Direct Combustion Noise Simulation of a Lean Premixed Swirl Flame using Stochastic Sound Sources

Abstract

A lean, swirl-stabilized gas turbine model combustor is simulated with a stochastic approach for combustion noise prediction. The employed hybrid and particle based method, FRPM-CN (Fast Random Particle Method for Combustion Noise Prediction) reconstructs temperature variance based direct combustion noise sources from local CFD-RANS turbulence and flow field statistics. Those monopole sound sources are used as right hand side forcing of the Linearized Euler Equations. First, findings from steady state CFD simulations are validated with experimental results. It is shown that the employed RANS models accurately reproduce the experimental flow field and combustion. Turbulence is treated with a two equation model and a global reaction mechanism is utilized for combustion. Subsequently, the specifications of the CCA (Computational Combustion Acoustics) setup is introduced and selected pressure spectra of the acoustics simulations are compared to experimental results, showing that FRPM-CN is able to deliver absolute combustion noise levels for the investigated burner at low computational costs.

Broadband Combustion Noise Simulation of the PRECCINSTA Burner Based on Stochastic Sound Sources

“…For the considered configuration, the use of sound hard walls in the experiment induces a frequency-dependent shift of amplitudes towards higher values. The comparison of the two configurations in the experiment disclosed that the originally considered stable case [39] turns out to be highly unstable when using sound hard walls. However, the fraction of turbulent combustion noise in the measured spectrum (blue curve) in Fig.…”

“…The Reynolds number of the burner for a similar operation point was estimated to Re = 35, 000, based on a cold flow case at the combustor exit nozzle diameter [38]. Validation is carried out for the flow field with averaged results from particle image velocimetry (PIV) for the velocity components at horizontal profile lines in the combustion chamber at h = 6mm, 10mm, 20mm, 40mm, as shown in Since the numerical studies focus on the broadband combustion noise phenomenon, the selected operation condition is based on an acoustically relatively stable case at atmospheric conditions [39]. Air and fuel mass flow rates areṁ air = 574g/min andṁ fuel = 30g/min at the respective inlets, while the burner is operated at P th = 25kW and Φ = 0.9 with a global mixture fraction of f = 0.0498.…”

Computational assessment of combustion noise of automotive compression-ignited engines

“…Combustion noise can be split -based on the phenomena involved-into direct and indirect components [27,28]. Direct noise is linked to periodic combustion oscillations or stochastic fluctuations of the heat release in the flame surface [29,30] whereas indirect noise, or entropy noise, is related to temperature non-uniformities which are connectively transported [30][31][32].…”

Combustion Noise Dependency on Thermal Load and Global Equivalence Ratio in a Swirl-Stabilized Combustor

“…The code is designed for the simulation of steady and unsteady turbulent reacting flows with an incompressible solver on unstructured meshes using a dual-grid approach. A description of the governing equations and employed turbulence and combustion models for this specific laboratory scale burner case can be found in Grimm et al [24]. A comprehensive numerical study using a compressible extension of the THETA code was performed by Lourier et al [25], where thermoacoustic phenomena occurring in this test case were investigated.…”

“…The source term model was introduced originally by Mühlbauer et al [26] and further developed by Grimm et al [27]. The following two sections, explaining the source term formulation, acoustic model and sound source reconstruction approach are taken from Grimm et al [24] and are given here for completeness.…”