Fluidic Oscillator

• US 20080156373A1
• Filed: 06/09/2005
• Published: 07/03/2008
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: Thermofluidics Limited
• Original Assignee: Thermofluidics Limited
• Inventors: Smith, Thomas Charles Brannam
• Granted Patent: US 7,908,855 B2
• Time in Patent Office: Days
• US Class Current: 137/14
• CPC Class Codes: F04F 1/04 generated by vaporising and condensing
• CPC Class Codes: Y10T 137/0396 Involving pressure control
• CPC Class Codes: Y10T 137/206 Flow affected by fluid contact, energy field or coanda effect [e.g., pure fluid device or system]

Abstract

The invention relates to fluidic oscillators including compressed gas driven pumps and liquid piston and thermoacoustic heat engines and heat pumps in which the intention is to generate large amplitude oscillations by eliminating the dependence of the oscillations on inertia. According to the principle embodiment represented by circuit 200 pressure or temperature variations 27′ drive pressure variations in vessel 11′ causing a flow of further working fluid between vessel 11′ and load 12′ wherein useful work is consumed. Said flow varies out of phase with said pressure variations in vessel 11′ by a first phase angle determined by inter alia the dissipative load 12′and the capacity of vessel 11′. Oscillations are sustained due to a second phase angle determined by inter alia subcircuit 13′ comprising dissipative processes 260, 262 and capacitive processes 261, 263 wherein each said dissipative process comprises any one, or combination of the following: viscous drag, thermal resistance or mechanical friction and each capacitive process comprises any one, or combination of the following: hydrostatic pressure change due to a flow, fluid compressibility, thermal capacitance, or elasticity; and wherein, the magnitude of the pressure changes in the working fluid increases or remains constant with time due to at least one mechanism giving rise to a gain.

Claims

1-60. -60. (canceled)

9. A feedback phase angle between the volume of working fluid contained within the first vessel and the pressure supplied or dissipated by an energy source or sink;

h. A thermal phase angle between the temperature of said heat exchanger means and the rate of flow of entropy through a surface therein;

i. The relative magnitudes of said dissipative and reactive components and said gain being chosen such that said load phase angle and said feedback phase angle are approximately equal to 90 degrees, and said thermal phase angle is approximately equal to 0 degrees.

61. A fluidic oscillator comprising:

at least one vessel arranged to contain a working fluid;

a pressuring means for pressurizing said working fluid;

a de-pressurizing means for de-pressurizing said working fluid;

wherein said pressurizing and de-pressurizing causes said working fluid to move in and out of said at least one vessel;

at least two time delay mechanisms associated with said working fluid to cause a phase shift between changes in mass and pressure of working fluid in said at least one vessel; and

including a gain mechanism that gives rise to a gain; and

wherein, when each said time delay mechanism comprises a dissipative process and a capacitive process said gain is sufficient that in normal operation the magnitude of said pressure changes in said working fluid increases or remains constant with time to permit steady oscillations independent of the inertia of the working fluid.

63. A fluidic oscillator as claimed in claim 61 configured as a heat engine which, when coupled to a load, has a load phase shift between displacement and pressure of working fluid in said load which in said normal operation matches said phase shift between changes mass and pressure of working fluid in said at least one vessel.

64. A fluidic oscillator as claimed in claim 63, wherein said load phase shift is substantially 90 degrees.

65. A fluidic oscillator as claimed in claim 61 further comprising a plurality of heat exchangers for giving rise to a flow of heat into and from said at least one vessel, and wherein, in operation, a total phase shift between a flow of heat through said heat exchangers and a saturation temperature of said working fluid in said at least one vessel is close to a value required to give a maximum difference between mean heat addition and heat rejection temperatures for the pressure amplitude within said working fluid during said operation.

66. A fluidic oscillator as claimed in claim 61 configured as a heat engine and further comprising high and low pressure working fluid reservoirs for supplying and removing working fluid respectively to and from said at least one vessel.

67. A fluidic oscillator as claimed in claim 61 configured as a heat engine and further comprising a second vessel from which working fluid is coupled to a load, wherein said working fluid has a passive gas component mainly occupying said second vessel, the fluidic oscillator further comprising a diffusion column or separation chamber to separate said passive component of said working fluid from an active component of said working fluid giving rise to said pressure changes in said working fluid.

