Large Eddy Simulation of the Thermoacoustic Response of Premixed Partially Cracked Ammonia Flames скачать в хорошем качестве

Large Eddy Simulation of the Thermoacoustic Response of Premixed Partially Cracked Ammonia Flames

This is a SlideCast of the presentation of Marcel Désor contributed to SoTiC '25 at NTNU in Trondheim, Norway. Here's the abstract: Ammonia is a potential chemical energy carrier for the future energy market. Utilizing it in gas turbine engines requires fuel flexibility, which increases the propensity for thermoacoustic instabilities. Predicting these instabilities requires models for the flame dynamics, which can be inferred – amongst other methods – from large eddy simulations (LES). For this purpose, a global chemical mechanism is optimized for use in LES of partially cracked ammonia flames in order to facilitate cost-effective simulation. Its performance both in canonical 1D configurations as well as in LES is assessed and compared to a detailed chemical scheme as well as experiment. LES are conducted using various levels of flame thickening in the context of the thickened flame model (TFLES), including a fully flame-resolving simulation without turbulence-chemistry interaction model. The objective is to assess damping introduced by the TFLES model. From the LES time series data, flame transfer functions (FTF) are identified and compared to experiment as well as to each other. Results indicate that the TFLES combined with the optimized global mechanism successfully predicts the FTF for a cracking ratio of 0.28, while deficiencies are observed for lower cracking ratios. This can be attributed to difficulties in predicting the correct response to strain when using such global mechanisms. It is also demonstrated that thickening does introduce damping of high frequency heat release fluctuations for turbulent flames. However, the FTFs of the present configuration reach zero gain already at lower frequency. It is also evident that without cracking, ammonia flames tend to be very thermoacoustically stable Journal publication of this work is in progress – stay tuned