A Bowed Blade based on’ spline Curve’ and Investigations on Its Aerodynamic Performance

Abstract

A new type of bowed blade based on’ spline curve’ is proposed and its analytic expression of the stacking line is simultaneously derived. In this new type of bowed blade, some typical shapes of bowed blade, such as ‘W type’, ‘Middle Inflexion type’, ‘C type’ and ‘Natural Spline type’ can be easily generated according to different prescribed conditions. Their applications are attempted to an axial fan and detail numerical investigations are implemented to evaluate their aerodynamic performance. Results indicate: bowed blade of “W type” may deteriorate the flow inside the impeller and worsen the impeller’s performance; bowed blade of ‘C type’, especially as its particular form--‘natural spline type’ can constrain the flow stall in the vicinity of the blade tip and enlarge the stable operating range for the impeller at small flow rate conditions but its aerodynamic performance may decrease a little at large flow rate conditions; bowed blade of ‘Middle Inflexion type’ may not only enlarge the stable operating range at small flow rate conditions but also hold better aerodynamic performance at larger flow rate conditions, which is a promised type of bowed blade with much practical value.