Abstract: An aircrew breathing regulator having facility for mixing ambient air with oxygen-enriched breathing gas in supplying breathing gas to an end user, includes a demand valve connected between an inlet for receiving oxygen-enriched breathing gas and an outlet for delivering breathing gas to the end user. Ambient air is entrained by flow of oxygen-enriched breathing gas through an injector nozzle to enter an ambient air inlet and mix with the oxygen-enriched breathing gas downstream of the demand valve. Pressure build-up downstream of the demand valve resulting from the flow restricting effect of the injector nozzle causes a pressure feedback onto a head of the valve tending to force it closed. This is overcome by nullifying the action on the demand valve of downstream pressure so that the valve is pressure balanced.

Abstract: The invention is directed to a flow controlling device for a discharge system, such as a drainage system, having a first vortex chamber with an inlet and an outlet and a second bigger vortex chamber with a peripheral inlet and a central outlet axial in relation to a vortex in the second chamber. The second vortex chamber is connected at its inlet to the outlet of the first vortex chamber. The first vortex chamber is symmetrical with respect to a median plane perpendicular to a vortex axis (A), the direction of both the inlet and the outlet of this chamber being parallel with the median plane. The first vortex chamber is asymmetric with respect to a plane parallel with the inlet direction and perpendicular to the median plane. The vortex axis (A) of the first vortex chamber being perpendicular to a tangent of the second vortex chamber at the peripheral inlet and the ratio between the diameters of the first vortex chamber and the second vortex chamber is less than 0.43:1.

Abstract: A fluidic oscillator which is free of feedback passages has an oscillation chamber having a length greater than its width, a pair of mutually facing and complementarily-shaped sidewalls and planar top and bottom walls, and first and second end walls. An input power nozzle is formed in said first end wall having a width W and a depth D, for issuing a stream of fluid into the oscillation chamber, and form alternately pulsating, cavitation-free vortices in said oscillation chamber on each side of the stream. An outlet opening formed in the downstream end wall and axially aligned with the power nozzle and has a width and depth such that internal pressure in the oscillation chamber is greater than ambient. The outlet wall is hingedly connected to a chamber wall and the chamber is such that it can be molded with the outlet wall hingedly connected thereto in one molding.

Abstract: Aircraft aircrew life support apparatus has a G-protection garment inflation pressure control valve disposed in a common body with a breathing demand regulator. Inflation pressure output by the garment inflation pressure control valve is ducted within the body to be directly applied as an operating force to a valve controlling outflow from a breathing-pressure control chamber of the regulator whereby positive pressure breathing obtains in the presence of G-load. The garment inflation pressure control valve comprises a pressure balanced valve adapted to be displaced against the bias of a spring in an opening direction by a pneumatic actuator. The pneumatic actuator is controlled by signals from an accelerometer sensing G-load for inflation of the garment when the aircrew member is subject to high G-load (typically in excess of 2G) and by signals from a cabin pressure sensor for inflation of the garment if the aircrew member is exposed to high altitude (typically in excess of 12000 metres).

Abstract: A fluidic oscillator which is free of feedback passages has an oscillation chamber having a length greater than its width, a pair of mutually facing and complimentary-shaped sidewalls and planar top and bottom walls, and first and second end walls. Stabilization ribs are formed on at least one of the top and bottom walls. An input power nozzle is formed in said first end wall having a width W and a depth D, for issuing a stream of fluid into the oscillation chamber, and form alternately pulsating, cavitation-free vortices in said oscillation chamber on each side of the stream. An outlet opening formed in the downstream end wall and axially aligned with the power nozzle and has a width and depth such that internal pressure in the oscillation chamber is greater than ambient. The outlet wall is hingedly connected to a chamber wall and the chamber is such that it can be molded with the outlet wall hingedly connected thereto in one molding.

Abstract: A high altitude G-valve produces a pressure signal in response to altitude and G-load without a connection to an external altitude sensing device. Bleed path pressure regulation by an aneroid valve and a G-sensing valve control a pilot valve which in turn controls a main valve. The main valve provides regulated air to the G-valve outlet in response to the pilot valve. A manually actuated button simulates a high-G load on the G-sensing valve to test the operation of the device.

