KR960013199B1 - Automotive exhaust noise attenuator - Google Patents

Abstract

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Description

Diffuser unit

1 is a perspective view showing the use of a rotating member to reduce the base track in accordance with the associated shared US Pat. No. 117,770.

1A is a view taken from the direction of 1A-1A in FIG.

2 is a cross-sectional view of a two-dimensional diffuser incorporating features of the present invention.

3 is a view taken from the direction 3-3 of FIG.

4 is a graph showing test results for the embodiment of the present invention shown in FIGS. 2 and 3 as well as the prior art.

5 is a cross-sectional view of an axisymmetric diffuser incorporating features of the present invention.

6 is a view taken from the 6-6 direction of FIG.

7 is a cross-sectional view of a two-dimensional stepped diffuser incorporating features of the present invention.

8 is a view taken in the 8-8 direction of FIG.

9 illustrates the use of a plate in the application of a heat exchanger in accordance with the knowledge of related shared US patent application no. 947,349.

FIG. 10 is a sectional view taken along line 10-10 of FIG.

11 is a cross-sectional view of a conversion system incorporating features of the present invention.

FIG. 12 is a view taken along the 12-12 direction of FIG.

Figure 13 shows another embodiment of a catalytic conversion system incorporating the features of the present invention.

FIG. 14 is taken along line 14-14 of FIG.

* Explanation of symbols for main parts of the drawings

200: article 202: upper surface

206: blunt base or end surface 208: separation line

210: rotating wall member or plate 212: support member or spacer

214: inlet edge portion 216: rear edge portion

218: upper surface 220: lower surface

22: U-shaped goal 224: U-shaped lobe

228: vortex

The present invention relates to a diffuser.

Diffusers are well known in the art. Webster's New Collegiate Dictionary (1981) defines a diffuser as a device for reducing the velocity of fluid through a system and increasing static pressure. The present invention relates to the most typical diffuser having an inlet flow cross-sectional area that is smaller than the flow cross-sectional area of the outlet. Diffusers can be used in particular to reduce the flow rate and increase the hydraulic pressure, but sometimes they are simply used according to the physical needs to increase the flow cross-sectional area of the passage, such as for connecting pipes of different diameters.

As used later in the description or claims, the diffuser has an inlet flow cross-sectional area that is smaller than the outlet flow cross-sectional area, and refers to a flow transport passage that reduces the flow rate and increases the static pressure in the main flow direction.

If the wall of the diffuser is too steep with respect to the main flow direction, two-dimensional boundary layer separation may occur in the streamlined direction. As used in the description or claims of the present invention, two-dimensional boundary layer separation in the streamlined direction means separating the total fluid from the surface of the body, which is the flow near the wall moving in the opposite direction of the total fluid flow direction. . Such separation will result in high losses, low pressure recovery and low speed drops. When this happens, the diffuser is said to stall. When the momentum in the boundary layer does not overcome the pressure increase as it descends downstream along the wall, stall occurs at the diffuser, at which point the flow velocity near the wall causes the direction to actually change. From that point on the boundary layer it cannot remain attached to the wall, creating a separation zone downstream of it.

To prevent stalling, the diffuser can be made long to increase the required diffusion angle. However, longer diffusion lengths are not acceptable in all applications due to space and weight limitations, for example. Thus, it is very possible to diffuse faster without stall (i.e. at shorter distances), or conversely, to expand to a larger flow cross section for a given diffuser length than can be present with prior art diffusers. desirable.

Conventional diffusers could be either one or two dimensional. Two-dimensional diffusers typically have four sides, two opposite sides parallel to each other, and the other two opposite sides spread toward each other toward the diffuser outlet. Conical and annular diffusers are also sometimes referred to as two-dimensional diffusers. Annular diffusers are often used in gas turbine engines. The three-dimensional diffuser may for example have four sides, with two pairs of opposite sides spreading out relative to each other.

One embodiment of a diffuser is present in catalytic conversion systems for automobiles, trucks and the like. Converters are used to reduce emissions (nitrogen oxides) and to oxidize carbon monoxide and unburned carbon water. The catalyst of choice is currently platinum. Platinum is very expensive, so it is important to use it effectively, which means that it has a long enough residence time to expose the high surface of platinum to the gas and to do acceptable work with as little catalyst as possible.

In recent years, exhaust gases are transported to transducers in cylindrical pipes or conduits with flow cross-sections of between about 2.5 and 5.0 square inches. The catalyst (present in the form of a platinum plated ceramic monolith or a plated ceramic fillet bed) has, for example, an elliptical flow cross section of two to four times the circular inlet conduit flow cross section.

