Pulse combustion device

1. A pulse combustion device comprising:

a plurality of combustors, each comprising a wall surface extending from an upstream inlet to a downstream outlet, the wall surface defining:

a main body portion extending downstream from the inlet; and

a nozzle downstream of the main body portion; and

a plurality of coupling conduits providing communication between the combustors, including for each given combustor:

first communication between a first location upstream of the nozzle of the given combustor and a first nozzle location along the nozzle of a first other of the plurality of combustors; and

second communication between a second location upstream of the nozzle of a second other of the plurality of combustors and a second nozzle location along the nozzle of the given combustor.

2. The device of claim 1 wherein:

the communication includes for each given combustor:

third communication between a third location upstream of the nozzle of such given combustor and a third nozzle location along the nozzle of a third other of the plurality of combustors; and

fourth communication between a fourth location upstream of the nozzle of a fourth other of the plurality of combustors and a fourth nozzle location along the nozzle of the given combustor.

3. The device of claim 2 further comprising a plurality of check valves positioned to:

essentially restrict the first communication to a direction from the given combustor;

essentially restrict the second communication to a direction to the given combustor;

essentially restrict the third communication to a direction from the given combustor; and

essentially restrict the fourth communication to a direction to the given combustor.

4. The device of claim 1 wherein:

the nozzle has a convergent portion, a divergent portion downstream of the convergent portion, and a throat therebetween; and

the first and second nozzle locations are proximate the throat of the nozzle along which they are located.

5. The device of claim 1 further comprising a rotary inlet valve sequentially opening and closing the inlets of the plurality of combustors.

6. The device of claim 1 further comprising:

a fuel source;

an oxidizer source; and

for each given combustor:

a fuel valve governing fuel flow from the fuel source to the given combustor; and

an oxidizer valve governing oxidizer from the oxidizer source to the given combustor.

7. The device of claim 1 wherein the plurality of combustors are arrayed in a circle about a central longitudinal axis of the device.

8. The device of claim 1 wherein the plurality of combustors comprises between three and fifty combustors, inclusive.

9. The device of claim 1 wherein the plurality of combustors comprises between three and six combustors, inclusive.

10. A pulse combustion device comprising:

a plurality of combustors, each comprising:

a wall surface;

an upstream inlet; and

a downstream outlet for discharging combustion products; and

means for varying an effective throat cross-sectional area of each such combustor during phases of a charge/discharge cycle of such combustor.

11. The device of claim 10 wherein for each such combustor, the inlet comprises a fuel inlet receiving fuel and an oxidizer inlet receiving oxidizer.

12. The device of claim 10 wherein:

each such combustor comprises a convergent/divergent nozzle and forming the outlet of such combustor; and

the means functions by discharging gas laterally into the nozzle, such gas including gas diverted from at least one other of the plurality of combustors.

13. A method for operating a pulse combustion device, the device comprising:

a plurality of combustors, each comprising:

a wall surface;

an upstream inlet; and

a downstream outlet, the method comprising for each combustor:

discharging gas laterally into the combustor between the inlet and the outlet; and

varying a rate of the discharging during a cycle of the given combustor so as to control a backpressure within the given combustor.

14. The method of claim 13 wherein the discharging gas comprises directing gas from at least one other of the plurality of combustors.