GB1575394A - Vortex diode - Google Patents

Description

(54) VORTEX DIODE (71) We, NICHOLAS SYRED, PETER JOHN ROBERTS AND BALDIP SINGH SIDHU all British subjects of University College, Newport Road, Cardiff do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention concerns vortex diodes in which fluid flow can be controlled by producing a vortex in the fluid so as to present a higher resistance to flow in one direction than in the other and is an improvement or modification of the invention described and claimed in our copending application 25974/76 (Serial No. 1571287).

A known form of vortex diode comprises a cylindrical chamber having a tangential port in the peripheral wall thereof and an axial port in an end wall thereof, the fluid flow entering and leaving the chamber by way of these ports. There are two modes of operation.

If the fluid flow enters through the axial port and exits through the tangential port no appreciable vortex is formed in the vortex chamber and the resistance to flow is relatively small. On the other hand if flow enters through the tangential port and exits through the axial port a vortex forms within the chamber and the resistance to flow is relatively high.

Herein, the two modes of operation are termed the low and high resistance modes respectively.

In the complete specification of the above identified application is described and claimed a vortex diode comprising a cylindrical vortex chamber, an axial port and at least one tangential port in communication with the chamber, and a flow passage at the end of the axial port remote from the chamber, characterised by the following geometric parameters:: (a) the minimum diameter dt of the or each tangential port at its region of merger with the chamber is substantially equal to the internal height of the chamber at the periphery of the chamber; (b) the ratio rt/dt, where rt and dt are respectively the radius of curvature at the junction of a tangential port with the chamber and the minimum diameter of the tangential port at it region of merger with the vortex chamber, lies in the range 0.5 to 2; (c) the ratio 'i/di, where r and dj are respectively the radius of curvature at the junction between the axial port and the vortex chamber and the diameter of the axial port at its region of merger with the vortex chamber, lies in the range 0.3 to 3;; (d) the ratio re/de, where re and de are respectively the radius of curvature at the junction between the axial port and the flow passage and the diameter of the axial port at its end remote from the chamber, lies in the range 0.3 to 4; (e) the ratio At/Ae, where Ae and At are respectively the cross-sectional area of the axial port at the end remote from the chamber and the or the total cross-sectional area of the tangential port or ports at the regions of merger with the chamber, lies in the range 0.5 to 2; (f) the ratio h/de, where h is the internal height of the chamber, ranges from 0.1 to 0.5; and (g) the ratio do/de, where de is the overall diameter of the chamber, ranges from 4 to 10.

According to the present invention a vortex diode comprises a cylindrical vortex chamber having an encircling peripheral channel resembling a toroid into which the chamber opens in a plane offset from the toroid axis and tangential with respect to the circular toroid section, an axial port in an end wall of the chamber and at least one tangential port communicating with the peripheral channel and having at its region of merger with the peripheral channel a diameter substantially equal to the toroid diameter characterised by the following geometric parameters:: (a) ri, the radius of curvature at the junction between the axial port and the vortex chamber lies in the range 0.3 dj to 3 dj, where dj is the diameter of the axial port at its region of merger with the vortex chamber, (b) the ratio rt/dt, where rt and dt are respectively the radius of curvature at the junction of a tangential port with the peripheral channel and the diameter of the or each tangential port at its region of merger with the peripheral channel, lies in the range of 0.5 to 2, (c) the ratio h/de, where h is the interval height of the vortex chamber and de is the diameter of the axial port at its end remote from the vortex chamber lies in the range from 0.1 to 0.5, (d) the ratio d /de, where do is the overall diameter of the chamber and channel, lies in the range from 4 to 10, and (e) the ratio At/Ac where Ae is the cross-sectional area of the axial port at the end remote from the vortex chamber and At is the total cross-sectional area of the or each tangential port at its or their region of merger with the peripheral channel lies in the range 0.5 to 2.0.

The invention will be illustrated by the following description of one embodiment thereof.

The desctiption is given by way of example only and has reference to the accompanying drawings in which: - Figure 1 is a section plan view of a vortex diode on the line A-A in Figure 2, Figure 2 is a section along the line B-B in Figure 1, and Figure 3 is an enlarged view of that portion of Figure 2 enclosed within the chain-dotted .rectangle of Figure 2.

Figures 1 and 2 show a vortex diode having a cylindrical vortex chamber 1 with a plurality of tangential ports 2 and an axial port 3. The illustrated embodiment has eight tangential ports 2 but this number is merely given as an example and the diode can have any desired number of tangential ports. The tangential ports 2 communicate with an enlarged channel 4 encircling the periphery of the vortex chamber. The channel 4 resembles a toroid and the chamber 1 opens into it in a place offset from the toroid axis and tangentially with respect to the circular toroid section as is more clearly illustrated in Figure 3.The tangentially opening chamber includes a weak vortical movement in the fluid in the peripheral channel and this enables the tangential diffuser angle to be increased hence allowing the length of the diffuser sections of the tangential ducts to be made shorter than those in the diodes described in the complete specification of Application 25974/76 (Serial No. 1571287) which gives rise to a more compact device, particularly where only a small number of tangential ports are provided.

