DE102012020689A1 - Jet nozzle for large penetration depths - Google Patents

Abstract

A diffuser (20) with a nozzle inlet (22), a nozzle outlet (23) and a flow channel (24) running from the nozzle inlet (22) to the nozzle outlet (23) in a main flow direction (H), the flow channel (24) being on its cross-sectional ends are delimited by diffuser walls (26) and have a smaller cross-sectional area (A) at the nozzle inlet (23) than at the nozzle outlet (22), and a central body (275) is arranged in the flow channel (24) within the diffuser (20).

Description

The invention relates to a diffuser and a method for calculating the geometry of a diffuser.

Nozzles are needed for a variety of technical problems, for example when drying components from long distances. Drying or tempering of components can be necessary both in the field of body painting, glass production or in the field of building air conditioning. For this purpose, a nozzle is needed that can effectively and effectively dry and / or aerate a good from a distance as large as possible. A very homogeneous velocity distribution of a dry air on the material to be dried can be of great importance, for example to achieve the most uniform possible drying of the material.

There are jet nozzles known that can be traversed by a fluid for drying a distant good. Such jet nozzles have in the interior a flow channel whose cross-section decreases in the flow direction. According to the physical flow principle of a nozzle while the fluid flowing through the jet nozzle, accelerated while its pressure decreases. By accelerating the fluid, it is possible to produce high penetration depths, which are necessary for drying goods.

From the publication US 6,098,904 a nozzle is known in which a pressure loss inside the nozzle is minimized. For this purpose, a nozzle with a tapering cross-section is used, in which a cartridge-shaped obstacle is introduced into the flow channel. The nozzle is intended for use at pressures of no more than 2 psi.

The publication US 2006/0151633 relates to a nozzle with exit-side rupture edges which are inclined inwards. This creates a vortex field that determines the beam field in the wake of a fluid flowing through the nozzle.

The invention has for its object to provide a jet nozzle with a uniform distribution of velocity as possible in the far field of emerging from the jet nozzle fluid, wherein a pressure loss is reduced to achieve large penetration depths.

This object is solved by the subject matters of the independent claims.

One aspect of the invention relates to a diffuser having a nozzle inlet, a nozzle exit and a flow channel extending from the nozzle inlet to the nozzle exit in a main flow direction, the flow channel being bounded at its cross sectional ends by diffuser walls and having a smaller cross sectional area at the nozzle entrance than at the nozzle exit a central body is arranged in the flow channel within the diffuser.

A diffuser is a special type of nozzle in which the cross-section of the flow channel does not taper, but widen as in a classic nozzle. Often, the diffuser is also referred to as a counterpart to the nozzle. While in a conventional nozzle, the cross-section of the flow channel tapers in the main flow direction, which causes an increase in velocity and a pressure drop at a fluid flowing through the nozzle, a diffuser causes the opposite: a fluid flowing through a diffuser is decelerated as it flows through the diffuser, wherein its pressure elevated. In order to be able to distinguish a diffuser from a conventional nozzle, the cross-sectional areas of the flow channel at the nozzle inlet and at the nozzle outlet can be compared with one another. If the cross-sectional area at the nozzle outlet is greater than the cross-sectional area at the nozzle inlet, then the nozzle may be a diffuser; conversely, the area ratio is a classic nozzle.

The flow channel of the diffuser is arranged in the interior of the diffuser and designed essentially as a free space. The flow channel is bounded by diffuser walls which determine the shape of the flow channel. The diffuser walls are formed as part of the diffuser. The diffuser is designed and provided to be flowed through by a fluid in a predetermined direction. The predetermined direction extends from the nozzle entrance to the nozzle exit and is referred to as the main flow direction. In the main flow direction thereby increases the cross-section of the flow channel, which is bounded by the diffuser walls. This enlargement or expansion of the flow channel may be, for example, continuous, stepped, logarithmic, exponential, along a polynomial function or along a combination of the aforementioned shape changing functions.

