MXPA97004168A - Eliptic vortice wall for fan vantilators - Google Patents

Abstract

The present invention relates to a transverse fan means, characterized in that it includes an impeller having a rotor having an outer diameter Do, a vortex wall having a tip separated from the rotor by a separation, slow and a rear wall, the which co-acts with the vortex wall to define a discharge portion that has an angle B, the tip has an elliptical surface that has foci and is separated from the rotor with: 0.02

Description

ELLIPTICAL VORTEX WALL FOR TRANSVERSE FANS DESCRIPTION OF THE INVENTION Transversal fans are also known as transverse and tangential flow fans. They are used in air conditioning applications because of their in-line flow capabilities and their proper relationship with plate-fin heat exchangers, which can extend the full length of a heat exchanger. In a transverse fan, the inlet and outlet are usually nominally at right angles, but angles from 0 to 180 ° are possible. The impeller is similar to a centrifugal, curved, forward fan wheel, except that it is closed at both ends. The flow is perpendicular to the drive shaft in the entire fan (two-dimensional flow), and the blade row is entered in the direction radially inward on the upward side, which passes through the interior of the impeller and then flows radially outward through the blade a second time. The flow is characterized by the formation of an eccentric vortex that runs parallel to the rotor axis and which rotates in the same direction as the rotor. A two-stage action occurs as the flow passes first through the suction (upwards) of the blade, and then through the discharge blades. He flow contracts as it moves through the impeller producing high speeds in the discharge blades (second stage). The flow leaves the impeller and contracts again as it rotates and tightens around the vortex. The combination of these effects results in high pressure coefficients, achieved by the transverse fans. A vortex wall separates the inlet from the outlet and acts to stabilize the vortex. Since there is only recirculation flow in the vortex region, useful work is not done there. The main effect in the vortex is the dissipation of energy. The stability of the fan, however, is highly sensitive to the separation of the vortex wall. This parameter must be controlled very carefully, since a separation has to be made between the high, stable operation and the noise tone generated by the interaction of the impeller with the wall of the vortex. The vortex wall is provided with an elliptical surface facing the impeller in place of a circular surface as is conventional. For a given space between the vortex wall and the impeller, an elliptical surface will provide improved flow performance or a reduction in sound when compared to a similarly placed circular surface. Basically, the smallest space or separation, most stable and least fan noise. The increase of flow or reduction of sound it depends on the orientation of the elliptical surface. If the main axis of the elliptical surface is in a line that corresponds to the direction of the vortex wall, the curved surface is narrower and the flow operation increases, whereas if the main axis of the elliptical surface is in a line perpendicular to the direction of the vortex wall, the curved surface is wider and there is a reduction in sound due to coercion with the passing blades. Alternatively, the standard sound or flow of a circular curved surface can be maintained, while improving the other factor by changing the separation between the impeller and the elliptical vortex wall. It is an object of this invention to improve the operation in transverse fans. It is another object of this invention to improve the noise ratings for a transverse fan. These objects and others as it will become apparent in the following, are realized by the present invention. Basically, the impeller and tip of the vortex wall coact to define a convergent-divergent space with the wall defining an elliptically curved surface and the impeller defining a circularly curved surface.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view of a transverse fan of the PREVIOUS TECHNIQUE showing the fluid trajectories through it; Figure 2 is a sectional view of the vortex wall of the present invention; Figure 3 is a sectional view of a modified vortex wall; and Figure 4 is a sectional view of a second modified vortex wall. In Figure 1, the number 10 generally designates a transverse fan of the PREVIOUS TECHNIQUE. The fan 10 includes an impeller or rotor 12, a vortex wall 16 and a rear wall 20. The curved inlet portion 20-1 of the rear wall 20 and the curved tip 16-1 of the vortex wall 16 coact with the impeller 12 to define and separate the suction side S, and the discharge side D, of the fan 10. The vortex wall 16 and the rear wall discharge portion 20 form an angle β. The circularly curved tip 16-1 and the cylindrical impeller 12 co-act to define a convergent-divergent flow path between the suction and discharge sides. Because both of the tip 16-1 and the impeller 12 are circular, they have different cylindrical surfaces in three dimensions and are symmetrical in both directions with respect to the throat. the convergent-divergent section to the extent of the minimum circular extension of point 16-1. With the rotation in the counterclockwise direction of the impeller 12, as illustrated, the air flow path is shown by the arrows. It will be noted that an arrow V defines a closed fluid path or vortex delimited in part by the vortex wall 16. The presence of the vortex V causes the air discharge of the impeller 12 to be applied between the vortex V and the rear wall 20 , as clearly shown in Figure 1, maintaining a high speed. Downstream of vortex V, the flow expands very rapidly in diffuser section 22 as it moves to the outlet of the fan. This expansion process is increased by the vortex V since without the vortex, the flow could be separated from the walls in the diffusing section 22. The present invention modifies the tip 16-1 of Figure 1, which is essentially a semi-cylinder in three dimensions, to portions of an elliptical surface. In Figure 2, the tip 116-1 of the vortex wall 116, there is a semi-elliptical surface of an ellipse having a major axis defined by the foci Fl and F-2 on the centerline of the wall 116 as shown in FIG. Figure 2. In Figure 3, the tip 216-1 of the vortex wall 216 is a semi-elliptical surface of an ellipse having a defined major axis. by foci Fl and F-2 on a line perpendicular to the center line of the wall 2X6 as shown in Figure 3. Figure 4 is like Figure 3 with respect to the surface of the tip 316-1 of the wall 316 , which is presented for the flow. However, the wall 316 is made of a metal sheet flexed at a J-shaped point 316-1 having an elliptical surface instead of having one or more massive walls 216 as in the embodiment of Figure 3. A point middle of the major axis between foci Fl and F-2 is the center of the ellipse from which the major and minor radii of the ellipse are determined. Accordingly, the basic physical difference between the tip 116-1 and the tips 216-1 and 316-1 is that the ellipse is rotated 90 ° between the embodiment of Figure 2 and the embodiments of Figures 3 and 4, and They have different elliptical surfaces. Except in the special case where the axis of the wall 116-216 or 316 is on a diameter of the impeller 12, the surfaces 116-1, 216-1 and 316-1 co-act with the impeller 12 to define a convergent-divergent throat, which is not symmetric with respect to the throat. Since this is the location for the vortex V, and that the blades of the impeller 12 have their smallest separations with the tips 116-1, 216-1 and 316-1 respectively, the constraints are very different from those of the fan 10 of Figure 1 of the PREVIOUS TECHNIQUE.

