Impact of the head cavity and submerged nozzle on corner vortices and pressure oscillations in a solid rocket motor with a backward-facing step

Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference, a numerical methodology using large eddy simulation was established in this study. Based on this methodology, the position of the backward-facing step of the motor was computed and analyzed to d...

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Main Authors: Hongbo Xu, Jie Hu, Chao Huo, Yifang He, Peijin Liu
Format: Article
Language:English
Published: KeAi Communications Co., Ltd. 2025-07-01
Series:Defence Technology
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Online Access:http://www.sciencedirect.com/science/article/pii/S2214914725000649
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author Hongbo Xu
Jie Hu
Chao Huo
Yifang He
Peijin Liu
author_facet Hongbo Xu
Jie Hu
Chao Huo
Yifang He
Peijin Liu
author_sort Hongbo Xu
collection DOAJ
description Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference, a numerical methodology using large eddy simulation was established in this study. Based on this methodology, the position of the backward-facing step of the motor was computed and analyzed to determine a basic configuration. Two key geometrical parameters, the head cavity angle and submerged nozzle cavity height, were subsequently introduced. Their effects on the corner vortex motion and their interactions with the acoustic pressure downstream of the backward-facing step were analyzed. The phenomena of vortex acoustic coupling and characteristics of pressure oscillations were further explored. The results show that the maximum error between the simulations and experimental data on the dominant frequency of pressure oscillations is 5.23%, which indicates that the numerical methodology built in this study is highly accurate. When the step is located at less than 5/8 of the total length of the combustion chamber, vortex acoustic coupling occurs, which can increase the pressure oscillations in the motor. Both the vorticity and the scale of vortices in the downstream step increase when the head cavity angle is greater than 24°, which increases the amplitude of the pressure oscillation by maximum 63.0%. The submerged nozzle cavity mainly affects the vortices in the cavity itself rather than those in the downstream step. When the height of the cavity increases from 10 to 20 mm, the pressure oscillation amplitude under the main frequency increases by 39.1%. As this height continues to increase, the amplitude of pressure oscillations increases but the primary frequency decreases.
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institution Matheson Library
issn 2214-9147
language English
publishDate 2025-07-01
publisher KeAi Communications Co., Ltd.
record_format Article
series Defence Technology
spelling doaj-art-9c70a708f50e400aa4e4cf40f7b0c49c2025-06-29T04:52:03ZengKeAi Communications Co., Ltd.Defence Technology2214-91472025-07-0149405416Impact of the head cavity and submerged nozzle on corner vortices and pressure oscillations in a solid rocket motor with a backward-facing stepHongbo Xu0Jie Hu1Chao Huo2Yifang He3Peijin Liu4School of Astronautics, Northwestern Polytechnical University, Xi'an, 710072, ChinaSchool of Astronautics, Northwestern Polytechnical University, Xi'an, 710072, ChinaCorresponding author.; School of Astronautics, Northwestern Polytechnical University, Xi'an, 710072, ChinaSchool of Astronautics, Northwestern Polytechnical University, Xi'an, 710072, ChinaSchool of Astronautics, Northwestern Polytechnical University, Xi'an, 710072, ChinaTaking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference, a numerical methodology using large eddy simulation was established in this study. Based on this methodology, the position of the backward-facing step of the motor was computed and analyzed to determine a basic configuration. Two key geometrical parameters, the head cavity angle and submerged nozzle cavity height, were subsequently introduced. Their effects on the corner vortex motion and their interactions with the acoustic pressure downstream of the backward-facing step were analyzed. The phenomena of vortex acoustic coupling and characteristics of pressure oscillations were further explored. The results show that the maximum error between the simulations and experimental data on the dominant frequency of pressure oscillations is 5.23%, which indicates that the numerical methodology built in this study is highly accurate. When the step is located at less than 5/8 of the total length of the combustion chamber, vortex acoustic coupling occurs, which can increase the pressure oscillations in the motor. Both the vorticity and the scale of vortices in the downstream step increase when the head cavity angle is greater than 24°, which increases the amplitude of the pressure oscillation by maximum 63.0%. The submerged nozzle cavity mainly affects the vortices in the cavity itself rather than those in the downstream step. When the height of the cavity increases from 10 to 20 mm, the pressure oscillation amplitude under the main frequency increases by 39.1%. As this height continues to increase, the amplitude of pressure oscillations increases but the primary frequency decreases.http://www.sciencedirect.com/science/article/pii/S2214914725000649Solid rocket motorBackward-facing stepHead cavitySubmerged nozzleLarge eddy simulationPressure oscillation
spellingShingle Hongbo Xu
Jie Hu
Chao Huo
Yifang He
Peijin Liu
Impact of the head cavity and submerged nozzle on corner vortices and pressure oscillations in a solid rocket motor with a backward-facing step
Defence Technology
Solid rocket motor
Backward-facing step
Head cavity
Submerged nozzle
Large eddy simulation
Pressure oscillation
title Impact of the head cavity and submerged nozzle on corner vortices and pressure oscillations in a solid rocket motor with a backward-facing step
title_full Impact of the head cavity and submerged nozzle on corner vortices and pressure oscillations in a solid rocket motor with a backward-facing step
title_fullStr Impact of the head cavity and submerged nozzle on corner vortices and pressure oscillations in a solid rocket motor with a backward-facing step
title_full_unstemmed Impact of the head cavity and submerged nozzle on corner vortices and pressure oscillations in a solid rocket motor with a backward-facing step
title_short Impact of the head cavity and submerged nozzle on corner vortices and pressure oscillations in a solid rocket motor with a backward-facing step
title_sort impact of the head cavity and submerged nozzle on corner vortices and pressure oscillations in a solid rocket motor with a backward facing step
topic Solid rocket motor
Backward-facing step
Head cavity
Submerged nozzle
Large eddy simulation
Pressure oscillation
url http://www.sciencedirect.com/science/article/pii/S2214914725000649
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