Abstract: In accordance with an illutrative embodiment of the present invention, a fluidic oscillator includes a transverse vacuum port which extends between the diffuser legs a predetermined distance below the leading edge surface of the splitter. When flow is down one leg, a slight negative pressure condition is created in the port and transmitted thereby to the other leg, which causes switching of the flow to such other leg. The process then repeats in response to negative pressure in the one leg to cause switching of the flow back thereto. Fluid flow thus is switched back and forth between the legs at a resonant frequency, so that continuously fluctuating pressures are applied to the surrounding medium.

Abstract: An apparatus and method for treating effluents is disclosed for selective solids control and/or dewatering of effluents, for example drilling fluids (or mud), slurries or sludges, or other clean up involving solids removal from a hydraulic system where flocculation would be employed. The apparatus is compact and portable for ease of on-site delivery and hookup and includes a plurality of mixers for mixing polymer materials with water and/or the effluent, a plurality of pumps for controlling the flow of effluents, water and mixed liquids, and a plurality of conveniently located valves and pump controls for control of the various functions of the apparatus from a centrally located control panel. An improved mixing device is provided for blending of shear-sensitive fluids which includes multi-port injection sites and a series of geometrical flow altering elements.

Abstract: Disclosed is a valve used in the water drainage system of an aircraft having a pressurized cabin. The valve includes a housing with a water inlet and outlet and in which a float is mounted by a spring. The float includes a stopper element adapted to engage the water outlet in the housing. The water inlet is in communication with the cabin pressure and the water being discharged and the outlet is in communication with atmospheric pressure outside the aircraft. The spring normally biases the float so that the stopper element is away from the water outlet when the plane is on the ground. As the plane gains altitude, the differential in pressure between atmospheric pressure and cabin pressure closes the valve, with the spring moving the stopper element into engagement with the water outlet. This occurs in response to the changing differential in pressure between the cabin pressure and atmospheric pressure.

Abstract: A fluid dispersal device utilizes alternately pulsating vortices to cyclically oscillate a fluid stream transversely of its flow direction in a desired flow pattern. A pair of pulsating fluid streams, which may issue from a fluidic oscillator are projected into an output region or chamber defined in a body member the output region or chamber having inlets for the pulsating fluid streams and at least one outlet opening with the outlet opening being positioned to issue pressurized fluid from the chamber into an ambient atmospher. Vortices formed in the chamber are alternately oppositely rotating and cause the flow pattern to cyclically sweep across the outlet. The vortices have axes normal to the direction of fluid flow and alternately spin in first and second directions in response to inflowing of the first and second pulsating fluid streams to the chamber and the output flow is cyclically swept back and forth as each vortex spins in the first and second directions respectively.

Abstract: In order to control fuel flow at a fuel delivery point for auxiliary power units, and for other low fuel flow applications, an altitude-sensitive fuel flow control device (10) includes a fuel inlet (12) in communication with a fuel source and a fuel outlet (14) in communication with a fuel combustor. The device (10) includes an axially extending rod (16) having a metering surface (22) intermediate the ends (24, 26) thereof which may be located in various positions relative to a fuel flow path (18a, 18b, 18c, 18d, 18e) extending from the fuel inlet (12) to the fuel outlet (14) by axial movement of the rod (16) which varies fuel flow within a preselected range of altitude-dependent fuel flow rates.

Abstract: An electromagnetic valve for use for discharge of molten metal from a container comprises a body (1) providing a discharge passage (2, 3) surrounded by an electrical induction coil (4), the passage having a first portion (2) adjacent the container having a radius greater than that of a second portion (3) extending from the first portion to the discharge end of the passage, whereby the frequency of the electric current supplied to the coil (4) can be chosen independently of the passage discharge diameter.

Abstract: A composition, suitable for use as an explosion suppression composition, and comprising a mixture of at least one particulate component selected from alkali metal bicarbonate, alkali metal sesquicarbonate, and alkali metal carbonate, and a free-flow additive in particulate form. Also, a discharge apparatus comprising a vessel containing the composition under pressure, and an explosion suppression system comprising a pressure change detector operatively connected to a discharge vessel.

Abstract: A fuel pressure regulator comprising a housing, a movable diaphragm mounted within the housing, the diaphragm including a first side communicating with the atmosphere and an opposite second side having first and second portions, a fuel chamber partially defined by the first portion of the second side of the diaphragm, a constant pressure chamber partially defined by the second portion of the second side of the diaphragm, a fuel inlet communicating with the fuel chamber, and a fuel outlet having an inlet end located adjacent the diaphragm within the fuel chamber and being selectively communicable with the fuel chamber in response to movement of the diaphragm relative to the inlet end.

