Experimental Study on Longitudinal Combustion Instability and Suppression of Oxygen/Ethanol Pintle Injector Rocket Engine
Year: 2026
Type: conference-paper
Abstract: The pintle injector liquid rocket engine can achieve a wide range of thrust adjustments and has a broad range of potential applications in future propulsion developments. However, high-frequency combustion instability in liquid rocket engines can have devastating consequences. This paper experimentally studies longitudinal combustion instability in a gaseous oxygen/ethanol pintle engine, adjusting the instability by regulating the operating parameters. The main results are as follows: when combustion instability occurs, the peak-to-peak value of the dynamic pressure inside the engine exceeds 65% of the ambient pressure. The dominant frequency in the high-frequency pressure signal spectrum is 1508 Hz, while the first-order longitudinal acoustic frequency of the combustion chamber is 1451 Hz. This indicates the occurrence of first-order longitudinal combustion instability in the combustion chamber. Additionally, a signal at around 52.4 Hz, possibly coupled with the engine's supply system, was observed. At a low oxidiser-to-fuel ratio, increasing the ethanol pressure drop reduces the amplitude of the pressure oscillations from 65% to 48% of ambient pressure; however, this still represents a relatively high level of combustion instability. Increasing the oxidiser-to-fuel ratio under low ethanol pressure drop results in a 60% amplitude of pressure oscillations in the combustion chamber. Increasing the ethanol pressure drop to 1.16 MPa suppresses the combustion instability in the chamber, reducing the amplitude to 5.9%.
Institution: Space Engineering University
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W7225656274