68. A fluidic oscillator as claimed in claim 61 configured as a heat engine and further comprising a second vessel from which working fluid is coupled to a load, wherein said working fluid is part vapor and part liquid, said first and second vessels being coupled by a conduit for said vapor and through a restriction for said liquid, for controlling said phase shift between changes mass and pressure of working fluid in said at least one vessel.

69. A fluidic oscillator as claimed in claim 61 further comprising two said working vessels coupled by a saturator and a conduit, said fluidic oscillator being coupled to a load, and wherein said load has inertance with reactive impedance with a magnitude equal to that of a compliance contained within said saturator and said conduit at a frequency of oscillation of the fluidic oscillator.

71. A pump comprising the fluidic oscillator of claim 61.

62. A fluidic oscillator comprising:

at least one vessel arranged to contain a working fluid;

a pressuring means for pressurizing said working fluid;

a de-pressurizing means for de-pressurizing said working fluid;

wherein said pressurizing and de-pressurizing causes said working fluid to move in and out of said at least one vessel;

at least two time delay mechanisms associated with said working fluid to cause a phase shift between changes in mass and pressure of working fluid in said at least one vessel; and

including a gain mechanism that gives rise to a gain; and

wherein said fluidic oscillator, when modeled as an electric circuit, has RC feedback, whereby said fluidic oscillator is operable to permit steady oscillations independent of the inertia of said working fluid.

70. A fluidic oscillator comprising a vessel arranged to contain a working fluid, the oscillator being arranged to permit steady oscillations independently of the inertia of said working fluid;

and wherein said oscillator has a load phase shift and a feedback phase shift each of substantially 90 degrees and a thermal phase angle of substantially 0 degrees.

72. Use of operating a fluidic oscillator comprising:

a fluidic oscillator comprising;

at least one vessel arranged to contain a working fluid;

a pressuring means for pressurizing said working fluid;

a de-pressurizing means for de-pressurizing said working fluid;

wherein said pressurizing and de-pressurizing causes said working fluid to move in and out of said at least one vessel;

at least two time delay mechanisms associated with said working fluid to cause a phase shift between changes in mass and pressure of working fluid in said at least one vessel; and

including a gain mechanism that gives rise to a gain;

the use comprising configuring said fluidic oscillator such that said time delay mechanisms each comprise dissipative and capacitive process to thereby permit steady oscillations independently of the inertia of said working fluid.

73. Use of operating a fluidic oscillator comprising:

a fluidic oscillator comprising;

at least one vessel arranged to contain a working fluid;

a pressuring means for pressurizing said working fluid;

a de-pressurizing means for de-pressurizing said working fluid;

wherein said pressurizing and de-pressurizing causes said working fluid to move in and out of said at least one vessel;

at least two time delay mechanisms associated with said working fluid to cause a phase shift between changes in mass and pressure of working fluid in said at least one vessel; and

including a gain mechanism that gives rise to a gain;

the use comprising configuring said fluidic oscillator such that, when modeled as an electric circuit, the oscillator has RC feedback, to thereby permit steady oscillations independently of the inertia of said working fluid.

74. A fluidic oscillator comprising:

a. first and second vessels arranged to contain a working fluid, the cross sectional area of said second vessel being minimized within limits set by surface tension and the cross sectional area of the first vessel being less than two times greater than the cross sectional area of the second vessel;

b. means for conjoining the first and second vessels so as to subject said two vessels to a common pressure;

c. means for communicating the volume of working fluid contained within the first vessel to the second vessel;

d. means for giving rise to pressure changes in the working fluid, located substantially within the second vessel;

e. a load comprising dissipative and reactive components giving rise to a load phase angle between the mass of working fluid contained within the first vessel and the pressure changes therein due to said load;

f. means for coupling the working fluid in the first vessel to said load such that changes in the volume of the working fluid contained in said first and second vessels give rise to transfer of work between the first vessel and the load;

g. gain means including means to provide viscous drag, hydrostatic pressure changes due to a flow, and thermal resistance;

h. the compliance of said working fluid and the reactive component of said load being arranged to resonate at frequency of oscillation, determined by said dissipative and reactive components and said gain.