The diffusion is very short due to space constraints. And the half angle of its flare can be 45 °. When the half angle exceeds about 7 °, the flow separates from the wall, so the exhaust flow from the inlet pipe remains in the cylinder and mostly impinges on a small portion of the catalytic oval inlet area. Due to insufficient diffusion in the diffusion, there is an uneven flow through the catalyst bed. These issues were presented by Daniel W. at the International Fuel and Lubrication Conference and Fair in Philadelphia, Pennsylvania, October 6-9, 1986. Wendland and William R. Discussed in SAE Document No. 861554, entitled Visualization of Flow Inside Automotive Catalytic Converters, published by Masses. In order to use the platinum catalyst more effectively and thereby reduce the required amount of catalyst, it is necessary to be able to diffuse the fluid better within such a short distance of the diffusion.

One object of the present invention is to provide a diffuser with improved operating characteristics.

Another object of the present invention is to provide a diffuser capable of performing the same amount of diffusion at a length shorter than the length according to the prior art.

However, another object of the present invention is to provide a diffuser capable of larger diffusion than a diffuser according to the prior art at a given length.

Accordingly, the present invention comprises two thin sidewall members disposed upstream of the conduit of the diffuser inlet and spaced apart from the conduit wall surface, the members being opposite in circumferential direction around the respective axis extending in the total fluid flow direction adjacent to the plate-like member. It has a rotating downstream that causes a number of adjacent vortices in the rotating diffuser section.

In one embodiment, the rotating member is disposed upstream of the diffuser inlet and is tightly supported with the surface of the diffuser inlet conduit. The convolution of the member includes a plurality of adjacent and alternating U-shaped lobes and grooves extending in the total fluid flow direction near the member and ending at the wavy downstream edge. The depth and lobe height of the grooves increase in the downstream direction, and the grooves and lobes are contoured and dimensioned such that each groove creates a pair of adjacent swirls downstream of the member downstream edge. The vortices energize the boundary layer adjacent the diffuser wall and delay or eliminate the separation. Thus, the diffuser can achieve the same amount of diffusion at shorter distances (i.e. can effectively operate at larger angles of diffusion) than would have been possible with prior art diffusers, or can provide a greater amount of diffusion for a given length. can do. Properly orienting the member, its grooves and lobes will result in the fluid leaving the grooves with the direction of the momentum that carries them to the diffuser wall surface.

The vortex from each sidewall surface at the groove exit will be a large vortex (large means that the vortex has the same diameter as the entire groove depth). These two vortices (one on each sidewall) saturate the flow field, which rotates in the opposite direction and tends to cause flow from the groove and from the near total fluid to immediately mix with the fluid near the diffuser wall surface downstream of the member. do. The net effect of these phenomena is to direct the total fluid outwards towards the diffuser wall surface and to generate a mixture of the total fluid within the diffuser compartment, all of which energize the boundary layer along the diffuser wall, thereby improving the diffuser performance. It is to let. If the circuit member is not close enough to energize the boundary layer and delay the separation or the diffuser wall is too inclined to prevent separation, the total diffuser performance is still due to the mixing of the total fluid in the diffuser caused by the large vortex Will be able to improve.

The grooves and lobes of the present invention are contoured to be full (ie flow direction two-dimensional boundary layer separation does not occur in the grooves). Thus, as this results in the separation fluid entering the valley, it is important that there is no streamlined two-dimensional fluid boundary layer on the member immediately upstream of its valley, which prevents the occurrence of strong swirling teeth. The prevention of streamlined two-dimensional boundary layers in the groove is an important consideration in the design. For example, two-dimensional boundary layer separation may occur if the slope of the groove bottom is too steep with respect to the near total fluid flow direction.

In order to reduce losses, the grooves and lobes have a U-shape in the cross section perpendicular to the downstream direction and are bent smoothly (for example, the groove side is smoothly connected to the groove bottom). The grooves and lobes form a smoothly waved surface that is wavy in cross section perpendicular to the downstream direction.

According to another aspect of the invention, the fluid flowing out of each groove preferably has a side velocity element as small as possible to minimize the secondary flow loss. For this reason, the groove side wall is parallel to the total direction of fluid flow entering the groove for a considerable distance downstream of the groove exit.

One important advantage of the present invention relates to the ability to enhance diffuser performance without introducing a loss of flow due to its presence in the flow field.

