The thermal expansion of gases due to heat release across the flame front of turbulent premixed flames modifies the turbulence. The present study has been performed to examine velocity changes and changes in turbulence across the flame front at different positions In the turbulent flame brush. The measurements employ an electrostatic probe with three identical sensors and a two-color, four-beam LDV. The LDV measures axial and radial components of the local gas velocity, while the electrostatic probe measures two dimensional movement of the flame front in the plane of the LDV velocity components. The component of the local gas velocity normal to the flame front tends to increase in passing through the flame front. The flame front thereby can generate anisotropy in initially isotropic turbulence. They also produce difference in turbulent spectra conditioned on unburnt or burnt gas. Local modification of turbulence by the flame front are demonstrated experimentally. The modifications are different at different Positions in the turbulent flame brush. On the centerline, inclination angle of the flame fronts are relatively small, and turbulence is enhanced manly in the axial direction, while off axis the flame fronts are more nearly vertical, and the enhancement is mainly in the radial direction.
