Patent Description:
Document <CIT> describes a Venturi-type mixing nozzle having a nozzle body with a main flow passage that has an inlet end and an outlet end. The main flow passage includes a passage constriction between the inlet end and the outlet end for creation of a negative pressure region in the main flow passage. The passage constriction is provided with a plurality of lateral inlet openings. In operation, a first fluid enters the main flow passage via the inlet end and a second fluid enters the main flow passage via the lateral inlet openings for being mixed with the first fluid in the main flow passage.

Other Venturi-type mixing nozzles are e.g. described in documents <CIT>, <CIT>, and <CIT>. All of these Venturi-type mixing nozzles are provided to allow mixing of a first fluid with a second fluid in a respective main flow passage provided by means of the Venturi-type mixing nozzles.

<CIT> discloses a fluid mixing apparatus for mixing a first fluid and a second fluid comprising a flow passage and a swirl-generating stator placed in the flow passage for flowing the passing first fluid in a direction of swirling around a flow passage axis line.

<CIT> discloses a device for introducing a gas into a tube segment according to the preamble of claim <NUM>.

<CIT> discloses an arrangement for mixing a first and a second gas flow comprising a line for the first flow, an inlet for the second flow in the line, and a streamlined body arranged to be displaced in the longitudinal direction of the line at the inlet in order to achieve a variable venturi effect.

The present invention relates to a Venturi-type mixing nozzle with a nozzle body that comprises a main flow passage having an inlet end and an outlet end, wherein a first fluid enters the main flow passage via the inlet end. The main flow passage comprises a passage constriction between the inlet end and the outlet end for creation of a negative pressure region in the main flow passage. The passage constriction comprises at least one lateral inlet opening through which a second fluid enters the main flow passage for being mixed with the first fluid in the main flow passage. At least one bluff body is arranged in the main flow passage between the inlet end and the at least one lateral inlet opening upstream of the at least one lateral inlet opening. The at least one bluff body is integrally formed with the nozzle body and extends in radial direction of the main flow passage towards a nozzle body central axis for creation of a low pressure zone that extends in the radial direction of the main flow passage along the at least one bluff body.

Advantageously, the at least one bluff body is positioned in the main flow passage upstream of the at least one lateral inlet opening such that its wake shields the at least one lateral inlet opening. The pressure in the shielded region of the at least one lateral opening may, thus, be reduced compared to the pressure in circumjacent unshielded regions of the passage constriction, such that pressure loss at the at least one lateral inlet opening is significantly reduced. As a result, injection of the second fluid into the main flow passage and, thus, mixing of the first and second fluids is improved and performed over a significantly reduced longitudinal length inside of the Venturi-type mixing nozzle.

According to one aspect, the low pressure zone is created such that the first fluid has a flow velocity in the low pressure zone that is reduced compared to a flow velocity that is otherwise attributed to the first fluid in the negative pressure region.

Thus, the second fluid is reliably injected close to the nozzle body central axis such that the first fluid will flow along the nozzle body wall, which improves boundary layer attachment, especially when the second fluid has a significantly lower flow density than the first fluid. More particularly, by injecting the second fluid close to the nozzle body central axis, the second fluid is directly and entirely surrounded by the first fluid for mixing of the first and second fluids. As a result, a respective surface area or shear layer between the first and second fluids is enlarged, which enhances the mixing of the first and second fluids. Thus, a respective volume of unburned fluid mix in an associated combustion device may advantageously be reduced, thereby reducing the severity of an unintended ignition inside the Venturi-type mixing nozzle.

According to one aspect, the at least one bluff body creates at least partly in the negative pressure region turbulences of the first fluid flowing around the at least one bluff body.

The creation of the turbulences further improves boundary layer attachment, thereby reducing an overall pressure drop of the Venturi-type mixing nozzle. More specifically, if the flow density of the second fluid is significantly lower than the flow density of the first fluid, e.g. if the first fluid is air and the second fluid is hydrogen, then a respective second fluid flow will tend to be laminar, having a lower Reynolds number than a given first fluid flow. As a result, the second fluid flow will be more susceptible to boundary layer separation than the first fluid flow. By creating the turbulences and injecting the second fluid close to the nozzle body central axis, the first fluid flow will be closer to the nozzle body wall than the second fluid flow. Because the denser first fluid flow is more turbulent (higher Reynolds number), it is therefore more resistant to boundary layer separation. Therefore, a respective downstream flow in the diverging part of the main flow passage will have better boundary layer attachment, and therefore a more uniform velocity profile and greater flow deceleration, resulting in a lower overall pressure drop. This lower overall pressure drop may advantageously be used to increase the operating range of the Venturi-type mixing nozzle and/or to reduce a required fan power for creation of the first fluid flow.

