CABARET Method on Unstructured Hexahedral Grids for Jet Noise Computation

To develop jet noise-reduction concepts, it is necessary to understand the physics underlying the noise-generation process. Decomposition of the sound field into azimuthal modes is one of the effective experimental methods that allows extracting subtle features of different types of noise sources. For turbulent flows, the interpretation of the noise analysis results using the azimuthal decomposition technique was developed by the authors in previous papers. In the present paper, a generalization of this method allowing the decomposition of the jet acoustic field into azimuthal modes by means of reduced number of microphones is developed. It is shown that jet noise measurements by only three microphones in each cross section allow reconstruction of three azimuthal mode directivities (axisymmetric, first, and second) for both low and moderate frequency bands. Furthermore, two-microphone measurements, provided the microphones are properly located, make it possible to reconstruct directivity of the axisymmetr...

Adaptation of the Azimuthal Decomposition Technique to Jet Noise Measurements in Full-Scale Tests

A method is proposed for decomposing the acoustic field of a compact source into azimuthal components using irregularly arranged microphones.

Generalization of the method of azimuthal decomposition of an acoustic field of a compact source for measurements in the vicinity of a rigid surface

On the Azimuthal Structure of Installed Jet Noise

A new scalable high-resolution CABARET MILES method coupled with a porous Ffowcs Williams–Hawking formulation for far-field noise modelling is applied for the computation of flow and noise from a high-speed turbulent jet, which corresponds to a converging axi-symmetric nozzle and static isothermal conditions of the Jet Exhaust Aerodynamics and Noise experiment. Computational simulation results are provided for a range of grid resolutions. The results for simple means, turbulent kinetic energy, and fourth-order velocity correlations are compared with the experimental data and with a reference LES-Smagorinsky calculation from the literature. Far-field-noise predictions are obtained based on several integral control surfaces, which are used for consistency of the model. The far-field noise spectra are also compared with the experiment. The directivity of the far field noise predicted is analysed with the Azimuthal Decomposition Technique and compared with jet noise data from the TsAGI experimental database.

V. F. Kopiev

Papers

Azimuthal components of turbulent jet sound field:measurement results and their implementation for validation ofmodern noise computation techniques