According to another aspect of the invention, it is preferred that the groove sidewall at the outlet is steep. It is believed that this increases the strength of the vortex produced by the side walls. The word steep, as used herein and in the claims, in a cross section perpendicular to the direction of the groove length, lines that contact the steepest point on each sidewall intersect to form an inclusion angle of less than about 120 °. . Most preferably, the walls are parallel to each other. For this application, the included angle may be considered 0 ° when the walls are parallel.

Walter M. United States Patent Application No. 857,907, filed April 30, 1986 by Fritz, Jr., describes wing portions, wherein the streamlined valleys and ridges formed therein are waves-like. Form a thin back edge. The valleys on one surface form the floor on the opposite surface. By providing a three-dimensional relief for low momentum boundary layer flow, the valleys and ridges help to delay or prevent the sudden effect of two-dimensional boundary layer separation on the wing suction surface. However, the present invention is intended to enhance the performance of the diffuser located immediately downstream of the circuit member.

These and other objects, features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments of the invention as shown in the accompanying drawings.

As will be described in more detail below, the rotating wall member of the present invention is used directly at the diffuser inlet or upstream of the diffuser inlet to facilitate the fluid diffusion and to create a fluid flow downstream of the member that energizes the boundary layer along the diffuser wall. The fluid mechanics used here is similar to the hydrodynamics contained in U.S. Patent No. 117,770 named Line Plates for reducing floor drags filed by Robert W., Patterson et al. On November 5, 1987. It is a partial consecutive application of the application. Figures 14 and 14A of US Patent 117,770 are reproduced in Figures 1 and 1A of the present application. In that application it is placed upstream of the bulky end surface of the moving bucket to reduce the underlying drag by creating a certain hydrodynamic flow pattern downstream of the plate of the circuit plate.

As described herein, with reference to FIGS. 1 and 1A, the article on which the foundation is based is generally indicated by reference numeral 200. The article 200 has a smooth, relatively flat top surface 202 through which fluid flows in the generally downstream direction indicated by arrow 204. The article 200 has a blunt base or end face 206. In the absence of convolutional members it is assumed that flow along the surface 202 is separated from the article along the line 208. For purposes of this discussion, the dividing line 208 will be considered the beginning or upstream edge of the blunt end face 206.

The convex wall member or plate 210 is disposed spaced apart from the surface 202 by support members or spaced stand 212, only one of which is shown in the figure. The plate 210 includes an upstream or introduction edge 214 and a downstream or trailing edge 216. The plate may be very thin, while the inlet edge 214 should be rounded, such as the introduction edge of the aircraft wing, in order for the uniform flow of contact to begin to flow over the top and bottom surfaces 218 and 220 of the plate. do. If desired, such as to reduce weight or minimize the base drag of the plate itself, the plate may be tapered to a smaller thickness towards the rear edge 216.

A plurality of U-shaped valleys 222 and lobes 224 are formed in the plate. Adjacent valleys and lobes are smoothly integrated with each other by forming a wavy or conical downstream that ends in a wave shape at the rear edge 216. Although the bone depth can remain constant thereafter as far as the bone depth can be reached up to the minimum downstream of the bone exit, the bone depth should be increased downstream for the resulting vortex. In FIG. 1, the plate introduction edge 214 is straight and the plate is flat for a short length. The valleys and lobes are smoothly connected into a flat portion. Preferably and as shown, the bone depth (and lobe height) is (0) at their upstream end and maximum at the downstream edge 216. However, the plate leading edge 214 may have a low amplitude waveform and the bone depth may be increased from its minimum width. The contour and shape of the bones and lobes are chosen so that the bones can be filled throughout their length.

Since the plate 210 is attached to the article 200, the plate itself creates a loss (drag) that should be minimized. If there are no lines and a smooth virtual plate that is generally parallel to the plane placed thereon, the floors and valleys of the valleys and lobes extend the same distance above and below the virtual plate.

The valleys and vortices created by the valleys and lobes on each side of the plate are shown schematically in the figure. A vortex with an axis in the direction of total fluid flow is created from each sidewall of each valley. Such a valley 226 creates a vortex 228 clockwise from the right wall (as shown in FIG. 1) and a vortex 230 rotating counterclockwise from its left wall. Adjacent valleys 232 on the opposite side of the plate to the left of the valleys 226 are counterclockwise from the right wall to engage or reinforce the counterclockwise rotation vortex 230 to effectively produce a single stronger vortex. Rotating whirlpool 234 is made. Similarly, the left wall of the valley 236 creates a clockwise rotational swirl 238 that engages the clockwise rotational swirl 228 emerging from the valley 226.