77. A fluidic oscillator according to claim 74 in which said working fluid is part liquid and part gas or vapor within the vessels, said fluidic oscillator further comprising means of permitting a flow of liquid between the first vessel and the second vessel driven by the hydrostatic pressure difference at a lower portion of each said vessel due to the liquid therein, and wherein said means of permitting a flow of liquid further provides a viscous drag intended to giving rise to a phase shift between the liquid levels in said first and second vessels;

78. A fluidic oscillator according to claim 74, said fluidic oscillator further comprising means of connecting said vessels to reservoirs of high or low pressure, located substantially within the second vessel, and pressure sources having a pressure difference there between coupled to said pressure reservoirs.

75. A fluidic oscillator comprising:

a. first and second vessels arranged to contain a working fluid;

b. means for conjoining the first and second vessels so as to subject said two vessels to a common pressure;

c. means for communicating the volume of working fluid contained within the first vessel to the second vessel;

d. means for giving rise to pressure changes in the working fluid, located substantially within the second vessel;

e. a load comprising dissipative and reactive components giving rise to a load phase angle between the mass of working fluid contained within the first vessel and the pressure changes therein due to said load;

f. means for coupling the working fluid in the first vessel to said load such that changes in the volume of the working fluid contained in said first and second vessels give rise to transfer of work between the first vessel and the load;

g. gain means including means to provide viscous drag, hydrostatic pressure changes due to a flow, and thermal resistance;

h. the compliance of said working fluid and the reactive component of said load being arranged to resonate at the frequency of the oscillations, determined by said dissipative and reactive components and said gain.

76. A fluidic oscillator comprising:

a. first and second vessels arranged to contain a working fluid;

b. means for conjoining the first and second vessels so as to subject said two vessels to a common pressure;

c. means for communicating the volume of working fluid contained within the first vessel to the second vessel;

d. means for giving rise to pressure changes in the working fluid, located substantially within the second vessel;

e. a load comprising dissipative and reactive components giving rise to a load phase angle between the mass of working fluid contained within the first vessel and the pressure changes therein due to said load;

f. means for coupling the working fluid in the first vessel to said load such that changes in the volume of the working fluid contained in said first and second vessels give rise to transfer of work between the first vessel and the load;

g. means including comprising further dissipative and reactive components giving rise to a feedback phase angle between the volume of working fluid contained within the first vessel and the pressure supplied or dissipated by an energy source or sink;

h. the relative magnitudes of said dissipative and reactive components and said gain being chosen such that said load phase angle and said feedback phase angle are substantially equal to 90 degrees.

79. A thermofluidic oscillator comprising:

a. first and second vessels arranged to contain a working fluid;

b. means for conjoining the first and second vessels so as to subject said two vessels to a common pressure;

c. means for communicating the volume of working fluid contained within the first vessel to the second vessel;

d. heat exchanger means located substantially within said second vessel intended to give rise to pressure changes in the working fluid by heating or cooling of part thereof;

e. A load comprising dissipative and reactive components giving rise to a load phase angle between the mass of working fluid contained within the first vessel and the pressure changes therein due to said load;

f. Means of giving rise to a gain comprising further dissipative and reactive components;

80. A thermofluidic oscillator comprising:

a. first and second vessels arranged to contain a working fluid which is part liquid and part vapor within the vessels;

b. means of cojoining said two vessels so as to subject them to a common pressure;

c. means of permitting a flow of liquid between the first vessel and the second vessel driven by the hydrostatic pressure difference at a lower portion of each said vessel due to the liquid therein;

d. heat exchanger means located substantially within said second vessel intended to heat and thereby expand part of said working fluid when liquid level is high therein and cool and thereby contract part of said working fluid when liquid level is low therein;

e. a load comprising dissipative and reactive components giving rise to a load phase angle between the volume of liquid contained within the first vessel and the pressure changes therein due to said load;

f. means of giving rise to a gain comprising thermal reservoirs having a temperature difference therebetween coupled to said heat exchanger means, and further dissipative and reactive components including thermal resistance arising due to said heat exchanger means, the compressibility of said working fluid, viscous drag arising from said flow of liquid between said first and second vessels, and the change in hydrostatic pressure therein;

g. a feedback phase angle between the volume of working fluid contained within the first vessel and the pressure therein due to said thermal reservoirs;

h. a thermal phase angle between the temperature of said thermal reservoirs and the rate of flow of entropy thereto or therefrom;

i. The relative magnitudes of said dissipative and reactive components and said gain being chosen such that said load phase angle and said feedback phase angle are approximately equal to 90 degrees, and said thermal phase angle is approximately equal to 0 degrees.