Abstract: A portable respirator system for supplying clean, breathable air to a hood or face mask is disclosed. The system can be carried on a waist belt and includes a housing containing air inlet and outlet plenums, and a battery powered, electric motor operated blower connected between the inlet and outlet plenums. The motor can be manually switched between high and low speed operation to supply high quantities of air upon demand caused by high respiration rate and otherwise supply lower quantities of air sufficient for low respiration rates to extend battery life between rechargings. A differential air pressure sensing switch is responsively connected for actuation when the difference between air pressure in the outlet plenum and the pressure of ambient atmosphere is less than a preselected value.

Abstract: An electronic-breathing mask system uses an electro-pneumatic valve for controlling air flow to a pilot. The system provides a continuous flow of air in an amount proportional to the pressure in the mask. The pressure in the mask is compared against a setpoint pressure to maintain a minimum derived pressure therein.

Abstract: A fluid swivel joint coupling has first and second body members pivotably connected together for pivoting about a swivel axis. The first body member includes an inlet portal, an outlet portal, a diverted fluid passageway opening into the outlet portal and a channel communicating the inlet portal with the diverted passageway. The second body member is pivotably mounted in flow communication with the outlet portal and has a second diverted passageway communicating through a second channel to a third portal. Each channel has an axis of elongation offset from the swivel axis so that fluid may enter the diverted passageway in the first body member tangentially from the first channel and flow therethrough in vortex fashion along the swivel axis into the second diverted passageway and leave the second diverted passageway tangentially to flow out the second channel.

Abstract: A pressure regulating valve 10 determines a fixed constant pressure drop across a metering valve 16 at a given altitude by comparing ambient pressure with a vacuum. Evacuated bellows 76 reacts with changes in altitude to bias a poppet 54 via rod 90, adjusting screw 100 and lever 66 towards or away from outlet 54.

Abstract: An electromagnetic valve for use for discharge of molten metal from a container, comprises a main body providing a discharge passage through which, in use, molten metal will flow; and electrical induction coil located about the passage; means to supply an alternating electric current to the coil whereby the coil provides an alternating magnetic field which induces electric currents in any molten metal in the passage; and a center member located in the passage, the arrangement being such that interaction between the magnetic field provided by the coil and the currents induced in the molten metal in the passage provides a force which as it is increased causes the flow rate of the molten metal through the valve to be reduced until the force is sufficient to urge the molten metal away from the wall of the passage until the molten metal is supported on the center member and the flow of molten metal is cut off.

Abstract: A drain assembly for aircraft which is operable to provide a drainage outflow course for discharge of cabin collecting liquids in an aircraft to the outside environment when the aircraft is at ground level or operating at altitudes up to a certain height but which is operable to seal tight that drainage course when the aircraft is operating above that certain height so that cabin depressurization cannot occur through the drainage course.

Abstract: An altitude compensating turbocharger control system including a boost regulator 54 for modifying a wastegate signal as a function of turbocharger output pressure and ambient pressure. The regulator includes a housing 52 that mounts a valve assembly 60 including a controller 98 for controlling the communication of an input chamber 94 with an output chamber 96 and the communication of the output chamber 96 with an ambient pressure port 82. The housing also mounts an aneroid capsule 62 and a force transmitting arm 70 for transferring and amplifying ambient pressure related forces generated by the aneroid capsule 62 to the controller. The pressure in the output chamber is a function of both input pressure and the atmospheric pressure sensed by the aneroid capsule and is communicated via a port 84 to a wastegate actuator 30 which opens and closes a wastegate valve 28.

Abstract: A flueric partial pressure sensor (10) includes a flueric bridge sensor (10a) having two bridge legs (11, 12) adapted for sensing a reference-gas and a sample-gas. A linear resistor (14, 15) and an orifice resistor (16, 17) are incorporated in each leg and arranged to cause asymmetric flow rates therethrough. Inlets to the two bridge legs are subject to a datum pressure within a datum pressure chamber (38) so that a change of datum pressure automatically changes control signals output by the sensor. The partial pressure sensor is disclosed in combination with a molecular sieve type gas concentration system (24) in an on-board oxygen enrichment of air system for an aircraft and enables the oxygen concentration in oxygen enriched air delivered by the system to be appropriate to breathing requirement at an altitude intermediate aircraft cabin and ambient atmospheric pressures.