The axial port 3 has a slight taper as seen from Figure 2, the port having a maximum diameter at its junction with the vortex chamber 1 and a minimum diameter at its opposite end communicating with a flow passage 5. Flow straightener vanes 6 can be provided in the flow passage. Such vanes 6 reduce cavitation in the flow through the diode and improve performance when functioning in the high resistance mode.

A projection 7 can be formed on the surface of the chamber directly opposite the axial port. The projection extends towards but stops short of junction of the axial port with the vortex chamber at the region of maximum diameter of the axial port. The axial port merges with the vortex chamber in a smooth continuous curved surface and the projection is formed with a complementary curved surface so as to reduce variation in cross-sectional area of the flow path at the junction of the axial port with the vortex chamber.

When operating in its low resistance mode flow enters the chamber 1 through the axial port 3 and exhausts through the tangential ports 2. The axial port forms a short conical diffuser section from which the flow diffuses radially outwardly in the vortex chamber in a substantially uniform pattern. The flow enters the channel 4 tangentially about the periphery of the chamber and passes into the tangential ports which again form conical diffusers to recover the pressure energy. As shown, the tangential ports can be formed as inserts 8 having a push-fit in the main body of the diode. The inserts can be cemented or bonded in position and are connected to a flow manifold. Alternatively, the tangential ports can be formed as drillings in the body of the diode. The diameter of the channel 4 is substantially equal to the diameter of each tangential port 2 at its region of merger with the channel.

For optimum performance of the vortex diode in both the high and low resistance modes of operation careful attention should be given to the geometry of the diode and the relationships of particular parameters. These parameters will be denoted by the following symbols which are shown in the drawings.

h - interval height of vortex chamber 1 do - overall diameter of the chamber 1 and channel 4.

di - diameter of axial port 3 at its region of merger with the vortex chamber 1 ri - radius of curvature at the junction between axial port 3 and the vortex chamber de - diameter of axial port 3 at its end remote from the vortex chamber re - radius of curvature at the junction of the axial port 3 with the flow passage communicating therewith dt - diameter of tangential port 2 at its region of merger with the peripheral channel rt - radius of curvature at the junction of the tangential port 2 with the peripheral channel.

The relationship between h and de is such that h/de lies in the range from 0.1 to 0.5 and the ratio do lies in the range from 4 to 10. Preferably, h/de is 0.2dc and diode is about 7 to give maximum resistance in the high resistance mode of operation.

To prevent flow separation at the junction of the axial port and the vortex chamber r should be greater than 0.3 di and not greater than 3 dj. Conveniently, ri can be 0.375 di to prevent flow separation.at the junction in the low resistance mode of operation. Further re should preferably lie within the range 0.3 de to 4 de.

For optimum results the area of the conical diffuser section formed by the axial port 3 at its junction with the vortex chamber is equal to or approaches the peripheral area of the chamber at the junction.

Thus, preferably, z di2 (dj + 2r cos 0) h 4 where 0 is half the angle of the diffuser section. That is 6 is the angle of inclination of the wall of the diffuser section to the longitudinal axis of the axial port. The angle of the diffuser section can be about 7 and hence 0 can be 3210. As a first approximation the cosine of such a small angle can be considered equal to 1 and consequently ~dj2 4 # # (di + 2ri) h As mentioned above the preferred relationship between ri and di is such that ri = 0.375 di Hence, substituting the value of ri in the previous equation gives 3T dj2 = n. 1.75di.h 4 from which h = di 7 The cross-sectional area Ae of the axial port at the end remote from the vortex chamber (z de2/4) and the total cross-sectional area At of the tangential ports at their region of merger with the peripheral channel (Xzdt2/4 where X is the number of tangential ports) should be such that At/Ac is within the range 0.5 to 2.0. Conveniently the ratio can be within the range 1.1 to 1.7.

Pressure loss at the tangential ports is influenced by the relationship between rt and dt. If the ratio rt/dt is small then a considerable pressure loss can be experienced. Alternatively an increase in the ratio r/dt will reduce the pressure loss in the low resistance mode but adversely affects the performance in the high resistance mode of operation. The ratio rt/dt lies in the range 0.5 to 2 and preferably this ratio is substantially 1. The length of each tangential port is such that the diameter at the end thereof remote from the vortex chamber is at least 2 dt. The tangentially-connected channel causes a vortical flow in the channel which enables the tangential diffuser angle to be made larger and angles of up to 100 may be used.Thus the length of diffuser to achieve the diameter of 2 dt is reduced compared with the diodes described in the complete specification of Application No. 25974/76 (Serial No.

