EP4283135A1 - Outlet flow guide device and fan with outlet flow guide device - Google Patents

Abstract

The invention relates to a fan and a guide device (1) for a fan, wherein the guide device (1) has several air guide vanes (L) arranged in a star shape at a central position (P), each with a leading edge (2, 4) and a trailing edge (3 ), wherein the air guide vane (L) has, at least in a partial area, a jagged or wavy leading edge (4) with a periodically repeating wave shape.

Description

The present invention relates to a guide device and a fan with a guide device, in particular a radial fan, an axial fan or diagonal fan with such a guide device.

Fans are used in many areas. There are many applications in which the air flow is highly turbulent. The turbulent flow from the fan leads to a significant increase in sound radiation, which means annoying noise development. With current fans or fan wheels, fan blades that are shaped in a fluid-mechanically favorable manner enable high performance, particularly with regard to the flow volume achieved or the pressure build-up. Basically, there is a need for low-noise fans with good aerodynamics at the same time, despite turbulent flow. However, strong noise development during operation of a fan, particularly that caused by rotor-stator interaction, often remains problematic.

There are various design measures in the prior art to reduce these problems. Many solutions deal with the blade shape of the fan blades. The publication DE 19948075 A To reduce running noise, uses an axial fan with blades that have a double sickle leading blade edge with a protruding outer corner. The US 3416725 A shows a wing shape with a double sickled leading edge and a slightly single sickled trailing edge.

The DE 10326637 B3 describes another solution, namely a fan with alternating direction of rotation, which has S-shaped sickle blades with a leading edge that recedes sharply towards the outside. Jagged or wavy trailing edges are used to reduce trailing edge noise (e.g GB2497739 or EP 1801422 A2 ). The DE 102009044824 A1 uses porosities in the form of holes in the area of the trailing edge to reduce the generation of sound at the trailing edge. Wavy or jagged leading edges are also known as a means of reducing noise in turbulent flow.

However, these solutions deal with the blade shape of the fan blades. However, alternative solutions are desirable that also have a technical effect in terms of smooth running and noise development with conventional fans (centrifugal fans, axial fans or diagonal fans).

Against this technical background, the invention deals with the problem of providing a fan that operates particularly quietly.

The invention solves this problem with a fan according to the independent claims. The dependent claims contain advantageous refinements. The invention relates to a solution consisting of an axial fan, diagonal fan or radial fan and a follow-up device modified according to the invention.

Before the invention is described in more detail, some terms and the terminology used are explained for a better understanding of the invention.

Guide devices in the sense of the present invention are bladed guide grilles which are arranged on the downstream side after the fan to guide air.

Furthermore, consider a typical axial or diagonal fan with usually several fan blades arranged in a star shape on a central hub for the fluidic suction and/or pressure of the air surrounding the fan or a gas to be conveyed by the fan. The fan blades can be connected to one another by a circumferential ring (slinger ring) on the radially outermost profile surface.

Furthermore, each fan blade has a front leading edge, which leads in the intended direction of rotation during operation, and a rear trailing edge, which lags behind in the intended direction of rotation during operation of the fan. Furthermore, depending on the direction of rotation and the fan blade profile, there is a suction side and a pressure side, with the suction side typically being on the convex side and the pressure side typically being on the concave side of the fan blade. As a rule, the leading and trailing edges are usually only optimally shaped for one direction of rotation. In this respect, the fan blade has a suction side, which sucks in the incoming air during operation, and a pressure side opposite the suction side, on which the pressure to expel the air builds up. The tracking device follows on this page.

The leading edge of the respective air guide blade of the guide device therefore faces the fan, while the trailing edge of the air guide blade of the guide device facing away from the fan.

A basic idea of the invention is that the leading edge of the air guide blades of the guide device has, at least in sections, a specific three-dimensional (or two-dimensional) wave-shaped shape or is correspondingly designed to be three- or two-dimensional wave-shaped.

According to the invention, a guide device is provided for a fan, the guide device having a plurality of air guide vanes arranged (preferably in a star shape at a central position, for example around a central axis), each with a leading edge and a trailing edge, the wing profile of which is curved and / or twisted is, wherein the respective air guide vane has, at least in a partial area, a jagged or wavy leading edge with a preferably periodically repeating wave shape. Alternatively, a non-periodic waveform can also be selected.

