Abstract
The flow field of a turbulent premixed V flame has been closely examined by using a three-color six-beam LDV system. A bi-modal distribution, composed of the velocity fluctuations of both the high velocity mode and the low velocity mode, is observed within the turbulent flame brush. In the radial component, the high velocity mode is identified as velocity fluctuations of the unburnt mixture and the low velocity mode as velocity fluctuations of the burnt gas. On the other hand, in the axial component, the high velocity mode is identified as velocity fluctuations of the burnt gas and the low velocity mode as velocity fluctuations of the unburnt mixture. Velocity vectors of the unburnt mixture are seen to be directed toward outer side of the burner, indicating that the flow divergence is remarkable in the unburnt mixture. The radial component of the velocity vectors of the unburnt mixture increases in the downstream. On the other hand, the velocity vectors of the burnt gas are slightly directed towards the centerline because of the thermal expansion across the flamelet. The axial component of the velocity vectors of the burnt gas increases in the downstream. The RMS (root-mean-square) of the fluctuations of the radial component of the gas velocity decreases in the unburnt mixture towards the centerline. It increases in the turbulent flame brush. It decreases in the burnt gas toward the centerline. The RMS of the fluctuations of the axial component of the gas velocity decreases both in the unburnt mixture and the burnt gas toward the centerline. Enhancement of turbulence in the turbulent flame brush is remarkable in the radial direction.
