WO2010110665A1

WO2010110665A1 - Vortex generator

Info

Publication number: WO2010110665A1
Application number: PCT/NL2010/050157
Authority: WO
Inventors: Pieter Meint Van Der Klok
Original assignee: Gimo Holding B.V.
Priority date: 2009-03-26
Filing date: 2010-03-26
Publication date: 2010-09-30
Also published as: NL2002675C2

Abstract

A vortex generator for creating a controlled swirl in a fluid flow, which vortex generator comprises a housing with a through-flow channel for a fluid flow, which through-flow channel has a channel wall and a central zone, and a number of swirl elements extending from the channel wall to the central zone, characterized in that the channel wall is provided with a protuberance extending into the through-flow channel, formed by a wall thickness which, viewed in through-flow direction, gradually increases to a greatest value and thereupon decreases again, for obtaining a venturi effect.

Description

The invention relates to a vortex generator for creating a controlled swirl in a fluid flow, which vortex generator comprises a housing with a through-flow channel for a fluid flow, which through-flow channel has a channel wall and a central zone and a number of swirl elements extending in the through-flow channel from the channel wall to the central zone.

From US 5113838 (Kim) and WO 03/064832 (Kim) such a vortex generator is known for use in the inlet channel and, if desired, in the outlet channel of a petrol engine or a diesel engine or the like. When used in the inlet channel, the vortex generator provides for an improved supply of air or an air/fuel mixture to the combustion chamber(s). An improved filling of the combustion chamber(s) leads, in turn, to a more efficient use of fuel, resulting in more limited fuel consumption at equal engine power or an increased engine power at equal fuel consumption.

The object of the invention is to provide an improved vortex generator which operatively provides a higher vorticity and more powerful acceleration to a fluid flow than the known vortex generators.

To this end, according to the invention, a vortex generator of the type described hereinabove is characterized in that the channel wall is provided with a protuberance extending into the through-flow channel, and formed by a wail thickness which, viewed in the through-flow direction, gradually increases to a greatest value and then decreases again, for obtaining a venturi effect.

In the following, the invention will be further described with reference to the accompanying drawing of a few exemplary embodiments. Fig. 1 schematically shows, in perspective view, a top plan view of an example of a first embodiment of a vortex generator according to the invention; Figs. 2 and 3 schematically show a top plan view and bottom view, respectively, of the vortex generator of Fig. 1;

Figs. 4 and 5 show, for the sake of completeness, two views, in isometric and trimetric perspective, respectively, slightly displaced relative to one another and viewed obliquely from above and from the front, of a vortex generator according to Figs. 1 to 3;

Fig. 6 schematically shows in top plan view, an example of another embodiment of a vortex generator;

Fig. 7 shows a cross section along the line A-A in Fig. 6; and Fig. 8 shows an example of a vortex generator designed as heating element.

The vortex generator 1 shown in Figs. 1 to 5 is suitable to be placed in a tubular fluid channel having a circular cross section. This may be an air inlet channel or a fuel inlet channel of an internal combustion engine, but other uses are conceivable too. For instance, if desired, a vortex generator can be utilized in an air filter of an internal combustion engine or in an outlet channel, but uses in other technical fields where it is useful to increase the fluid flow are possible too.

The vortex generator shown has a substantially cylindrical housing 2, which forms a through-flow channel 3 for a fluid flow. In Figs. 4 and 5, schematically, with arrow Fi (entrance side) and Fo (exit side) a fluid flow is indicated. The through-flow channel has a channel wall 4 formed by the inside surface of the housing 2, and a central zone C around the central axis H of the through-flow channel (see Figs. 3 and 4). The housing 2 has a wall thickness d that is relatively limited compared to the diameter D of the housing. As will be described further in the following, the wall thickness of the housing varies between the entrance side of the housing (this is the top side in Figs. 4 and 5) and the exit side of the housing (= underside in Figs. 4 and 5). In this example, four swirl elements 5, 6, 7, 8 are present in the housing 2, which elements project from the channel wall 4 of the housing 2 to the central zone C of the through-flow channel 3. The swirl elements are blade- shaped and extend obliquely to the central axis H and to the channel wall 4 and hence also obliquely to the main direction of the fluid flow. The position of the swirl elements is for instance comparable to that of the blades of an airplane propeller or a modern windmill or the blades of a fan. The swirl element can be placed, at will, in a manner such that a controlled swirl or vortex is obtained, which is directed either clockwise or anti -clockwise. The blade-shaped swirl elements are connected in a connection zone by an elongated base 5b, 6b, 7b, 8b to the channel wall 4, with the elongated base and the connecting zone extending obliquely to the central axis H. In this example, the blade-shaped swirl elements each form a tip, in that the upper edge and the lower edge of each swirl element are edges bent towards each other. For the sake of clarity, the edges bent towards each other of swirl element 6 are indicated in Fig. 2 with reference numerals 61 and 62.

