CN111810441A

CN111810441A - Fan, manufacturing method thereof and method for discharging medium

Info

Publication number: CN111810441A
Application number: CN201910880319.0A
Authority: CN
Inventors: 谭发程; 塞巴斯蒂安·威斯曼; 张伟良; 夏茂燕; 阮志新; 侯志泉; 屈小章
Original assignee: Hunan Medex Electric Co Ltd; Hunan Lince Rolling Stock Equipment Co Ltd
Current assignee: Hunan Medex Electric Co Ltd; Hunan Lince Rolling Stock Equipment Co Ltd
Priority date: 2019-09-18
Filing date: 2019-09-18
Publication date: 2020-10-23

Abstract

The present invention relates to the field of extraction of gaseous media and their discharge under pressure. In order to obtain a solution which reduces the interference noise/frequency range without having to take separate insulation measures, a fan with a rotary part (10) is proposed, wherein a gaseous medium is sucked in by the rotary part and discharged again under pressure. The rotating member (10) has a plurality of blades (16a-16g), wherein at least two of the plurality of blades differ from each other in a characteristic (16a '-16 g') that has an effect on a media pulse applied to a component of the wind turbine by a respective one of the blades (16a-16g) during operation.

Description

Fan, manufacturing method thereof and method for discharging medium

Technical Field

The present invention relates to the field of extraction of gaseous media and their discharge under pressure, and in particular to the field of fans, such as centrifugal fans, axial fans and diagonal fans.

Background

The starting point of the invention will be explained on the basis of an exemplary application of a centrifugal fan for cooling a converter by means of an air flow.

It has been found that when centrifugal fans are used in many converters and similar devices, unpleasant noise is generated during operation due to so-called rotational noise.

As each radial blade passes around a surrounding component, such as the casing wall, a corresponding individual pulse is generated that produces a rotational tone or rotational noise through harmonic regression. This can be clearly seen in the spectrum and is described by the following equation: f. of_D(n x z)/60, wherein f_DThe fundamental frequency of the rotational noise is represented, n represents the rotational speed, and z represents the number of blades.

For a fan wheel with seven blades and a rotational speed of 1450 rpm, the fundamental frequency of the rotational noise is expected to be about 170Hz, i.e. f_D＝(1450×7)/60min^-1169.16Hz 170 Hz. This frequency and its harmonics have a large effect on the fan sound audible to the human ear.

The above problem is explained by taking a centrifugal fan as an example, but it is also equally applicable to an axial flow fan and a diagonal flow fan.

In order to reduce the unpleasant noise generated by the fan during operation and to take into account the overall sound effect requirements, some isolation measures have been taken, but this involves additional costs and additional costs.

Disclosure of Invention

It is an object of the present invention to provide a fan, a method of manufacturing the fan, and a method of discharging a gaseous medium under pressure, whereby the problems of known solutions can be avoided or at least reduced.

The invention therefore seeks to provide a solution which, on the one hand, reduces the unpleasant noise/frequency and, on the other hand, does not necessitate separate insulation measures or the like.

According to a first aspect of the invention, a fan is proposed, having a rotary part by means of which a gaseous medium can be extracted and released again under pressure, wherein the rotary part has a plurality of blades, at least two of which differ from one another with respect to a characteristic which has an effect on a medium pulse which a respective blade exerts on a component of the fan during operation.

According to a second aspect of the present invention there is provided a method of manufacturing a fan having a rotating member through which a gaseous medium can be drawn and released under pressure, the rotating member having a plurality of blades, wherein the method comprises arranging the blades into at least two blades which differ from one another with respect to a characteristic which has an effect on the medium pulse applied by a respective blade to a component of the fan during operation.

According to a third aspect of the present invention, there is provided a method for discharging gaseous medium under pressure, i.e. drawing the medium through a rotating member of a fan on which each blade exerts a medium pulse when passing a component of the fan as the rotating member rotates, wherein the method comprises causing the respective medium pulses of at least two of the plurality of blades to differ from each other by virtue of the at least two blades differing from each other with respect to a characteristic that has an effect on each applied medium pulse.

A part of the background of the invention will be seen from the following description.

