Rocket injector subscale stability assessment with telescoping throat or moveable injector plate
Systems and methods for subscale testing of rocket engine injector stability. The system includes a combustion chamber with telescoping throat that is continuously axially moveable via an actuator. A modular injector plate comprises one or more first rocket engine injector elements configured to inject one or more propellants, such as a fuel and an oxidizer, into the chamber. The injector plate and/or the telescoping throat may be continuously translated, to thereby continuously vary a combustion volume of the chamber and create a dynamically tunable downstream boundary. The injectors are thus exposed to acoustic modes of varying frequency, covering the range of acoustic modes expected in a full scale rocket engine. The injector plate is removably attached to an upstream end of the chamber for replacement of the first injectors with different, second injectors for subsequent testing.
1. A system for subscale testing of rocket injector stability, the system comprising:
a chamber having a sidewall extending axially;
a throat at a downstream end of the chamber; and
an injector plate spanning across a cross-section of the chamber to provide a barrier at an upstream end of the chamber, the injector plate removably positioned at an upstream end of the chamber, the injector plate comprising one or more injectors configured to inject one or more propellants into the chamber, the injector plate being one of a plurality of different injector plates configured to be removably attached to the chamber, wherein the injector plate is continuously moveable through the chamber between the sidewall in an axial direction to continuously vary a combustion volume of the chamber located between the injector plate and the throat, and wherein the chamber is configured to have a single injector plate attached to the chamber during testing.
2. The system of claim 1 , wherein a positioning of the throat remains fixed.
3. The system of claim 1 , further comprising an actuator configured to axially move the injector plate.
4. The system of claim 1 , wherein the throat has an inner diameter that decreases from a first inner diameter to a second inner diameter in an upstream direction and increases from the second inner diameter to a third inner diameter in the upstream direction.
5. The system of claim 1 , further comprising a sensor configured to detect a pressure within the combustion volume.
6. The system of claim 1 , wherein the throat defines a converging-diverging nozzle shape.
7. A subscale rocket injector stability test system comprising:
a chamber;
an injector plate spanning across a cross-section of the chamber to provide a barrier at an upstream end of the chamber, the injector plate removably attached to the upstream end of the chamber, and the injector plate structurally holding one or more injectors configured to inject one or more propellants into the chamber, wherein the injector plate is one of a plurality of different injector plates configured to be removably attached to the chamber for interchanging the injector plate with a different injector plate of the plurality of different injector plates, the different injector plate structurally holding one or more different injectors, wherein a single injector plate is configured to be attached to the chamber during testing; and
a telescoping throat positioned at a downstream end of the chamber, wherein the telescoping throat is continuously moveable in an axial direction to continuously vary a combustion volume of the chamber located between the injector plate and an upstream end of the telescoping throat.
8. The system of claim 7 , wherein the telescoping throat is positioned within the chamber.
9. The system of claim 7 , wherein a sidewall of the telescoping throat is positioned external to the chamber.
10. The system of claim 7 , further comprising a first actuator configured to axially move the telescoping throat.
11. The system of claim 10 , further comprising a second actuator configured to axially move the telescoping throat, wherein the first actuator and the second actuator move the telescoping throat simultaneously.
12. The system of claim 7 , wherein the telescoping throat further comprises a cooling channel.
13. The system of claim 7 , wherein the telescoping throat defines a converging-diverging nozzle shape.
14. The system of claim 7 , wherein, in a downstream direction, the telescoping throat has a first inner diameter that decreases to a second inner diameter and the second inner diameter increases to a third inner diameter.
15. The system of claim 7 , further comprising a sensor configured to detect a pressure within the combustion volume.
16. A method of subscale testing rocket injector stability, the method comprising:
injecting into a combustion chamber one or more propellants from one or more injectors supported by a modular injector plate to cause combustion, the modular injector plate being one of a plurality of different injector plates configured to span across a cross-section of the combustion chamber to provide a barrier at an upstream end of the combustion chamber and to be removably attached to the combustion chamber for interchanging the modular injector plate with a different injector plate of the plurality of different injector plates, the different injector plate structurally holding one or more different injectors, wherein a single modular injector plate is attached to the combustion chamber during the injecting;
continuously varying a combustion volume within the combustion chamber; and
detecting acoustic data from within the combustion volume as the combustion volume is varied.
17. The method of claim 16 , wherein continuously varying the combustion volume comprises continuously moving an external telescoping throat positioned at a downstream end of the combustion chamber.
18. The method of claim 16 , wherein continuously varying the combustion volume comprises continuously moving the modular injector plate.
19. The method of claim 16 , wherein continuously varying the combustion volume comprises continuously moving an internal telescoping throat through the combustion chamber.
20. The method of claim 16 , further comprising replacing the modular injector plate with the different injector plate supporting the one or more different injectors.