JPH0512247B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a Coanda spiral flow generation device. More specifically, the present invention stabilizes Coanda spiral flow and suppresses backflow, which is useful for transporting, drying, and classifying powder and granular materials, transporting fibrous materials, opening fibers, and transporting gaseous fluids. This invention relates to an improved Coanda spiral flow generation device that can generate Coanda spiral flow.

(Background Art) Regarding fluid motion, the inventor of this invention differs from the conventional concept of laminar flow/turbulent flow, and although it is in the turbulent region based on conditions such as Reynolds number, it is a physical phenomenon that is completely different from turbulent flow. In addition, we have proposed the Coanda spiral flow and its utilization method as an example of the industrial use of this physical phenomenon.

Regarding this spiral flow, when a vector in the pipe radial direction is added to the fluid vector in the pipe direction, the fluid swirls, a dynamic boundary layer is formed near the inner wall of the pipe based on this swirling flow, and the fluid spirals. It moves at high speed in the direction of the pipe while drawing. In this spiral flow, the fluid moves at high speed, and due to the presence of a dynamic boundary layer, even if solid particles are present, they do not collide with the inner wall of the pipe as in the case of turbulent flow. In addition, in such Coanda spiral motion, density concentration occurs at the center of the tube axis, and unlike normal turbulent flow, the velocity distribution is concentrated at the center of the tube axis, and the degree of turbulence in the flow is small. Show characteristics.

Therefore, when powder and granules are transported through pipes using air, etc., the Coanda spiral flow prevents contact and collision of the powder with the inner wall of the pipe, and prevents damage and wear of the powder. In addition, abrasion of the inner wall surface of the pipe is also suppressed.

In addition, when transporting air, gas, etc., pressure loss due to contact with the inner wall surface of the pipe can be significantly suppressed.

Therefore, even if it is a long-distance pipeline, high-speed transportation with little pressure loss is possible.

The centrifugal force generated by this spiral motion, concentration of density at the center of the tube axis, and concentration of velocity distribution are used to classify solid particles and remove water contained in them during transportation by air, etc. It can also be dried.

Furthermore, it is possible to defibrate aggregates of short fibers during pipe transport, and to smoothly route long filaments such as wires and ropes even in long-distance pipes of 500 m or more. .

Although Coanda spiral flow has such excellent characteristics, there are still points that need to be improved regarding its generation.

This is because backflow of fluid often occurs in the region where Coanda spiral flow is generated, and the Coanda spiral motion may become unstable due to this backflow phenomenon.

Therefore, in the region where Coanda spiral flow is generated, there is a need for a measure to prevent the generation of backflow in order to take advantage of its excellent characteristics and to maintain these characteristics stably.

(Purpose of the Invention) This invention was made in view of the above-mentioned circumstances, and is intended to suppress the generation of backflow and the destruction of the spiral motion to stabilize the Coanda spiral flow, which has already been put into practical use. The object is to provide an improved method for realizing Coanda spiral flow, in particular a device therefor.

(Disclosure of the Invention) In order to achieve the above object, the Coanda spiral flow generating device of the present invention has a cylindrical pipe whose one end face is connected to a transportation pipe, and the inner wall of the other end face of the pipe is smoothly curved. An annular slit is formed between the auxiliary cylinder and the bent surface of the auxiliary cylinder, which has an inner wall bent at a right angle or an acute angle facing the surface, and a radius of the fluid is formed from the annular slit to the inner wall surface in the pipe connection direction. A Coanda spiral flow generation device having an inclination to impart a direction vector, characterized in that the cross-sectional area of the opening end surface of the auxiliary cylinder is adjustable, and the auxiliary Coanda flow generation device is provided on the opening end surface of the generation device. It is said that

The spiral flow generating device of the present invention will be described in more detail with reference to the attached drawings.