It has been found that by structural variations, such as blade angle and blade outer profile (trailing edge), an asymmetry can be created which can eliminate or impede harmonic propagation of the velocity of the gaseous medium after leaving the centrifugal impeller. Here, despite the hydrodynamic asymmetry of the impeller geometry, the mechanical symmetry with respect to the center of mass is maintained, which in particular means that the balance is subject to similar or even identical preconditions as in known fan impellers. It can also be assumed that, with a corresponding impeller geometry, no relevant negative changes in terms of intensity and vibration behavior are detectable either. Furthermore, the reduction of the vibration excitations which are generated by the dynamic acoustic excitations in the surrounding components brings about the advantage that these components are thus exposed to lower loads.

This particularly achieved asymmetry allows an improved noise behavior to be achieved, which is based on the fact that the individual pulses of the individually formed blades differ from each other, so that the generated rotational noise is reduced to some extent in its frequency spectrum in the known solution.

The asymmetry described above has already occurred when one characteristic of the two impellers, which has an influence on the medium pulse applied by the components of the fan during operation of the respective blades, differs from each other. This means that for this property all but one of the blades are identical, so that this one blade differs from all the other blades with respect to this property. The difference between the two impellers is also related to one or more pairs of blades, which exist independently of the difference (here the concept of "a pair" does not have to be arranged adjacent to each other), and there is at least one difference in one characteristic each.

The asymmetry preferably comprises that, when the rotary member is theoretically rotated one full revolution around a portion corresponding to one or both of the blades, the part which has theoretically rotated differs from the part which has theoretically not rotated with respect to the blades by at least one characteristic which has an effect on the media pulse applied by the respective blade to the part of the fan during operation. In other words, a blade does not, in terms of its structure, repeat itself by its rotation over one or two angular regions between two adjacent blades. In the case of a conventional symmetrical impeller with 6 identical and equally spaced blades, the blades repeat themselves once every (theoretically) 60 degrees of rotation. Preferably, in the fan according to the invention, the rotation element repeats itself only once (theoretically) for a complete revolution.

It should be noted that although the present invention is primarily described and illustrated in terms of an example of a centrifugal fan, the considerations and features presented herein are applicable to any type of fan. It will be clear to a person skilled in the art that the various embodiments can be used directly or similarly for other types of fans, and therefore the invention is not to be construed as being limited to centrifugal fans.

In an advantageous embodiment of an aspect of the invention, the characteristic that has an influence on the medium pulse exerted by one of the respective blades on the components of the fan in operation comprises: the profile and/or pitch of the trailing edge of the blade; the profile and/or pitch of the leading edge of the blade; deviation of the arrangement of the blades with respect to an output arrangement given by the symmetry of the rotating member, wherein the rotational symmetry corresponds to the number of blades of the rotating member; and/or the surface profile of the blade.

In the present invention, in particular the configuration of the trailing and leading edges of the blades, the arrangement of the blades (with respect to the output arrangement predetermined by the rotational symmetry), and/or the respective surface profiles of the blades may be considered.

In the known solutions, the surface profile of the blade has been improved with respect to a relatively simple curved surface. Also in the present invention, it is possible to provide that all the blades are modified in the same manner, for example, providing concave portions, convex portions, curvature deviations, etc. If the surface profile is part of the property or group of properties which, within the scope of the invention, makes at least two blades different from one another, this difference can also be formed in that one blade has a known surface profile without modification, while the other or further blades have a modified surface profile, which is to be understood as meaning that the associated blades have their own modifications which differ from one another.

In the known arrangement of fan blades, there is rotational symmetry corresponding to the number of blades, so that approximately one cross section of a fan with 6 blades coincides with itself again when turning 60 degrees around the axis of rotation. Here, the arrangement comprises, inter alia, the actual position of the blade, as well as the orientation of the blade.

It is believed that in addition to the orientation and position of the blade, the profile of the trailing edge of the blade has a particularly strong influence on the media pulses generated when the edge passes through the components of the wind turbine. It has been found that besides the profile, the inclination of the edge can also be used as a property that can be varied. In known centrifugal fans, the trailing edge is arranged, for example, parallel to the axis of rotation. In the inclined position of the discharge cross-section, a delay in the angle of impact of the gas flow is produced. Preferably, if the profile of the edge is modified or averaged over the extent of the edge, the inclination angle can be in the range of 5 ° to 15 °, particularly preferably in the range of 8 ° to 12 °.