According to one aspect, the at least one bluff body is adapted to ensure that the second fluid is fully surrounded by the first fluid after having entered the main flow passage through the at least one lateral inlet opening.

Thus, a direct and entire surrounding of the second fluid by the first fluid upon its injection into the main flow passage can easily and reliably be achieved.

The at least one bluff body is integrally formed with, the nozzle body.

Accordingly, a robust and solid nozzle body may be provided, which may advantageously be manufactured using cost-effective processes, such as casting or injection moulding.

At least one bluff body may be attached to, or integrally formed with, a bluff body support that is mounted to the nozzle body.

Thus, even retrofitting of existing Venturi-type mixing nozzles may be considered and the nozzle body may respectively be manufactured using cost-effective methods, such as casting, turning or extruding.

Preferably, the at least one lateral inlet opening is connected to a support channel that is arranged at a predetermined angle of more than <NUM>° relative to the nozzle body central axis such that the second fluid is injected into the main flow passage in a direction that points away from the at least one bluff body.

Accordingly, the second fluid may directly be injected into turbulences of the first fluid flowing around the at least one bluff body such that mixing of the first and second fluids may further be improved.

According to a variant, the at least one lateral inlet opening is connected to a support channel that is arranged at a predetermined angle of less than <NUM>° relative to the nozzle body central axis such that the second fluid is injected into the main flow passage in a direction that points towards the at least one bluff body.

Thus, the second fluid may be injected into the main flow passage such that it flows all along the at least one bluff body up to a closest possible point relative to the nozzle body central axis.

According to one aspect, the at least one bluff body may be wedge-shaped and may comprise an arc-shaped or straight surface that faces the nozzle body central axis. The at least one bluff body may also be pin-shaped and may comprise an arc-shaped surface that faces the inlet end. The at least one bluff body may also be plate-shaped.

Accordingly, various different forms and shapes are available for realization of the at least one bluff body.

The at least one bluff body may comprise an overhang that shields at least partly the at least one lateral inlet opening in direction of the nozzle body central axis.

Such an overhang may advantageously be provided for initially guiding the second fluid after injection through the at least one lateral inlet opening into the main flow passage.

Preferably, the at least one lateral inlet opening is punctiform or slot-shaped.

Thus, the at least one lateral inlet opening may be manufactured using a cost-effective process, such as e.g. drilling or milling.

According to one aspect, at least one additional bluff body is arranged in the main flow passage downstream of the at least one lateral inlet opening.

Such an additional bluff body may advantageously create swirl or turbulence of the second fluid, thereby further improving mixing of the first and second fluids.

According to one aspect, the at least one bluff body has a width that amounts at least to half of a hydraulic diameter of the at least one lateral inlet opening, and at most to twice the hydraulic diameter. Preferably, the at least one bluff body has a height that amounts at least to half of a hydraulic diameter of the at least one lateral inlet opening, and at most to a radial distance between the nozzle body and the nozzle body central axis at the passage constriction.

Thus, the at least one bluff body may easily be optimised for proper functioning, at least to the greatest possible extent.

A longitudinal distance between the at least one bluff body and the at least one lateral inlet opening preferably amounts at most to a hydraulic diameter of the at least one lateral inlet opening.

Accordingly, creation of the low pressure zone that extends in the radial direction of the main flow passage from the at least one lateral inlet opening along the at least one bluff body may reliably be achieved.

Preferably, the hydraulic diameter of the at least one lateral inlet opening is less than the Maximum Experimental Safety Gap of the second fluid.

If the second fluid is a combustible gas, this advantageously prevents a flame from being able to travel in operation upstream the Venturi-type mixing nozzle into the associated lateral inlet opening, thereby safely preventing a flame flashback event.