In this example, the swirl elements are disposed in two pairs, while in the example shown, the swirl elements 5 and 6 together form a pair, as do the swirl elements 7 and 8. In or near the central zone C of the through-flow channel 3, the swirl elements forming a pair are interconnected by their tips, as shown at the reference numerals 9 and 10.

Between the interconnected tips of a pair of swirl elements 5 and 6 shown at reference numeral 9 and the interconnected tips of the swirl elements 7 and 8 shown at reference numeral 10, in this example, there is a free interspace 11.

As remarked hereinabove, viewed from the entrance side of the housing to the exit side, the wall of the housing 3 has a varying thickness, in that initially, the distance between the channel wall 4 and the central axis H increases to a smallest value and, thereupon, gradually increases again. At the location of the smallest value of the distance between the channel wall 4 and the central axis H, the wall thickness is the greatest. In this embodiment, the area with the greatest wall thickness 12 is closer to the exit side than the entrance side of the vortex generator, yet a different location is possible too. Also, if desired, the increase of the wall thickness may start only at some distance from the entrance side and/or the decrease of the wall thickness may end already at some distance before the exit side.

Through the use of a wall thickness which gradually increases to a greatest value and thereupon gradually decreases again, viewed from one end of the through-flow channel to the other, a converging and subsequently diverging through-flow channel is formed. Therefore, the through-flow channel forms a venturi tube, which provides for an increase of the through-flow velocity of a fluid flowing through the through-flow channel. The area 12 with the greatest wall-thickness is also called the throat of the venturi tube.

Viewed from the entrance side of the housing, the bases 5b, 6b, 7b and 8b of the swirl elements 5 - 8 extend from a point located before the throat 12 to a point located beyond the throat 12.

In this example, the swirl elements have a shape bent in two directions, i.e., viewed both in the flow direction of the fluid and transversely thereto, i.e. in the direction from the base to the tip, the blades 5 - 8 are curved. This can clearly be seen with blade 6 in Fig. 5, as indicated with arrow 14. It is noted that use of the blades bent in two directions is not strictly required. Blades bent in one direction or even having a flat shape are possible too.

Further, the swirl elements can each have, at the exit side, a wing section 15, 16, 17, and 18. In this example, the wing sections project from the channel wall to a point located at some distance from the tip of the respective swirl element. The wing sections include a somewhat greater angle with the through-flow direction of the channel than the rest of the associated swirl elements and therefore operatively project further into the fluid flow than the main surfaces of the swirl elements. As a result, the wing sections enhance the swirl effect further.

The swirl elements can further be advantageously provided with a number of openings 19 in the blades 5 - 8. In this example, the openings 19 consist of three through-bores per swirl element. The through-bores opera tively prevent or at least reduce the occurrence of turbulences at the rear side of the swirl elements. Such turbulences are undesired because, as a result, the swirling effect generated by the swirl elements and the through-flow velocity are adversely affected. The vortex generators described and illustrated by way of example are suitable for use in a round tube, or holder or the like. However, a vortex generator according to the invention can also be designed with a different cross sectional shape, such as, for instance, an ovoid shape or an angular shape, optionally with rounded corners, etc. A vortex generator can be fastened in many different ways in a tube, holder or the like. For instance by means of gluing, retaining pins or a Seeger ring, etc. For easy placement of the vortex generator, this can be provided, according to the invention, with a through-slot extending in the housing from the entrance side to the exit side, which slot allows the housing to be squeezed together somewhat during placement of the vortex generator into a casing, such as a tube or a suitable holder. If the vortex generator is made of slightly resilient material, it will rebound and clamp itself after placement. A suitable glue can then be used or suitable mechanical retaining means can be utilized. Another advantage of use of a slot is that it can compensate for differences in expansion between the material of the vortex generator and the material of the surroundings.