Abstract: Apparatus useful on space vehicles as a valve for establishing external pressure in a pressure container or otherwise as an engine for performing work. The apparatus is responsive to atomspheric pressure retained in a plenum are applied to one side of a piston which atomspheric pressure is greater than an external pressure applied to the other side of the piston in a vacuum environment. A method for operation of such apparatus is also disclosed.

Abstract: The present invention relates to a dilution control oxygen regulator for providing a desired oxygen concentration at different altitudes and pressures. Two valves supply oxygen and air to a recipient's mask. A pressure transducer in the mask measures suction pressure which is compared with a prescribed pressure command signal for a particular altitude to produce a pressure error. The error signal is compensated by a proportional-plus-integral controller, and is biased between the two gas valves proportional to an oxygen concentration schedule which prescribes a desired oxygen concentration percentage based on altitude. The biased and compensated error signal is used as valve opening displacement commands for establishing desired valve opening areas. A feedback loop around the electromechanical valve actuator means improves the stability and accuracy of valve settings.

Abstract: A pressure regulator comprises a high-pressure chamber (2), and an atmospheric pressure chamber (3) having an opening (4) for controlled high-pressure (C), between which a diaphragm (5) is disposed having a sealing disc (6) resiliently movable in relation thereto, said diaphragm (5) selectively closing both an atmospheric pressure input port (8) and a through port (7) between high-pressure chamber (2) and atmospheric pressure chamber (3) in the sealing disc (6), and said sealing disc (6) being pressed towards the diaphragm (5) under the action of at least one spring (9). In order to permit a control of the high-pressure dependent on atmospheric pressure, for example of the boost pressure of a turbo charger for internal combustion engines, the pressure regulator has a bellow (11) responding to changes in the atmospheric pressure (A) for changing the bias of the spring (9) upon changing atmospheric pressure (A). The action of the bellow (11) on the spring bias is expediently adjustable.

Abstract: An altitude compensation unit for governing the combustion mixture in an automotive vehicle engine carburetor in response to changes in altitude above a predetermined altitude comprising a housing, an aneroid bellows anchored to the housing, and a force balancing pressure transducer valve fixed with respect to the housing. The transducer valve procides an output fluid pressure which varies in relation to the value of a force applied to the valve, with the output pressure force and the input force acting in opposition to each other on a valve transducer element. The transducer element is disposed in a predetermined position when the forces are balanced. A force transmission member supported by the housing transmits force between the capsule and the transducer element. A transducer output pressure responsive actuator alters the combustion mixture in response to output pressure from the transducer.

Abstract: An oxygen partial pressure controller regulates the oxygen partial pressure (PPO.sub.2) of the product gas of a pressure swing adsorption oxygen enriching system by means of a bleed valve which increases gas flow through the adsorptive system thereby decreasing the PPO.sub.2 of the product gas. The controller includes a solenoid valve which permits the bleed valve to function when the adsorption system pressure and PPO.sub.2 is high. An aneroid controls the product gas flow as a function of altitude when the bleed valve is permitted to function.

Abstract: There is disclosed a fluidic oscillator in which a stream of fluid is directed against a barrier member in an oscillation chamber. The barrier member serves as one wall of the oscillation chamber and in conjunction with other shaped wall surfaces of the oscillation chamber creates a pair of alternately pulsating control vortices for causing the fluid in the power stream to pass alternately to a pair of outlet passages. The vortices alternate both in strength and in a phase opposition to control flow of the jet stream in alternate fashion through the outlet passages. In a preferred embodiment of the invention, the pair of outlet passages are on opposite sides of the barrier member and converge to a common outlet to thereby provide a fan spray as the outlet passages alternate in the passage of the stream of fluid therethrough to the common outlet.

Abstract: A pressure compensating, water flow control device in which the incoming water is split between first and second flow paths. The first flow path is in the form of a closed loop and the second flow path includes a vortex chamber. The outlet from the device is co-axial with said vortex chamber. Both ends of the closed loop communicate with an inlet zone. The vortex chamber is, in one form, connected to said inlet zone by a passage and, in another form, said chamber and said inlet zone are contiguous.

