This paper presents a new method of computer-aided blade geometric design, which combines several typical methods of computational geometry developed recently (including Bezier patches, 5-spline patches and Bezier-B-spline mixed patches, etc. ) with the space shaping for aerojet blades.On the basis of the classic works on computational geometry[1] [2][3] and recent research results in China [4][ 5 ],the geometric design of a heavily cambered aerojet blade has been investigated.Aa the curvature of the blade surface... This paper presents a new method of computer-aided blade geometric design, which combines several typical methods of computational geometry developed recently (including Bezier patches, 5-spline patches and Bezier-B-spline mixed patches, etc. ) with the space shaping for aerojet blades.On the basis of the classic works on computational geometry[1] [2][3] and recent research results in China [4][ 5 ],the geometric design of a heavily cambered aerojet blade has been investigated.Aa the curvature of the blade surface is large chordwise but small in the radial direction, several surface patches are used chordwise and one in the radial direction to build a whole blade surface. Thus, an integral mathematical model for a blade configuration is obtained and jointed by a set of 3 times 2 order mixed surface patches with a common expression P(u,v) = [U][M]k[B][N][V] (see eq. (1) (1 a ) (1 b ) (1 c ) (1 d ))It is quite important to give the spatial position vector matrix [B] of the polygonal mesh vertices of the blade surface. In this paper the vertices are simplified to be given in three basic sections(see fig. 3 ).Present method is capable of easy moving the vertices on the screen and improving the adjustable parameters so that a desired blade surface can be formed to meet the requirements of the optimum geometric design.A practical example given in this paper has shown that the method is simple and clear, adaptable and flexible for modification, and its computational quantity is not great. It may be seen that the method is beneficial to aerodynamic calculations of three dimensional flow field in cascade and finite element strength analysis, and also it can be combined with digital control manufacture of blades. Therefore, it will make a contribution to a blade computer-aided design and manufacture system (CAD/CAM). |