Analysis of the pressure fields in a swirling annular jet flow

Perçin, Mustafa; Vanierschot, Maarten; Oudheusden, B.W. van

doi:10.1007/s00348-017-2446-3

Cited by 42 publications

(28 citation statements)

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“…Recently, clear evidence of a double-helical structure has been identified in the flow field of the same annular jet flow in both the velocity and pressure fields (Percin et al 2017;Vanierschot et al 2018). This double helix has the same features as the singlehelical PVC found in numerous other round or annular swirling jets: its branches are winded in the counter-swirl direction and the helix itself precesses along the central axis in the swirl direction.…”

Section: Coherent Structure Extractionmentioning

confidence: 81%

“…However, considering the frequency spectra of the temporal coefficients of these four pairs (figure 4), not one single but several distinct peaks are present. For instance the peak found at St = 0.27 in the studies of Percin et al (2017) and Vanierschot et al (2018) can be found in mode pairs II and III. This indicates that contributions from several different structures in the flow with their own dynamics are present in a single mode pair.…”

Section: Coherent Structure Extractionmentioning

confidence: 98%

“…Both u and w show large values in a region immediately downstream of the CRZ and in the shear layer between the vortex breakdown bubble and the jet. Comparison with the statistical data of Percin et al (2017) shows that despite the low energy content of the two precession motions (around 4 % and 2 %, respectively), the impact on the second-order statistics in the near-bubble region is significant with contributions of around 16 % for u u and v v and of 30 % for w w. Analogous to the production of turbulent kinetic energy caused by mean shear, the contribution of the coherent flow component to the production of the kinetic energy can be written as…”

Section: Mode Pair I: a Single-helical Pvcmentioning

confidence: 99%

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Single- and double-helix vortex breakdown as two dominant global modes in turbulent swirling jet flow

et al. 2019

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Section: Coherent Structure Extractionmentioning

confidence: 81%

Section: Coherent Structure Extractionmentioning

confidence: 98%

Section: Mode Pair I: a Single-helical Pvcmentioning

confidence: 99%

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Single- and double-helix vortex breakdown as two dominant global modes in turbulent swirling jet flow

et al. 2019

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“…In some cases, the precessing is weak, whereas in others, it is coupled with strong velocity and pressure fluctuations [7,[19][20][21][22][23][24][25][26][27]. The phenomenon of the precessing vortex core (PVC) has been studied extensively for different swirling flow 3 configurations, including swirling jets.…”

Section: Introductionmentioning

confidence: 99%

On Impact of Helical Structures on Stabilization of Swirling Flames with Vortex Breakdown

Дулин

Lobasov

Chikishev

et al. 2019

Flow Turbulence Combust

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We report on a study of the impact of coherent helical vortex structures on the shape of the reaction zone and heat release in swirling methane/air flames in regimes with a vortex breakdown. Three kinds of atmospheric flames are considered, viz., fuel-lean and fuel-rich premixed flames and a partially premixed fuel-rich lifted flame. Based on the measurements of the velocity fields by a stereo PIV in combination with the OH PLIF and HCHO PLIF, the impact of the coherent flow structures on large-scale corrugations of the reaction zone is evaluated. Helical vortex structures, detected in both the non-reacting and reacting high-swirl flows by using proper orthogonal decomposition, are found to promote combustion both in the lean premixed and fuel-rich partially premixed flames. In the first case, based on the phase-averaged intensity of the HCHO×OH signal and the location of the helical vortex structure in the inner mixing layer, it is concluded that the vortex locally increases the heat release rate by enlarging the flame front and enhancing the mass exchange between the combustion products inside the recirculation zone and the fresh gases. The events of the local flame extinctions are detected in the instantaneous PLIF snapshots for the lean mixture, but they do not cause extinction of the entire flame or a blow-off. In case of the lifted flame, the outer helical vortex structure promotes combustion by locally intensifying the mass exchange between the fuel-rich jet with the surrounding air.

