Fluid Dynamical Analysis of Atmospheric Reacting and Isothermal Swirling Flows

A series of unconfined swirling premixed natural gas/air flames was investigated. Reynolds-numbers spanned from 10,000 to 42,300. Respective isothermal flows were studied additionally to gain insight into changes of fluid dynamical features caused by combustion. Statistical moments, Reynolds-stresses, temporal time scales, spatial length scales, and power spectral densities were deduced from one- and two-point laser Doppler velocimetry (LDV) data. Properties of the turbulent flows and dependencies on Reynolds-number, swirl number, and chemical reactions are discussed. Most distinct differences between combusting and isothermal flows were precessing vortex cores (PVC) occurring only for the latter cases. The study is aimed to serve as a database of a generic flame geometry featuring important characteristics of industrial applications for validation of numerical simulations. Therefore, nozzle exit profiles as important inlet conditions to numerical simulations are thoroughly documented.