Instantaneous flow field measurements in the interstage section between a fan and the outlet guiding vanes at different axial positions

Abstract

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 theeff =U k Effective cooling velocity, normal to sensor wire U mean Mean velocity of the U component.V Radial component of velocity W Circumferential component of velocity W* In and out coming velocity relative to blade system C Meridional component velocity U circ Circumferential velocity at blade tip α, β Angles of sensor wires, relative to probe axis  Fluid density  Thermal conductivity  Fluid viscosity Φ Yaw angle of hot-wire probe, aligned to the assumed outflow angle.Θ Circumferential traverse position relative to TDC ABBREVIATIONS OGV Outlet guide vanes TDC Top dead center TNBB EU-Project TurboNoiseBB from the Horizon 2020 programme SLS Fan working line notation for "sea level static"