A classic diffuser reduces the speed of a fluid passing through the diffuser and increases the pressure. A slowing down of the fluid is not always desirable for a jet nozzle since this can lead to a very uneven velocity distribution over the cross section. Therefore, a central body is arranged in the interior of the flow channel, ie in the interior of the diffuser, which is designed as a flow body. The central body is in the diffuser arranged to be flowed around by a fluid flowing through the diffuser in the main flow direction. By introducing the central body into the flow channel, the flow behavior, in particular the speed and the pressure of the fluid flowing through the diffuser, is influenced. In this case, the speed and the pressure of the fluid flowing through the flow channel can be influenced and / or determined both in the near field and in the far field by the shape of the central body. For example, the central body may cause a reduction in the free cross-sectional area of the flow channel at the nozzle exit. This means that, although the entire cross-sectional area at the nozzle outlet is greater than the cross-sectional area at the nozzle inlet, the freely permeable surface portion may be of the same size or smaller. In this case, the freely flow-through surface portion of the cross-sectional area of the flow channel, which can be traversed by a fluid flowing through the diffuser. The space in the flow channel, which is occupied by the central body, however, can not be traversed by a fluid.

The central body is at least partially disposed in the interior of the flow channel. A part of the central body may protrude from the flow channel. In this case, the central body is preferably arranged such that it is arranged in a space region near or at the nozzle exit. The space region of the flow channel, which is formed adjacent to the nozzle inlet, is preferably formed free of a central body. The central body may be spaced from the diffuser walls in the diffuser.

Such a diffuser with a central body arranged in the flow channel can be used to achieve particularly large penetration depths and enables a homogeneous velocity distribution in the far field of the fluid ejected from the diffuser. The diffuser reduces the pressure loss of the fluid compared to a diffuser without a central body and serves to achieve large penetration depths. In existing drying systems, the diffuser can lead to the reduction of a required pumping capacity at a constant penetration depth. The far field is the beam area after the nozzle exit where atmospheric turbulence dominates the beam spread. In the far field, in particular, no more core beam can be detected in the beam field. Usually, the far field starts at a distance after the nozzle exit, which is six to eight times the diameter of the cross section of the nozzle exit.

The exact shape or geometry of the central body can be calculated using a computer simulation to obtain a certain penetration or temperature distribution in the jet for a particular fluid.

The central body may be formed differently shaped. Thus, the central body may be formed, for example, as an ellipsoid, as a pyramid, or as a cuboid body. The central body is designed as a flow obstacle and has a volume and a shape that significantly influences the flow behavior of a fluid flowing through the diffuser.

In contrast to the initially mentioned and previously known nozzles, the present invention relates to a diffuser that achieves a particularly favorable heat transfer to the target.

The diffuser can be designed to be free of inner edges at its diffuser exit. This means that the diffuser at its diffuser outlet in longitudinal section has at least straight or outwardly inclined edges. The output edges may be formed in particular rounded. As a result, a desired and / or predetermined flow distribution is achieved.

According to one embodiment, the central body is arranged in the middle of a cross section through the flow channel. Due to the arrangement of the central body in the middle of the flow channel, the central body can be flowed around on all its sides by a fluid flowing through the diffuser. As a result, the central body can influence the fluid or the speed and the pressure of the fluid with all its body surfaces and sides.

In this case, the central body can be held by a holder in the flow channel, that it is arranged at a predetermined location in the interior of the flow channel. In the calculation of the flow behavior and the geometry of the central body and the diffuser walls, the shape of the holder can be included in the calculation in order to achieve the best possible flow behavior.

The central body does not have to be arranged along the entire central axis of the flow channel, but can for example only in the second half of the flow channel, ie the nozzle outlet facing half of the flow channel, be arranged centrally in this.

