FLUIDIC APPARATUS

Abstract: A vortex amplifier (1) having a vortex chamber is included in a fluid flow line (2). A sensor (4) in the fluid flow line (2) upstream of the vortex chamber and operable in response to changes in the fluid flow controls a valve (5) in a further flow line (3) for introducing a control fluid into the vortex chamber. The arrangement results in an automatic control in the fluid flow line (2).

Description: The present invention concerns fluidic apparatus. The aim of the invention is to provide an automatic control arrangement in a fluid flow line which does not rely upon or use a conventional valve but rather uses a fluidic device known as a vortex amplifier which does not have moving parts and seals which suffer wear and corrosion during use. A vortex amplifier comprises a vortex chamber through which a main flow passes radially to emerge at an axial outlet. The main flow can be regulated and controlled by a control flow introduced tangentially into the vortex chamber. There may be more than one tangential inlet for the control flow. A device as is defined by the preamble of claim 1 is shown in US Patent specification 3,638,672. In the device shown a fluid flowing in the main flow duct of a vortex amplifier is caused to flow through a restrictor prior to admission to the chamber of the vortex amplifier. A control flow duct leads from a point in the main flow duct above the restrictor to the tangential control flow duct via a shuttle valve in a chamber, which is connected to the main flow duct upstream and downstream of the shuttle valve. The arrangement is such that normally the shuttle valve is closed, but as the velocity of flow of a fluid in the main duct increases, so does the pressure drop across the restrictor and hence the shuttle valve. At a pre-determined flow rate in the main duct, the shuttle valve opens, so allowing fluid to flow from the main flow duct into the control flow duct causing the vortex valve to operate to reduce the flow of fluid in the main duct and vice versa. The nature of the device is such that instead of controlling the flow in the main duct accurately, there is a tendency for it to oscillate about the desired value. Also, necessarily, the control fluid has to be the same as the main fluid the flow of which has to be controlled. This may not be desired. It is an object of the present invention to provide a fluidic flow control device which has an improved response to variations in the flow of a fluid in a duct and in which the fluid flowing in the duct is isolated from that flowing in a control duct. According to the present invention there is provided a fluidic apparatus comprising the features as outlined in claim 1. The invention will be described further, by way of example, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic representation of a first embodiment of a fluidic apparatus; Figure 2 is a diagram of an embodiment similar to Figure 1; Figure 3 is a diagram of a second embodiment; and Figure 4 is a diagram of a further embodiment. A vortex amplifier (12) is included in a fluid flow line (2), the fluid being gas or liquid. The vortex amplifier is a fluidic device having a vortex chamber with radial, axial and tangential ports. In the present arrangement the flow in line (2) enters the vortex chamber of the amplifier at the radial port and exits from the chamber at the axial port. The flow direction along the line (2) is indicated by the arrow. A second flow line (3) communicates with the tangential port of the vortex amplifier. A flow along the line (3) into the vortex chamber can be used to control the flow along the line (2). With no control flow along the line (3) the pressure drop through the vortex amplifier is very low and can in effect be ignored. The main flow along the line (2) can be regulated by a small control flow along the line (3). A vortex is created in the chamber of the vortex amplifier and the flow is reduced in direct proportion to the control flow applied along the line (3). Increasing the control flow can result in a complete cut-off of the main flow. A detector or sensor (4) is arranged in the flow line (2) upstream of the vortex amplifier (1). The detector or sensor (4) is coupled to a control (5) in the flow line (3). For example, the sensor (4) can be a pressure transducer which senses pressure variations in the flow line (2) upstream of the vortex amplifier and transmits signals to the control (5), which can be a valve, in the line (3). The flow in the line (3) is admitted tangentially into the vortex chamber of the vortex amplifier and by increasing the control flow the main flow along the line (2) can be progressively throttled or decreased to a minimum value or complete cut-off. Accordingly, in the above example the control flow can be regulated in response to signals received from the sensor (4) to allow the vortex amplifier to control the main flow along the line (2). The control fluid in line (3) an be the same as the fluid in the line (2). Alternatively the control fluid can be different to the main flow. In many applications a suitable control fluid is compressed air. The vortex amplifier can be provided with a plurality of control ports. Figure 2 is an arrangement similar to that in Figure 1 but showing more detail. In Figure 2, a pressure transducer (10) capable of accurately measuring pressure in main flow line (12) at a desired position upstream of the vortex amplifier (11) provides an analogue signal output which is connected as analogue input to a programmable controller (13). The controller (13) can comprise an electronic unit with proportional, integral and differential terms as part of its control algorithm. Within the controller (13) the measured pressure can be compared to a desired set point pressure and should corrective action become necessary an analogue signal is sent to a valve (14) in the control flow line (15). The control flow can be compressed air from a separate source and the valve modulates the flowrate of the compressed air in response to signals from the transducer (10). The arrangement provides automatic adjustment of the flow in the fluid line and typical uses are for maintaining substantially constant pressure in ventilation ducting, glove boxes, fume cupboards, clean rooms and the like. The arrangement can be used for fire damping in a ventilation shaft or duct. Thus the sensor can be a fire or smoke detector and the control flow can automatically increase to shut off the supply thereby acting as a damper. The control flow can be an inert gas supply. The arrangement can also be used for mixing different fluids. The sensor can be chosen to detect a parameter of interest in the fluid flowing along the line (2). The signal from the transducer can control the valve (5) in the line (3) so that an amount of a different fluid added to the vortex chamber through the control port or ports can be varied according to some preset value. Mixing of the fluid entering the vortex amplifier along line 2 and the control fluid entering along line 3 takes place in the vortex chamber. Figure 3 depicts an enclosed volume (2) which is to be maintained at a desired controlled positive pressure with respect to the external environment. A fan (21) blows air into the chamber and a vortex amplifier (22) is included in a flow line (23) from the volume (20). A pressure sensor (24) in the column (20) controls a valve (25) in a control flow line (26) to thereby provide automatic adjustment of the flow from the volume (20). A pressure sensor (24) in the volume (20) controls a valve (25) in the control flow line (26) to thereby provide automatic adjustment of the flow from the volume (20) along the flow line (23) and to maintain the desired positive pressure within the volume (20). A controlled bleed inlet (27) can be provided at the volume (20). Alternatively the fan can be provided downstream of the vortex amplifier whereby to suck air out of the volume (20) and to maintain the volume at a controlled negative pressure. Figure 4 depicts such an arrangement in which a single fan or suction pump (40) communicates with a plurality of vortex amplifiers (41) arranged in parallel and each amplifier controlling an associated volume or chamber (42). As before, a control flow which can be compressed air is regulated by a valve (43) responsive to a transducer (44) in the flow line from the chamber. In this way it is possible to regulate and control the pressures in the individual chambers (42). For example, the chambers (42) can each be maintained at a different negative pressure by means of the single fan or suction pump (40). Although each control flow line is shown with its individual fan (45) it is possible to couple the control flow lines to a common fan or to a common source of compressed air. In a further application the invention can be employed to control flow along a pipeline in which the flow can comprise slugs of liquid separated by gas pockets. Such a situation can arise in a pipeline from an oil or gas well in which the flow can comprise slugs of oil separated by gas pockets. The high speed of travel of the slugs can result in damage to equipment at the receiving end of the pipeline. A control flow at the vortex amplifier can slow down the slugs in the pipeline. In this case the transducer in the pipeline will be capable of detecting oil or gas slugs and applying a signal to the valve in the control flow line to permit increased control flow. The vortex amplifier in effect acts as buffer in the main flow line. The control flow can be the same as the main flow.