The difference in the blade may also be at the leading edge, similar to the trailing edge.

In a preferred variant of the above embodiment, the characteristic that has an effect on the medium pulse applied by one of the respective blades to the components of the fan during operation comprises a profile of the trailing edge of the blade, wherein at least two blades differ with respect to a deviation of the profile of their respective trailing edges from the profile of the given output trailing edge.

As a profile for a given output trailing edge, and also as a reference for quantifying deviations or differences between blades, for example, a straight edge can be assumed in a centrifugal fan, which has a straight course parallel to the axis of rotation, or else a slanted straight edge. It should be understood here that the output trailing edge profile is used only as a standard comparison ruler, and that it is not to say that such an output trailing edge profile is already present in the blade manufacture. However, the output profile is not limited to a straight line form, especially in view of the blade profiles that are already dominant in various fan configurations.

In a further preferred variant of the above-described embodiment, the characteristic which is influenced by the medium pulse which the respective blade exerts on the components of the fan in operation comprises a profile of a leading edge of the blade, wherein at least two blades differ with respect to their respective leading edge profile with respect to a given output leading edge profile.

Accordingly, the above description for the trailing edge also applies to the leading edge.

In another preferred variant of the above embodiment, the profile of the trailing edge and/or the leading edge of at least one blade varies over the extent of the trailing edge or the leading edge from the output trailing edge profile or the output leading edge profile, wherein the maximum deviation in one direction is greater than 1/150 for the length of the blade and the maximum deviation in the opposite direction is greater than 1/150 for the length of the blade.

The profile deviation of the edge may be regular (e.g. in the form of a wave or a sawtooth), but is preferably irregular. The size of the deviations is set here for the relevant effects of the media pulses, whereby microscopic unevenness of the edges (for example caused by machining) cannot be interpreted as said deviations.

In a preferred variation of the above embodiment, the maximum deviation in one direction is less than 1/15 for the vane length, and the maximum deviation in the opposite direction is less than 1/15 for the vane length.

Preferably, the deviation of the profile from the theoretical output profile is such that the maximum deviation is within the range determined by the above values. In particular, in the case of an irregular edge configuration, this can be arranged such that the deviation is approximately zero on average with respect to the inclined output profile.

In a further preferred variant of the above-described embodiment, the characteristic which has an influence on the medium pulse exerted by the components of the wind turbine during operation comprises a shift in the arrangement of the respective blades relative to an output arrangement given by the rotational symmetry of the rotary part, wherein the shift in the arrangement comprises the orientation and/or position of the blades.

By the arrangement of the blades, which is regarded as asymmetrical, it is also possible to influence the media pulse, which is generated by the blades when they pass through another component of the fan, in a desired manner. In this case, for example, in the case of centrifugal fans, the blade arrangement in relation to the (theoretically) conventional arrangement is changed on the one hand in such a way that the blades rotate about an axis parallel to the axis of rotation and are thus offset in their orientation. Another variation may thus be described as: the blades are arranged offset in a plane defined by the impeller of the centrifugal fan. Preferably, the in-plane offset and the change in orientation may be combined.

In an advantageous embodiment of the invention, each of the blades differs from the other blades in at least one characteristic that has an effect on the medium pulse applied by the respective blade to the components of the fan during operation.

The greater the respective differences between the blades, the greater the "smearing" of the rotational noise over a broad frequency spectrum, thereby making the corresponding sound less noticeable.

In a further advantageous embodiment of the invention, the fan is a centrifugal fan or a diagonal fan and the rotary element comprises a base plate and/or a cover plate, wherein the outer contour of the base plate and/or the cover plate has a variation in the circumferential direction with respect to a circle, and the maximum deviation outwards is smaller than 1/15 for the blade diameter and the maximum deviation inwards is smaller than 1/15 for the blade diameter.

