Apparatus and Method for Controlling a Pressure Gain Combustor

• US 20140260294A1
• Filed: 04/27/2012
• Published: 09/18/2014
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: Exponential Technologies Inc.
• Original Assignee: Exponential Technologies Inc.
• Inventors: Farshchian, Soheil
• Granted Patent: US 10,451,275 B2
• Time in Patent Office: Days
• US Class Current: 60/773
• CPC Class Codes: F02C 5/10 the working fluid forming a resonating or oscillating gas column, i.e. the combustion chambers having no positively actuated valves, e.g. using Helmholtz effect
• CPC Class Codes: F02C 5/11 using valveless combustion chambers
• CPC Class Codes: F02C 7/22 Fuel supply systems
• CPC Class Codes: F02C 9/26 Control of fuel supply F02C9/48 takes precedence; fuel valves F02C7/232
• CPC Class Codes: F02K 7/02 the jet being intermittent, i.e. pulse-jet
• CPC Class Codes: F23C 2205/10 with pulsating fuel supply
• CPC Class Codes: F23N 2005/181 using detectors sensitive to rate of flow of air
• CPC Class Codes: F23N 2005/185 using detectors sensitive to rate of flow of fuel
• CPC Class Codes: F23N 5/00 Systems for controlling combustion regulating fuel supply F23N1/00, regulating air supply or draught F23N3/00
• CPC Class Codes: F23N 5/20 with a time programme acting through electrical means, e.g. using time-delay relays
• CPC Class Codes: F23R 7/00 Intermittent or explosive combustion chambers
• CPC Class Codes: G05D 7/0617 specially adapted for fluid materials
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

A method of controlling operation of a pressure gain combustor comprises: determining a fuel injector duty cycle and a combustion frequency that meets a target load set point and a target fill fraction of the combustor; determining a fuel supply pressure setting, a fuel injector timing setting and an ignition timing setting that achieves the determined fuel injector duty cycle and combustion frequency; and sending a fuel supply pressure control signal with the fuel supply pressure setting to a fuel pressurizing means of the combustor, a fuel injector control signal with the fuel injector timing setting to a fuel injector of the combustor, and an ignition timing control signal with the ignition timing setting to an ignition assembly of the combustor.

Claims

1. A method of controlling operation of a pressure gain combustor having a fuel pressurizing means, a fuel injector, and an ignition assembly, the method comprising:

(a) determining a fuel injector duty cycle and a combustion frequency that meets a target load set point and a target fill fraction of the combustor;

(b) determining a fuel supply pressure setting, a fuel injector timing setting and an ignition timing setting that achieves the determined fuel injector duty cycle and combustion frequency; and

(c) sending a fuel supply pressure control signal with the fuel supply pressure setting to the fuel pressurizing means, a fuel injector control signal with the fuel injector timing setting to the fuel injector, and an ignition timing control signal with the ignition timing setting to the ignition assembly.

2. A method as claimed in claim 1 wherein the step of determining the fuel injector duty cycle comprises measuring an air flow rate through the combustor and determining a fuel flow rate that is proportional to the air flow rate and which meets the target load set point.

3. A method as claimed in claim 2 wherein the step of determining the fuel injector duty cycle further comprises measuring an air flow rate through the combustor and determining a fuel flow rate that meets the target load set point and achieves a stoichiometric oxidant/fuel ratio.

4. A method as claimed in claim 2 further comprising selecting at least one equivalence ratio, and determining a fuel flow rate that meets the target load set point and the selected equivalence ratio.

5. A method as claimed in claim 1 further comprising measuring a pressure inside an oxidant/fuel mixing chamber of the combustor and wherein the fuel pressurizing means operating at the fuel pressure setting provides a pressure sufficient to deliver fuel into the mixing chamber to achieve the determined fuel flow rate.

6. A method as claimed in claim 1 further comprising determining an ignition phase lag for the combustor and wherein the ignition timing control signal further includes the determining ignition phase lag.