If the plate 210 is properly spaced and oriented relatively to the surface 202 and the blunt end surface 206, then the vortices generated therein energize the boundary layer flow over the surface 202 downstream of the plate, This results in the flow being attached on the article surface above the virtual separation line 208. Moreover, the groove fluid flowing from the bone and onto the surface 202 is otherwise directed downward into the space behind the blunt end surface in order to reduce the separation bubbles formed thereby reducing the base drag further (in FIG. 1).

For purposes of the following discussion and still referring to FIG. 1, P is the length of the wave from floor to floor at plate back edge 216. A is the wave height or amplitude (and may be referred to as bone depth) from the floor to the floor, and H is the distance between the closest wave peak of the surface 202 and back edge 216. And D is the distance between the trailing edge 216 and the blunt end, which is the dividing line 208 as described above. Preferably the wave length P from peak to peak is constant throughout the bone length.

Since the vortices are not sufficiently formed for a certain distance of the plate edge 216 and because the vortex needs to provide energy to the boundary layer upstream of the line 208, the rear edge 216 is blunt end surface 206. It is located at the same distance (D) from one to two oscillation widths (A) upstream of. If D is less than A or even 0, it does not mean that no benefit is obtained. However, it is believed that this benefit is diminished. Similarly, if the plate is placed too upstream from the end surface 206, the vortices are very or completely attenuated before reaching the end surface 206 and thereby provide little or no benefit.

The distance H should be large enough to avoid the occurrence of a second flow field or blockage near the surface 202 that may confuse and lead to boundary layer separation on the surface 202 before reaching the line 208.

H should be at least about the thickness of the boundary layer. At the same time, the distance H should be small to keep the vortex as close as possible to the surface 202. The slope θ of the bone bottom with respect to the total fluid flow direction adjacent to the plate cannot be too shallow or too steep. If the slope is too shallow, the occurrence of vortex forces may be too weak, or they may not occur at all as a result of loss due to surface friction. (θ) is believed to be at least about 5 °. On the other hand, if the slope is too steep, the bone will not be filled (ie there will be a two-dimensional flow boundary layer separation within the bone). This will interfere with the formation of the vortex. The longer the slope, the greater the vortex strength, as long as the valley is full. It is believed that the slope above about 30 ° will not be full. The appropriate angle for any particular application will need to be determined by experiment.

As far as the steepness of each bone sidewall is concerned, generally parallel sidewalls are preferred for a distance at the back edge 216 and upstream. The steepness of the sidewalls can be represented by the included angle (C, described in FIG. 1), which is the angle between the steepest points along the opposite sidewall of the valley. As mentioned above, the closer the angle C is to (0 °), the better. However, the angle (C) should not be greater than about (120 °) at the goal exit.

Preferably the total length of the plate from the leading edge 214 to the rear edge 216 should be equal to or slightly larger than the length L of the valleys and ridges. Although not destructive, excessive length offers no benefit and simply adds unnecessary surface drag, cost and weight. As noted above, the introduction edge 214 should be rounded, creating a vortex that is strong enough to provide benefits (ie, drag reduction) which are considered valuable when the valleys are full throughout the length and take into account the needs of a particular application. The valleys and lobes are sized and shaped at full length.

In general, the wave length P should not be less than about half or greater than about 4 times the wave amplitude A in order to form a strong vortex without inducing excessive pressure losses. The sum of the downstream outflow cross-sectional flow areas at the bone exit must be large enough relative to the total downstream outflow area of the blunt end surface to have a good impact on the foundation drag. Practical considerations such as physical limitations, costs and weights, and even coalescing, have varying degrees of impact on the final configuration chosen.

Figures 2-3 show other applications for the line wall members or flat plates described in Figures 1 and 1A. And its application is the subject of the present invention. With reference to FIGS. 2-3, the conduit is generally indicated by the reference numeral 300. Conduit 300 includes conveying portion 302 and diffuser portion 304. Both are rectangular in cross section taken perpendicular to the flow direction and the flow direction is in the direction of arrow 306. The delivery portion 302 and the diffuser portion 304 both include flat and parallel sidewalls 308. The diffuser portion 304 thus provides only two-dimensional diffusion. The plate 310 is a shared portion of the conveying portion 202 and the diffuser portion 304 and is in the same space as the diffusion inlet 312. Line plate 314 is disposed within conduit carrier 302. One is attached to the upper wall 316 and the other is attached to the lower wall 318 of the carrying portion by the legs 320. The large vortex generated by the plates is shown by spiral 322 and has axes generally parallel to the downstream direction 306.

