2.2. Laser diagnostics
The flow field was studied using a conventional fibre-coupled 2D LDV system (Dantec) in the for- ward scattering mode. The off-axis detection angles were either 10° or 80° to monitor axial and radial or axial and tangential velocity compo- nents. The probe volume length varied corre- spondingly from 2500 to 200lm. The probe volume diameter remained constant (240 lm) for both configurations. Notice, that the measured PDFs of the axial velocity component were unaf- fected by the extended probe volume. Combustion air and fuel were seeded with MgO particles approximately 1 lm in diameter. Measurement uncertainties for mean and fluctuations were esti- mated to be