Vortex flow control device for stormwater management

Abstract

A vortex flow control valve having a main chamber 7 with inlet 6 and outlet 8. The main chamber 7 has a protrusion 15 at the centre of end wall 14, and a spiral shaped side wall with a streamwise decr

Description

Technical field The invention relates to a vortex flow control device to control the flow of water, specifically the stormwater. Background Vortex flow control (VFC) valves are used in stormwater management systems to regulate the flow of water. They utilize the principles of fluid dynamics to create a vortex, which controls the rate at which water is released downstream. The key features and working principles of these devices are: • Flow regulation: Vortex valves are designed to limit the flow rate to an almost constant level regardless of the upstream water head, up to a certain design point. This is beneficial for preventing flooding or overflow in downstream water treatment systems or watercourses. • No moving parts: One of the main advantages of vortex valves is that they typically do not have any moving parts, which reduces the risk of mechanical failure and the need for maintenance. • Self-activating: The vortex flow control valve operates based on water height and does not require external energy or manual intervention to function. • Energy dissipation: By creating a vortex, these valves also help in dissipating energy from the flowing water, reducing the potential for erosion in the watercourse downstream. • Debris blockage: VFC devices often handle stormwater which can carry debris, one of the main challenges during the design of such a system is to minimise the risk of blockages. There are three known work regimes of a vortex flow control valve. In the orifice flow regime (1) the head is too small for the vortex to form, therefore the flow goes straight from the inlet to the outlet. When the transition (2) occurs, an intermittent vortex flow can be observed. During vortex flow regime (3), a steady vortex is formed, having a much higher head / flow slope. In the orifice flow and the vortex flow regimes, the head is proportional to the square of the flow rate, therefore in both of those regimes the VFC is equivalent to a traditional orifice valve. The main benefit of the VFC comes from the fact that the equivalent orifice diameter is much smaller than the key parameters of the VFC valve, which allows passing larger debris through the valve. Therefore, by controlling the main dimensions of the valve (cross-section shape and width, VFC depth, inlet and outlet sections) it is possible to control the heads and the flow rates where the flush (4) and reattachment (5) transitions occur. The vortex flow control valves currently available in the prior art have a restricted operating range given by the heads and the flow rates of the flush and reattachment transitions, therefore the idea of the invention allows to produce an alternative "one size fits all design" VFC valve having a wider operating range in terms of transition head values. Furthermore, stable vortex generation and inlet flow blockage are important challenges and several design adjustments proposed by the invention optimise the flow control performance. Summary The invention relates to a vortex flow control device comprising an inlet channel (6), a main chamber (7), and a circular cross-section outlet duct (8). An embodiment of the invention provides a flow control assembly comprising the main catchpit separated into two portions: the one upstream the vortex flow control valve and the one downstream located behind the baffle part having the main valve attached to it. The water enters the catchpit by an inlet tube to the first portion of the catchpit, then enters the valve through the inlet section and leaves the catchpit by an outlet channel coupled to the baffle plate that prevents water from entering the rest of the catchpit space. If the valve blockage occurs due to large debris at the vortex flow control valve inlet, a system of bell syphons placed at the flush tube in the first portion of the catchpit or above the bypass valve in the second portion of the catchpit will suck the excess water to the main outlet without filling the whole catchpit with water. The vortex flow control valve may be designed and manufactured using different features i.e. the end wall protrusion, spiral case indentation, multi-section design. Brief description of the drawings The Figure 1 presents a generic flow-head performance curve necessary to understand the operation of the vortex flow control valve and its different flow regimes. The Figure 2 presents a single section vortex flow control device (VFC). The Figure 3 illustrates the full assembly of the vortex flow control valve / device inside the catchpit showing the vertical bypass valve with mounted over bell syphon cap (9). The Figure 4 presents a multi-section VFC device with spiral case sections. The Figure 5 presents a multi-section VFC device with round sections. The Figure 6 presents a multi-section VFC device with a flush tube (10). The Figure 7 presents a cross-section of a multi-section VFC device with a flush tube and bell syphon. The Figure 8 presents a cross-section of a multi-section VFC device with an internal cone part (18) located inside the outlet duct and mounted on the baffle plate and having an orifice at the tip. Description of the invention The invention is related to a vortex flow control (VFC) device which may comprise a single section or multiple sections. The multiple sections are of different radii or circumference and are arranged along the axial direction allowing the inlet flow radius selection for more precise control of the head-flow characteristic curve. Each section of the device comprises an inlet channel (6); a main chamber (7); and a circular cross-section outlet duct (8). The main chamber is connected to the inlet channel on its one end and to the outlet duct on its other end. The inlet channel has either a straight duct or a small opening angle to channel the flow tangentially inside the main chamber and has a round or rectangular cross section. The main chamber (7) comprises a side wall (11); a first end wall (12) which is a flat wall near the outlet duct and is connected to one side of the side wall (11); a fillet or chamfer feature (13) present in between, and connecting, the outlet duct and the first end wall; and a second end wall (14), having a protrusion (15) in the centre, connected to other side of the side wall (11) opposite to the outlet duct. The side wall (11) of the device is either round or spiral shaped with strictly decreasing local radius in the flow direction. The sections have may have spiral or round geometries. The device further comprises a flush tube (10), connected to the smallest section, to remove potential blockages accumulated in the inlet chamber of the device. The flush tube works independently from the section and has a flush tube bell syphon cap (16), to allow higherflush impulse and better blockage removal capacity. The flush tube (10) allows to mitigate a potential blockage as once the blockage occurs at the inlet of the valve, the water level in the catchpit begins to rise and when it reaches the top of the flush tube, the water flows downwards and removes the blockage at the inlet of the valve. As an additional feature to the flush tube, the flush tube bell syphon cap (16) is activated when the water level reaches the top of the flush tube and creates a higher impulse jet of water as the full height of the syphon is being sucked inside the volume flow control valve through the flush tube. The bypass valve bell syphon cap (9) located over the vertical bypass pipe inside the downstream portion of the catchpit assembly allows draining excess water in the case where the blockage at the VFC inlet occurs and the water level in the downstream section goes up above the level of the bypass pipe inlet. In that case the syphon helps draining the water to the lower level of the bell syphon cap. The internal cone (18) located at the beginning of the outlet duct and mounted directly on the baffle plate has an orifice at the tip of the cone. This part guides the vortex flow leaving the main chamber and allows more stable vortex formation during the transition regime. The invention further discloses a method to manufacture a vortex flow control device comprising the steps of injection moulding the side wall (11) by a mould having one or more indentations aligned in the axial direction; and producing several casing parts of different axial depth by removing a portion of the produced casing part to adjust its axial dimension. The mould with indentation features can be used to produce different vortex flow control devices having the same section but different axial depth, therefore adjusting the design flow while key head parameters are kept quasi constant. An embodiment of the invention discloses a flow control assembly comprising a main catchpit separated into two portions: the one upstream the vortex flow control valve and the one downstream located behind the baffle part having the main valve attached to it. The water enters the catchpit by an inlet tube to the first portion of the catchpit, then enters the valve through the inlet section and leaves the catchpit by an outlet channel coupled to the baffle plate that prevents water from entering the rest of the catchpit space. If the valve blockage occurs due to large debris at the vortex flow control valve inlet, a system of bell syphons placed at the flush tube in the first portion of the catchpit or above the bypass valve in the second portion of the catchpit will suck the excess water to the main outlet without filling the whole catchpit with water. Prior art studies in the experimental and numerical fields (scientific articles on CFD and experimental) show the formation of a stable air core in the middle of the vortex flow. The protrusion (15) of the device guides the vortex motion of the main flow and replaces the air core. Under certain operating conditions the air core can become unstable and induce vibrations on the structure. With the protrusion all the column is incompressible, less prone to the flow rate / velocity fluctuations. The devices of prior art use a circular rotation moulded casing, which is cheaper to produce but less efficient hydrodynamically. The invention has a spiral casing with locally decreasing radius which has lower hydrodynamic losses and a better redistributed hydrodynamic load as compared to the prior art. The idea of the multi-section vortex flow control valve part allows keeping the same manufacturing mould for different volume flow control valve operating regimes, mainly due to the production cost of the mould. The baffle (17) blocks the water from reaching the larger sections, the inlets of which also need to be blocked.