Preferably, the first fluid is air and the second fluid is a combustible gas.

Thus, the Venturi-type mixing nozzle may advantageously be used with a combustion device that is adapted for combustion of a gas/air mixture, e.g. a hydrogen/air mixture.

According to one aspect, the passage constriction comprises a plurality of lateral inlet openings, wherein the at least one bluff body is arranged in the main flow passage between the inlet end and two or more of the plurality of lateral inlet openings.

Thus, a simplified construction of the Venturi-type mixing nozzle may advantageously be enabled, wherein provision of a separate bluff body for each lateral inlet opening can be omitted.

According to one embodiment, the nozzle body central axis is an axis of symmetry.

Accordingly, a symmetrical nozzle body may easily be provided.

Preferably, the at least one bluff body has the shape of a saw tooth, a rounded unsymmetrical tooth, a pyramidal tooth, a dome, a conical tooth, or a wedge-type fin.

Thus, the at least one bluff body may be provided with a shape selected out of various different available shapes, which may easily be formed in an efficient and uncomplicated manner.

According to one embodiment, the at least one bluff body extends in radial direction of the main flow passage at least partly from the nozzle body towards the nozzle body central axis.

Thus, an improved shielding of the at least one lateral inlet opening by means of the at least one bluff body's wake may be obtained. The pressure in the shielded region of the at least one lateral opening may, thus, further be reduced compared to the pressure in circumjacent unshielded regions of the passage constriction, such that pressure loss at the at least one lateral inlet opening is significantly reduced.

Preferably, the low pressure zone created by the at least one bluff body extends in the radial direction of the main flow passage from the at least one lateral inlet opening along the at least one bluff body.

Thus, a required supply pressure for the second fluid may advantageously be reduced.

Furthermore, the present invention relates to a combustion device with a Venturi-type mixing nozzle as described above.

In this case, the at least one bluff body of the Venturi-type mixing nozzle has preferably a shape that is designed dependent on the size of an associated lateral inlet opening, such that the associated lateral inlet opening has a hydraulic diameter that is smaller than a so-called "Maximum Experimental Safe Gap" of the second fluid. This advantageously prevents a flame from being able to travel in operation of the combustion device upstream the Venturi-type mixing nozzle into the associated lateral inlet opening, thereby safely preventing a flame flashback event.

Exemplary embodiments of the present invention are described in detail hereinafter with reference to the attached drawings. In these attached drawings, identical or identically functioning components and elements are labelled with identical reference signs and they are generally only described once in the following description.

<FIG> shows an exemplary Venturi-type mixing nozzle <NUM> with a nozzle body <NUM> that forms a main flow passage <NUM>. According to one aspect, the Venturi-type mixing nozzle <NUM> is used for mixing of a combustible gas, e.g. hydrogen, with air in an associated combustion device at a desired concentration or ratio. Such a combustion device may e.g. be used in building heating systems.

The main flow passage <NUM> has an inlet end <NUM> and an outlet end <NUM> and is illustratively formed along the longitudinal direction of the nozzle body <NUM>. More specifically, the main flow passage <NUM> in the nozzle body <NUM> is generally formed as a tubular channel with a smooth inner surface <NUM>.

According to one aspect, the main flow passage <NUM> has a passage constriction <NUM> that is arranged between the inlet end <NUM> and the outlet end <NUM>. Illustratively, the main flow passage <NUM> is funnel-shaped between the inlet end <NUM> and the passage constriction <NUM> and, thus, having a converging inflow section. Between the passage constriction <NUM> and the outlet end <NUM>, the main flow passage <NUM> is illustratively conical and, thus, having a diverging outflow section.

Preferably, at least one bluff body is arranged in the main flow passage <NUM> between the inlet end <NUM> and the passage constriction <NUM>, i.e. in the converging inflow section. Illustratively, a plurality of bluff bodies is provided but, however, only two bluff bodies are separately labelled with the reference signs <NUM>, <NUM>, for simplicity and clarity of the drawing. In the following description, reference is generally made to one or both of the bluff bodies <NUM>, <NUM>, representative for all respectively provided bluff bodies.

