Vortex nozzle interaction in solid rocket motors: A scaling law for upstream acoustic response

Area of Science:

• Fluid dynamics
• Aerospace engineering
• Combustion science

Background:

• Vortex nozzle interactions are a known source of pressure pulsations in solid rocket motors.
• Understanding these pulsations is critical for motor stability and performance.

Purpose of the Study:

• To develop a scaling law for predicting pressure pulsation magnitude in solid rocket motors.
• To investigate the influence of nozzle geometry on vortex-induced pressure pulsations.

Main Methods:

• A two-dimensional frictionless flow model was employed.
• A scaling law was deduced based on fluid dynamic principles.

Main Results:

• The magnitude of pressure pulsations is proportional to the product of upstream dynamic pressure and vortex circulation.
• The derived scaling law is applicable to both integrated nozzles with cavities and simple right-angle nozzle geometries.
• Deviations were observed only for unrealistically strong vortex circulations.

Conclusions:

• A validated scaling law provides a predictive tool for vortex-induced pressure pulsations in solid rocket motors.
• The findings are relevant for the design and optimization of solid rocket motor nozzles.
• The model's validity extends across different nozzle configurations, highlighting the fundamental nature of the scaling law.