According to one embodiment, the central body is shaped and arranged in the flow channel such that the central body on the diffuser walls reduces flow separation of a fluid flowing through the diffuser. A fluid having a widening flow channel or a Diffuser flows through, can experience different flow behavior. If an opening angle or an extension of the flow channel in the flow direction is sufficiently small, this is called an applied flow behavior or a fluctuating, partially detached flow behavior. If the diffuser has a more open flow channel, that is to say a further widening flow channel, the flow in the flow channel can lose its pulsating character, wherein one speaks of a detached flow behavior. In a detached flow arise in the flow channel and in the wake flow vortex of the fluid. Such flow vortices can interfere with the desired flow behavior of the fluid flowing through the diffuser. The central body is shaped and arranged in the flow channel, that it reduces flow separation and / or completely prevented. As a result, the flow behavior of the fluid is improved. Thus, the central body can influence the flow behavior of the fluid not only in the interior of the diffuser, but also in the far field of the fluid, ie a space region into which the already exited from the diffuser fluid penetrates.

According to one embodiment, the central body is rotationally symmetrical with respect to a central axis of the flow channel. Not only can the central body itself be rotationally symmetrical, but also the diffuser, in particular the diffuser walls, which define the flow channel. A rotationally symmetrical design of the central body and / or the diffuser and / or the flow channel can lead to a particularly homogeneous velocity and pressure distribution in the far field of the fluid.

According to one embodiment, the nozzle exit has at least ten percent greater cross-sectional area than the nozzle entrance. In this case, the cross section of the flow channel widens in the main flow direction preferably steadily. With a ten percent larger area is meant the total area of the respective cross-section. In particular, the cross-section at the nozzle exit may have a partial region of the central body which reduces the free cross-sectional area. The cross-sectional area of the nozzle exit may also be at least 50% or 100% larger than the cross-sectional area of the nozzle entrance.

According to one exemplary embodiment, the flow channel of the diffuser is formed so widening in the main flow direction that the flow channel without the central body would cause a flow separation of a fluid flowing through the diffuser. The flow channel of the diffuser is designed so that it expands so much that it would cause a flow separation without the central body. Thus, the diffuser without the central body would be unsuitable as a jet nozzle and would lead to a deterioration of the flow quality of the fluid. The central body is formed in the diffuser so as to prevent or at least reduce this flow separation.

According to one embodiment, the central body is replaceably mounted in the flow channel of the diffuser. The diffuser may have a plurality of central bodies which may be mounted in the flow channel depending on the intended use of the diffuser. Such variable central bodies can lead to very different flow behavior of a fluid flowing through the diffuser. Thus, the same diffuser can be used for different applications by a simple replacement of the central body. A holder can be designed to receive different central body in the flow channel so that the central body are detachably fastened to the holder.

According to one embodiment, the diffuser is designed and provided to be flowed through by a predetermined fluid under a predetermined pressure and a predetermined speed in the main flow direction. The exact shape of the diffuser walls and / or the central body may be tuned to a particular fluid. As the fluid, for example, ambient air may be used for drying goods. Alternatively, a special gas mixture may be provided for drying, which can be inserted under the predetermined pressure in the nozzle inlet of the diffuser. The exact shape and geometry of the diffuser including the central body is tuned to this predetermined fluid. In this case, the pressure and / or the speed of the fluid can be predetermined with which the fluid is introduced into the nozzle inlet. The diffuser may also be provided for use with a predetermined fluid having different pressures and / or for use with different fluids.

According to one embodiment, the diffuser is designed as a long-throw nozzle. A jet nozzle is a nozzle, which is intended for the greatest possible penetration depths. The penetration depth of a nozzle determines the distance or the distance from the nozzle outlet at which the fluid flowing through the nozzle has a desired flow behavior after flowing through the nozzle. For example, the penetration depth may mean a predetermined distance by which a material to be dried is spaced from the nozzle exit of the long throw nozzle. For dry nozzles for coatings, the penetration depth z. B. be between 2 and 3 m.

According to one embodiment, the diffuser walls are inclined in longitudinal section at least in places by an expansion angle of at least 10 ° with respect to the central axis of the flow channel. Usually, with an opening angle of at least 7-10 ° in the case of a diffuser, it is assumed that a flow separation occurs. The diffuser walls of the diffuser are in this case designed so that a flow separation would result without the central body, since the opening angle is at least 10 °. In this case, the opening angle of the flow channel with respect to its central axis does not have to be at least 10 ° along the entire flow channel, but may also be only so steep at places. The opening angle of the flow channel is at least in places from 10 ° to 30 °, preferably from 15 ° to 25 °.