The bluff bodies <NUM>, <NUM> protrude illustratively from the smooth inner surface <NUM> of the main flow passage <NUM> and are preferably attached to, or integrally formed with, the nozzle body <NUM>. In other words, the bluff bodies <NUM>, <NUM> are formed as bumps or dents on the otherwise smooth inner surface <NUM> inside of the main flow passage <NUM> and, thereby, form additional constrictions of the main flow passage <NUM>.

<FIG> shows the Venturi-type mixing nozzle <NUM> of <FIG> with the nozzle body <NUM> that forms exemplarily along its nozzle body central axis <NUM> the main flow passage <NUM> having the inlet end <NUM>, the outlet end <NUM>, and the passage constriction <NUM>. Illustratively, the nozzle body central axis <NUM> is a plane of symmetry.

The passage constriction <NUM> is arranged between the inlet end <NUM> and the outlet end <NUM> for creation of a negative pressure region <NUM> in the main flow passage <NUM> during operation of the Venturi-type mixing nozzle <NUM>. The negative pressure region <NUM> is only by way of example and for illustration purposes delimited by means of two dashed lines.

According to one aspect, the passage constriction <NUM> comprises at least one lateral inlet opening. Preferably, a plurality of lateral inlet openings is provided but, however, only two lateral inlet openings are illustrated and separately labelled with the reference signs <NUM>, <NUM>, for simplicity and clarity of the drawing. In the following description, reference is generally made to one or both of the lateral inlet openings <NUM>, <NUM>, representative for all respectively provided lateral inlet openings.

As described above at <FIG>, the bluff bodies are arranged in the main flow passage <NUM> between the inlet end <NUM> and the passage constriction <NUM>. More specifically, the bluff bodies <NUM>, <NUM> are preferably arranged in the main flow passage <NUM> between the inlet end <NUM> and the lateral inlet openings <NUM>, <NUM>. The bluff body <NUM> is illustratively arranged between the inlet end <NUM> and the lateral inlet opening <NUM>, and the bluff body <NUM> is illustratively arranged between the inlet end <NUM> and the lateral inlet opening <NUM>.

According to one aspect, one bluff body is provided for each lateral inlet opening. However, at least one bluff body may alternatively also be provided for two or more lateral inlet openings. In other words, it is possible to provide a single bluff body for all lateral inlet openings.

Each one of the bluff bodies <NUM>, <NUM> preferably extends at least partly from the nozzle body <NUM> and, more particularly, from the smooth inner surface <NUM> of the main flow passage <NUM> towards the nozzle body central axis <NUM>, preferentially in radial direction <NUM> of the main flow passage <NUM>, for creation of an associated low pressure zone during operation of the Venturi-type mixing nozzle <NUM>. At least one of the bluff bodies <NUM>, <NUM> may be attached to, or integrally formed with, the nozzle body <NUM>. Alternatively, at least one of the bluff bodies <NUM>, <NUM> may be attached to, or integrally formed with, a bluff body support that is adapted to be mounted to the nozzle body. Furthermore, at least one of the bluff bodies <NUM>, <NUM> may be in contact with the nozzle body <NUM> or, alternatively, be spaced apart therefrom.

A respective low pressure zone that is associated with the bluff body <NUM> is illustratively labelled with the reference sign <NUM>, and a respective low pressure zone that is associated with the bluff body <NUM> is illustratively labelled with the reference sign <NUM>. Each one of the associated low pressure zones <NUM>, <NUM> extends along the respectively associated bluff body <NUM>, <NUM>, preferably from its associated lateral inlet opening <NUM>, <NUM> along the respectively associated bluff body <NUM>, <NUM>, and preferentially in the radial direction <NUM> of the main flow passage <NUM>.

In an exemplary operation of the Venturi-type mixing nozzle <NUM>, a first fluid <NUM> enters the main flow passage <NUM> via the inlet end <NUM> and a second fluid <NUM> enters the main flow passage <NUM> via the lateral inlet openings <NUM>, <NUM> for being mixed with the first fluid <NUM> in the main flow passage <NUM>. By way of example, the first fluid <NUM> is air and the second fluid <NUM> is a combustible gas, e.g. hydrogen. More specifically, the first fluid <NUM> that enters the main flow passage <NUM> via the inlet end <NUM> backs up in the converging section between the inlet end <NUM> and the passage constriction <NUM> such that the negative pressure region <NUM> is created due to an acceleration of the first fluid <NUM> by means of the nozzle effect. Since the lateral inlet openings <NUM>, <NUM> open into the passage constriction <NUM>, the second fluid <NUM> is drawn into the main flow passage <NUM>, where the second fluid <NUM> is mixed with the first fluid <NUM>. Illustratively, the second fluid <NUM> is guided to the lateral inlet openings <NUM>, <NUM> via associated support channels <NUM>, <NUM>, which are exemplarily arranged at an angle of <NUM>° relative to the nozzle body central axis <NUM>.