In Figure 2, the shortest side of the ellipse produces a convergent -divergent shorter section. As a result of the configuration of the tip 116-1, the flow could be increased than in the case of the tip 16-1 with all the other factors that are the same. In Figure 3, the longer side of the ellipse produces a longer convergent-divergent section. As a result of the configuration of the tip 216-1, there would be a quieter operation and less tonal content than in the case of tip 16-1 with all the other factors that are the same. The modality of Figure 4 works in a similar way. The configuration of Figure 2 can be modified to increase the throat or gap of the converging-diverging portion to reduce flow to provide quieter operation with both flow and silent operation which is better than in the case of point 16- 1. Similarly, the configurations of Figures 3 and 4 can be modified by reducing the throat of the convergent-divergent portion to increase the flow, while increasing the noise, but with the flow and sound that is better than in the case of the point 16-1. In redesigning the tip of the circular fin 16-1 of Figure 1 of the PREVIOUS TECHNIQUE, the range of the radius of the minor axis of the ellipse that redefines the tip 16-1, Rmenor must be in the range of: p less 0.02 < < 0.15 where DQ is the diameter of the impeller 12. For a given value for Rmenor »the range of Rmayor, the largest radius of the elliptical tip 116-1 or 216-1 should be in the range of: ^ riayor 1.1 < < 6.0 or less For the embodiments of Figures 2 and 3, the minimum space or separation between the vortex wall and the impeller, "is in the range of: space 0.02 < < 0.15 Do and the range of vortex wall angles ß is in the range of: 0 ° _ ß_ < _ 50 ° From the above explanation, it should be clear that the circular tip 16-1 of the PREVIOUS TECHNIQUE may be modified at tip 116-1 or 216-1 using the teachings of the present invention and that another modification may be made by changing ^ space 'as shown in the above. Also, Figures 2 and 3 represent extreme limits of the orientation of the elliptical surface and intermediate positions are possible.

Claims (1)

1. CLAIMS 1. A transverse fan means, including an impeller having a rotor having an outer diameter DQ, a vortex wall having a tip separated from the rotor by a spacing, of SADAC ^ 0 and a rear wall, which coactuates with the wall of the vortex to define a discharge portion having an angle, characterized in that the tip has an elliptical surface having foci and separated from the rotor and in which the elliptical surface has a greater radius Rmayorf a smaller radius, such that: ^ nayor 1.1 < - < 6.0 p less where ^ nenor 0.02 < < 0.15 Do 2. The fan means according to claim 1, characterized in that the rear wall coact with the vortex wall to define a discharge portion having an angle ß with: "" space 0.02 < - < 0.15 DQ and 0o < ß < fifty