are numerically investigated. In contrast, a computational study is adopted using Reynolds Averaged Navier Stokes (RANS) equations with the Shear Stress Transport (SST) k-ω turbulence model. The numerical results of the Deutsches Zentrum für Luft- und Raumfahrt or German Aerospace Centre (DLR) scramjet model are validated with the reported experimental values that show compliance within the range, indicating that the adopted simulation method can be extended for other investigations as well. The performance of the ramps in the strut-based scramjet combustor is analyzed based on parameters such as wall pressures, combustion efficiency and total pressure loss at various axial locations of the combustor. From the numerical shadowgraph, more shock interactions are observed upstream of the strut injection region for the ramp cases, which decelerates the flow downstream, and additional shock reflections with less intensity are also noticed when compared with the DLR scramjet model. The shock reflection due to the ramps enhances the hydrogen distribution in the spatial direction. The ignition delay is noticed for ramp combustors due to the deceleration of flow compared to the baseline strut only scramjet combustor. However, a higher flame temperature is observed with the ramp combustor. Because more shock interactions arise from the ramps, a marginal increase in the total pressure loss is observed for ramp combustors when compared to the baseline model.

show abstract

“…Zhao and Ye (2019) performed the studies on the pulsed jet frequency of the jet in supersonic cross flow to find the optimal amplitude and frequency by analyzing the mixing features. Li et al (2017) numerically investigated the jet mixing and penetration improvement by the pulsed jet and showed that the pulsating jet is a useful injection technique when compared with the steady-state jet. Liu et al (2018) numerically studied this flow physics too and illustrated that the optimal frequency exists to have the maximum combustion efficiency.…”

Section: Introductionmentioning

confidence: 99%

Inlet air and fuel flow pressure fluctuation effect on supersonic combustion

Tahsini

2020

AEAT

View full text Add to dashboard Cite

Purpose The purpose of this paper is to analyze the effect of pressure fluctuations on the combustion efficiency of the hydrogen fuel injected into the supersonic oxidizing cross flow. The pressure fluctuations are imposed on inlet air flow and also on the fuel flow stream. Two different situations are considered: the combustion chamber once without and again with the inlet standing oblique shock wave. Design/methodology/approach The pressure fluctuations are imposed on inlet air flow and also on the fuel flow stream. Two different situations are considered: the combustion chamber once without and again with the inlet standing oblique shock wave. The unsteady turbulent reacting flow solver is developed to simulate the supersonic flow field in the combustion chamber with detail chemical kinetics, to predict the time-variation of the combustion efficiency due to the imposed pressure fluctuations. Findings The results show that the response of the reacting flow field depends on both the frequency of fluctuations and the existence of the inlet shock wave. In addition, the inlet standing shock wave has some attenuating role, but the reacting flow shows an amplifying role on imposed oscillations which is also augmented by imposing anti-phase fluctuations on both inlet and fuel flow streams. Originality/value This study is performed to analyze the instabilities in the supersonic combustion which has not been considered before in this manner.

show abstract

Mixing enhancement and penetration improvement induced by pulsed gaseous jet and a vortex generator in supersonic flows

Cited by 55 publications

References 57 publications

Effect of scramjet inlet vortices on fuel plume elongation and mixing rate

Effect of scramjet inlet vortices on fuel plume elongation and mixing rate

The Combustion Characteristics of Double Ramps in a Strut-Based Scramjet Combustor

Inlet air and fuel flow pressure fluctuation effect on supersonic combustion

Contact Info

Product

Resources

About