On the one hand, it has been found that the base plate and the cover plate of the impeller of a centrifugal fan have an influence on the rotational noise in addition to the blades, and the invention therefore also relates to influencing the rotational noise by a corresponding configuration of the contour. On the other hand, by adjusting the cover plate and/or the base plate, compensation for imbalances of the blade arrangement caused by deviations between the blades can be achieved.

In another advantageous embodiment of an aspect of the invention, the varying size of the components of the rotating member is arranged such that the centre of mass of the rotating member coincides with the axis of rotation of the rotating member.

The dimensional changes used that result in the center of mass of the rotating member being coincident with the axis of rotation of the rotating member (i.e., no imbalance is created) are not limited to the deviations between the blades as described above. For example, these variations may also be arranged to have no or little effect on the rotational noise, such as the material thickness of the blades (comparison between blades or comparison of the interior of one blade).

Advantageous embodiments of the invention are characterized in particular in the dependent claims, wherein further advantageous features, embodiments and implementations will be clear to a person skilled in the art from the above description and the following discussion.

Drawings

The invention will be further described and explained with reference to exemplary embodiments shown in the drawings. In the figure:

fig. 1a and 1b schematically show a centrifugal fan in order to illustrate the noise emitted during operation.

Fig. 2 is a schematic side view of an impeller as an aspect of a first embodiment of a fan according to the present invention.

Fig. 3 is a view of the blades of the impeller shown in fig. 2.

Figures 4a and 4b are further views of the impeller shown in figure 2.

Fig. 5a and 5b are views comparable to fig. 4 of a conventional impeller.

Fig. 6a and 6b show details of the trailing edge of a fan blade according to an embodiment of the invention and the trailing edge of a conventional blade, respectively.

FIG. 7 is a plan view of a base plate of an impeller of a wind turbine according to one embodiment of the present invention.

Figure 8 shows an impeller for a fan according to one embodiment of the invention with a base plate as shown in figure 7.

FIG. 9 shows a blade of a wind turbine according to another embodiment of the present invention.

Fig. 10 shows the blade of fig. 9 in an installed state in the impeller.

Fig. 11a and 11b are views of a cover plate of a blower according to an embodiment of the present invention.

Fig. 12 is a view of an impeller with the cover plate of fig. 11.

Fig. 13 is another illustration of the impeller shown in fig. 2.

FIG. 14 schematically illustrates a flow chart of one embodiment of a method for manufacturing a wind turbine in accordance with the present invention.

Figure 15 schematically shows a flow chart of an embodiment of a method for discharging gaseous medium under pressure according to the invention.

Detailed Description

In the drawings and their description, corresponding or related parts (as applicable) have been indicated with corresponding or similar reference numerals, even in different embodiments.

Fig. 1 schematically shows a centrifugal fan in order to illustrate the noise emitted during operation. Fig. 1a and 1b show velocity profiles in the housing and after the vane outlet, respectively.

Fig. 2 shows a schematic side view of an impeller as an aspect of a first embodiment of a fan according to the present invention. The fan is a centrifugal fan in which the impeller 10 has a base plate 12 and a cover plate 14 between which the

blades

16a, 16b, 16c, 16d and 16e are mounted. The basic cost of the impeller and other components of the fan (in this case a centrifugal fan) are well known to those skilled in the art and therefore a detailed description thereof need not be provided here.

Since fig. 2 shows the impeller 10 from the side, all of the blades cannot be seen.

Each blade has its trailing edge, i.e. 16a ', 16b', 16c 'and 16 d'.

Fig. 3 shows a view of the blades of the impeller shown in fig. 2. The blades 16a to 16g have respective trailing edges 16a '-16g' shown on the left side in fig. 3. The edges facing the base plate and the cover plate (not shown here) are designed as is conventional. In this embodiment, the leading edges 16a "to 16 g" (shown on the right in fig. 3) are also of conventional design.

It can be seen in fig. 3 that the trailing edges 16a '-16g' of the blades 16a to 16g each have a profile such that each trailing edge is different from all the trailing edges of the other blades. In other words, all trailing edges 16a 'to 16g' are different two by two.