Abstract: A drain structure for facilitating the draining of liquid condensate from inside an aircraft whenever air pressures inside and outside the aircraft are substantially equal. A pressure-sensitive apparatus is provided in conjunction with a drain opening through the aircraft's outer skin so that liquid can pass through the drain opening only while the apparatus is open. The apparatus includes a housing and a valve in the form of a slider movable within the housing to open and close the apparatus in response to the pressure differential between the inside and the outside of the aircraft. The housing defines a liquid passageway between the inside of the aircraft and the drain opening, and the slider closes the apparatus by blocking this liquid passageway whenever there is a substantial pressure differential between the inside and the outside of the aircraft.

Abstract: A selector valve for an aircraft breathing system wherein oxygen enriched gas is provided by two sources, the primary source being fractionalized air and the secondary, backup, source being bottled oxygen is comprised of a control valve with three operating modes and a shuttle valve. In the first operating mode gas is provided from the primary source, in the second operating mode gas is provided from the primary source within certain operating parameters and outside these parameters gas from the secondary source is provided. In the third operating mode, gas from the secondary source is provided. The shuttle valve responds to the secondary source gas pressure and directs gas from either source to the pilot based on preset conditions.

Abstract: A "bilge-like" valve, adapted to be mounted on the lowermost wall of an aircraft fuselage, is disclosed in which the valve has a normally open condition to drain accumulated condensate through a registering opening in the fuselage wall when the interior cabin is depressurized, and assumes a closed condition in response to a differentially higher cabin pressure relative to outside air pressure to seal off the interior of the fuselage. A valve housing retainer is affixed to the inner surface of the fuselage wall in registration with the wall opening for detachably retaining a valve housing incorporating a piston-like reciprocating valve member and biasing spring that is insertable and removable through the wall opening from the exterior of the aircrafts fuselage for ease of servicing.

Abstract: A Bourdon tube apparatus is provided for monitoring the pressure of a fluid pressure source. The output of the Bourdon tube is translated into a curvilinear motion which is transmitted to a linearly movable actuator valve or indicator. To enhance the force output linear response or linear output of the Bourdon tube actuator, an abutment block is provided which contacts one or more turns of the Bourdon tube adjacent its closed end to prevent expansion movement of the Bourdon tube in a direction opposite to the desired linear output movement. The Bourdon tube is mounted for calibrational purposes by having its open end connected by a flexible pipe to a support post which is rotationally mounted for movement about its longitudinal axis and defines a fluid conduit connection between the pressure source being monitored and the open end of the Bourdon tube.

Abstract: Mixing apparatus for two liquids such as cold and hot water having separate annular inlets (5, 6), spaced apart, for both of the liquids and provided with an external (7, 8, 9, 10) and internal (13, 14) guides for directing one liquid to the inlet (6) of the other liquid and the discharge of the mixed liquid. Both the external (7, 8, 9, 10) and the internal (13, 14) guides of the one liquid are mainly cylindrical in front of the inlet (6) of the other liquid. At the annular inlet (6) of the other liquid an annular vortex chamber (15) is provided.

Abstract: A pair of liquid flow passages are formed in a chamber and liquid flow through the passages is alternately blocked and unblocked by alternately pulsating vortices which causes alternate pulsations of fluid flow through the pairs of liquid flow passages.

Abstract: In one form of the invention, the control apparatus includes two stages: a poppet first stage and a piston second stage. The poppet first stage includes an altitude sensitive evacuated bellows coupled to a poppet valve. The second stage piston includes a pair of opposing head portions separated by a rod portion. The apparatus includes an output port which is coupled to a low pressure pneumatic signal or to a high pressure pneumatic signal, depending upon the position of the piston. For altitudes less than a predetermined altitude, e.g., 20,000 feet, the first stage develops a pneumatic servo signal which causes the piston to be in a first position which couples the output port of the apparatus to ambient air pressure. For altitudes greater than the predetermined altitude, the first stage develops a pneumatic servo signal which causes the piston to be in a second position which couples the output port of the apparatus to a high pressure pneumatic signal.

Abstract: An altitude compensation device for automobile engines or the like having a bellows adapted to detect the altitude and a plurality of valve mechanisms adapted to be actuated by the expansion or contraction of the bellows to adjust respective compensation air. The device has a disc mounted in the body of the device for free up and downward movement keeping a horizontal posture. The disc is carried by the bellows making a point contact with the central portion of the upper face of the bellows, so that it is almost free from the tilting of the bellows attributable to a vibration or the like. The valve mechanisms are operatively supported by the disc so as to be actuated uniformly by the bellows through the medium of the disc. Also, means are provided for adjusting the valve mechanisms independently of one another.