In the Figures, reference numeral 20 indicates a through-slot. Further, in the example shown, the housing is provided at the outside with screw thread, so that the vortex generator can be screwed down. In the example, the screw thread is divided over segments of the housing, which are spread over the circumference. In the example shown, on both sides of the slot 20, there is a screw thread segment 21, 22 directly adjoining the slot 20, and in both directions, approximately 120° further, two more screw thread segments 23, 24 are utilized. It is possible to use a different number of screw thread segments or a fully circumferential screw thread. It is also possible to use screw thread (segments) that do not extend over the full distance between the entrance side and the exit side of the housing.

A vortex generator according to the invention can be manufactured from any material suitable for the intended use, for instance plastic or metal. Advantageously, a vortex generator for use with combustion engines can be manufactured from aluminium of airplane quality (quality indication Al 7075), which is flexible and resilient. The vortex generator can be made from one solid piece of material, with the aid of a computer controlled milling machine so that for attaching the swirl elements to each other and the housing no connecting means such as mounting lips, or connecting methods such as welding are necessary.

According to a further elaboration of the invention, a vortex generator provided with wing sections 15, 16, 17, 18 can be designed with movable wing sections. This may be achieved by locally reducing the material thickness at the location of the boundary line between the body of the swirl element and a wing section of the swirl element, so that a hinging action is enabled, with the wing section pivoting relative to the body of the swirl element. To this end, the wing section furthermore should not have a fixed connection to the channel wall. It is noted that swirl elements provided with wing sections which may or may not be pivotable can also be used, if desired, with a vortex generator without venturi effect.

An example of a vortex generator with swirl elements that are provided with movable wing sections is shown in Figs. 6 and 7.

Fig. 6 schematically shows another example of a vortex generator according to the invention in top plan view, i.e. a view from the entrance side of the vortex generator and Fig. 7 shows a cross section along the line A-A in Fig. 6.

The vortex generator of Figs. 6 and 7 is designed with a greater wall thickness and a greater thickness of the swirl elements than a vortex generator according to Figs. 1 to 5. Such a heavier designed vortex generator is for instance highly suitable for use in ships' diesel engines. The vortex generator 30 shown in Figs. 6 and 7 has six swirl elements 31 - 36, which are connected both to a housing 37 which encloses the swirl elements and a central hub element 38. In this example, the housing 37 has no slot and neither is it provided with screw thread in this example. Again, the swirl elements each have a base 31b - 36b which forms a connection to the inside surface of the housing or the channel wall 39 of the through-flow channel 40 of the vortex generator 30.

Again, the through-flow channel 40 has a first portion 41, initially converging from the entrance side, indicated with an arrow Fi to the exit side indicated with an arrow Fo, and a section 42 subsequently diverging, so that, again, a venturi tube with a throat 43 is obtained. Again, the bases of the swirl elements extend on both sides of the throat 42. The swirl elements have wing sections 51 - 56, which are located at the exit side of the through-flow channel. The wing sections are each connected to the body of the swirl elements via a hinge zone or bending zone formed by a notch or groove 57. Further, the wing sections are clear from the inside surface of the housing, as can be seen in Fig. 6, with the slots 58 between the outer edges of the wing sections and the housing. Through the use of such pivotable or flexible wing section, the wing sections can pivot away from the fluid flow under the influence of strong fluid flows as indicated with an arrow 59 at wing section 52, so that the flow resistance diminishes. When using a suitable, resilient material, such as the above-mentioned aluminium of airplane quality, the wing sections rebound by themselves when the fluid flow weakens. In the example shown, the wing sections have somewhat rounded forms which extend from the lower edge to the notch.

