Theoretical predictions of direct and indirect noises in the cylindrical combustion chamber with a choked nozzle

Combustion noise in propulsion systems, particularly in choked-nozzle combustion chambers, remains a critical challenge for propulsion system design. This study extends the semi-analytical approach of Duran et al. from subsonic to choked-nozzle conditions, developing a theoretical model to predict direct and indirect noise. A cylindrical model combustion chamber with a choked throat is investigated, incorporating entropy wave dissipation and acoustic wave attenuation. The model is validated against Domenico's experimental data, demonstrating errors within 4.6 % for indirect noise and 0.49 % for direct noise. This investigation systematically evaluates three critical factors governing combustion noise generation: Combustion chamber geometry effects, Flow field parameter variations and Unsteady heat release characteristics. The developed semi-analytical methodology provides fundamental insights into noise generation mechanisms and propagation dynamics in choked-nozzle systems.