Investigation of flame generated turbulence in a large-scale and low-intensity turbulent premixed flame with a 3-element electrostatic probe and a 2-D LDV

An attempt has been made to examine the flame-generated turbulence in a lar ge-scale and low-intensity turbulent premixed name by measuring change of t he local gas-velocity vector across the flame front in relation with local movement of the flame front. In order to achieve this measurements, special ly arranged diagnostics, composed of an electrostatic probe with three iden tical sensors and a two-color four beam LDV (laser-doppler velocimeter) sys tem, have been adopted. From simultaneous measurements by these two instrum ents at the same point, local movement of the flame front in a vertical pla ne above a vertically oriented burner can be measured by the electrostatic probe, and simultaneously, the instantaneous axial and radial components of the local gas velocity in the same plane can be measured by the suitably o riented LDV system. Thus, change of the power spectrum density function and individual change of the local gas-velocity vector can be examined in rela tion with local movement of the name front. The kinetic energy of turbulence in the burnt gas flow is increased in the frequency range that corresponds to the flamelet passing frequency. The kin etic energy of turbulence in the burnt gas flow is larger at low frequency but is smaller at high frequency than that in the approach flow. The turbul ence intensity is significantly increased in the radial direction in the bu rnt gas flow, inducing anisotropy in an initially isotropic turbulence.