Measurements of turbulence intensity in the standard 1Â m3 vessel

The standard 1 m3 vessel is an apparatus recommended for assessment of dust explosion indices by ISO, European and American Standards. Unlike the standard 20-l sphere, only few authors reported measurements of turbulence intensity in 1 m3 vessel. The paper presents results of such measurements performed in 1 m3 vessel built and used at Experimental Mine Barbara of Central Mining Institute, Poland. Transient flow velocity in the vessel generated by an air injection from the dust dispersion system was measured with use of Bi-Directional Velocity Probe developed by McCaffrey&Heskestad. The velocity was measured in several points along the vessel's axes and in two directions at each point. From the measurements the root-mean-square of instantaneous velocity u'rms and the characteristic length scale of turbulence were calculated. The results confirm discrepancy between turbulence intensity in the time periods characteristic for 1 m3 vessel and 20-l sphere, reported previously by other authors. The analysis of possible reasons of the discrepancy identifies the dust dispersion system as the main source of ambiguity, particularly the design and operation of the fast acting valve.