The differences here result in the contour in this sense differing from the inherent, unavoidable fluctuations of the part geometry (on a sufficiently small scale, differences can always be recognized for parts which should be identical apart from production factors) by orders of magnitude (preferably significantly higher) so that the lines do not, or at least not completely, coincide when the contour lines of the two trailing edges are superimposed. Within the scope of the invention, the contour is preferably designed such that the edge from the base plate to the cover plate is randomly or at least pseudo-randomly convex or concave with respect to an imaginary "center line" in terms of edge continuity. However, it is also possible to arrange that the contour of the edge is expressed as a certain rule or mathematical function, wherein it is nevertheless preferred that the edges of all blades differ from each other by using different rules or functions and/or setting different parameters for the same rule or function. It should again be mentioned here that although it has been found to be particularly advantageous to design the blades differently two by two so that no blade is substantially identical to any of all the other blades as is conventional, the invention is not limited thereto. The advantages of the invention can be achieved even if only one pair of blades is designed differently from each other.

Figure 4 shows another view of the impeller of figure 2. Fig. 4a shows a plan view of the impeller 10 with the cover plate removed so that the position and orientation of the blades 16a to 16g on the base plate 2 can be seen.

As a result of the trailing edges 16a 'to 16g' of the blades 16a to 16g having profiles different from one another, these blades also have mass distributions different from one another. Here, in order to still be able to achieve coincidence of the centre of mass with the axis of rotation of the impeller 10 (the impeller 10 having no or at most a negligible small or allowed imbalance) in a manner well understood by those skilled in the art, the blades 16a to 16g are rotated about an axis parallel to the axis of rotation of the impeller 10 in each of the outer ends in a substantially perpendicular orientation relative to the plane defined by the base plate and at respective spaced locations, so that the centre of mass of the impeller 10 (with the cover plate 14 in this case) is in the desired position.

Here, the configuration of the profile of the trailing edges 16a 'to 16g' and the arrangement of the individual blades are associated with each other. To avoid the possibility of parts being mistaken during assembly, the blades 16a to 16g may be coded together with the base plate 12 (or the cover plate 14, in which case the blades are first attached to the cover plate 14). This can be achieved by: each blade has a uniquely arranged and/or joined extension, while the base plate is provided at a corresponding location with a mating slot for receiving said extension (see also fig. 7).

Fig. 5 shows a view comparable to fig. 4 of a conventional impeller. As can be seen in fig. 5a, the conventional impeller has symmetry every 60 degrees of rotation. This is also true for fig. 5 b.

FIG. 6 shows details of the trailing edge of a fan blade according to an embodiment of the invention and the trailing edge of a conventional blade.

The blade 16 shown in fig. 6a, which is arranged between the base plate 12 and the cover plate 14 of the fan rotor, has a trailing edge 16' which differs from the corresponding trailing edge of a blade of a conventional fan (fig. 6b) firstly by its irregularities. In addition, the centerline 18 (which represents a linear average of the profile of the trailing edge 16a' from its point of contact with the base plate 12 to its point of contact with the cover plate 14) is inclined relative to a vertical line between the base plate 12 and the cover plate 14 (which is parallel to the axis of rotation of the impeller). Although it may be provided that the centre line and the profile coincide with each other at the respective ends, this is not essential to the invention.

Figure 7 shows a plan view of the base plate of the impeller of a wind turbine according to one embodiment of the present invention.

The base plate 12' of this embodiment has an irregular perimeter, which is shown in fig. 7 in comparison to an approximately circular perimeter 22. Based on this regular perimeter 22, irregularities of the base plate 12' can be easily identified. This embodiment of the outer contour of the bottom plate 12 'causes the media pulses caused by the bottom plate 12' when the impeller with the bottom plate rotates to lose continuity and/or regularity, thereby generating less disturbing noise.

Also visible in fig. 7 are mounting slots 20 provided on the base plate 12' for receiving corresponding extensions of the blades when assembling the impeller, wherein these mounting slots 20 can be used in a corresponding arrangement, expansion and/or shaping for enabling the blades to be mounted only in a predetermined manner and setting. This can prevent an imbalance of the impeller caused by an inadvertent exchange of two irregular blades, for example.

