Simon Mendez

Large-Eddy Simulations of Perfectly Expanded Supersonic Jets Using an Unstructured Solver

Large-eddy simulations of supersonic jets are performed to validate the development of a second-order finite volume unstructured solver for aeroacoustic applications. Two supersonic jets issuing from an axisymmetric nozzle at Mach number 1.4 are computed: one unheated jet with a Reynolds number of 150,000 and one heated jet with a Reynolds number of 76,000 and a temperature ratio of 1.75. Flow and noise results are compared with the experimental database fromNASAGlennResearchCenter. The nozzle is included in the computational domain.The present study shows that the results from the unstructured solver are in good agreement with the experimental data for time-averaged and fluctuating quantities, velocity spectra in the jet, and the sound obtained in the near field and the far field using the integration of the Ffowcs–Williams and Hawkings equation.

Large-Eddy Simulation of the Acoustic Response of a Perforated Plate

An original numerical configuration is designed to compute the acoustic response of a multi-perforated plate submitted to normal acoustic excitation with Large-Eddy Simulation (LES). It consists in simulating an infinite perforated plate, the periodicity of the geometry allowing to reduce the computational domain to a periodic configuration containing only one perforation. The numerical configuration is adapted from the experimental set up studied by Bellucci et al. A low Mach and low Reynolds numbers bias flow is imposed through the perforated plate, resulting in a jet issuing from the hole, but no grazing flow is considered. Flow and acoustic results from LES are presented. The dynamic results show that the jet does not respond in the same way for every frequencies, resulting in different acoustic responses. Acoustic results are compared with available experimental measurements and to three existing analytical and numerical models. The overall agreement between all data is very good, in particular at low frequencies. Excellent agreement is observed with the most sophisticated model, developed by Jing & Sun. Notably, the LES results show the relevance of the hypotheses of this model concerning the shape of the jet separation at the aperture inlet.

Large-Eddy Simulation of a Turbulent Flow around a Multi-Perforated Plate

The film cooling technique is often used to protect the hot components in gas turbines engines by introducing cold air through small holes drilled in the wall. The hot products are mixed with the injected gas and the temperature in the vicinity of the wall is reduced. Classical wall functions developed for impermeable walls and used in Reynolds-Averaged Navier-Stokes methods cannot predict momentum/heat transfer on perforated plates because the flow is drastically modified by effusion. In order to obtain a better understanding of the flow structure and predominant effects, accurate simulations of a turbulent flow around an effusion plate are reported. Large-Eddy Simulations of the flow created by an infinite multi-perforated plate are presented. The plate is perforated with short staggered holes inclined at an angle of 30 deg to the main flow, with a length-to-diameter ratio of 3.46. Injection holes are spaced 6.74 diameters apart in the spanwise direction and 11.68 diameters apart in the streamwise direction. Results for mean velocity and velocity fluctuations are compared with measurements made on the LARA large-scale isothermal experiment [1].

Damping Eect of Perforated Plates on the Acoustics of Annular combustors

This paper aims at showing the inuence of perforated plates on the acoustic modes in aeronautical gas turbines combustion chambers. The analytical model developed by Howe 1 was implemented in a 3D acoustic Helmholtz solver to account for the eect of perforated plates. First, an analytic test case is used to validate the coding in the acoustic solver. Then, a computation of the acoustic modes in an actual industrial chamber is conducted, taking into account the perforated liners. Both longitudinal and azimuthal modes are studied.