According to one aspect, the bluff bodies <NUM>, <NUM> are provided for creation of the low pressure zones <NUM>, <NUM> in the negative pressure region <NUM> such that the first fluid <NUM> has a flow velocity in the low pressure zones <NUM>, <NUM> that is at least reduced compared to a flow velocity that is otherwise attributed to the first fluid <NUM> in the negative pressure region <NUM>. More particularly, the bluff bodies <NUM>, <NUM> are preferably adapted to ensure that the second fluid <NUM> is fully surrounded by the first fluid <NUM> after having entered the main flow passage <NUM> through the lateral inlet openings <NUM>, <NUM>.

<FIG> shows a section of the main flow passage <NUM> with the smooth inner surface <NUM> that is formed by the nozzle body <NUM> of the Venturi-type mixing nozzle <NUM> of <FIG>. Illustratively, the bluff body <NUM> protrudes from the smooth inner surface <NUM> of the main flow passage <NUM> at a predetermined position upstream of the lateral inlet opening <NUM>. The bluff body <NUM> is preferably attached to, or integrally formed with, the nozzle body <NUM>.

According to one aspect, the bluff body <NUM> creates at least partly turbulences <NUM> of the first fluid <NUM> flowing around the bluff body <NUM>. Preferably, the turbulences <NUM> are at least created in the negative pressure region <NUM>.

In an exemplary operation of the Venturi-type mixing nozzle <NUM>, the second fluid <NUM> is drawn through the lateral inlet opening <NUM> along the bluff body <NUM> into the main flow passage <NUM> such that the first fluid <NUM> flows along the smooth inner surface <NUM> and directly surrounds the second fluid <NUM> downstream of the lateral inlet opening <NUM>. By creating the turbulences <NUM> of the first fluid <NUM> around the second fluid <NUM>, mixing of the first and second fluids <NUM>, <NUM> is significantly improved.

<FIG> shows a Venturi-type mixing nozzle <NUM> with a nozzle body <NUM> that forms a main flow passage <NUM> having an inlet end <NUM> and a passage constriction <NUM> that is illustratively provided with a plurality of lateral inlet openings <NUM>. The Venturi-type mixing nozzle <NUM> is illustratively provided with a plurality of bluff bodies. However, for simplicity and clarity of the drawing only a single bluff body is separately labelled with the reference sign <NUM>.

According to one aspect, the Venturi-type mixing nozzle <NUM> is embodied similar to the Venturi-type mixing nozzle <NUM> of <FIG> so that a detailed description of the Venturi-type mixing nozzle <NUM> may be omitted for brevity and conciseness. However, in contrast to the Venturi-type mixing nozzle <NUM> of <FIG>, the bluff body <NUM> of the Venturi-type mixing nozzle <NUM> is attached to, or integrally formed with, a bluff body support <NUM> that is adapted to be mounted to the nozzle body <NUM>. By way of example, the bluff body support <NUM> is ringshaped and at least partly funnel-shaped.

<FIG> shows a Venturi-type mixing nozzle <NUM> with a nozzle body <NUM> that forms a main flow passage <NUM> having an inlet end <NUM>, an outlet end <NUM>, and a passage constriction <NUM> that is illustratively provided with a plurality of lateral inlet openings <NUM>. The Venturi-type mixing nozzle <NUM> is illustratively provided with a plurality of bluff bodies. However, for simplicity and clarity of the drawing only a single bluff body is separately labelled with the reference sign <NUM>.