Claims

1. A vortex flow control device comprising:an inlet channel (6);a main chamber (7); anda circular cross-section outlet duct (8);wherein the main chamber is connected to the inlet channel on its one end and to the outlet duct on its other end;wherein the inlet channel has either a straight duct or a small opening angle to channel the flow tangentially inside the main chamber and has a round or rectangular cross section;wherein the main chamber (7) comprises:a side wall (11);a first end wall (12) which is a flat wall near the outlet duct and is connected to one side of the side wall (11);anda second end wall (14), having a protrusion (15) in the centre, connected to other side of the side wall (11) opposite to the outlet duct;wherein there is a flush tube (10), to remove potential blockages accumulated in the inlet chamber of the device.

2. The device of claim 1, wherein the main chamber (7) further comprises a fillet or chamfer feature (13) eventually present in between, and connecting, the outlet duct and the first end wall.

3. The device of claim 1, wherein the side wall (11) is spiral shaped with strictly decreasing local radius in the flow direction.

4. A vortex flow control device comprising multiple sections, of different radii or circumference, arranged along the axial direction allowing the inlet flow radiusselection for more precise control of the head-flow characteristic curve, wherein each section comprises:an inlet channel (6);a main chamber (7); anda circular cross-section outlet duct (8);wherein the main chamber is connected to the inlet channel on its one end and to the outlet duct on its other end;wherein the inlet channel has either a straight duct or a small opening angle to channel the flow tangentially inside the main chamber and has a round or rectangular cross section;wherein the main chamber (7) comprises:a side wall (11);a first end wall (12) which is a flat wall near the outlet duct and is connected to one side of the side wall (11);a fillet or chamfer feature (13) present in between, and connecting, the outlet duct and the first end wall;a second end wall (14), connected to other side of the side wall (11) opposite to the outlet duct, wherein the second end wall (14) has a protrusion (15) in the centre; andan operating section restricted by a baffle (17) cut to size to prevent the working fluid from reaching the larger sections;wherein there is a flush tube (10), connected to the smallest section, to remove potential blockages accumulated in the inlet chamber of the device.

5. The device of claim 4, wherein the side wall (11) is spiral shaped with strictly decreasing local radius in the flow direction.

6. The device of claim 4, wherein the sections have spiral geometries.

7. The device of claim 4, wherein the sections have round geometries.

8. The device of claim 4, wherein the flush tube works independently from the section.

9. The device of claim 8, wherein the flush tube has a Bell syphon cap (16), to allow higher flush impulse and better blockage removal capacity.

10. The device of claim 1, further comprising a vertical bypass pipe, located over the outlet pipe, having a mounted bell syphon cap (9).

11. The device of claim 4, further comprising a vertical bypass pipe, located over the outlet pipe, having a mounted bell syphon cap (9).

12. The device of claim 4, further comprising an orifice cone (18) mounted on the baffle plate and protruding inside the outlet duct (8).

13. A method to manufacture a vortex flow control device according to claim 1 or 4 comprising:injection moulding the side wall (11) by a mould having one or more indentations aligned in the axial direction; andproducing several casing parts of different axial depth by removing a portion of the produced casing part to adjust its axial dimension.

Images