A Hybrid RANS/LES Approach to Modeling of Swirling Jet Flows

Kannepalli, Chandrasekhar; Chenoweth, James; Arunajatesan, Srinivasan; Hosangadi, Ashvin

doi:10.2514/6.2008-3853

Cited by 3 publications

(2 citation statements)

References 12 publications

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“…A generalized subgrid scale methodology for variable density flow is discussed in the literature, and shown to have excellent agreement with DNS [Moin, 1991]. Hybrid RANS/LES approaches have recently shown promising results [Stoellinger and Zemtsop, 2007;Chenoweth et al, 2008;Kannepalli et al, 2008;Gopalan et al, 2010].…”

Section: Dynamic Smagorinsky Modelmentioning

confidence: 99%

Swirling jets for the mitigation of hot spots and thermal stratification in the VHTR lower plenum.

Rodríguez¹

2011

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The literature indicates that a prismatic-core very high temperature reactor can experience thermal stratification and hot spot issues in the lower plenum (LP). This research hypothesizes that the complex thermalhydraulic phenomena in the LP requires a sophisticated computational fluid dynamics (CFD) code with state-of-the-art turbulence models and advanced swirling jet technology to mitigate the two issues. The primary research goals were to increase the heat transfer and mixing capacity of swirling jets, extend swirling jet theory, and to apply those advancements for the mitigation of the thermalhydraulic issues. First, it was demonstrated that the Fuego CFD code successfully modeled a set of key LP thermalhydraulic phenomena. Thereafter, a helicoid vortex swirl model was developed to investigate the impact of the swirl number (S) on mixing and heat transfer. The development of azimuthal and axial velocities that are solely functions of S permitted the analysis of the central recirculation zone's (CRZ) impact on the LP flow field. At this point, several characteristics were found in common between the helicoid vortex and other axisymmetric, Newtonian, incompressible vortices found in the literature. This observation resulted in a more fundamental understanding of how vortices behave, and which traits can be exploited for the purpose of maximizing heat transfer and mixing. Because the CRZ is a strong function of the azimuthal and axial velocities, shaping those velocity profiles had a substantial impact. Eventually, this led to the discovery that vortices may be expressed as alternating series that expand geometrically with odd exponents. This helped corroborate that the 15 axisymmetric vortices discussed in this research are part of a vortex family with seven common traits. This also led to the development of new vortices that are based on one or two series terms that satisfy the Navier-Stokes equations and conservation of mass. In addition, the impact of Reynolds number and swirl decay were explored in order to further quantify their impact. Finally, the above theories and modeling insights were applied towards a comprehensive set of LP calculations that showed that the swirling jets mitigated the entrainment and hot spot issues, while resulting in a reasonable pressure drop. Contents

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Section: Dynamic Smagorinsky Modelmentioning

confidence: 99%

Swirling jets for the mitigation of hot spots and thermal stratification in the VHTR lower plenum.

Rodríguez¹

2011

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“…The RST model performed much better but was computational expensive[65].A RANS/LES model (combination of a RANS model and Large Eddy Simulation (LES) model) was used to simulate flow with a small swirl number. Results indicated that the length scales governing the swirl and axial velocity were different and simulations would be more accurate if they could cover a large range of mixing length scales[66].Recent numerical studies of supersonic flow or interior scramjet flow field simulations have used k-ε, k-ω turbulence models or combinations of both. Numerical investigation of scramjet combustors with combustion conducted by Vyas (2010)[7] and Tourani (2011)[67] used a k-ε turbulence,Mack (2006) [38] andJianwen (2008) [68] used a k-ω turbulence model whileRodriguez (2005) [61] andBhagwandin (2009) [69] used Mentor's SST k-ω turbulence model.…”

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confidence: 99%

Mixing Enhancement in a Scramjet Combustor Using Fuel Jet Injection Swirl.

Flesberg

2018

22nd AIAA International Space Planes and Hypersonics Systems and Technologies Conference

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The scramjet engine has proven to be a viable means of powering a hypersonic vehicle, especially after successful flights of the X-51 WaveRider and various Hy-SHOT test vehicles. The major challenge associated with operating a scramjet engine is the short time residence time of the fuel and oxidizer in the combustor. The fuel and oxidizer have only milliseconds to mix, ignite and combust in the combustion chamber. Combustion cannot occur until the fuel and

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Three-Component Laser-Doppler-Anemometry Measurements in Turbulent Swirling Jets

Semaan

Naughton

2013

AIAA Journal

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A Hybrid RANS/LES Approach to Modeling of Swirling Jet Flows

Cited by 3 publications

References 12 publications

Swirling jets for the mitigation of hot spots and thermal stratification in the VHTR lower plenum.

Swirling jets for the mitigation of hot spots and thermal stratification in the VHTR lower plenum.

Mixing Enhancement in a Scramjet Combustor Using Fuel Jet Injection Swirl.

Three-Component Laser-Doppler-Anemometry Measurements in Turbulent Swirling Jets

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