Figure 8 shows an impeller for a fan according to one embodiment of the invention with a base plate as shown in figure 7. In fig. 8, a bottom plate 12 'as part of an impeller 10' is shown along with blades and a cover plate 14 comparable to those shown in fig. 2 and 3.

FIG. 9 shows a blade of a wind turbine according to another embodiment of the present invention. Similar to the blades 16a to 16g described above, the blade 16h is provided with a trailing edge 16 h' having an irregularly shaped profile, and an extension 24 (which matches a corresponding mounting slot of the base plate as shown, for example, in fig. 7). In addition, the leading edge 26 of the blade 16h also has an irregular profile, which also helps to reduce disturbing noise.

Fig. 10 shows the blade of fig. 9 in the installed state in the impeller. In this side view of the impeller 10 ", the blades 16h shown in fig. 9 are shown mounted between the base plate 12 and the cover plate 14 of the impeller 10".

FIG. 11 shows a view of a cover plate of a blower according to one embodiment of the invention. Here, fig. 11a shows a plan view of the cover plate 14 ', while fig. 11b shows a perspective view of the cover plate 14'. To show irregularities in the outer contour of the cover 14 ', the regular perimeter 22' is again used here as reference as in fig. 7.

Fig. 12 shows a view of an impeller with the cover plate of fig. 11. Similar to the impeller 10 "shown in fig. 8, the impeller 10 '" is provided with a base plate 12 ' having an irregular perimeter, wherein the impeller 10 ' "further comprises blades having an irregular trailing edge profile, and at least one blade 16g having an irregular trailing edge and an irregular leading edge (see fig. 9). The impeller 10 "'also includes a cover plate 14' as shown in fig. 11a and 11 b.

Fig. 13 shows another illustration of the impeller of fig. 2. As described above, the impeller 10 includes the base plate 12, the plurality of blades 16a to 16g (the blade 16d is hidden by the cover plate 14 in fig. 13), and the cover plate 14.

It should be noted that the illustrated contours of the trailing edge, leading edge, floor and cover plate are merely illustrative and are not intended to limit the invention to any particular form.

In step 101, two blades are first formed, wherein in this step the trailing edge, the leading edge and/or the surface profile are each designed such that they differ from one another.

In step 103, at least one further blade is formed, wherein this further blade is in turn designed such that it differs from all blades of the previous design in at least one respect (trailing edge profile, leading edge profile and/or surface profile). This step is repeated until the desired number of blades is obtained.

In step 105, the position and orientation of the blades are first temporarily determined, wherein these positions and/or orientations are iteratively adjusted in step 107 until the desired reduction is achieved for imbalances caused by different blade configurations, thereby completing the manufacture of the wind turbine in this regard.

It should be understood that the above-described method is only one embodiment of the method of the present invention. In particular, the order of the individual manufacturing steps can be varied, as well as the respective dependencies. Thus, for example, it is possible to first set the position and orientation of the blades, in which case, given the specific conditions for a particular configuration of the individual blades, undesirable imbalances are sufficiently avoided, so that the corresponding profile of the blade is determined taking into account the above-mentioned conditions. In the case of an adjustment of the outer contour of the base plate and/or cover plate, an adjustment of the orientation and/or position of the vanes is not necessary or can be added, wherein the above-mentioned adjustment is preferably an irregular adjustment, as shown for example in fig. 7, 8, 11 and 12.

In step 111, the fan is operated, thereby starting to suck the medium and discharge the medium under pressure.

Here, the rotary part of the fan is rotated such that different blades of the rotary part pass one part of the fan in sequence. Each pass is represented by steps 113,115 and 117, where the series of steps is repeated until the fan is shut down (step 119).

The construction of the blades results in a difference in the media pulses which in turn relate the pass steps 113,115 and 117 (only three pass steps are used here at random, but this is not to be understood as limiting) to the components, so that the media pulses do not collectively generate disturbing noise.

While various aspects or features of the invention have been described in connection with the accompanying drawings, it will be apparent to those skilled in the art that the combinations shown and discussed herein are not exclusive, unless otherwise specified. In particular, a feature or a combination of features from different embodiments may be used interchangeably.

