RELATIVE FLOW AND TURBULENCE MEASUREMENTS WITHIN AND DOWNSTREAM OF ANAXIAL-FLOW ROTOR

This article presents the results of an experimental investigation on the relative flow within and behind an axial fan rotating row. The flo w within the rotor passages has been surveyed over blade-to-blade surf aces with a laser-Doppler velocimeter (LDV), while the flow leaving th e rotating blades has been measured by means of stationary hot-wire pr obes and fast-response miniature pressure transducers. A phase-locked sampling and ensemble-averaged technique has been applied to separate periodic and random contributions from the instantaneous signals of th e different stationary measuring instruments. Within the rotor both ax ial and tangential velocity components and the related variances have been measured by rotation of the single-channel laser-Doppler optics o perating in back-scatter mode. In the plane aft of the rotor all mean velocity and Reynolds stress components of the relative flow have been determined using a 12-orientations single-sensor hot-wire technique. The static and relative total pressure distributions have been obtaine d from the velocity components and the ensemble-averaged total pressur e distributions given by the fast-response miniature pressure transduc ers. The results, shown in terms of secondary vector plots and contour s of mean flow characteristics, turbulence intensity, and Reynolds str ess components, give a detailed picture of the rotor flow kinematic st ructure and of the relative total pressure loss and turbulence distrib utions.