Numerical investigation of passive scalar transport and mixing in a turbulent unconfined coaxial swirling jet

Kadu, Pravin Ananta; Sakai, Yasuhiko; Ito, Y.; Iwano, Koji; Sugino, Masatoshi; Katagiri, Takahiro

doi:10.1016/j.ijheatmasstransfer.2019.118461

Cited by 9 publications

(2 citation statements)

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“…For the results of the work of Kadu et al (2019), the DNS simulations showed a good agreement for mean streamwise velocity and RMS streamwise velocity compared to experimental results. The case with intermediate swirling strength case exhibited a faster centerline decay and radial spread in the mean streamwise velocity in the downstream region compared to the non-swirling case.…”

Section: Turbulence and Swirling Flowmentioning

confidence: 63%

“…Johnson and Roback (1983) used these statistics to analyze the effects of swirl in a coaxial flow by introducing passive scalars through inner jet only and found that the spreading rate of scalars increases with an increase in swirling strength. Entropy may be also a parameter to analyze the diffusion of scalars Kadu et al (2019).…”

Section: Turbulence and Swirling Flowmentioning

confidence: 99%

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Simulação numérica de um escoamento turbulento não-reativo no interior de uma caldeira ciclônica industrial usando LES e URANS

Pereira¹

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A numerical simulation of a non-reactive turbulent flow inside a cyclonic industrial CO boiler was investigated in order to understand the swirling formation, the fluid behavior in different locations inside the domain and the distribution of chemical species. As 80% of the energy matrix in Brazil is generated by combustion processes and government regulations about NOx emissions are becoming more restrict, enhancing combustion efficiency in a CO boiler with a turbulent swirling flow to reduce pollutant emissions has become an engineering research topic. Enhancing mixing processes through turbulent swirling flows might reduce thermal NOx formation. Computational fluid dynamics simulations were realized using the in-house MFSim code with the turbulent closure models LES, URANS Standard k − ε, URANS Standard k − ε Modified and URANS Realizable k − ε. A theoretical basis about turbulence, LES and URANS closure models, mixing and swirling flows was provided. A state of art comprising different authors pointed out that some works with URANS Standard k − ε demonstrated a premature solid-body rotation formation due to its eddy viscosity assumption and that swirling flows may reduce pollutant emissions by improving mixing of reactants and decreasing flame temperature. Validations concerning multi-component mixing flows and Immersed Boundary method were presented. From the results, LES and URANS Standard k − ε presented similar velocity field results, capable of capturing the swirling formation. When analyzing three URANS closure models, a turbulent kinetic energy graph illustrated that it is relevant to observe the modeled part and the value obtained from velocity field fluctuations. The modified model presented low turbulent viscosity values and an LES-like behavior, with similar results to the standard model. The realizable model presented distant results comparing to the other models studied and there was no reverse flow in its swirling core. Adding different chemical species did not modify the velocity field and the highest mixing level was obtained in the most intense turbulent swirling region, close to the inlets. The data provided may assist in the comprehension of swirling formation, mixture processes inside a boiler and temperature control to reduce pollutant emissions.

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Section: Turbulence and Swirling Flowmentioning

confidence: 63%

Section: Turbulence and Swirling Flowmentioning

confidence: 99%