Further, in this example, the swirl elements have, on the front side of the vortex generator, an at least partly bevelled top edge, as indicated at 63. It is preferred that at the entrance side, the hub element 38 has a pointed, streamlined form in order to reduce the flow resistance. The pointed shape is indicated in the top plan view of Fig. 6 with a dot 64.

For the sake of completeness it is noted that bevelled edges of the swirl elements and flexible wing sections can also be used with a vortex generator of the type shown in Figs. 1 to 5 or with a vortex generator of a known type.

This also holds for a coating which, at a microscopic scale, is slightly rough and can be advantageously applied to the swirl elements and the channel wall of a vortex generator and which has a flow resistance reducing effect.

The vortex generator of Figs. 6 and 7 can be manufactured, as can the one of Figs. 1 to 5, from one solid block of material through a milling operation.

Fig. 8 shows an example of an electrically heated vortex generator, which renders a separate heating element, as is used with some engines as a starting aid, superfluous. A separate heating element often comprises an insulated, serpentine-bent metal strip, through which an electric current is fed and which is arranged in the air inlet channel of an engine. However, the heating element has a useful function only during starting of the engine, but after starting merely forms an obstacle in the air flow. This drawback can be obviated through the use of a vortex generator also designed as heating element.

The example shown in Fig. 8 relates to a vortex generator 70 with swirl elements 71 - 76 arranged in pairs in a metal housing provided with a venturi. In this example, three pairs 71, 72; 73, 74; 75, 76 of swirl elements are used, with the swirl elements of a pair being connected to each other by the tips located in the central area of the housing in a manner similar to that described hereinabove and shown in Figs. 1 to 5. The interconnected tips of each pair lie clear of the other pairs. Again, the swirl elements can have wing elements which may or may not be flexible, or bevelled edges or the like, as has been described in connection with the other Figures. In this example, the housing consists of four sections 80, 81, 82, 83 which are separated from each other by slots 84, 85, 86, 87 extending from the entrance side to the exit side of the vortex generator. The slots 85, 86 and 87, which separate the respective sections 80 and 81, 81 and 82, and 82 and 83 from each other, however, are electrically connected via pairs of swirl elements 75/76; 71/72 and 73/74 bridging the slots, so that between electric terminals 90, 91 to be further described, an electric circuit is formed. The housing is further enclosed by a sleeve 88 of electrically insulating material. In this example, the insulating sleeve 88 is in turn enclosed by a metal sleeve 89. The adjacent sections 80 and 83 of the housing, which are separated from each other by the slot 84, are each provided with an electric terminal 90, 91 which comprises a metal pin or bolt 94, 95 respectively, which extends through an opening in the sections 80, 83, respectively, and corresponding openings in the insulating sleeve 88 and in the metal sleeve 89 and through an insulating disc 92 and 93.

The insulating discs fall in a customary manner, with or without a shoulder, into an opening in the metal sleeve and abut against the insulating sleeve. The bolt or pin 94, 95 is provided with fastening means, such as, for instance, nuts 96, 97 for an electric conductor. The conductive path for a current flowing from the electric terminal 90 to the electric terminal 91 is schematically indicated by an interrupted line 100 and runs from terminal 90 and section 80 via swirl element 75 and the swirl element 76 connected thereto by the tip to section 81; then, from section 81 via swirl elements 71 and 72 to section 82 and from section 82 via swirl elements 73 and 74 to section 83 and terminal 91. It is noted that after the foregoing, various modifications and/or variants are obvious to the skilled person.

For instance, vortex generators can be equipped with more or fewer numbers of swirl elements than is the case in the examples described and illustrated. In the case of a vortex generator also usable as electric heating element, in general, between the swirl elements of each pair a slot is provided in the housing, and an additional slot is provided between the swirl elements provided with an electric terminal and belonging to the different pairs.

Further, various aspects of the described and illustrated vortex generators can, if desired, be used separately or in other combinations. A flow resistance reducing coating can also be utilized, for instance, with a vortex generator without venturi effect. The same holds for a vortex generator usable as heating element or for the use of a slot in the housing and/or of screw thread on the housing. Such modifications are understood to fall within the framework of the invention.