FIG. 1 shows an example of the apparatus of the present invention. In this example, the Coanda spiral flow generation device consists of a main Coanda spiral flow generation device 1 and an auxiliary Coanda flow generation device 2. The main Coanda spiral flow generation device 1 includes a cylindrical pipe 4 connected to a pipe line 3, an auxiliary pipe 5,
and the smooth curved surface 6 of the cylindrical tube and the right-angled or acute-angled bent end surface 7 of the auxiliary tube 5 facing thereto.
The annular slit 8 formed between the auxiliary cylinder 5 and the open end surface 9 of the auxiliary cylinder 5 constitute the annular slit 8 formed between the auxiliary cylinder 5 and the auxiliary cylinder 5. From the annular slit 8 of this device 1, a pressurized fluid, such as air or a gas such as an inert gas or a reactive gas, or a liquid, can be introduced uniformly in order to generate a spiral flow 10 in the conduit 3. Pressurized fluid is supplied from a supply pipe 12 through a distribution chamber 11 for the purpose of Further, the interval between the slits 8 can be adjusted depending on the desired flow velocity and the state of the Coanda spiral flow. This interval may be fixed.

The cross-sectional area of the opening end surface 9 of the auxiliary cylinder 5 can be adjusted by tightening the adjustment piece 13 and the depth of insertion into the opening end surface 9 of the auxiliary Coanda flow device 2. can. Adjustment of this cross-sectional area is necessary to control the absorption and introduction of external fluids.

Note that the cylindrical tube 4 has an inclination of an angle θ.

The auxiliary Coanda flow device 2 also has substantially the same structure as the main Coanda spiral flow generation device 1. Pressurized fluid is inserted through the annular slit 14. This auxiliary Coanda flow device can be freely inserted into the open end surface 9 of the main Coanda spiral flow generation device 1.

In the Coanda spiral flow generation device having such a structure, when pressurized fluid is inserted through the annular slit 8, at the outlet of the slit 8, the pressurized fluid moves in a streamline as indicated by the arrow α due to the Coanda effect. A dynamic boundary layer is formed near the inner wall of the pipe. Also,
A large negative pressure area is generated on the opposite side of the slit 8,
The inflow of fluid from the open end face 9 is promoted. The motion vector of the pressurized fluid and the motion vector of the fluid from the opening end surface 9 are combined to form a spiral motion 1.
Generates 0. When introducing powder from the opening end face 9, this powder is introduced into the spiral motion 1.
0 through the conduit 3.

Since the Coanda flow is previously introduced by the auxiliary Coanda flow device 2, a buffer space is formed near the outlet of the slit portion 8 of the main Coanda spiral flow generation device 1 by inserting the device 2. Therefore, compared to the case where the auxiliary Coanda flow device 2 does not exist, the pipe line 3
The Coanda spiral motion 10 is stabilized, and the backflow phenomenon is also suppressed.

This suppression of the backflow phenomenon can also be explained with reference to FIG.

That is, although FIG. 5a shows the case where the auxiliary Coanda flow device 2 is not used, when the pressurized fluid is fed from the annular slit 8, the inner wall surface of the cylindrical tube 4 has a high temperature due to the Coanda effect. A boundary layer of velocity is formed. Therefore, the velocity distribution becomes a protruding distribution state along this inner wall surface. External fluid is sucked into the open end surface 9 by the generation of negative pressure as pressurized fluid is introduced from the annular slit 8 . The generation of the spiral flow creates a velocity distribution in which the center of the tube axis has a higher velocity A.

However, in the cylindrical tube 4, due to the dynamic pressure caused by the high-speed boundary layer formation on the inner wall surface,
Backflow (backflow) B often occurs and may be ejected from the opening end face 9. This phenomenon is thought to be caused by the collapse of fluid velocity and pressure balance in the Coanda spiral flow generation region of the cylindrical tube 4.

Therefore, in the present invention, as shown in FIG. 5b, a high-speed flow C is fed from the auxiliary Coanda flow device 2 at the opening end face 9 toward the center of the tube axis. This maintains said balance;
Furthermore, it promotes Coanda spiral flow generation.

In order to further facilitate the above-mentioned balance formation, the cross-sectional area of the opening end face 9 can be controlled, and the amount of fluid sucked in from the outside can also be controlled.