In a particularly advantageous exemplary embodiment, it is provided that the wave course of the wave crests and wave troughs, which is formed by the wave shape, extends essentially or completely in the plane formed by the respective air guide vane in the area of the leading edge and/or extends substantially along the wave crests a tangent extends along the surface of the air deflector in the area of the respective wave crest. In other words, this means that the respective wave crest extends from the blade edge in the extension of the wing profile and not from the surface of the profile of the air guide wing, so that the leading edge is designed to be corrugated as such. In this respect, the wing profile in the surface course on the leading edge is not modified by the wave shape according to the invention, but rather the leading edge itself.

In a preferred embodiment of the invention it is provided that the corrugated leading edge of the air guide blades has several or a large number of periodically repeating wave sections or wave shapes.

1. a. gemäß einer sinusförmigen oder nahezu sinusförmigen Wellenform oder
2. b. gemäß eine Potenzfunktion n-ter Ordnung, insbesondere der Form $$\mathrm{f}\left(\mathrm{x}\right)=\mathrm{a}·{\mathrm{x}}^{\mathrm{n}}$$
   

wobei a = f(r)
wobei, a eine Funktion darstellt, welche die Erstreckung der Spitze in Abhängigkeit vom Radius r beschreibt und wobei n vorzugsweise in einem Bereich zwischen -5 und 5 liegt.In a particularly advantageous exemplary embodiment, the waveform of the leading edge of the air guide blades can be described or approximated according to one of the following mathematical functions:

1. a. according to a sinusoidal or nearly sinusoidal waveform or
2. b. according to a power function of the nth order, in particular of the form $$\mathrm{f}\left(\mathrm{x}\right)=\mathrm{a}·{\mathrm{x}}^{\mathrm{n}}$$
   

where a = f(r)
where, a represents a function which describes the extent of the tip as a function of the radius r and where n is preferably in a range between -5 and 5.

With a wave or waveform that can be approximated by a power function or alternatively a polynomial function, the wave trough is advantageously rounded or rounded off.

In addition, it is favorable if the leading edge of the air guide blades has a wavy or jagged edge shape essentially over the entire course of the blade, but at least over a contiguous partial area of more than 20%, preferably more than 50% of the length of the air guide blades in the radial direction or Span direction considered.

A further variant is that the leading edge of the air guide blades has areas with non-corrugated edge profiles between or next to the corrugated profiles, but at least over a contiguous partial area a profile as described above.

1. i) Anstellwinkelverlauf über den Radius weist zwei oder mehr Wendepunkte auf;
2. ii) überlagerte Variation einer periodischen oder nicht periodischen Welle gegenüber lediglich einem kontinuierlichem (d.h. nicht gewellten) Vorderkantenverlauf;
3. iii) die Sehnenlänge der Luftleitschaufeln ändert sich;
4. iv) die Profilschnitte sind in Richtung der Anströmkante verlängert, insbesondere stetig;
5. v) die Wölbung der Luftleitschaufeln ändert sich im Bereich der Anströmkante.

A combination of several geometric design elements according to the invention is particularly advantageous, with the wave shape being characterized by at least one of the following constructive measures:

1. i) Angle of attack progression over the radius has two or more turning points;
2. ii) superimposed variation of a periodic or non-periodic wave versus just a continuous (ie non-wavy) leading edge progression;
3. iii) the chord length of the air guide vanes changes;
4. iv) the profile sections are extended in the direction of the leading edge, in particular continuously;
5. v) the curvature of the air guide blades changes in the area of the leading edge.

In a further preferred embodiment of the invention it is provided that the profile of the air guide blades, viewed at least in a profile section in the area of a wave crest, each has a dent protruding from the top and a dent extending into the underside or vice versa.

The present invention relates in particular to an axial or diagonal fan, as well as a radial fan, which each has a guide device as described above or one or more air guide vanes downstream of the fan in the flow direction.

The following advantages and features are associated with the invention. The special design of the front edge of the guide device with the modification described is fundamentally aimed at different sound generation mechanisms than modifications to the trailing edge or trailing edge. The advantage of the invention, in contrast to the trailing edge modification, is that it explicitly reduces the noise generated by the interaction of the impeller and stator.