According to one aspect, the Venturi-type mixing nozzle <NUM> is embodied similar to the Venturi-type mixing nozzle <NUM> of <FIG> so that a detailed description of the Venturi-type mixing nozzle <NUM> may be omitted for brevity and conciseness. However, in contrast to the Venturi-type mixing nozzle <NUM> of <FIG>, the bluff body <NUM> of the Venturi-type mixing nozzle <NUM> is attached to, or integrally formed with, a bluff body support <NUM> that is adapted to be mounted to the nozzle body <NUM>. Illustratively, the bluff body support <NUM> is cruciform and consists of two crossing bars, each supporting two exemplary bluff bodies.

By way of example, the bluff body support <NUM> is provided with one or more positioning members <NUM>. The positioning members <NUM> preferably interact with associated counterpart members <NUM> provided at the nozzle body <NUM> in order to enable an adequate positioning of the bluff body support <NUM> at the nozzle body <NUM>. Illustratively, the associated counterpart members <NUM> are slots and the positioning members <NUM> are extensions of the crossing bars of the bluff body support <NUM> that fit into the slots.

<FIG> shows the nozzle body <NUM> of <FIG> that forms the main flow passage <NUM> having the nozzle body central axis <NUM>. The nozzle body <NUM> is provided with the bluff body <NUM> and the lateral inlet opening <NUM>.

Part (A) of <FIG> further illustrates an exemplary support channel <NUM> which may e.g. be used instead of the support channel <NUM> of <FIG>. By way of example, the support channel <NUM> is connected to the lateral inlet opening <NUM> and preferably arranged at a predetermined angle <NUM> of more than <NUM>° relative to the nozzle body central axis <NUM> such that the second fluid (<NUM> of <FIG>) is injected into the main flow passage <NUM> in a direction that points away from the bluff body <NUM>.

Part (B) of <FIG> further illustrates another exemplary support channel <NUM> which may e.g. be used instead of the support channel <NUM> of <FIG>. By way of example, the support channel <NUM> is connected to the lateral inlet opening <NUM> and preferably arranged at a predetermined angle <NUM> of less than <NUM>° relative to the nozzle body central axis <NUM> such that the second fluid (<NUM> of <FIG>) is injected into the main flow passage <NUM> in a direction that points towards the bluff body <NUM>.

<FIG> shows the bluff body <NUM> and the lateral inlet opening <NUM> formed on/in the nozzle body <NUM> of <FIG>. In parts (A) to (D) of <FIG>, different possible forms and shapes of the bluff body <NUM> are illustrated.

In part (A), the bluff body <NUM> is exemplarily wedge-shaped and has an arc-shaped surface <NUM> that faces the nozzle body central axis (<NUM> in <FIG>), as well as a straight surface <NUM> that faces the lateral inlet opening <NUM>. In other words, the bluff body <NUM> has a sawtooth-like shape.

In part (B), the bluff body <NUM> is exemplarily wedge-shaped and has a straight surface <NUM> that faces the nozzle body central axis (<NUM> in <FIG>), as well as a straight surface <NUM> that faces the lateral inlet opening <NUM>. In other words, the bluff body <NUM> has at least approximatively a V-shaped form.

In part (C), the bluff body <NUM> is exemplarily pin-shaped and has an arc-shaped surface <NUM> that faces the inlet end (<NUM> in <FIG>), as well as a straight surface <NUM> that faces the lateral inlet opening <NUM>. In other words, the bluff body <NUM> has the shape of a half or semi-circular cylinder.

In part (D), the bluff body <NUM> is exemplarily plate-shaped. Illustratively, the plate-shaped bluff body <NUM> has two opposing flat surfaces <NUM>, <NUM>, wherein the flat surface <NUM> faces the lateral inlet opening <NUM>.

<FIG> shows the bluff body <NUM> and the lateral inlet opening <NUM> formed on/in the nozzle body <NUM> of <FIG>. The bluff body <NUM> protrudes from the nozzle body <NUM> into the main flow passage <NUM>.

More specifically, part (A) of <FIG> is a sectional view of part (B) of <FIG>, which further illustrates the straight surfaces <NUM>, <NUM> of the exemplarily wedge-shaped bluff body <NUM>. By way of example, the straight surface <NUM> is at least approximately arranged at an angle of <NUM>° relative to the nozzle body <NUM>.