The preceding description of FIGS. 1 and 1A relating to the size, shape, contour, and position of the circuit plate 210 equally applies to the circuit plate 314, and in FIG. Otherwise it corresponds to line 203 in FIG. 1 inside the diffuser to split at the inlet.

Thus, not only the angle [theta] but also the dimensions L, D, H, A and P must all be selected in the same manner as described with respect to FIG. 1 and FIG. In the application of FIGS. 1 and 1A, the circuit member reduces the underlying drag on the moving object, while the present invention provides energy to the boundary layer along the diffuser wall and generalizes the total fluid flow within the diffuser 304. This will increase the performance of the diffuser by causing mixing and diffusion. Two-dimensional diffusers, such as those of FIGS. 2 and 3, are tested with or without circuit flat. With respect to FIGS. 2 and 3, the diffuser has the following dimensions. B = 53.59 cm; F = 83.06 cm; And E = 13.72 cm, with respect to line plate, D = 5.84 cm; L = 16.00 cm; H = 0.64 cm; A = 5.84 cm; P = 4.32 cm; Wi = 1.27 cm; Wo = 3.05 cm; θ ₁ = 11 °; And θ ₂ = 15 ° sidewalls of each valley are parallel to each other as shown in FIG. 3. 2 and 3 depict the test instrument in the dimensions defined above, but such dimensions and their relative to each other are not intended to limit the invention. For example, the valleys on both sides of each plate may be the same (ie, Wi = Wo and a ₁ = a ₂ ).

Appropriate configurations for particular applications can only be obtained using the guidelines presented herein.

In a series of two tests (i.e. with line plate and without line plate), the diffuser's coefficient of performance is measured for the diffuser half angle (α) from about 2 ° to 10 °, which is the exit band from about 1.4 to 3.1. It is equivalent to the entrance ratio range. The results of the test are shown in the graph of FIG. 4, where curve A represents the uncirculated flat plate and B represents the use of the circuit flat. For diffuser half angles greater than about 6 ° (at least up to the maximum angle tested), the present invention outperforms the same diffuser without line plate (in terms of performance factor), at 10 ° half angle the present invention It is larger than the maximum performance factor of the diffuser (ie at 6 ° half angle) and about 28% larger than that of the same diffuser with 10 ° half angle and uncirculated plate. The present invention delays the onset of boundary layer separation to higher half angles.

5 and 6 illustrate the use of the present invention with a three-dimensional diffuser 400 that is axial symmetric. In that case the convoluted thin wall member 402 is axisymmetrical, where the lobes and valleys extend downstream and radially (in height and depth).

The present invention can also be used with a stepped diffuser as shown in FIG. 7 and FIG. A stepped diffuser is considered a diffuser with an extremely steep diffuser half angle, such as 90 °.

This type of diffuser is typically a conduit that includes a stepwise change in passage cross-sectional flow area. Fluid flowing through conduit 502 in the downstream direction in FIGS. 7 and 8 is represented by arrow 300. The conduit has an inlet 501 of rectangular cross section and also an outlet 503 of rectangular cross section. The inlet has side walls 504 parallel to each other and downstream, and the top and bottom walls 507 are also parallel to the downstream and to each other.

Step change in the passage cross-sectional area occurs in plane 508. Discontinuities are only at the top and bottom walls 507. The side wall 504 is parallel to the total length of the outlet portion 503 even beyond the discontinuous surface. Line plates similar to those shown in FIGS. 2 and 3 are disposed and supported adjacent to each of the upper sidewall and the lower sidewall 507. The distance D upstream of the plate upstream of plane 508 should be somewhere from about zero to twice the depth of the bone, preferably one to two times the depth of the bone.

Although with a stepped diffuser such as that shown in FIG. 7 the rotating plate cannot keep the flow attached to the wall, the circuit plate is the distance downstream of the plane 508 where the attachment to the top and bottom walls of the flow occurs. Can be reduced. The bottom line is that the cascading diffuser will have less loss than would otherwise be possible without the use of line plates. Also, in this embodiment a single perhaps larger (in terms of wave amplitude) plate placed in the center of the conduit will also benefit, even if the line plates are placed adjacent to each top and bottom wall. .

