Turbulence characterization of a high-pressure high-temperature fan-stirred combustion vessel using LDV, PIV and TR-PIV measurements

An experimental study on turbulent premixed expanding flames using simultaneously Schlieren and tomography techniques

“…Indeed the turbulent intensity increase is responsible for an increase of the wrinkling and therefore of the turbulent flame speed. This rise of the wrinkling is mainly provoked by the decrease of the small turbulent scales as already shown by Galmiche et al [18] and Brequigny et al [24] on the same vessel. Moreover it is important to notice that the flame radius observed here are quite small below 20 mm.…”

“…It was particularly shown that the fans generated homogeneous and isotropic turbulence in a central portion of 40 mm diameter. In [18], the turbulence intensity was found to be proportional to the rotational fan speed but the integral length scale independent of the fan speed and equal to 3.4 .…”

“…In previous work [18], the turbulent flow was fully characterized by using Laser Doppler Velocimetry and Particle Imaging Velocimetry in non-reactive conditions. It was particularly shown that the fans generated homogeneous and isotropic turbulence in a central portion of 40 mm diameter.…”

Investigation of pressure effects on the small scale wrinkling of turbulent premixed Bunsen flames

“…Concerning turbulence characteristics, integral length scales remain almost constant and smaller scales are reduced with pressure. The integral length scale is an inherent parameter of the experimental setup and can be related to geometrical characteristics such as the blade pitch angle of the impellers for turbulent spherically expanding flames [14,15] or the turbulence grid mesh for stationary burners [7,16,17]. As pressure increases, the turbulence energy spectra show that the high frequencies have more energy [15], meaning that the pressure increase generates smaller time scale turbulent structures and consequently smaller turbulent length scales.…”

Analysis of the Bivariate EMD Behavior for Separating Coherent Structures from Interference Fluctuations in Isotropic Homogeneous Turbulence

“…It was generated by six fans in a spherical combustion chamber with a mean velocity inside the chamber equal to zero. The turbulence field was characterized by using high rate particle image velocimetry and Integral length-scale, Integral time-scale and energy spectra were determined Galmiche et al [2]. This flow field is perturbed by a mono-tone signal as a synthetic fluctuation p(t) = Asin(2π f.t), that mimics coherent structures.…”