GB2141561A

GB2141561A - Vortex valves

Info

Publication number: GB2141561A
Application number: GB08316531A
Authority: GB
Inventors: Timothy John Lamb; Robert Philip Maudsley Smisson; Stephen Peter Hides
Original assignee: Hydro International Ltd
Current assignee: Hydro International Ltd
Priority date: 1983-06-17
Filing date: 1983-06-17
Publication date: 1984-12-19
Also published as: GB2141561B; GB8316531D0

Abstract

A vortex valve comprises a housing (2) having a tangential inlet aperture (16) and an outlet (12). At low inlet pressures, there is little pressure drop between the inlet and the outlet, but at high inlet pressures the incoming flow creates a vortex within the housing (2) which significantly reduces the flow rate through the outlet (12). Adjustment means (20), such as a sliding gate is provided to vary a parameter (for example the cross- sectional area) of the inlet aperture, thereby to alter the characteristics of the valve. <IMAGE>

Description

SPECIFICATION Vortex valves This invention relates to vortex valves.

Vortex valves are devices for controlling fluid flow by a hydraulic effect without requir ing moving parts. US Patent No. 4,026,783 discloses a vortex valve having a conical vortex chamber with a tangential inlet and an outlet disposed at the vertex of the cone. At low flow rates, water entering through the inlet passes through the vortex chamber to the outlet with substantially no pressure drop and the valve can be considered to be open.

However, at high flow rates, water enters through the inlet with enough energy to create a vortex in the vortex chamber which results in a considerable pressure drop between the inlet and the outlet and may greatly restrict flow through the outlet, or even substantially cut it off altogether. Thus the valve serves to limit the rate of flow through it automatically. Vortex valves of this type can be used, for example, to control the flow of storm water in sewers, to ensure that equipment downstream of the valve is not overloaded during periods of heavy rainfall.

Hitherto, vortex valves have had fixed characteristics, and it has therefore been necessary to design each valve specifically for the conditions in which it is to be used. After installation, the valve cannot readily be altered to meet changed conditions.

According to the present invention there is provided a vortex valve comprising a housing defining a vortex chamber, the housing having an inlet aperture, through which fluid may enter the vortex chamber in a manner to promote swirl within the vortex chamber, and an outlet at one axial end of the vortex chamber, adjustment means being provided for varying at least one parameter of the inlet aperture or outlet.

The parameter of the inlet aperture or outlet which is variable may be any one or more of the following: a) its cross-sectional area b) its axial extent c) its radial extent d) its axial position along the vortex chamber e) the perpendicular distance between the axis of the vortex chamber and a line passing through the centre of the inlet aperture and extending in the direction of flow through the aperture.

Other parameters of the inlet aperture or outlet may also be variable. By changing any one of these parameters, the flow characteristics of the vortex valve are varied.

The adjustment means may comprise a slide valve which is movable across the inlet aperture and retained in a desired position.

The slide may be operated manually or automatically.

For a better understanding of the present invention and to show how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a plan view of a vortex valve; Figure 2 is a diagrammatic exploded plan view of part of the valve of Fig. 1; and Figure 3 is a view taken in the direction of the arrow Ill in Fig. 1.

The vortex valve shown in the Figures comprises a housing 2 made up of a conical circumferential wall 4 and an end wall 6. At the end of the housing away from the end wall 6 there is a short cylindrical portion 8 terminating at a flange 10 in which an outlet aperture 12 is formed. An inlet aperture 14 (Fig. 3) is cut in the circumferential wall 4 of the housing 2, and from this aperture extends an intake duct 16. The intake duct 16 has an intake opening 18.

At a position near the circumferential wall 4, the intake duct 1 6 is provided with an adjusting arrangement 20, indicated only generally in dotted outline in Fig. 1.

The adjusting arrangement 20 is shown in more detail in Figs. 2 and 3. It comprises a gate 22 which is vertically slidable in upright guides 24 between a fully open position, as shown in Fig. 3, and a fully closed position, in which the lower edge of the gate rests on the floor of the intake duct 16. The guides 24 are interconnected at their upper ends by a crossbar 26. It will be appreciated from Fig. 2 that the intake duct 1 6 comprises a short portion 28 which is attached to the circumferential wall 4 around the inlet aperture 14 and a longer portion 30 which is on the upstream side of the gate 22. The gate 22 is movable in a gap between the portions 28 and 30.

This gap is exaggerated in Fig. 2; in reality the gate 22 is a sliding fit between facings 32 provided on the ends of the intake duct portions 28 and 30. It will be appreciated from Fig. 3 that the facings 32 extend around the sides and top only of the intake duct portions 28 and 30 but not along the bottom. The floor of the intake duct 1 6 merges in a flush manner with the circumferential wall 4 of the housing 2. The facings 32 are made from any suitable material which will provide a reliable seal against the gate 22 while permitting sliding movement of the gate 22.

As shown in Fig. 3, when the gate 22 is in its fully raised position, it completely clears the inlet-aperture 1 4. Similarly, the uprights 24, as viewed in the direction facing towards the inlet aperture 14, lie outside the periphery of the aperture 14. These features are important in order to ensure that flow along the intake duct 1 6 and through the aperture 14, when the gate 22 is raised, creates as little turbulence as possible, since any turbulence will increase the pressure drop across the valve and thus reduce the maximum flow rate through the valve.

