Observation of Flow in a Ring Inlet Chamber

We present the results of visualization and quantitative measurements of the flow in a simplified model ring chamber of the type used in axial-flow turbomachinery (see Fig. 1) to distribute flow entering a machine radially to the blading. The observations reveal that above a critical Reynolds number the flow swirls circumferentially around the ring chamber. The device then performs much like a vortex valve, a strong vortex being created in the exit tube beyond the center body. It is shown that the pressure loss in this case can be calculated fairly well using an analysis similar to that of Binnie and Hookings [1]. The exit-tube vortex is also responsible for the occurrence of a piercing whistling sound the frequency of which can be estimated using Vonnegut’s [2] theory for the vortex whistle. Observations are also presented for the symmetric flow situation which occurs at subcritical Reynolds numbers and for the case where swirl in the ring chamber is prevented by a baffle.