Walter Am, filed Heat Transfer Enhancement, filed December 29, 1986. Shared US Pat. No. 947,349 to Fritz, Jr., et al., Describes a line plate similar to that used herein, but is used in heat transfer devices that enhance heat transfer across walls having fluids flowing on both sides thereof. 9 and 10 of the present application correspond to FIGS. 8 and 9 of the known application, respectively, and define a circuit wall or plate 800 disposed in a tube or conduit carrying a fluid flowing in the direction of arrow 804. Illustrated. As best shown in FIG. 10, the plate 800 extends generally across the tube along its diameter. Lobes and valleys downstream of the plate 800 remove adjacent thermal vortex layers from the inner wall surface 810 of the tube and cause adjacent reverse rotational vortices 806 and 808 to mix the central flow with the fluid flowing adjacent to the wall. Occurs downstream. It is a net effect to increase the coefficient of heat transfer between the fluid and the walls of the conduit 802 for the purpose of eventually exchanging heat energy between the fluid in the conduit and the fluid surrounding the conduit. As shown in FIG. 9, it is contemplated to place multiple rotating plates 800 in conduits spaced along the axis of the conduit at a distance that will ensure the enhancement of heat transfer along the full length of the conduit.

This is of course required because the vortices generated by each plate 800 eventually disappear due to wall friction and viscous effects.

Although the present invention is not a heat transfer mechanism, it utilizes the same line plate disposed in the conduit for the purpose of affecting fluid flow dynamics in the conduit diffusion downstream of the plate. Such plates may be subjected to large vortices to energize the boundary layer to increase diffuser performance and to increase total fluid mixing (which also increases diffuser performance) across the duct in a direction perpendicular to the total fluid flow. We found it to be generated.

A special application for the wall members of the present invention is used in catalytic conversion systems such as for automobiles. Such a conversion system is indicated by reference numeral 900 in FIGS. 11 and 12. The conversion system 900 includes a cylindrical gas delivery conduit 902, an annular gas receiving conduit 904, and a diffuser 906 that is a transition duct or interlude therebetween.

The total fluid flow direction is indicated by arrow 905 and parallel to the axis 907 of the delivery conduit 902. The diffuser 906 extends from the circular outlet 908 of the delivery conduit to the elliptical inlet 910 of the receiving conduit 904.

The receiving conduit holds the catalyst bed (not shown). The catalyst bed is a Hanacom monolith with honeycomb cells parallel to the downstream direction.

The entrance face of the monolith is at the entrance 910. However, it may be further moved downstream to allow for an additional diffusion distance between the delivery conduit outlet 908 and the catalyst. Catalytic converters and catalysts for catalyst beds are known in the art.

As best shown in FIG. 12, diffusion only occurs in the direction of the major axis 12 of the ellipse. The shortening of the ellipse maintains a constant length equal to the diameter of the delivery conduit outlet 908. Thus, the diffuser of this embodiment is an effective two-dimensional diffuser. Placed within the delivery conduit 902 is a line plate 914 with a number of parallel valleys therein. The plate 914 extends across the conduit 902 along a substantially radial plane perpendicular to the major axis 912 of the elliptical gas receiving conduit 804.

Plate 914 is attached to conduit 902 at its axial edge 920.

The valley sidewalls 924 are parallel to each other at the downstream wavy edges 922 of the plate and also parallel to the elliptic major axis 912. The appropriate plate size and configuration need to be determined by experiments using the knowledge of the present invention as a guide, but at least two complete bones must be present on one side of the plate (there are three in the example of FIG. 12). It is believed that they must have a depth in the confluence downstream of a large portion of the available area in the conduit. Although it is believed that the best results are obtained when the direction of bone depth is parallel to the main direction of diffusion, the enhanced diffusion is directed to the plate 914 oriented in virtually any direction, such as when it is perpendicular to the direction shown in FIG. It is believed that it may be obtained.

If the conduits 902 of FIGS. 11 and 12 have a diameter of 5.08 cm, one set of possible dimensions for the plate 914 may be a 15 ° bone slope; Wave amplitude (A) of 2.54 cm; 0.76 cm bone butterfly (w); And a plate thickness of 0.08 cm.

13 and 14 show another embodiment of a catalytic conversion system. Represented by the present system reference 950, it includes a cylindrical gas delivery conduit 952, an elliptical gas receiving conduit 954, and a diffuser 956 that is a transition duct or conduit therebetween.