Abstract: An oxygen regulator for controlling the flow of breathing oxygen and uncontaminated air at various altitudes includes a balanced oxygen valve (20) and a balanced air valve (50) which cooperate with a dilution aneroid valve (62) to provide breathable mixture whose oxygen percentage increases with altitude to a predetermined altitude. Above that altitude one hundred percent oxygen is provided. A gas loading aneroid valve (110) operates to increase the oxygen pressure in accordance with altitude over a range of altitude.

Abstract: An atmospheric pressure compensation device has a reed valve of a resiliently bendable sheet material extending over a flat valve seat which defines therein an opening leading to an air passage to be connected to an air bleed of a carburetor, for example. The angular position of the freely bendable end portion of the reed valve relative to the valve seat is varied by a bellows member which is expansible and contractible in response to variation in the atmospheric pressure, to thereby control the rate of air flow through the opening and the passage to the air bleed. A fulcrum member is disposed in engagement with the reed valve to urge the same against the valve seat. The point of engagement of the fulcrum member with the reed valve is variable along the length thereof to vary the freely bendable length of the reed valve.

Abstract: A carburetor air control valve device which accurately meters air flow to each of the ports of a carburetor. A plurality of closure members of the poppet type are operated by expansion of a bellows member, as the bellows member expands in response to changes in density of the air to which the valve device is subjected. Each of the closure members is adapted to control flow of air to a port of an automotive carburetor.

Abstract: A fluid resistor with a fluid tight structure including two planar members having a surface of each contacting in close proximity. One of the planar members has a laminated structure including a substrate and at least one thin layer of substantially uniform thickness formed on the substrate. A groove extends through the layer. The groove and the surface of the other planar member define a capilliary passageway of substantially constant depth for restricted fluid flow.

Abstract: The fluidic oscillator consists of a resonant fluid circuit having a fluid inertance and a dynamic fluid compliance. The inertance is a conduit interconnecting two locations of a chamber on each side of a working fluid jet issuing into one end of the chamber, the inertance conduit serving to transfer working fluid between the two locations. Through one or more output orifices located approximately at the opposite end of the chamber, the fluid exits from a chamber exit region which is shaped to facilitate formation of a vortex (the dynamic compliance) from the entering fluid. The flow pattern in the chamber and particularly the vortex in the chamber exit region provide flow aspiration on one side and surplus of flow on the opposite side of the chamber, which effects accelerate and respectively decelerate the fluid in the inertance conduit such as to cause reversal of the vortex after a time delay given by the inertance.

Abstract: An anti-G valve and control system for providing a multivariable, multi-profile, pressurization of aircrew anti-G garments are disclosed. The ramp characteristic, the ramp onset level, a step onset, the step level, a limit pressure, are all controllable over the normal operating range. In addition, an optional ready pressure control is provided to just fill the anti-G suit volume and greatly decrease inflation time required to reach higher pressures.

Abstract: An apparatus for regulating the flow rate of a fluid, comprising a casing having an annular or cone-shaped fluid passage, for radial flow (inwardly or outwardly) between an inlet and outlet which are spaced radially and form unobstructed flow paths to the whole of the fluid passage. The geometry of the fluid passage is defined for a compressible and incompressible fluid so that laminar flow is achieved in the fluid passage. The apparatus further provides a very rapid dynamic response, essentially free of hysteresis, and substantially no internal generation of fluid flow turbulence resulting in a minimum of noise and freedom from cavitation. In an adjustable configuration the apparatus provides a proportional fluid valving function. In a nonadjustable configuration the apparatus provides a laminar flow restriction.

Abstract: The fluidic oscillator consists of a resonant fluid circuit having a fluid inertance and a dynamic fluid compliance. The inertance is a conduit interconnecting two locations of a chamber on each side of a working fluid jet issuing into one end of the chamber, the inertance conduit serving to transfer working fluid between the two locations. Through one or more output orifices located approximately at the opposite end of the chamber, the fluid exits from a chamber exit region which is shaped to facilitate formation of a vortex (the dynamic compliance) from the entering fluid. The flow pattern in the chamber and particularly the vortex in the chamber exit region provide flow aspiration on one side and surplus of flow on the opposite side of the chamber, which effects accelerate and respectively decelerate the fluid in the inertance conduit such as to cause reversal of the vortex after a time delay given by the inertance.