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“…Specifically, aero-engine combustors have been experimentally investigated through POD decomposition techniques. Based on the PIV measurements, the presence of a Vortex Breakdown Bubble (VBB) and a Precessing Vortex Core (PVC) have been partially revealed and characterised in strongly swirling jets using modal decomposition analysis both in non-reacting [155][156][157][158][159][160][161][162] and reacting [45,[163][164][165][166] conditions. Nevertheless, as a consequence of experimental diagnosis shortcomings (e.g., the sampling frequency of the Stereo PIV system can be sometimes much smaller than the PVC frequency [157]), temporal and spatial-detailed CFD simulations have emerged as a potential tool to successfully characterise the coherent structures within the combustor through pressure, vorticity and species signals decomposition rather than dealing just with velocity.…”

Section: Studies Based On Advanced Spectral Analysismentioning

confidence: 99%

Computational study on the non-reacting flow in Lean Direct Injection gas turbine combustors through Eulerian-Lagrangian Large-Eddy Simulations

Gil¹

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Aeronautical gas turbine engines present the main challenge of increasing the efficiency of the cycle while keeping the pollutant emissions below stringent restrictions. This has led to the design of new injection-combustion strategies working on more risky and problematic operating points such as those close to the lean extinction limit. In this context, the Lean Direct Injection (LDI) concept has emerged as a promising technology to reduce oxides of nitrogen (NO x ) for next-generation aircraft power plants. ResumenEl principal desafío en los motores turbina de gas empleados en aviación reside en aumentar la eficiencia del ciclo termodinámico manteniendo las emisiones contaminantes por debajo de las rigurosas restricciones. Ésto ha conllevado la necesidad de diseñar nuevas estrategias de inyección/combustión que operan en puntos de operación peligrosos por su cercanía al limite inferior de apagado de llama. En este contexto, el concepto Lean Direct Injection (LDI) ha emergido como una tecnología prometedora a la hora de reducir los óxidos de nitrogeno (NO x ) emitidos por las plantas propulsoras de los aviones de nueva generación. ResumEl principal desafiament als motors turbina de gas utilitzats a la aviació resideix en augmentar l'eficiència del cicle termodinàmic mantenint les emissions contaminants per davall de les rigoroses restriccions. Aquest fet comporta la necessitat de dissenyar noves estratègies d'injecció/combustió que radiquen en punts d'operació perillosos per la seva aproximació al límit inferior d'apagat de flama. En aquest context, el concepte Lean Direct Injection (LDI) sorgeix com a eina innovadora a l'hora de reduir els òxids de nitrogen (NO x ) emesos per les plantes propulsores dels avions de nova generació.En els cremadors LDI, el combustible líquid s'injecta en unes proporcions de mescla pobre directament en la càmera de combustió, on es troba un flux d'aire coaxial arremolinat. Aquest flux altament turbulent promou l'atomització de la pel.lícula de combustible líquid i el mesclat l'esprai amb el aire. Al mateix temps també genera una zona de recirculació immediatament aigües avall del sistema d'injecció que incrementa de forma considerable incesante han sido indispensables para mí, y me resulta imposible explicar y agradecer con palabras la importancia que has tenido en la consecución de este logro. Tu manera de ver la vida, de ilusionarte y de ser feliz dándole valor a los pequeños detalles que muchas veces pasamos por alto pero que todos tenemos a nuestro alcance debería estudiarse en las escuelas. Estoy seguro de que de esta manera el mundo sería un lugar mucho mejor. Gracias por enseñarme tanto. Contents Contents i List of Figures v List of Tables xi Nomenclature xiiiA Full set of results for the L9 orthogonal array parametric study on the geometrical features 293 Global Bibliography 301x LIST OF FIGURES 7.7 Liquid spray penetration profiles for the simulations of the L9 array.262 7.8 Evolution of the Swirl Number along the swirler. . . . . . . . . . . 7.9 Dispersion values of some...

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Analysis of the pressure fields in a swirling annular jet flow

Cited by 42 publications

References 41 publications

Single- and double-helix vortex breakdown as two dominant global modes in turbulent swirling jet flow

Single- and double-helix vortex breakdown as two dominant global modes in turbulent swirling jet flow

On Impact of Helical Structures on Stabilization of Swirling Flames with Vortex Breakdown

Computational study on the non-reacting flow in Lean Direct Injection gas turbine combustors through Eulerian-Lagrangian Large-Eddy Simulations

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