According to one embodiment, the central body is shaped to effect a substantially homogeneous flow velocity distribution perpendicular to the directional vector of the main flow direction in the far field of a fluid exiting the diffuser. The near field is the area of the space into which the fluid flowing out of the diffuser flows directly after leaving the diffuser, that is to say a space region which is arranged adjacent to the diffuser exit. In the near field, an inhomogeneous velocity distribution of the fluid may be present due to the central body. In the near field, the central body can cause a "deterioration" in the flow characteristics of the fluid. The central body can be shaped and calculated so that it causes a homogeneous velocity distribution or a defined temperature distribution in the far field, in particular at a predetermined penetration depth or target depth of the fluid.

The diffuser may be for use in drying a product at a predetermined distance from the nozzle exit. This predetermined distance corresponds to the penetration depth or the target depth of the diffuser. The central body is shaped and / or calculated so that it causes a uniform velocity distribution or a defined temperature distribution at this target depth - measured from the nozzle exit. This leads to a uniform drying of a good such. As a body paint, a liquid glass, etc.

According to one embodiment, a plurality of central bodies are arranged in the flow channel within the diffuser. In this case, the central bodies are shaped so that a fluid, after it has flowed out of the diffuser, has an optimal flow distribution.

• – Auswählen eines vorbestimmten Fluids zum Durchströmen des Diffusors entlang eines Strömungskanals des Diffusors,
• – Auswählen einer vorbestimmten Eindringtiefe für das vorbestimmte Fluid nachdem das Fluid den Strömungskanal durchströmt hat,
• – Berechnen einer optimierten Form für Düsenwände, die den Strömungskanal des Diffusors an seinen Querschnittsenden begrenzen und
• – Berechnen einer optimierten Form für einen im Strömungskanal des Diffusors angeordneten Zentralkörper.

Another aspect relates to a method for calculating the geometry of a diffuser with the steps:

• Selecting a predetermined fluid to flow through the diffuser along a flow channel of the diffuser,
• Selecting a predetermined penetration depth for the predetermined fluid after the fluid has passed through the flow channel,
• - Calculate an optimized shape for nozzle walls that limit the flow channel of the diffuser at its cross-sectional ends and
• Calculating an optimized shape for a central body arranged in the flow channel of the diffuser.

In the calculation, the shape of a holder for the central body in the interior of the flow channel can be further included. Furthermore, this method can be used to achieve certain different penetration depths for uniformly shaped diffuser walls with a differently shaped geometry of the central body. In this method, therefore, only a new geometry of the central body is calculated, wherein the geometry of the diffuser walls enters as a boundary condition in the calculation.

For the exact calculation of the diffuser geometry, either a computer simulation or test experiments from a wind or flow channel can be used. Furthermore, the experimental results can also be checked and / or connected with a computer simulation.

When calculating the central body geometry z. For example, a genetic algorithm that converges quickly can be used. The geometry can be optimized so that at a predetermined distance from the diffuser exit a predetermined, in particular homogeneous heat transfer takes place. Furthermore, the geometry of the central body can also be optimized to the effect that the pressure of the medium flowing into the diffuser is kept to a minimum, so the power requirement is minimized.

As a boundary condition, the feed pressure of the fluid and / or the geometry of the diffuser walls can be included in the calculation. For the method, the physical properties of the fluid, the geometry of the diffuser (and thus the geometry of the nozzle walls) and / or a fixed distance from the nozzle outlet can be specified. For this predetermined, fixed distance from the nozzle outlet, the separating properties of the fluid jet can be optimized. The fixed distance can z. B. be the predetermined penetration depth.

