A MULTI-ELEMENT AIRFOIL FOR PULP SCREENS

摘要

The operation of pulp screening apparatus (10) may be improved by employing a multi element foil (14) having a leading foil section (22) and a trailing fo il section (24) spaced from and trailing leading section (14) so that adjacent surfaces of the sections one formed by a portion of a pressure side (38) of the leading section (22) and the other by the leading end (40) of the traili ng foil (24) section define opposed walls of a passage (42) for fluid directing fluid flow from the pressure side (28) of the leading foil (22) section to a cambered low pressure side (34) of the trailing section (24). The angle of attack (.alpha.) of the complete multi element foil (14) is set to be significantly less than the angle of attack of the trailing foil section (24 ) to increase the negative pressure pulse generated by the trailing section (2 4) and thereby improve operation of the screening device.