The total fluid flow direction is indicated by arrow 958 and parallel to the axis 906 of the delivery conduit. The diffuser 956 extends from the circular outlet 965 of the delivery conduit and smoothly transitions to the elliptical inlet 964 of the receiving conduit, which is a catalyst bed (not shown) whose inlet side coincides with the plane of the inlet 964. Keep).

In this embodiment, the diverter system is considered to match the two-dimensional diffuser described in FIGS. 2 and 3. Thus, a pair of slightly curved line plates 966 are disposed in the delivery conduit 952, both of which are in a direction generally parallel to the minor axis 968 of the elliptical receiving conduit and perpendicular to the diameter line perpendicular to the plinth 970. Extends across it.

The plate 966 is located up to, but spaced from, the surface of the delivery conduits disposed above and below the diameter line or the tip 968.

Plane 972 shows the axial position along diffuser 956 where two-dimensional streamlined boundary layer separation will occur if no circuit plate 966 is used.

The downstream waved edge 924 must be spaced downstream of plane 972 to delay flow separation above plane 972. If the distance D is about one to two times the maximum difference amplitude of the plate 966, it is believed that the best results will be obtained. This allows some downstream distance for the large vortex caused by the circuit plate to develop more fully before reaching the position of plane 972.

In this embodiment, the waveforms of the upper plate and the lower plate are out of phase. The waveforms may also be in phase as shown in the embodiments of FIGS. 7 and 8, which may create a combination of vortices generated, thereby increasing further mixing.

If a diameter of 5.08 cm is assumed for the delivery conduit 952, it is recommended that the maximum wave amplitude be between about 1.27 cm and 1.91 cm for the liver plate 966.

While the invention has been shown and described with respect to its preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the claimed invention.

Claims (30)