• 1. Ein vorgegebener Druckbedarf für ein Gebläse, das das Fluid in den Düseneingang einspeist, z. B. ein minimaler Druckbedarf als Zielvorgabe.
• 2. Ein maximaler Wärmeübergang an einem Gut, d. h. ein möglichst hoher Wärmeanteil des Fluids wird an das Gut abgegeben, z. B. zur Kühlung oder Erwärmung des Guts.
• 3. Die Wärmeübergangsverteilung des Fluids kann auf ihre Homogenität hin optimiert werden.
• 4. Der Fluidstrahl kann nach Austritt aus dem Düsenausgang dahingehend optimiert werden, dass der Fluidstrahl sich möglichst geradlinig fortsetzt.
• 5. Der Fluidstrahl kann nach Austritt aus dem Düsenausgang dahingehend optimiert werden, dass der Fluidstrahl eine vorgegebene, begrenzte Auftrefffläche auf ein Gut aufweist.
• 6. Eine Austrittsgeschwindigkeit des Fluids aus dem Düsenausgang kann als Zielkriterium vorgegeben werden, z. B. eine minimale oder maximale Austrittsgeschwindigkeit.

One or more of the following target criteria may be provided for the method:

• 1. A predetermined pressure requirement for a fan that feeds the fluid into the nozzle inlet, z. B. a minimum pressure requirement as a target.
• 2. A maximum heat transfer to a good, ie the highest possible heat content of the fluid is delivered to the estate, eg. B. for cooling or heating of the estate.
• 3. The heat transfer distribution of the fluid can be optimized for its homogeneity.
• 4. The fluid jet can be optimized after exiting the nozzle exit to the effect that the fluid jet continues as straight as possible.
• 5. The fluid jet can be optimized after exiting the nozzle exit to the effect that the fluid jet has a predetermined, limited impact surface on a good.
• 6. An exit velocity of the fluid from the nozzle outlet can be specified as a target criterion, z. B. a minimum or maximum exit velocity.

One or more of these criteria may be selected as the target criteria, after which the procedure is terminated. In carrying out the method, the geometry of the central body (and possibly the diffuser walls) is varied until the target criteria are achieved taking into account the predetermined boundary conditions. As a result, this method provides a particular form of diffuser with a particular geometry of a central body that, when used, meets the target criteria.

One aspect relates to using a diffuser as described above for drying at least one product, wherein the material may be spaced from the nozzle exit of the diffuser at a predetermined distance. Such a diffuser can also be used for air conditioning.

The invention will be described in more detail with reference to exemplary embodiments shown in FIGS. Individual features shown in the figures may be combined with features of other embodiments. Show it:

1 a schematic sectional view of a diffuser without a central body,

2 a schematic sectional view through a diffuser with a central body,

3 a schematic representation of the velocity distribution of a fluid flowing through a diffuser without central body,

4 a schematic representation of the velocity distribution of a fluid, the in 3 shown diffuser flows through a first central body and

5 a schematic representation of the velocity distribution of a fluid, the in 3 flows through the diffuser shown with a second central body.

1 shows a diffuser 1 with a nozzle entrance 2 and a nozzle exit 3 , where the nozzle exit 3 has a cross-sectional area A greater than a cross-sectional area E of the nozzle entrance 2 is trained. The diffuser 1 has diffuser walls 6 on, leaving a free space inside the diffuser 1 as a flow channel 4 limit. The diffuser 1 is substantially rotationally symmetrical with respect to a central axis M of the flow channel 4 educated.

At the nozzle entrance 2 is the diffuser 1 adapted and provided, a fluid (not shown) in a main flow direction H in the flow channel 4 involved. This is the nozzle entrance 2 open along its cross-sectional area E. The main flow direction H points along the center axis M of the flow channel 4 from the nozzle entrance 2 to the nozzle exit 3 , At the nozzle exit 3 of the diffuser 1 is the diffuser 1 designed to be that at the nozzle entrance 2 fluid flowed into the flow channel from the flow channel 4 emanates while the diffuser 1 leaves.

