Theoretical and Experimental Identification of Acoustic Spinning Mode in a Cylindrical Combustor

Kurzfassung

The analytical solution for the eigenmodes of a cylindrical combustor allows for several realizations of the first tangential mode. The limiting cases of standing and spinning first tangential modes are well known. The general solution for a first tangential mode, however, allows for a large variety of realizations. In this study the analytical solution of the acoustic problem and a numerical time-resolved simulation of the acoustic pressure field are compared with experimental data from hot-fire tests. The experimentally observed pressure data are in excellent agreement with the simulation for all possible theoretical solutions. The approach enables detailed insight into the dynamics of the pressure field and thus constitutes a tool for the characterization of acoustic pressure waves in a cylindrical combustor even when the amplitude of the investigated eigenmode is small as compared with the mean pressure fluctuation.