Since the auxiliary Coanda flow device 2 needs to be fed as an axial center flow, it cannot be replaced with a normal turbulent jet flow. In the turbulent jet flow, the generation of the Coanda spiral flow itself is inhibited.

In the apparatus shown in FIG. 1, the pressure of the pressurized fluid can be 2 to 10 kg/cm ² and the inclination angle θ can be approximately 1/4 to 1/8. Furthermore, conditions for the auxiliary Coanda flow device can be selected from approximately the same range. The flow rate of Coanda spiral flow can be controlled within the desired range, but
It is possible to achieve high speeds of 100 to 200 m/s. Further, the cross-sectional area of the opening end surface 9, that is, the inflow cross-sectional area of the external fluid can be adjusted as appropriate in accordance with the Coanda spiral flow.

FIG. 2 shows another example of the invention. In the case of the example shown in FIG. 2, the auxiliary Coanda flow device 16 is not similar in cross-sectional shape to the main Coanda spiral flow generation device 15. 1st
It does not have an inclined part toward the pipe like the example shown in the figure.

In the other example shown in FIG. 3, the auxiliary Coanda flow device 17 also does not have this slope.

In the case of yet another example shown in FIG.
8 is different from those shown in FIGS. 1 to 3 in the position of the annular slit. The pressurized fluid is inserted at an angle β.

For example, using the apparatus shown in Figure 1, a pressure of 2
Kg/cm ² , flow rate 0.9N/min air through slit 8,
When injected from 14, the flow velocity at the 20 m pipe outlet is
A spiral flow of 75m/sec is obtained. By changing the insertion position of the auxiliary Coanda flow device 2, the flow velocity can be stably varied from 30 to 95 m/sec. Spiral pitch is 5m to 20m
changes up to.

When the auxiliary Coanda flow device 2 was not used, backflow occurred at a rate of about once every 5 seconds, and it was difficult to maintain a stable Coanda spiral flow, resulting in a pulsating state.

Furthermore, when attempting to transport alumina powder by air flow, the backflow caused the alumina powder to blow out backwards, making the transport operation extremely difficult.

However, in the method of the present invention, this alumina powder could be transported stably at high speed.

Of course, the device of the present invention is not limited to these examples. Various other embodiments are possible.

(Effects of the Invention) As described above, the device of the present invention makes it possible to effectively suppress the destruction of Coanda spiral flow and the occurrence of backflow, which could not be avoided with conventional Coanda spiral flow generation devices. Become.

Therefore, it is possible to stably carry out high-speed transportation of fluid and adjust the vorticity.

[Brief explanation of the drawing]

Figures 1, 2, 3, and 4 are
FIG. 3 is a sectional view showing another example of the Coanda spiral flow generation device of the present invention. FIG. 5 is a sectional view of the apparatus shown in FIG. 1, outlining the effects of the present invention. The numbers in the figure indicate the following. 1, 15, 18...Main Coanda spiral flow generating device, 2,16,17,19...Auxiliary Coanda flow device, 3...Pipe line, 4...Cylindrical pipe, 5
...Auxiliary tube, 6...Curved surface, 7...Bending surface,
8... Annular slit, 9... Open end surface, 10...
Coanda spiral flow, 11...distribution chamber, 1
2... Supply pipe, 13... Adjustment piece, 14... Annular slit.

Claims (1)

[Claims] 1. The inner wall surface of the other end of a cylindrical tube whose one end surface is connected to a transportation pipeline is smoothly curved, and the bending of an auxiliary tube has an inner wall of the end surface bent at a right angle or an acute angle opposite to the curved surface. In a Coanda spiral flow generation device, an annular slit is formed between the opening end surface of the auxiliary cylinder and the inner wall surface in the pipe connection direction is inclined to give a radial vector to the fluid. 1. A Coanda spiral flow generation device, wherein the cross-sectional area of the Coanda spiral flow generation device is adjustable, and an auxiliary Coanda flow generation device is provided on an open end surface of the generation device.