Impact of acoustic boundary conditions on confined combustion noise
Résumé
Combustion noise is here experimentally investigated on a 40 kW burner composed of two identical stages fed with air and propane. The purpose of the study is to investigate and characterize combustion noise depending on the boundary impedances and injection conditions (i.e. staging, equivalence ratio and air mass flow rate). Noise study can only be accurately performed if the test bench provides a width broadband spectral sound emission, but in such laboratory high power experiment, combustion and acoustic may couple to generate strong instabilities. The amplitudes and frequencies of these instabilities depend on the operating points and the acoustical boundary conditions. Work presented in this report shows that operating point and inlet boundary conditions can be adjusted to create the best experimental conditions for investigation of combustion noise.