Axial machines for incompressible flow

Abstract

Axial fans and pumps may be treated as incompressible flow devices, producing large flow rates and small pressure rises. Axial pumps in service deliver up to 80 000 m³ h ⁻¹ against resistances equivalent to a level change of 20 m, and have been applied to irrigation, draining, dock dewatering and circulation duties. Fans have been applied to ventilation duties and cooling tower circulation, and commonly produce pressure rises of the order of 500 Nm⁻²; special designs give higher pressure rises. Sizes clearly vary with duty, from kitchen ventilation fans to machines up to 4 m in diameter.