In 2 is a diffuser 20 shown, the identical to that in 1 shown diffuser 1 is constructed. The diffuser 20 has a nozzle entrance 22 , a nozzle outlet 23 , a flow channel 24 and nozzle walls 26 on, like in the diffuser 1 dimensioned and formed. A cross-sectional area E of the nozzle entrance 22 is smaller than a cross-sectional area A of the nozzle exit 23 ,

The flow channel 24 has a rectilinear central axis M. In an alternative embodiment, the central axis of the flow channel 24 also be curved.

Unlike the in 1 shown diffuser 1 points the diffuser 20 a central body 25 on that inside the flow channel 24 on the diffuser walls 26 is attached. The central body 25 is spaced from the diffuser walls 26 and in the middle of the flow channel 24 arranged. The central body 25 is formed with respect to the central axis M is substantially rotationally symmetrical. The central body 25 For example, it may be formed as an ellipsoid, drop-shaped, or the like, and forms a three-dimensional flow obstruction for the diffuser 20 along the flow channel 24 flowing fluid. The central body 25 is in half of the flow channel, which is adjacent to the nozzle exit 23 is trained. The other half of the flow channel, which is adjacent to the nozzle entrance 22 is formed, is formed Zentralkörperfrei. The central body 25 influences the flow behavior of a fluid flowing through the diffuser.

The influence of the central body on the flow behavior is determined by comparing the velocity distribution in the near field N and in the far field F of the diffuser 1 (please refer 1 ) with the near field N and in the far field F out of the diffuser 20 outflowing fluid (see 2 ) clear. The cross section of the flow channel 4 of the diffuser 1 expands in the main flow direction H far enough that within the flow channel 4 adjacent to the nozzle exit 3 Vortex fields and backflows or flow separations W1 on the diffuser walls 6 arise. This results in at least one side of the diffuser, a stationary separation region in which the flow loses its pulsating character. A the diffuser 1 flowing fluid has in the near field N on a relatively homogeneous velocity distribution.

The velocity distributions of the fluid in the respective near and far field are in the 1 and 2 shown by graphs. In the far field F of the radiation field S, the velocity distribution is inhomogeneous. Adjacent to the extension of the center axis M, the velocity of the fluid particles is greater than the velocity of fluid particles farther from the extension of the center axis M and far-field from the diffuser 1 move away.

Furthermore, a portion of the fluid can be lost in the lateral area, if in the flow pattern further vortex W2 occur outside the diffuser 1 can arise.

This compares to the diffuser 20 with the central body 25 a beam field S ', which, as in 2 shown, has a different flow behavior.

As in 2 shown, prevents the central body 25 the occurrence of vortices both inside the diffuser 20 as well as in the beam field S 'of the diffuser 20 leaked fluid. While the velocity distribution in the near field N is due to the central body 25 has a minimum near the extension of the central axis M, the velocity distribution in the far field F of the beam field S 'over substantially long distances perpendicular to the extension of the central axis M is substantially homogeneous.

The in 2 shown diffuser 20 suitable for use as a jet nozzle, for example, for drying of components at long distances. The components are preferably arranged in far field F. The distance of the near field N and the far field F from the nozzle exit depends u. A. after the pressure of the fluid introduced into the diffuser. By means of the central body 25 Reduced pressure drops can have greater penetration depths, ie greater far field distances from the diffuser 20 can be achieved with homogeneous velocity distributions. Alternatively, even with a constant penetration depth, the required pumping power can be reduced by introducing a fluid at a reduced pressure into the diffuser 20 is admitted.

Through the central body 25 becomes a flow separation near the diffuser walls 26 not only reduced, but prevented. At the same time the velocity profile of the fluid at the nozzle outlet and in the wake is influenced and improved.

The central body 25 may be designed exchangeable, that is, the diffuser 20 can be equipped with different central bodies, which are calculated and shaped for different penetration depths. The central body 25 can do so in a holder, not shown in the figures inside the flow channel 24 be attached.

In this case, either a single central body may be provided for a particular application, or a plurality of central body for a single application.

