Patent ID: 6739835
Filing Date: 2004-05-25
Classification: F04D,Y10S

Abstract:
A blade part in a turbofan, comprising:a hub coupled with a rotating axis of a driving part; a plurality of blades arranged radially at a circumferential part of the hub; and a shroud coupled with a plurality of the blades and arranged so as to confront the hub wherein the blades lie between the hub and the shroud, and wherein each cross-section of the blades is defined by NACA four digits, so as to form an airfoil wherein, if a chord line is an X-axis and a leading edge in an origin, and a chord c is 1, x is a chordwise, X-axis direction, relative coordinate and yt(x) is a thickness function so as to satisfy yt&af;(x)=tc0.2&it;(0.2969&it;x-0.126&it;x-0.3516&it;x2+0.3100&it;x3-0.1015&it;x4),wherein Yc(x) is a Y-axis relative coordinate of a mean camber line and &thgr; is a slope of the mean camber line so as to satisfy 0&leq;x<P,â€ƒ&it;yc&af;(x)=Mp2&it;(2&it;Px-x2),Î¸=tan-1&it;{2&it;MP2&it;(P-x)},P&leq;x&leq;1,â€ƒ&it;yc&af;(x)=M(1-P)2&it;(1-2&it;P+2&it;Px-x2),Î¸=tan-1&it;{2&it;M(1-P)2&it;(P-x)},where M is a % value of a relative y coordinate of a maximum camber and P is a 10% value of a relative x coordinate of the maximum camber andwherein a coordinate (xu,yu) of the top camber line of the blade is defined by xu=xâˆ’yt(x)sin &thgr;, yu=yc(x) +yt(x) cos &thgr; and a coordinate (xl,yl) of the bottom camber line satisfies xl=x+yt(x)sin &thgr;, yc(x)âˆ’yt(x) cos &thgr;l(x)u(x) such that each of the blades form an airfoil constructed with a top camber line defined by a NACA 4-digit airfoil and a bottom camber line lying closer to the top camber line than a bottom camber line defined by the NACA 4-digit airfoil.