As an example of one possible use of the valve, the intake 1 8 may be connected to the outlet of a storage tank for receiving storm water, and the outlet 1 2 may be connected to a combined sewer which, as well as receiving storm water passing through the vortex valve, also receives domestic sewage and the storm water from other storage tanks. Under normal conditions, including conditions of moderate rainfall, water entering the storage tank will pass through the intake 1 8 and the intake duct 16, past the gate 22 (assuming it is open) and through the valve 2 to the combined sewer without creating a vortex in the housing 2.However, under storm conditions, the flow through the intake duct 1 6 will increase and it will be appreciated that, in the absence of the vortex valve, the resulting flow into the sewer could well be greater than the maximum capacity of the sewer. However, if the storage tank fills at a rate faster than the maximum flow rate through the vortex valve, the level in the storage tank will rise. Eventually, the hydrostatic pressure head in the intake will reach a level at which the energy of the water passing through the inlet aperture 14 is high enough to initiate a vortex -in the vortex chamber. This will cause a sudden drop in the flow rate through the valve, so avoiding overloading of the sewer.

The level in the storage tank will rise further to absorb the rainfall. When the storm stops, no further rainwater will enter the storage tank, and so its level will fall at a rate controlled by the characteristics of the valve.

Clearly it is desirable for the characteristics of the valve to be matched to the capacity of the combined sewer and to the characteristics of the vortex valves on other storage tanks which supply the combined sewer. The required characteristics of the valve will also depend on the maximum expected rainfall. In some cases, the necessary information is not readily available, and so the valve described above can be used to some advantage to enable adjustments to be made to the system after instailation. For example, if it is found that the valve permits a flow rate in excess of the maximum capacity of the combined sewer, the gate 22 can be lowered so that the vortex will be initiated earlier in the cycle and will be stronger so that the flow passing through the valve will be lower for the same upstream pressure.It will be appreciated that lowering the gate 22, will not only reduce the area of the aperture 14, but will also move the centre of the open area away from the axis of the vortex chamber as seen in the view of Fig. 3. The resulting effect will be that a vortex will be initiated in the vortex chamber 2 at a lower flow rate than is the case when the gate 22 is fully raised. It will be appreciated, therefore, that the effect of the gate 22 is not merely that of a restrictor valve, reducing the maximum possible flow rate to the vortex valve through the intake duct 16, but actually affects the characteristics of the valve itself.

For this reason, it is important for the gate 22 to be placed as close as possible to the circumferential wall 4 of the housing 2. Furthermore, it is desirable for the gate 22 to extend parallel to the tapering circumferential wall 4, as shown in Fig. 2.

It will be appreciated that the gate 22 is only one of a number of possible ways of modifying the aperture 14. For example, an iris-type diaphragm could be used, particularly where the intake duct 1 6 is circular. Another possibility is for the gate 22 to be replaced by a pair of overlapping plates the oppositely facing edges of which are shaped to define, for example, a rectangular opening. By sliding the plates over each other, the size of the opening can be changed without altering its shape.

In the embodiment described above, the main components of the valve are fabricated from steel. The diameter of the end plate 6 is double that of the outlet 1 2 and equal to the length of the vortex chamber. The diameter of the end plate 6 may, for example, be approximately 2 metres. As can be seen from Fig. 3, the axis of the vortex chamber is inclined to the horizontal, so that the lowest portion of the conical circumferential wall 4 is horizontal.

Claims

1. A vortex valve comprising a housing defining a vortex chamber, the housing having an inlet aperture through which fluid may enter the vortex chamber in a manner to promote swirl within the vortex chamber about a swirl axis, and an outlet at one axial end of the vortex chamber, adjustment means being provided for varying at least one parameter of the inlet aperture or of the outlet.

2. A vortex valve as claimed in claim 1, in which the variable parameter is the crosssectional area of the inlet aperture or the outlet.

3. A vortex valve as claimed in claim 1 or 2, in which the variable parameter is the axial extent of the inlet aperture or the outlet with respect to the swirl axis.

4. A vortex valve as claimed in any one of the preceding claims, in which the variable parameter is the radial extent of the inlet aperture or the outlet with respect to the swirl axis.

5. A vortex valve as claimed in any one of the preceding claims, in which the variable parameter is the axial position of the inlet aperture or the outlet along the vortex chamber.

6. A vortex valve as claimed in any one of the preceding claims, in which the variable parameter is the perpendicular distance be tween the axis of the vortex chamber and a line passing through the centre of the inlet aperture and extending in the direction of flow through the inlet aperture.

7. A vortex valve as claimed in any one of the preceding claims, in which the adjustment means comprises a slide valve which is disposed adjacent, and movable across, the inlet aperture.

8. A vortex valve as claimed in claim 7, in which the slide valve is disposed in an intake duct which communicates with the vortex chamber through the inlet aperture.

9. A vortex valve as claimed in claim 8, in which the slide valve is guided in guide means which is disposed outside the intake duct.

10. A vortex valve as claimed, in any one of claims 7 to 9, in which the slide valve comprises a plate which is substantially parallel to the plane of the inlet aperture.

11. A vortex valve as claimed in any one of claims 1 to 6, in which the adjustment means comprises a device for changing the cross-sectional area of the inlet aperture without changing its shape.

1 2. A vortex valve substantially as described herein with reference to, and as shown in, the accompanying drawings.