A fluidic device for providing analogue output control includes a main channel, a first control channel, a second control channel, a comparator which receives respective input fluid flows from the main, the first and the second control channels. The first control channel is configured such that the input fluid flow therefrom carries an oscillating pressure wave signal, the second control channel includes a flow regulator controllable to vary the mass flow rate of the input fluid flow from the second control channel, and the main channel is configured such that the input fluid flow therefrom is at a reference mass flow rate. The comparator is configured such that the input fluid flows from the first control and the second control channels act in combination on the input fluid flow from the main channel to produce an output fluid flow from the comparator having a PWM mass flow rate characteristic.

A fluidic device for providing analogue output control includes a main channel, a first control channel, a second control channel, a comparator which receives respective input fluid flows from the main, the first and the second control channels. The first control channel is configured such that the input fluid flow therefrom carries an oscillating pressure wave signal, the second control channel includes a flow regulator controllable to vary the mass flow rate of the input fluid flow from the second control channel, and the main channel is configured such that the input fluid flow therefrom is at a reference mass flow rate. The comparator is configured such that the input fluid flows from the first control and the second control channels act in combination on the input fluid flow from the main channel to produce an output fluid flow from the comparator having a PWM mass flow rate characteristic.

A fluid flow resistor includes: a body having entry and exit fluid flow ports, and an internal fluid flow path fluidly extending between the entry and exit fluid flow ports; the internal fluid flow path having a first spiral fluid flow path in a first spiral direction, and a second spiral fluid flow path in a second spiral direction opposite the first spiral direction; each of the first spiral flow path and the second spiral flow path having a plurality of discrete flow chambers fluidly connected in series via interconnecting fluid flow restriction passages; the first and second spiral flow paths having a connecting fluid flow path therebetween; the fluid flow resistor being configured to resistively permit fluid flow from the entry fluid flow port to the exit fluid flow port via the first spiral flow path, the connecting fluid flow path, and the second spiral flow path, in succession.

This invention relates to a vortex station and method for producing a vortex similar to one of a group consisting of dust-devils and waterspouts. The apparatus comprises a ground platform forming a base for the vortex station, a plurality of vanes to direct an air flow into a vortex station and about the vortex station in a substantially swirling manner, at least one wind turbine disposed near the centre of said vortex station, in a path of a concentrated air flow, wherein the movement of the air in the vortex station is such that an atmospheric buoyancy vortex is created in the centre of the vortex station, a supply of a working fluid (e.g. water) to the vortex station at or near the centre of the vortex station such that the air is of a saturated condition or an at least partially saturated condition with the working fluid (e.g. water), the working fluid (e.g. water) supplied at a sufficient quantity or amount so as to assist with maintaining buoyancy and stability of a vortex created.

This invention relates to a vortex station and method for producing a vortex similar to one of a group consisting of dust-devils and waterspouts. The apparatus comprises a ground platform forming a base for the vortex station, a plurality of vanes to direct an air flow into a vortex station and about the vortex station in a substantially swirling manner, at least one wind turbine disposed near the centre of said vortex station, in a path of a concentrated air flow, wherein the movement of the air in the vortex station is such that an atmospheric buoyancy vortex is created in the centre of the vortex station, a supply of a working fluid (e.g. water) to the vortex station at or near the centre of the vortex station such that the air is of a saturated condition or an at least partially saturated condition with the working fluid (e.g. water), the working fluid (e.g. water) supplied at a sufficient quantity or amount so as to assist with maintaining buoyancy and stability of a vortex created.

A vortex-controlled variable flow resistance device ideal for use in a backpressure tool for advancing drill string in extended reach downhole operations. The characteristics of the pressure waves generated by the device are controlled by the growth and decay of vortices in the vortex chamber(s) of a flow path. The flow path is designed to produce alternating primary and secondary vorticesone clockwise and one counter-clockwisewhere the primary vortex is stronger and produces higher backpressure than the secondary vortex. This in turn generates alternating weak and strong pressure pulses in the drill string. The weak pulses may be barely perceptible so that the effective frequency of the pulses is determined by the stronger primary vortices.

A vortex-controlled variable flow resistance device ideal for use in a backpressure tool for advancing drill string in extended reach downhole operations. The characteristics of the pressure waves generated by the device are controlled by the growth and decay of vortices in the vortex chamber(s) of a flow path. The flow path is designed to produce alternating primary and secondary vorticesone clockwise and one counter-clockwisewhere the primary vortex is stronger and produces higher backpressure than the secondary vortex. This in turn generates alternating weak and strong pressure pulses in the drill string. The weak pulses may be barely perceptible so that the effective frequency of the pulses is determined by the stronger primary vortices.

A drain includes a vortex throttle, to remove water from a pressure sensing line. The vortex throttle resists the flow of air through it. Therefore, for a given diameter of inlet and outlet ports the mass flow rate through the vortex throttle is much smaller than through a plain hole of the same diameter. The inlet and outlet ports may therefore be made larger than in known arrangements (so reducing the risk of blockage), but the operation of the vortex throttle restricts the mass flow of air through the drain pipe (so minimizing the detrimental effects on the engine's operation). Collected water effectively drains from the pressure sensing line, without the disadvantages of known arrangements.

A drain includes a vortex throttle, to remove water from a pressure sensing line. The vortex throttle resists the flow of air through it. Therefore, for a given diameter of inlet and outlet ports the mass flow rate through the vortex throttle is much smaller than through a plain hole of the same diameter. The inlet and outlet ports may therefore be made larger than in known arrangements (so reducing the risk of blockage), but the operation of the vortex throttle restricts the mass flow of air through the drain pipe (so minimizing the detrimental effects on the engine's operation). Collected water effectively drains from the pressure sensing line, without the disadvantages of known arrangements.

An example method includes providing fluid communication between an internal bore of a drill string and an annulus between the drill string and a borehole through a fluid channel in a side of a collar coupled to the drill string. Fluid may be circulated through the internal bore of the drill string. A fluid telemetry signal may be generated by selectively generating a vortex within the fluid channel. Providing fluid communication between the internal bore and the annulus through the fluid channel may include providing fluid communication between the internal bore and a vortex basin at least partially defining the fluid channel, through at least one of a first fluid flow path and a second fluid flow path between the vortex basin and the internal bore; and providing fluid communication between the vortex basin and the annulus through a fluid outlet of the vortex basin.