抄録
The authors experimentally study the characteristics of the flow around/inside a cross-flow fan, namely, a cross-flow impeller. In order to eliminate complicated influence of many casing factors, the impeller rotates in open space without any casings. As a result, at some aspect ratios L/D_2's, including the singular aspect ratio L/D_2 = 0.6 at which the outflow rate Q. out of the impeller and the maximum vorticity ω_<max> attain the maximum values, the authors reveal minute fluctuating pressures on an impeller's end wall. In our previous pressure measurements (Hirata et al., 2012 & 2013), the eccentric vortex inside the impeller is prevented to revolute by means of the insertion of a tongue, in order to detect the spatial structure of flow more precisely. On the other hand, the authors conduct the measurements without the tongue. By comparing the distributions for L/D_2 = 0.6 with those for L/D_2 = 1.0, the authors reveal that the radial position of an eccentric-vortex center becomes inward with decreasing L/D_2. For L/D_2 = 0.6, the authors confirm the minimum-pressure coefficient C_<pmin> which is a reduced minimum pressure defind by p_<min>/0.5pu_2^2 tends to decrease with decreasing Re at 2r/D_2 ? 0.5. ForL/D_2 = 1.0, this tendency is converse.