Claims: A fluidic apparatus comprising a first fluid flow line (2) having a vortex chamber (1) so arranged that fluid flowing in the first fluid flow line (2) enters the vortex chamber (1) radially and emerges from it axially, a second fluid flow line (3) for introducing a control fluid into the vortex chamber (1) and a sensor (4) in the first fluid flow line (2) upstream of the vortex chamber (1) operable to regulate and control the supply of control fluid to the vortex chamber (1) the sensor (4) being adapted to produce a control signal which is related to a parameter of the fluid flow in the first fluid flow line (2) and there being provided a control means (5) in the second fluid flow line (3) responsive to the control signal from the sensor (4) to regulate the flow of control fluid in the second fluid flow line (3) in response to changes in the fluid flow in the first fluid flow line (2), characterised in that the second fluid flow line (3) has no fluid connection with the first fluid flow line (2) a non-fluid connection exists between the sensor (4) and the control means (5), and the control signal is related to a parameter of the fluid flow or to the pressure in the first fluid flow line (2) thereby the control means (5) responsive to the control signal regulates the flow of control fluid in response to changes in the fluid flow or in pressure in the first fluid flow line (2). A fluidic apparatus according to Claim 1 characterised in that the sensor (4) is adapted to detect changes in the pressure existing in the first fluid flow line (2). A fluidic apparatus according to Claim 2 characterised in that an enclosed volume (20) is included in the first flow line (2) upstream of the vortex chamber (22) and the sensor (24) detects changes in the pressure within the enclosed volume (20) to maintain the pressure within the enclosed volume (20) at a desired value. A fluidic apparatus according to Claim 3 characterised in that there is included a plurality of enclosed volumes (42) and associated vortex chambers (41) connected to a single pump (40).

Inventors: BLANCHARD, ALAN, FORD, LIONEL HOUSTON
Applicants: UNITED KINGDOM ATOMIC ENERGY AUTHORITY
Application year: 1989
Main classification: F15C1
IPC codes: F15C1