The low Reynolds number turbulent flow and mixing in a confined impinging jet reactor

Florian Schwertfirm, Johannes Gradl, Hans C. Schwarzer, Wolfgang Peukert, Michael Manhart

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

Turbulent mixing takes an important role in chemical engineering, especially when the chemical reaction is fast compared to the mixing time. In this context a detailed knowledge of the flow field, the distribution of turbulent kinetic energy (TKE) and its dissipation rate is important, as these quantities are used for many mixing models. For this reason we conduct a direct numerical simulation (DNS) of a confined impinging jet reactor (CIJR) at Re = 500 and Sc = 1. The data is compared with particle image velocimetry (PIV) measurements and the basic flow features match between simulation and experiment. The DNS data is analysed and it is shown that the flow is dominated by a stable vortex in the main mixing duct. High intensities of turbulent kinetic energy and dissipation are found in the impingement zone which decrease rapidly towards the exit of the CIJR. In the whole CIJR the turbulence is not in equilibrium. The strong mixing in the impingement zone leads to a rapid development of a monomodal PDF. Due to the special properties of the flow field, a bimodal PDF is generated in cross-sections downstream the impingement zone, that slowly relaxes under relaminarising conditions. The time required for meso-mixing is dominating the overall mixing performance.

Original languageEnglish
Pages (from-to)1429-1442
Number of pages14
JournalInternational Journal of Heat and Fluid Flow
Volume28
Issue number6
DOIs
StatePublished - Dec 2007

Keywords

  • Confined impinging jet reactor
  • Direct numerical simulation
  • Opposing jets
  • Particle image velocimetry
  • Turbulent mixing

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