The front edge modification described is also designed for axial or diagonal fans with a centrifugal ring. The front edge modification described is also designed for centrifugal or diagonal fans with a cover plate. The invention can also be used to reduce noise in typical flow situations (no head gap vortex, increased tangential components due to the closed ring, backflow in the outside area and wake effects of the gap flow) and in addition to the points mentioned below by reducing the resulting interaction mechanisms.

• Es ergeben sich reduzierte Schallleistungspegel und reduzierte tonale Anteile in der Schallabstrahlung. Letzteres trägt neben einer reduzierten A-Bewertung des Lärms auch zu einer Verbesserung der psychoakustischen Wahrnehmung bei.
• Die üblicherweise eingesetzte Gestaltungsweise mit starker Sichelung der Nachleiteinrichtung zur Erreichung der akustischen Zielwerte kann ersetzt werden durch eine Gestaltung mit reduzierter Sichelung und erfindungsgemäßer Modifikation der Vorderkante.
• Die mögliche Reduzierung der Sichelung führt zu einer Erhöhung der Festigkeit bei einer Nachleitradeinrichtung mit tragender Funktion. Die erhöhte Festigkeit erlaubt eine Verringerung des Materialeinsatzes.
• Eine Reduktion der Sichelung bedeutet ferner auch bei nicht-tragenden Leiteinrichtungen eine Reduktion des Materialbedarfs aufgrund der reduzierten Schaufellänge.
• Bei gleichem Schallpegel kann durch die beschriebene Modifikation der Abstand zum vorgelagerten Laufrad reduziert werden. Dies ermöglicht kompaktere Ventilatoreinheiten und/oder eine Erhöhung der Schaufelfläche der Nachleiteinrichtung und somit eine Steigerung des Wirkungsgrades.

The modification of the tracking device according to the invention has the following advantages, in particular compared to the solutions known in the prior art:

• This results in reduced sound power levels and reduced tonal components in the sound radiation. In addition to a reduced A-rating of the noise, the latter also contributes to an improvement in psychoacoustic perception.
• The design method usually used with a strong crescent of the tracking device to achieve the acoustic target values can be replaced by a design with reduced crescent and modification of the front edge according to the invention.
• The possible reduction of the crescent leads to an increase in the strength of a guide wheel device with a load-bearing function. The increased strength allows the use of materials to be reduced.
• A reduction in the sickle also means a reduction in the material requirement for non-load-bearing guide devices due to the reduced blade length.
• With the same sound level, the distance to the impeller in front can be reduced using the modification described. This enables more compact fan units and/or an increase in the blade area of the guide device and thus an increase in efficiency.

Other advantageous developments of the invention are characterized in the subclaims or are shown in more detail below together with the description of the preferred embodiment of the invention with reference to the figures.

Fig. 1

ein erstes Ausführungsbeispiel einer Nachleiteinrichtung;

Fig. 2

ein zweites alternatives Ausführungsbeispiel einer Nachleiteinrichtung;

Fig. 3

ein drittes Ausführungsbeispiel einer Nachleiteinrichtung;

Fig. 4

ein viertes Ausführungsbeispiel einer Nachleiteinrichtung;

Fig. 5

einen Luftleitflügel mit gewellter Anströmkante und

Fig. 6

ein Ausschnitt eines Luftleitflügels mit partiell gewellter Anströmkante.

Show it:

Fig. 1

a first embodiment of a tracking device;

Fig. 2

a second alternative embodiment of a tracking device;

Fig. 3

a third embodiment of a tracking device;

Fig. 4

a fourth embodiment of a tracking device;

Fig. 5

an air guide wing with a wavy leading edge and

Fig. 6

a section of an air deflector with a partially wavy leading edge.

The invention is explained below using an exemplary embodiment with reference to Figures 1 to 6 explained in more detail, with the same reference numbers in the figures indicating the same structural and / or functional features.

The Figures 1 to 4 show alternative embodiments of a guide device 1 with air guide vanes L, each with a corrugated leading edge 2, 4.

