Fan device

Abstract

An air moving device for improving P-Q characteristics and noise by suppressing the production of vortices. An annular wall spaced from blade tips, is formed of a plurality of annular plates and spacers with a slit defined between adjacent annular plates. The width of each slit is set to satisfy the formula W.ltoreq.(.nu..multidot.R.sub.ec /v) where .nu. is the kinematic viscosity of air, v is the peripheral speed of the blade tips, W is the width of the slits and R.sub.ec is the critical Reynold's number. Thus, as a fan is rotated, air is drawn in a laminar flow through the slits to the inner periphery of the annular wall. Thereby, it is possible to suppress the separation of air flow on the suction side of blade surfaces and the production of vortices, thus improving the air moving state.

Dependencies are inferred from the claim text.