GB870171A - Improvements in blades for compressors - Google Patents

Abstract

870,171. Compressor blades. UNITED AIRCRAFT CORPORATION. March 16, 1959 [Sept. 4, 1958], No. 8960/59. Classes 110 (1) and 110 (3). An aerofoil blade for a compressor comprises a rigid spar forming a part of the aerofoil surfaces of the blade and upper and lower bimetallic sheets extending chord wise to form a continuation to the leading and/or trailing edges of the blade. A solid leading section 12 extends the full length of the blade and connected to it are upper and lower bimetallic sheets 14, 16 forming the trailing section. The outer layer 28 of sheet 14 and the inner layer 30 of sheet 16 are of the same material and have a larger temperature coefficient of expansion than the layers 32, 34. Thus an increase in temperature will cause the trailing edge of the blade to deflect as shown by the dotted lines. Alternatively, the leading section may be bimetallic with a solid trailing section or both leading and trailing sections of bimetallic construction may be attached to the rigid spar. The sheets are attached by welding and only one bimetallic sheet may be attached while the other is free in a lengthwise slot in the solid member. The bimetal sheet may vary lengthwise of the blade either in thickness with the material becoming thinner towards the tip or in width, Fig. 9, the material 94 increasing chordwise towards the tip. In another modification both width and thickness of the bimetallic sheets may vary over the length of the blade. In Fig. 15, a blade is shown having a bimetal portion 140 in which is embedded a heating element 142 whose temperature can be controlled by a battery and rheostat. This gives a fine control setting for the blade camber.