1571287) wherein the tangential diffuser angle is 7". The use of the tangentially-connected chamber therefore allows the vortex diodes of the present invention to be more compact than those described in the above complete specification.

WHAT WE CLAIM IS: 1. A vortex diode comprising a cylindrical vortex chamber having an encircling peripheral channel resembling a toroid into which the chamber opens in a plane offset from the toroid axis and substantially tangential with respect to the circular toroid section, an axial port in an end wall of the chamber and at least one tangential port communicating with the peripheral channel and having at its region of merger with the peripheral channel a diameter substantially equal to the toroid diameter characterised by the following geometric parameters:: (a) ri, the radius of curvature at the junction between the axial port and the vortex chamber lies in the range 0.3 di to 3 di, where di is the diameter of the axial port at its region of merger with the vortex chamber, (b) the ratio rt/dt, where rt and dt are respectively the radius of curvature at the junction of a tangential port with the peripheral channel and the diameter of the or each tangential port at its region of merger with the peripheral channel, lies in the range 0.5 to 2, (c) the ratio h/de, where h is the internal height of the vortex chamber and de is the diameter of the axial port at its end remote from the vortex chamber lies in the range from 0.1 to 0.5, (d) the ratio do/de, where do is the overall diameter of the chamber and channel, lies in the range from 4 to 10, and (e) the ratio At/Ac where Ae is the cross-sectional area of the axial port at the end remote from the vortex chamber and At is the total cross-sectional area of the or each tangential port at its or their region of merger withthe peripheral channel lies in the range 0.5 to 2.0.

2. A vortex diode as claimed in claim 1 in which the ratio ri equals 0.375 di.

3. A vortex diode as claimed in claim 1 in which the ratio rt/dt is substantially 1, 4. A vortex diode as claimed in claim 1 in which h/dc is 0.2.

5. A vortex diode as claimed in claim 1 in which diode is about 7.

6. A vortex diode as claimed in claim 1 in which At/Ac is in the range 1.1 to 1.7.

7. A vortex diode according to claim 1 in which re, the radius of curvature at the junction of the axial port with a flow passage at the end of the axial port remote from the chamber lies in the range 0.3 de to 4 de.

8. A vortex diode according to claim 1 in which the diameter of the axial port decreases progressively towards its end remote from the vortex chamber.

9. A vortex diode according to claim 1 in which the area of the axial port at its junction with the vortex chamber is substantially equal to the adjacent peripheral area of the vortex chamber.

10. A vortex diode according to claim 1 substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. chamber therefore allows the vortex diodes of the present invention to be more compact than those described in the above complete specification. WHAT WE CLAIM IS:

1. A vortex diode comprising a cylindrical vortex chamber having an encircling peripheral channel resembling a toroid into which the chamber opens in a plane offset from the toroid axis and substantially tangential with respect to the circular toroid section, an axial port in an end wall of the chamber and at least one tangential port communicating with the peripheral channel and having at its region of merger with the peripheral channel a diameter substantially equal to the toroid diameter characterised by the following geometric parameters:: (a) ri, the radius of curvature at the junction between the axial port and the vortex chamber lies in the range 0.3 di to 3 di, where di is the diameter of the axial port at its region of merger with the vortex chamber, (b) the ratio rt/dt, where rt and dt are respectively the radius of curvature at the junction of a tangential port with the peripheral channel and the diameter of the or each tangential port at its region of merger with the peripheral channel, lies in the range 0.5 to 2, (c) the ratio h/de, where h is the internal height of the vortex chamber and de is the diameter of the axial port at its end remote from the vortex chamber lies in the range from 0.1 to 0.5, (d) the ratio do/de, where do is the overall diameter of the chamber and channel, lies in the range from 4 to 10, and (e) the ratio At/Ac where Ae is the cross-sectional area of the axial port at the end remote from the vortex chamber and At is the total cross-sectional area of the or each tangential port at its or their region of merger withthe peripheral channel lies in the range 0.5 to 2.0.

2. A vortex diode as claimed in claim 1 in which the ratio ri equals 0.375 di.

3. A vortex diode as claimed in claim 1 in which the ratio rt/dt is substantially 1,

4. A vortex diode as claimed in claim 1 in which h/dc is 0.2.

5. A vortex diode as claimed in claim 1 in which diode is about 7.

6. A vortex diode as claimed in claim 1 in which At/Ac is in the range 1.1 to 1.7.

7. A vortex diode according to claim 1 in which re, the radius of curvature at the junction of the axial port with a flow passage at the end of the axial port remote from the chamber lies in the range 0.3 de to 4 de.

8. A vortex diode according to claim 1 in which the diameter of the axial port decreases progressively towards its end remote from the vortex chamber.

9. A vortex diode according to claim 1 in which the area of the axial port at its junction with the vortex chamber is substantially equal to the adjacent peripheral area of the vortex chamber.

10. A vortex diode according to claim 1 substantially as hereinbefore described with reference to the accompanying drawings.