A diffusing device having conduits for conveying fluid in a downstream direction and having wall means for forming an inner flow surface of said conduits, said conduits comprising an upstream fluid transfer section having an outlet having a first flow cross-sectional area; The downstream fluid receiving portion has an inlet end of the second cross-sectional area that is greater than the first flow cross-sectional area, the wall means connecting the outlet end and the inlet end whereby fluid flows from the outlet end to the fluid receiving part. A thin vortex generating wall member having a downstream extending flow surface disposed in and facing the fluid transfer conduit upstream of the outlet at the outlet end, the member extending in the total fluid flow direction when moving downstream; A plurality of contiguous, alternating, spaced apart from the inner flow surface and ending at the downstream edge And a convex of U-shaped lobes and valleys, wherein the bone depth and lobe height increase in the total fluid flow direction, to ensure that each valley produces a pair of adjacent large vortices downstream of the outlet end, The contour and dimension of the valleys and lobes are selected and the pair of vortices issued by each valley rotate in opposite directions around each axis extending in the downstream direction. The apparatus of claim 1, wherein the valleys and lobes each start the upstream edge with no depth and no height. The lobe of claim 1, wherein each of the valleys has a smooth U shape along its length in a cross section perpendicular to the downstream direction, and a lobe adjacent the valleys to form a smooth waved surface in a cross section perpendicular to the downstream direction. Diffusion device characterized in that the soft connection. 4. The diffusing device of claim 3, wherein the wave amplitude from the downstream edge to the floor is A and the downstream edge is positioned between about 1A and 2A of the end of the delivery conduit. 4. The diffusing device of claim 3, wherein the outlet end of the delivery conduit and the inlet end of the intake conduit are located in the same plane, whereby the flow cross-sectional area is substantially step-like in the plane. . 4. The apparatus of claim 3, wherein the intake conduit inlet end is spaced downstream from the intake conduit outlet end, the apparatus comprises a diffuser portion coupling the outlet end to the inlet end, the diffuser portion from the outlet end. And a diffuser having a cross-sectional area gradually increasing to the inlet end. 7. The downstream edge of the wall member according to claim 6, wherein the downstream edge of the wall member is arranged such that the massive vortex generated from the valleys increases the number of performances of the diffuser which creates a mixture of total fluid in the diffuser portion. Diffuser. 7. The large volume of vortices produced by the member in such a way that the wall member is sufficiently close to the inner flow forming surface of the fluid delivery conduit to energize the boundary layer within the diffuser and increase the coefficient of operation of the diffuser. A diffuser device, characterized in that disposed. 7. The wall member of claim 6, wherein the flow separation from the diffuser wall begins at a diffuser half angle greater than the angle that would have started if the convolutional member had not been present. Diffuser. 7. The diffusing device of claim 6, wherein said delivery portion of said conduit is symmetric about a downstream extension axis. The apparatus of claim 10, wherein the diffuser is a three-dimensional diffuser and the wall member is symmetric about the axis. 11. The diffusing device of claim 10, wherein said delivery portion is cylindrical and said wall member extends across a diameter plane. 7. The diffusing device of claim 6 wherein said wall member extends beyond a majority of a butterfly of said delivery portion of said conduit. 4. The slope of claim 3 wherein the slopes of the bottoms of the valleys relative to the direction of total fluid flow are between 5 ° and 30 °, each of the valleys comprising a pair of opposing sidewalls, wherein the edge of the member downstream edge And the lines connecting the pair of side walls at each steep point to each other form an inclusion angle between 0 ° and 120 °. The device of claim 3, wherein the slopes of the bottoms of the valleys relative to the total fluid flow direction are between 5 ° and 30 °, each valley comprising a pair of opposing sidewalls that are generally parallel to each other. Fusing device. 7. The apparatus of claim 6, wherein the apparatus is a catalytic converter for delivering exhaust gas from the delivery section to the reception section and through the reception section, wherein the reception section has a catalyst bed disposed therein. Device. 17. The diffusing device of claim 16, wherein said delivery portion is cylindrical and said diffuser and receiving conduit portion are generally elliptical in cross section perpendicular to the downstream flow direction. 18. The apparatus of claim 17, wherein the diffuser is a two-dimensional diffuser having a diffuser parallel to the major axis of the elliptic cross-sectional area. A diffusing device according to claim 17, wherein the direction of the bone depth is parallel to the major axis of the elliptical cross-sectional area. 20. The diffusing device of claim 19, wherein each wall member is disposed generally along a plane with a ring comprising a minor axis of the elliptical cross section, the valleys alternately above and below the plane. A gas delivery conduit having an outlet of a first flow cross-sectional area, a receiving conduit comprising a catalyst bed having an inlet of a second cross-sectional area larger than the first flow cross-sectional area and a delivery conduit outlet, and a flow surface connecting the outlet to the inlet; A catalytic conversion system comprising an individual conduit defining a diffuser having: a vortex generating wall member having a downstream induction surface disposed opposite said opposing conduit at said outlet, an upstream edge and a downstream edge, said member Has a plurality of adjacent and alternating U-shaped lobes and valleys extending in a nearby total flow direction and spaced apart from the inner flow surface and ending at the downstream edge, wherein the bone depth and lobe height are in the total fluid flow direction. A pair of contiguous, each goal being downstream of said outlet and within said dog conduit The valleys, lobes, contours and sizes are determined to ensure the creation of a large vortex, and the pair of adjacent vortices created by the respective valleys is rotated in opposite directions around each of the axes which are extended in the downstream direction. Characterized catalytic conversion system. 22. The catalytic conversion system of claim 21, wherein each of the valleys has a downstream extending bottom portion having a slope that is less than about 5 degrees and not greater than about 30 degrees with respect to the downstream direction. 23. The lobe of claim 22, wherein each of the valleys has a smooth U-shape along its length in a cross section perpendicular to the downstream direction, and a lobe adjacent the valleys to form a smooth waved surface in the cross section perpendicular to the downstream direction. Catalytic conversion system, characterized in that the soft connection with the field. 24. The catalytic conversion system of claim 23, wherein the wave amplitude from floor to floor of the downstream edge is A and the downstream edge is located between about 1A and 2A downstream of the delivery conduit outlet. 23. The method of claim 22, wherein the downstream edge of the wall member is arranged such that the large vortex from the valleys releases a mixture of total fluid in the median conduit and increases the coefficient of performance of the diffuser. Catalytic Conversion System. 24. The catalytic conversion system of claim 23, spaced apart from each other and disposed adjacent and spaced apart from opposite inner surfaces of the delivery conduit. 24. The catalytic conversion system of claim 23, wherein the delivery conduit outlet is circular and the receiving conduit inlet is elliptical, and the direction of the depth dimension of the valleys is generally parallel to the major axis of the elliptical inlet. The catalytic conversion system of claim 23, wherein each of the valleys comprises a pair of parallel and opposing sidewalls. 29. The catalytic conversion system of claim 28, wherein the diffuser is a two-dimensional diffuser whose direction of diffusion is generally parallel to the valley sidewalls. 24. The method of claim 23 wherein the valleys and ridges are sized, contoured and arranged to fill over their length, whereby a two-dimensional boundary layer separation over the valleys and lobes occurs during normal operation. Catalytic conversion system characterized in that not.

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