List of reference numerals

10,10 ', 10 ", 10"' impeller

12, 12' sole plate

14, 14' cover plate

16a-16h blade

16a '-16 h' trailing edge

18 center line

20 mounting groove

22, 22' regular perimeter

24 extension part

26 leading edge

101 form two blades

103 form a further vane

105 determining position and orientation

107 adjusting position and/or orientation

111 start-up

113,115,117 pass through

119 and stopping the machine.

Claims

1. A fan having a rotating member through which a gaseous medium is drawn and discharged again under pressure,

wherein the rotating member has a plurality of blades,

at least two of the plurality of blades differ from each other in a characteristic that has an effect on a media pulse applied by a respective one of the blades to a component of the wind turbine during operation.

2. The fan of claim 1, wherein the characteristic that affects a media pulse applied to a component of the fan by a respective one of the blades during operation comprises:

-the profile and/or the pitch of the trailing edge of the blade,

-the profile and/or the pitch of the leading edge of the blade,

-deviation of the arrangement of the blades with respect to the output arrangement given by the symmetry of the rotating member, wherein the rotational symmetry corresponds to the number of blades of the rotating member, and/or

-the surface profile of the blade.

3. The fan of claim 2 wherein the characteristic that has an effect on the media pulse applied to the components of the fan by the respective one of the blades during operation comprises a profile of a trailing edge of the blade, wherein the at least two blades are different with respect to a deviation of the profile of their respective trailing edges from a profile of a given output trailing edge.

4. The wind turbine of claim 2 or 3, wherein the characteristic that has an effect on a media pulse applied to a component of the wind turbine by a respective one of the blades during operation comprises a profile of a leading edge of the blade, wherein the at least two blades are different with respect to a deviation of their respective leading edge profiles from a given output leading edge profile.

5. The wind turbine of claim 3 or 4, wherein the deviation of the profile of the trailing edge and/or leading edge of at least one blade from the output trailing edge profile or output leading edge profile varies over the extent of the trailing edge or leading edge, wherein the maximum deviation in one direction is greater than 1/150 for the length of the blade and the maximum deviation in the opposite direction is greater than 1/150 for the length of the blade.

6. The fan of claim 5 wherein the maximum deviation in the direction is less than 1/15 for the blade length and the maximum deviation in the opposite direction is less than 1/15 for the blade length.

7. The wind turbine of any one of claims 2 to 6, wherein the characteristic that has an effect on a media pulse applied to a component of the wind turbine by a respective one of the blades during operation comprises a shift in an arrangement of the blades relative to an output arrangement given by rotational symmetry of the rotor, wherein the shift in the arrangement comprises an orientation and/or position of the blades.

8. The wind turbine of any preceding claim, wherein each of the plurality of blades differs from each other of the plurality of blades in at least one characteristic that has an effect on a media pulse applied to a component of the wind turbine by a respective one of the blades during operation.

9. The fan according to any of the preceding claims, wherein the fan is a centrifugal fan or a diagonal flow fan, the rotational element comprises a base plate and/or a cover plate,

wherein the outer contour of the base plate and/or cover plate has a deviation varying in the circumferential direction with respect to a circle,

wherein the maximum deviation outward is less than 1/15 for the vane diameter and the maximum deviation inward is less than 1/15 for the vane diameter.

10. The fan according to any of the preceding claims, wherein the varying dimensions of the components of the rotational member are such that the centre of mass of the rotational member coincides with the rotational axis of the rotational member.

11. Method for manufacturing a fan having a rotating member through which a gaseous medium is sucked and discharged again under pressure, wherein the rotating member has a plurality of blades, the method comprising:

the blades are arranged in such a way that at least two of the plurality of blades differ from each other in respect of a characteristic that has an effect on a media pulse applied by a respective one of the blades to a component of the wind turbine during operation.

12. A method of discharging a gaseous medium under pressure comprising:

drawing the media using a rotating member of a fan, wherein the rotating member has a plurality of blades,

wherein each blade produces a media pulse on a component of the fan as it passes over the component as the rotating member rotates,

the method comprises differentiating the media pulses of at least two of the plurality of blades from each other due to different characteristics of the at least two blades having an effect on the applied media pulses.