7. A method as claimed in claim 1 wherein the target fill fraction is a value between 0.8 and 1.1.

8. A method as claimed in claim 1 wherein the step of determining the combustion frequency comprises:

determining a maximum fuel injection duration (“

MID”

) in the combustor that is a function of the target fill fraction, and a required fuel injection duration per detonation cycle (IDDC) being the duty cycle divided by the combustion frequency, and

selecting the combustion frequency such that the IDDC is less than or equal to the MID.

9. A controller for a pressure gain combustor having a fuel pressurizing means, a fuel injector, and an ignition assembly, the controller comprising a processor and a memory programmed with steps and instructions executable by the processor to:

(a) determine a fuel injector duty cycle and a combustion frequency that meets a target load set point and a target fill fraction of the combustor;

(b) determine a fuel supply pressure setting, a fuel injector timing setting and an ignition timing setting that achieves the determined fuel injector duty cycle and combustion frequency; and

(c) send a fuel supply pressure control signal with the fuel supply pressure setting to the fuel pump, a fuel injector control signal with the fuel injector timing setting to the fuel injector, and an ignition timing control signal with the ignition timing setting to the ignition assembly.

10. A controller as claimed in claim 9 wherein the step of determining the fuel injector duty cycle comprises measuring an air flow rate through the combustor and determining a fuel flow rate that meet the target load set point.

11. A controller as claimed in claim 10 wherein the step of determining the fuel injector duty cycle further comprises measuring an air flow rate through the combustor and determining a fuel flow rate that meets the target load set point and a stoichiometric oxidant/fuel ratio.

12. A controller as claimed in claim 11 further programmed with the step of selecting at least one equivalence ratio, and determining a fuel flow rate that meets the target load set point and the selected equivalence ratio.

13. A controller as claimed in claim 9 further programmed with the step of measuring a pressure inside an oxidant/fuel mixing chamber of the combustor and wherein the fuel supply pressure setting provides a fuel supply pressure sufficient to deliver fuel into the mixing chamber to achieve the determined fuel flow rate.

14. A controller as claimed in claim 9 further programmed with the step of determining an ignition phase lag for the combustor and wherein the ignition timing control signal further includes the determining ignition phase lag.

15. A controller as claimed in claim 9 wherein the target fill fraction is a value between 0.8 and 1.1.

16. A controller as claimed in claim 9 wherein the step of determining the combustion frequency comprises:

determining a maximum fuel injection duration (“

MID”

) in the combustor, and a required fuel injection duration per detonation cycle (IDDC) being the duty cycle divided by the combustion frequency, and

selecting the combustion frequency such that the IDDS is less than or equal to the MID.

17. A controller as described in claim 9, wherein the pressure gain combustor is fluidly coupled to a compressor and turbine system to generate mechanical power.

18. A pressure gain combustor comprising:

(a) a fuel pressurizing means,

(b) a fuel injector fluidly coupled to the fuel pressurizing means;

(c) a mixing chamber fluidly coupled to the fuel injector and to an oxidant supply;

(d) a combustion chamber in fluid communication with the mixing chamber;

(e) an ignition assembly in fluid communication with the combustion chamber; and

(f) a controller comprising a processor and a memory programmed with steps and instructions executable by the processor to;

(i) determine a fuel injector duty cycle and a combustion frequency that meets a target load set point and a target fill fraction of the combustor;

(ii) determine a fuel pump pressure setting, a fuel injector timing setting and an ignition timing setting that achieves the determined fuel injector duty cycle and combustion frequency; and

(iii) send a fuel pump control signal with the fuel pump pressure setting to the fuel pump, a fuel injector control signal with the fuel injector timing setting to the fuel injector, and an ignition timing control signal with the ignition timing setting to the ignition assembly.

19. A pressure gain combustor as described in claim 18, wherein an exhaust outlet of the combustor is fluidly coupled to a compressor and turbine system to generate mechanical power.

20. A pressure gain combustor as claimed in claim 19 wherein an input load fort the target load set point is the rotational speed of a turbine shaft of the turbine system.