The diffuser may have a cross-sectional diameter of 150 mm to 300 mm and z. B. be provided for drying a good, which is spaced from 2 to 3 meters from the diffuser. The diffuser may thus be provided for dimensionless distances LID of about 6 to 20. L designates the intended distance of the material from the diffuser exit (eg the penetration depth) and D the diameter of the diffuser at the diffuser exit.

The central body 25 it fills in sections at least 10%, preferably at least 25% of the cross-sectional area of the flow channel 24 out. The exact shape and dimensioning of the central body 25 may depend on a planned application of the diffuser 20 be educated.

The 3 shows a schematic representation of the velocity distribution of a fluid, the central body-free diffuser 30 flows through. The diffuser 30 corresponds to a nozzle with a substantially constant cross-sectional widening in the flow direction and is in 3 shown in longitudinal section. The total opening angle of the diffuser walls is about 20 °.

The fluid is evenly distributed in a nozzle inlet 32 brought in. The expansion of the diffuser in the flow direction is problematic because due to the large opening angle, the flow separates. The beam field S of the fluid is different from the (in 3 ) detached lower diffuser wall and flows only at the (in 3 ) upper diffuser wall through the diffuser 30 and out of the nozzle exit 33 out. This results in the 3 shown unbalanced velocity distribution downstream of the nozzle exit 33 ,

For cooling and / or heating one of the diffuser 30 Guts spaced is the in 3 As shown, it is difficult to use the jet of fluid shown because it can not be aligned with a target. Also for air conditioning applications such nozzles are not usable because they cause very unpleasant drafts. In addition, with the replacement large flow losses associated with the need for compensation, an increased energy expenditure, eg. B. for an upstream fan through which the fluid in the nozzle inlet 32 brought in.

4 and 5 each show a schematic representation of the velocity distribution of a fluid containing the in 3 flows through the shown diffuser. Unlike the in 3 shown diffuser 30 has the in 4 respectively. 5 shown diffuser 30 ' respectively. 30 '' a central body 35 ' respectively. 35 '' on. The central body 35 ' respectively. 35 '' is inside the diffuser 30 ' respectively. 30 '' arranged and extends parallel to its longitudinal axis. The central body 35 ' respectively. 35 '' is almost as long as the diffuser 30 ' respectively. 30 '' ,

The shape of the nozzle walls of the diffuser 30 ' and 30 '' corresponds to the shape of the nozzle walls of the diffuser 30 without central body. The forms of the central body 30 ' and 30 '' were calculated using a numerical optimization, z. Using a genetic algorithm. The central body 35 ' respectively. 35 '' causes a concern of the flow of fluid entering the nozzle inlet 32 flows in, on the diffuser walls and the central body. The resulting jet of fluid may be using the diffusers 30 ' respectively. 30 '' be used purposefully.

The optimized central body has in the two embodiments shown a waisted, elongated teardrop shape and is. With respect to the longitudinal axis of the diffuser formed rotationally symmetrical. The central body 35 ' respectively. 35 ' is almost as long as the diffuser 30 ' respectively. 30 '' , For example, the central body may be 0.9 to 1.1 times as long as the diffuser.

An essential advantage of using a diffuser with a central body is that a significantly more homogeneous heat transfer distribution can be achieved at the target. This is based on the much more homogeneous beam distribution in the far field. At the in 4 and 5 In the embodiments shown, there is no separation of the flow from the diffuser walls. The fluid flows through the diffuser 30 ' respectively. 30 '' both close to the diffuser walls and close to the central body 35 ' respectively. 35 '' fitting. As a result, the fluid can emerge from the diffuser in a jet with a homogeneous distribution of velocity, which propagates further in the direction of the extended longitudinal axis of the diffuser.

The arrangement of the central body in the diffuser improves the heat transfer distribution in the far field by 25% to 30% compared to a diffuser without central body. At the same time, there is also an increase in the heat transfer of up to 5% to the material to be heated / cooled.

The use of a diffuser with central body also causes no significant pressure loss, on the contrary, the pressure loss can be reduced by up to 0.5%.