Claims

1. A vortex generator for creating a controlled swirl in a fluid flow, which vortex generator comprises a housing with a through-flow channel for a fluid flow, which through-flow channel has a channel wall and a central zone, and a number of swirl elements extending from the channel wall to the central zone, characterized in that the channel wall is provided with a protuberance extending into the through-flow channel, formed by a wall thickness which, viewed in through-flow direction, gradually increases to a greatest value and then decreases again, for obtaining a venturi effect.

2. A vortex generator according to claim 1, wherein the swirl elements each comprise a blade-shaped body with an elongated base which is connected to the channel wall in an elongated connecting zone which extends substantially obliquely to the through-flow direction of the channel, wherein the blade-shaped body has a tip located in the central zone, characterized in that the connecting zone, viewed in the through-flow direction, extends from a point located before the greatest value of the wall thickness to a point located beyond the greatest value of the wall thickness.

3. A vortex generator according to claim 2, characterized in that the blade-shaped body of a swirl element at the end located beyond the greatest value of the wall thickness is provided with a wing section, which makes a larger angle with the through-flow direction than the base.

4. A vortex generator according to claim 3, characterized in that the said end section of the blade-shaped body of a swirl element is not connected to the channel wall and is connected to the rest of the blade-shaped body via a bending zone, which allows the wing section to swivel relative to the blade- shaped body under the influence of a fluid flowing through the vortex generator.

5. A vortex generator according to claim 4, characterized in that the bending zone is formed through the use of a locally smaller material thickness.

6. A vortex generator according to any one of the preceding claims 2 to 5, characterized in that the swirl elements are arranged in a number of pairs of each time two neighbouring swirl elements, of which the blade-shaped bodies are interconnected by their tips, and that between the interconnected tips of different pairs a free interspace is present.

7. A vortex generator according to claim 6, characterized in that the tips are narrow with regard to the base.

8. A vortex generator according to any one of the preceding claims, characterized in that the vortex generator is manufactured from one piece of material.

9. A vortex generator according to any one of the preceding claims, characterized in that the vortex generator is manufactured by means of a milling operation from a solid block of material.

10. A vortex generator according to claim 9, characterized in that the vortex generator is manufactured from aluminium.

11. A vortex generator according to any one of claims 2 to 9, characterized in that the blade-shaped bodies of the swirl elements are bent both in the through-flow direction and in a direction from the channel wall to the tip.

12. A vortex generator according to any one of claims 2 to 10, characterized in that the blade-shaped body of a swirl element is provided with a number of through bores whose central axis is substantially parallel to the central axis of the through-flow channel.

13. A vortex generator according to any one of the preceding claims, characterized in that the housing is provided with a slot extending from the entrance end to the exit end of the through-flow channel, which slot allows the vortex generator to be somewhat squeezed together for purposes of mounting/dismounting.

14. A vortex generator according to any one of the preceding claims, characterized in that the housing is at least partly provided with external screw thread.

15. A vortex generator according to any one of the preceding claims, characterized in that at least the channel wall and the swirl elements are provided with a coating which, at a microscopic scale, is somewhat rough.

16. A vortex generator according to any one of the preceding claims, characterized in that the swirl elements and the housing are manufactured from electrically conductive material and that the swirl elements are arranged in a number of pairs of each time two swirl elements, wherein the swirl elements of a pair are interconnected in the central zone, yet in the central zone the pairs are arranged in a manner so as to be insulated from each other, wherein the housing is enclosed by electrically insulating material and further, at the location of two adjacent swirl elements of different pairs, is provided with two electric terminals, wherein the housing is provided with through slots provided each time between two swirl elements of the same pair and with a through-slot located between the two electric terminals, in order to allow the vortex generator to be used as electric heating element.

17. A vortex generator according to any one of the preceding claims, wherein the swirl elements are connected in the central zone to a hub element, characterized in that the hub element has a pointed end at the entrance side of the through-flow channel.

18. An internal combustion engine with at least one combustion chamber and at least one inlet channel and/or outlet channel connected thereto, characterized by at least one vortex generator according to any one of the preceding claims placed in an inlet channel and/or outlet channel.