LDV IN HIGH ASPECT RATIO CURVED DUCTS WITH RECTANGULAR CROSS SECTION

Results of LDV measurments in the incompressible flow field inside two different curved ducts of C and S shapes are provided. Ducts are of high aspect ratio rectangular cross section intended for isolation of secondary flow effects . Measurments are performed using single component He-Ne forward scatter LDV system . The system operates in dual beam fringe mode with signal processing by counting. Mean streamwise velocity profiles and turbulence intensities are obtained at different streamwise locations together with several lateral traverses. Measurments are performed in conditions of moderately turbulent boundary layers on duct walls and manifested the curvature effects on internal flow and boundary layer behaviour. Lateral traverses indicated the presence of G8rtler vortex system expected on concave walls at such moderately turbulent Reynolds' number. Obtained results clarify the flow nature in curved ducts and help in setting and checking the relevant computational codes.