13th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
The unsteady flow field of a representative fan stage was measured by DLR using hot-wire anemometry. The hot-wire measuring technique allows to determine unsteady flow structures (e.g. the wake of each individual rotor blade). The phase-resolved mean flow velocities as well as the fluctuation components values of the velocity were determined, which then led to the computation of the local turbulence distribution in the flow field. The measurements were performed at different axial positions up- and downstream of the fan. The calculated local turbulence distribution of the flow downstream of the rotating blades shows an increase of the turbulence intensity from about 0.8% to 3% outside of the wake to about 4% up to 24 % in the wake flow depending on the operating point. The measured data also gives a good impression of the mixing process of the wakes with increasing axial distance downstream of the rotor.