Acoustical behavior of a turbulent, ducted, premixed, hydrogen- flame burner

Abstract

The acoustic source structure, acoustic farfield, and duct terminating impedances fully describe the acoustics of a source within a duct. A main goal in the study of noise generated by turbulent combustion is to characterize the structure of the flame as an acoustic source. Data describing the farfield and duct terminating conditions allow for the testing of combustion noise models.

The acoustic farfield of a premixed flame burner is documented for various power levels and air-to-fuel ratios. The terminating impedance of the burner exhaust is determined by a method using the transfer function between two microphones that communicate with the acoustic field inside the duct. High temperature probes isolate the microphones from extreme temperatures within the duct while only slightly distorting the results. The real part of the terminating impedance agrees with a correlation in the literature for hot flow leaving a duct.