LIST OF REFERENCE NUMBERS

1

diffuser

2

nozzle inlet

3

nozzle exit

4

flow channel

6

nozzle wall

20

diffuser

22

nozzle inlet

23

nozzle exit

24

flow channel

25

central body

26

nozzle wall

30

diffuser

30 '

diffuser

30 ''

diffuser

32

nozzle inlet

33

nozzle exit

35 '

central body

35 ''

central body

A

output surface

e

input surface

F

far field

H

Main flow direction

M

central axis

N

near field

S

Strahlfeld

S '

Strahlfeld

S ''

Strahlfeld

W1

whirl

W2

whirl

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 6098904 [0004]
• US 2006/0151633 [0005]

Claims (14)

Diffuser with a nozzle inlet ( 22 ), a nozzle exit ( 23 ) and one of the nozzle entrance ( 22 ) to the nozzle outlet ( 23 ) in a main flow direction (H) extending flow channel ( 24 ), wherein the flow channel ( 24 ) at its cross-sectional ends of diffuser walls ( 26 ) is limited and at the nozzle entrance ( 22 ) has a smaller cross-sectional area (E) than at the nozzle exit ( 23 ), and wherein in the flow channel ( 24 ) within the diffuser ( 20 ) a central body ( 25 ) is arranged. Diffuser according to claim 1, wherein the central body ( 25 ) in the middle of a cross section through the flow channel ( 24 ) is arranged. Diffuser according to claim 1 or 2, wherein the central body ( 25 ) shaped and so in the flow channel ( 24 ) is arranged such that the central body ( 25 ) on the diffuser walls ( 26 ) a flow separation of the diffuser ( 20 ) is reduced by flowing fluid. Diffuser according to one of the preceding claims, wherein the central body ( 25 ) with respect to a central axis (M) of the flow channel ( 24 ) is rotationally symmetrical. Diffuser according to one of the preceding claims, wherein the nozzle outlet ( 23 ) in cross section (A) at least 10% larger area than the nozzle entrance ( 22 ) in cross-section (E). Diffuser according to one of the preceding claims, wherein the flow channel ( 24 ) of the diffuser ( 20 ) is formed in the main flow direction (H) so strong widening that the flow channel ( 24 ) without the central body ( 25 ) a flow separation of the diffuser ( 20 ) caused by flowing fluid. Diffuser according to one of the preceding claims, wherein the central body ( 25 ) interchangeable in the flow channel ( 24 ) of the diffuser ( 20 ) is attached. Diffuser according to one of the preceding claims, wherein the diffuser ( 20 ) is designed and provided to be flowed through by a predetermined fluid under a predetermined pressure at a predetermined speed in the main flow direction (H). Diffuser according to one of the preceding claims, wherein the diffuser ( 20 ) is designed as a long-throw nozzle. Diffuser according to one of the preceding claims, wherein the diffuser walls ( 26 ) in longitudinal section at least in places by an expansion angle of at least 10 ° with respect to the central axis (M) of the flow channel ( 24 ) are inclined. Diffuser according to one of the preceding claims, wherein the central body ( 25 ) is shaped in such a way that in the far field (F) one of the diffusers ( 20 ) leaked fluid causes a substantially homogeneous flow velocity distribution perpendicular to the direction vector of the main flow direction (H). Diffuser according to one of the preceding claims, wherein in the flow channel ( 24 ) within the diffuser ( 20 ) a plurality of central bodies ( 25 ) are arranged. Method for calculating the geometry of a diffuser ( 20 comprising the steps of: selecting a predetermined fluid to flow through the diffuser along a flow channel ( 24 ) of the diffuser ( 20 ), - selecting a predetermined penetration depth for the predetermined fluid after the fluid reaches the flow channel ( 24 ), - calculating an optimized shape for diffuser walls ( 26 ), which the flow channel ( 24 ) of the diffuser ( 20 ) at its cross-sectional ends and - calculating an optimized shape for one in the flow channel ( 24 ) of the diffuser ( 20 ) arranged central body ( 25 ). Use of a diffuser according to one of claims 1 to 12 for drying at least one good and / or for air conditioning.

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