Studies on the Flow of Cross-Flow Impellers : 2nd Report, Analytical Study

Abstract

Using an actuator model, velocity and pressure distributions of a flow around a cross-flow impeller are derived, which are in good agreement with experimental results on impellers with radial blades. Under the assumption that the stability of an eccentric vortex in the radial direction inside an impeller is achieved when an input furnished to the flow by impeller-bladings balances with energy dissipation by fluid viscosity, the stability conditions are discussed. Critical Reynolds number of stability for an axisymmetric vortical flow is given as a function of eccentricity of vortex. Performance of a fan with a simple casing around an impeller is obtained by numerical computation and influences of several parameters on it are clarified. It is found that only one circumferential location of stability of a vortex to make input maximum exists for a given eccentricity.