Experimentelle Untersuchung der Schallabstrahlung einer turbulenten vorgemischten Freistrahlflamme

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The proposed project deals with experimental investigations of noise emissions of a turbulent premixed free jet flame under anechoic conditions. Obtained measurement data are used to validate associated numerical projects (TP2 (Janicka), TP3 (Schröder), and TP4 (Bockhorn) as well as to gain insight into the origin of combustion noise. The generic burner setup features both fundamental character and technical relevance. In the experiments, velocity fields are measured in detail, chemiluminescence images are recorded in order to visualize flame shape and position, respectively, and sound emissions are acquired with respect to frequency and direction. Acoustic data is obtained in the near field and in the far field of the flame. The simple de-sign of the burner allows for the investigation of the impact of different parameters on noise emissions. These parameters are mean mixing ratio of fuel and air mixture, spatial gradient of the mixing ratio, preheat temperature, momentum, and initial shear layer of the free jet flame. Hereby, turbulent length and time scales of the reacting flow are altered such that experiments cover different combustion regimes. Moreover, technical applications are mimicked by investigating lean mixtures and technically premixed flows. In addition to validation purposes, experimental data are used to establish an empirical model for noise emissions of turbulent premixed flames as a function of the aforementioned parameters.