An experimental study of the turbulent kinetic energy balance for the eddy entrainment, combustion in depth process of region 3 has been carried out. The influence of approach turbulence scale, intensity and laminar burning velocity on each term in the balance equation has been examined for propane-air and acetylene-air flames and the important role of small scale turbulent motion is highlighted. It is observed that either an increase in intensity or a reduction in scale of approach turbulence increases the magnitude of all terms except that for convection. The core region of the flame shows jet-like behaviour. The entrainment, combustion in depth process produces a very high level of fluctuating vorticity. Therefore, the dominant terms appear to be those of viscous dissipation and advection. Finally, a large increase in laminar burning velocity enhances the contribution of the advection term at the expense of a reduction in the convection term.