Part (B) of <FIG> is a sectional view of part (A) of <FIG>, which further illustrates the arc-shaped surface <NUM> and the straight surface <NUM> of the exemplarily wedge-shaped bluff body <NUM>. By way of example, the straight surface <NUM> is at least approximately arranged at an angle of <NUM>° relative to the nozzle body <NUM>.

<FIG> shows the bluff body <NUM> and the lateral inlet opening <NUM> formed on/in the nozzle body <NUM> of <FIG>. The bluff body <NUM> protrudes from the nozzle body <NUM> into the main flow passage <NUM> having the nozzle body central axis <NUM>. According to one aspect, the bluff body <NUM> is provided with an overhang that shields at least partly the lateral inlet opening <NUM> in direction of the nozzle body central axis <NUM>.

More specifically, part (A) of <FIG> is a sectional view of part (B) of <FIG>, which further illustrates the exemplarily wedge-shaped bluff body <NUM> with the straight surface <NUM>. However, instead of the straight surface <NUM> of part (B) of <FIG> that is at least approximately arranged at an angle of <NUM>° relative to the nozzle body <NUM>, a straight surface <NUM> is provided that is exemplarily arranged at an angle of <NUM>° relative to the nozzle body <NUM> and embodied such that it shields the lateral inlet opening <NUM> at least partly in direction of the nozzle body central axis <NUM> by extending the wedge-shaped bluff body <NUM> over the lateral inlet opening <NUM>. The angle may be selected in an application-specific manner and, thus, be smaller or greater than <NUM>°.

Part (B) of <FIG> is a sectional view of part (A) of <FIG>, which further illustrates the exemplarily wedge-shaped bluff body <NUM> with the arc-shaped surface <NUM>. However, instead of the straight surface <NUM> of part (A) of <FIG> that is at least approximately arranged at an angle of <NUM>° relative to the nozzle body <NUM>, an arc-shaped surface <NUM> is provided that is embodied such that it shields the lateral inlet opening <NUM> at least partly in direction of the nozzle body central axis <NUM> by extending the wedge-shaped bluff body <NUM> over the lateral inlet opening <NUM>.

<FIG> shows the bluff body <NUM> and the lateral inlet opening <NUM> formed on/in the nozzle body <NUM> of <FIG>. The bluff body <NUM> protrudes from the nozzle body <NUM> into the main flow passage <NUM>. The bluff body <NUM> is exemplarily embodied wedge-shaped according to <FIG>, part (B), with the straight surfaces <NUM>, <NUM>. According to one aspect, at least one additional bluff body <NUM> is arranged in the main flow passage <NUM> downstream of the lateral inlet opening <NUM>.

More specifically, in part (A) of <FIG> a single additional bluff body <NUM> is arranged downstream of the bluff body <NUM>. By way of example, the single additional bluff body <NUM> has a shape that is similar to the shape of the bluff body <NUM>. In part (B) of <FIG>, the single additional bluff body <NUM> is simply horizontally mirrored.

It should be noted that in <FIG> the additional bluff body <NUM> is only by way of example wedge-shaped with straight surfaces, such that it exhibits a triangular cross section, but not for limiting the invention accordingly. Instead, the additional bluff body <NUM> may have various suitable shapes and forms, as exemplarily described hereinafter with reference to <FIG>.

<FIG> shows the bluff body <NUM> and the lateral inlet opening <NUM> formed on/in the nozzle body <NUM> of <FIG>. The bluff body <NUM> protrudes from the nozzle body <NUM> into the main flow passage <NUM>. The bluff body <NUM> is exemplarily wedge-shaped according to <FIG>, part (B), with the straight surfaces <NUM>, <NUM>. Furthermore, the additional bluff body <NUM> of <FIG> is arranged in the main flow passage <NUM> downstream of the lateral inlet opening <NUM>.

More specifically, in part (A) of <FIG> the single additional bluff body <NUM> is illustratively pin-, plate- or bloc-shaped, e.g. similar to <FIG>, part (C) or (D). In part (B) of <FIG> the single additional bluff body <NUM> is illustratively wedge-shaped with an arc-shaped surface and a straight surface, e.g. similar to <FIG>, part (A).

<FIG> shows the Venturi-type mixing nozzle <NUM> of <FIG> with the nozzle body <NUM> that forms the main flow passage <NUM> having the inlet end <NUM>, an outlet end <NUM>, and the passage constriction <NUM>. The Venturi-type mixing nozzle <NUM> further incudes the bluff body support <NUM> with the bluff body <NUM>.