The guide devices 1 shown are designed for a fan, the respective guide device 1 having several air guide vanes L arranged in a star shape at a central position P, each with a leading edge 2, 4 (leading edge) and a trailing edge 3 (trailing edge), the air guide vane L being at least in a partial area each has a jagged or wavy leading edge 4 with a wave shape.

The air guide vanes L are fastened on the inside to the central ring 10 (or a mounting body 10 as shown in the figures) and run radially outwards to a circumferential ring 11. A mounting flange 12 can also be provided on the circumferential ring 11, as shown in the figures be. The corrugated leading edge 4 of an air guide vane L has a detailed view of the Figure 5 clearly visible, several or a large number of periodically repeating waveforms and in this exemplary embodiment runs along the entire length of the air guide blade L.

The Figure 6 shows a section of an alternative air guide blade L in which the leading edge 2, 4 has a wavy course only in the partial area with the reference number 4 (thus partially).

The implementation of the invention is not limited to the preferred exemplary embodiments given above. Rather, a number of variants are conceivable, which make use of the solution presented even in fundamentally different designs.

Claims (13)

Guide device (1) for a fan, wherein the guide device (1) has a plurality of air guide vanes (L), each with a leading edge (2, 4) and a trailing edge (3), the wing profile of which is curved and / or twisted, the respective air guide vane (L) has, at least in a partial area, a jagged or wavy leading edge (4) with a periodically or non-periodically repeating waveform. Guide device (1) according to claim 1, characterized in that the wave course of the wave crests and troughs, which is formed by the wave shape, extends essentially or completely in the plane formed by the air guide vane (L) in the area of the leading edge and / or the wave crests extend essentially along a tangent along the surface of the air guide wing (L) in the area of the respective wave crest. Guide device (1) according to claim 1 or 2, characterized in that the corrugated leading edge (4) of the air guide vanes (L) has several identical or different waveforms that repeat periodically. Guide device (1) according to claim 1, 2 or 3, characterized in that the waveform along the leading edge (2, 4) can be described according to one of the following mathematical functions: a. a sinusoidal or nearly sinusoidal waveform; b. a power function of nth order or nth degree with -5 ≦ n ≦ 5. Guide device (1) according to one of the preceding claims, characterized in that the leading edge (4) of the air guide blades (L) has a wavy or jagged edge shape essentially over the entire course has, but at least over a contiguous portion of more than 20%, preferably more than 50% of the length of the air guide blades (L) viewed in the radial direction. Guide device (1) according to one of the preceding claims 4 to 5, characterized in that the leading edge (4) of the air guide blades (L) has non-corrugated edge profiles between or next to the corrugated profiles, but at least over a contiguous partial area a profile according to claim 3. Tracking device (1) according to one of the preceding claims, characterized in that the waveform is characterized by at least one of the following constructive measures: A) the angle of attack curve has two or more turning points over the radius; B) a superimposed variation of a periodic or non-periodic wave versus just an unwaved continuous leading edge course; C) the chord length of the air guide vanes changes; D) the profile cuts are extended in the direction of the leading edge, preferably continuously; E) the curvature of the air guide vanes changes in the area of the leading edge. Guide device (1) according to one of the preceding claims, characterized in that the wave shape is designed on the leading edge (4) in such a way that there is a wave crest at the respective inner or outer leading edge end. Guide device (1) according to one of the preceding claims, characterized in that the plurality of air guide vanes (L) are arranged in a star shape at a central position (P). Air guide vane (L) designed for a guide device (1) for a fan, the air guide vane (L) being provided with a leading edge (2, 4) and a trailing edge (3), wherein the air guide vane (L) has a jagged or wavy leading edge (4) is formed with a periodically repeating waveform as defined in one of claims 1 to 8. Axial fan or diagonal fan with a centrifugal ring further comprising a guide device (1) according to one of claims 1 to 9 or one or more air guide vanes (L) downstream of the fan in the flow direction according to claim 10. Diagonal fan or radial fan with a cover plate further comprising a guide device (1) according to one of claims 1 to 9 or one or more air guide vanes (L) downstream of the fan in the flow direction according to claim 10. Axial fan or diagonal fan or radial fan with a guide device (1) according to one of claims 1 to 9.

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