The main purpose of this study is to investigate the local velocity acceleration in a boundary layer diffusion flame over a flat plate. To know the effect of separation on the local velocity acceleration, two typical flow domains with and without separation were chosen. For these two flow domains, flow visualization by means of paraffine smoke tracers has been made, and measurements of mean velocity and turbulent intensity distribution by using a laser Doppler velocimeter, in addition to measurements of concentration and mean temperature profiles, have been made to know the difference between two flow domains. Time-mean density profiles have been obtained from the data of concentration and temperature profiles. The obtained results are as follows.
1) The local velocity acceleration near the visible flame zone is shown clearly in the case without separation.
But, in the case with separation, the local velocity acceleration is observed only at low free stream velocity. As increasing the free stream velocity it is not distinctly observed in the mean velocity profile.
But, in both cases with flame, the mean velocity profiles are distorted, and accelerated downstream as free stream velocity is decreased and as fuel injection rate is increased.
2) The turbulent intensity is significantly decreased by the combustion in the case with separation.
But in the case without separation, the turbulent intensity is increased near the visible flame zone in comparison with the cold flow.
In both cases, the peak value of turbulent intensity appeared just at the visible flame zone, where the mean velocity gradient is not high.
3) There are not shown the large differences in the profiles of concentration, temperature, and density by the separation.