However, in contrast to <FIG> the lateral inlet opening <NUM> is now exemplarily slot-shaped instead of being punctiform. In other words, in all variants of the present invention that are described in detail with reference to the drawings, one or more slot-shaped lateral inlet openings may be provided instead of, or in addition to, respective punctiform lateral inlet openings.

<FIG> shows the lower part of <FIG> with the bluff body <NUM> and the lateral inlet opening <NUM> formed on/in the nozzle body <NUM>. The bluff body <NUM> is illustratively embodied according to part (A) of <FIG> with the straight surface <NUM> and protrudes from the nozzle body <NUM> into the main flow passage <NUM> having the nozzle body central axis <NUM>. Furthermore, the lateral inlet opening <NUM> is connected to the support channel <NUM> at the passage constriction <NUM>.

According to one aspect, the bluff body <NUM> has a height H that amounts at least to half of a hydraulic diameter D of the lateral inlet opening <NUM>, and at most to a radial distance R between the nozzle body <NUM> and the nozzle body central axis <NUM> at the passage constriction <NUM>. In addition, or alternatively, a longitudinal distance L between the bluff body <NUM> and the lateral inlet opening <NUM> preferably amounts at most to the hydraulic diameter D of the lateral inlet opening <NUM>. The hydraulic diameter D is preferably smaller than a so-called "Maximum Experimental Safe Gap" of the second fluid (<NUM> of <FIG>).

<FIG> shows the Venturi-type mixing nozzle <NUM> of <FIG>, with the nozzle body <NUM> that forms the main flow passage <NUM> having the passage constriction <NUM>, wherein the lateral inlet opening <NUM> and the support channel <NUM> are formed according to <FIG>. Upstream of the lateral inlet opening <NUM> and the support channel <NUM>, the wedge-shaped bluff body <NUM> with the arc-shaped surface <NUM> according to part (A) of <FIG> is exemplarily arranged. Preferably, the bluff body <NUM> has a width W that amounts at least to half of the hydraulic diameter D of the lateral inlet opening <NUM> according to <FIG>, and at most to twice the hydraulic diameter D.

By way of example, the Venturi-type mixing nozzle <NUM> is provided with five additional support channels <NUM>, <NUM>, <NUM>, <NUM>, <NUM> that are connected to respectively associated lateral inlet openings which, however, are not separately labelled for simplicity and clarity of the drawings. Illustratively, the support channels <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are radially oriented with respect to the main flow passage <NUM>, while the support channel <NUM> is inclined with respect to the radial direction of the main flow passage <NUM>.

Claim 1:
Venturi-type mixing nozzle (<NUM>) with a nozzle body (<NUM>) that comprises a main flow passage (<NUM>) having an inlet end (<NUM>) and an outlet end (<NUM>), wherein a first fluid (<NUM>) enters the main flow passage (<NUM>) via the inlet end (<NUM>), the main flow passage (<NUM>) comprising a passage constriction (<NUM>) between the inlet end (<NUM>) and the outlet end (<NUM>) for creation of a negative pressure region (<NUM>) in the main flow passage (<NUM>), wherein the passage constriction (<NUM>) comprises at least one lateral inlet opening (<NUM>, <NUM>) through which a second fluid (<NUM>) enters the main flow passage (<NUM>) for being mixed with the first fluid (<NUM>) in the main flow passage (<NUM>), wherein at least one bluff body (<NUM>, <NUM>) is arranged in the main flow passage (<NUM>) between the inlet end (<NUM>) and the at least one lateral inlet opening (<NUM>, <NUM>) upstream of the at least one lateral inlet opening (<NUM>, <NUM>), the at least one bluff body (<NUM>, <NUM>) is integrally formed with the nozzle body (<NUM>), the at least one bluff body (<NUM>, <NUM>) extending in radial direction (<NUM>) of the main flow passage (<NUM>) towards a nozzle body central axis (<NUM>) for creation of a low pressure zone (<NUM>, <NUM>) that extends in the radial direction (<NUM>) of the main flow passage (<NUM>) along the at least one bluff body (<NUM>, <NUM>).