RU2000126488A - AXIAL FAN - Google Patents

Claims (1)

1. An axial fan (1; 30) rotating in the (XY) plane and containing a central hub (3; 33), a plurality (n) of blades (4; 34), comprising more than three, with each blade having a root part (5 ; 35) and the end part (6; 36), and the blades (4; 34) are also bounded by the first edge (7; 37) and the second edge (8; 38), and consist of sections with aerodynamic profiles (18), in which the blade installation angle (β) gradually and continuously decreases from the root part (5; 35) to the end part (6; 36) of the blade (4; 34), while the blade installation angle (β) is defined as the current angle waiting for the plane of rotation (XY) and a straight line connecting the front edge and the rear edge of the aerodynamic profile (18) of each section of the blade, and the blades (4; 34) are separated from each other by unequal angles (θ _{i ... n} ), characterized in that these unequal intermediate angles (θ _{i ... n} ) can vary as a percentage (θ%) by values between 1.5% and 8.5% compared to the configuration with equal intermediate angles (θ =) for fans with the same number (n) of blades, i.e.:
1.5% ≤θ% ≤8.5%,
Where

so that the fan (30) is essentially balanced naturally in that the projection of the convex edge (7) onto the plane (XY) is determined by the parabolic segment, and that the projection of the concave edge (8) onto the plane (XY) is determined by a geometric curve of the second degree . 2. The fan according to claim 1, characterized in that it contains seven blades (34), and that unequal intermediate angles (θ _{i ... n} ) of the blades (34) have the following values, expressed in degrees: θ1-55.381; θ2 = 47.129; θ3 = 50.727; θ4 = 55.225; θ5 = 50.527; θ6 = 48.729; θ7 = 52.282.
3. The fan according to any one of the preceding paragraphs, characterized in that the projection of the concave edge (8) onto the plane (XY) is determined by a parabolic segment.  4. The fan according to claim 1, characterized in that the projection of the concave edge (8) onto the plane (XY) is defined by an arc of a circle.  5. A fan according to any one of the preceding paragraphs, characterized in that the aerodynamic profiles (18) have a surface (18a) containing at least one straight section (t).  6. A fan according to claim 5, characterized in that the aerodynamic profiles (18) have a surface (18a) containing a segment following the initial section (t), which is essentially composed of circular arcs. 7. The fan according to claim 5 or 6, characterized in that the aerodynamic profiles (18) have a chord length (L) and a rear part (18b) defined by a convex curve, which in combination with the surface (18a) determines the value (G _max ) the maximum profile thickness in the region between 15% and 25% of the total chord length (L), measured from the edge that first meets the air flow.  8. The fan according to any one of the preceding paragraphs, characterized in that each blade (4) in the projection onto the plane (XY) is bounded by four points (M, N, S, T) lying in the plane (XY), and is defined as a function of the angle (B) relative to the width of one blade (4) pulled together at the center of the fan, and also differs in that the four points (M, N, S, T) are determined by the following characteristics: points (M) and (S) are located at the hub (3 ) or at the root part (5) of the scapula (4) and are determined by the rays (16.17) coming out from the center of the fan and forming an angle (B); point (N) is located at the end (6) of the blade (4) and is shifted counterclockwise by an angle (A) = 3/11 (B) relative to the bisector (13) of the angle (B); point (T) is located at the end (6) of the blade (4) and is shifted counterclockwise by an angle (A) = 3/11 (B) relative to the beam exiting the center of the fan and passing through point (S).  9. The fan according to claim 8, characterized in that the projection of the convex edge (7) onto the plane (XY) at point (M) has a first tangent (21) inclined at an angle (C) equal to three quarters (A), relative to ray (17) passing through point (M), and also characterized in that the projection of the convex edge (7) onto the plane (XY) at point (N) has a second tangent inclined at an angle (W) equal to six angles (A ), relative to the ray (14) passing through the point (N), while the first and second tangents (21, 22) are in front of the corresponding rays (17, 14), when the direction is rotated I fan (1) is such that the convex edge (7) of the first to meet the air flow, wherein the first and second tangents (21, 22) are arranged so as to define a curve in the plane (XY), that has a single convex portion without points of inflection. 10. The fan according to any one of paragraphs. 4-9, characterized in that the circular arc formed by the projection of the concave edge (8) onto the plane (XY) has a radius (R _eu ) equal to the radius (R) of the hub (3).  11. The fan according to any one of the preceding paragraphs, characterized in that the blades (4) are formed from sections whose aerodynamic profiles (18) have an angle (β) that gradually and continuously decreases from the root part (5) to the end part (6) vanes (4) in accordance with the cubic law of change as a function of radius.