2023 Fiscal Year Research-status Report
Establishment of a unified experimental-numerical framework to elucidate and predict noise emission in carbon-free combustion
| Project/Area Number |
23KK0069
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| Research Institution | Kyoto University |
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Principal Investigator |
黒瀬 良一 京都大学, 工学研究科, 教授 (70371622)
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| Co-Investigator(Kenkyū-buntansha) |
PILLAI ABHISHEKLAKSHMAN 京都大学, 工学研究科, 助教 (90887332)
甲斐 玲央 九州大学, 総合理工学研究院, 助教 (60977057)
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| Project Period (FY) |
2023-09-08 – 2028-03-31
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| Keywords | Combustion noise / Carbon-free combustion / Swirling flames / Experiment / Numerical simulation |
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| Outline of Annual Research Achievements |
The achievements of the fiscal year of 2023 are as follows:
Experiments: (1) Some components of the Stanford burner, such as the injector and the main fuel supply tubes that were originally made out of brass, were newly designed and fabricated with Stainless Steel to accommodate the operation with ammonia. (2) The modified burner was fired with a lean H2/NH3/air mixture (equivalence ratio = 0.6) at a bulk injector exit velocity of 15 m/s. In addition, time-resolved measurements of chemiluminescence (which indicates the heat release rate) and pressure fluctuations inside the combustor were performed in this preliminary experimental run, and the experimental data is currently being analyzed for flame dynamics and direct combustion noise.
Numerical Simulations: A Large-Eddy Simulation (LES) of the turbulent swirling hydrogen/ammonia/air premixed flame under the same conditions as the above-mentioned experiment was performed. The complex geometry of the Stanford burner is discretized by the LES grid using the burner’s CAD data. A newly developed Flamelet Model is implemented in this LES for hydrogen/ammonia combustion. Validation of the hydrogen/ammonia/air premixed flame predicted by the LES with the experiment is currently underway.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The objective for the 1st year (Oct. 2023 - Sept. 2024) of this research project was to investigate the direct combustion noise (DCN) from confined hydrogen flames for a range of H2/air mixture compositions (i.e., various H2 to air mass ratios). However, keeping in mind the budget constraints, the research plan was slightly modified by combining the tasks of Year 1 and Year 3, meaning instead of using only hydrogen, the DCN from both hydrogen flames and hydrogen/ammonia flames are being studied using experiments and numerical simulations in Year 1. The original burner setup available at Stanford was incompatible for use with NH3 because some of its components were made of Brass (Brass cannot be used for NH3 operation). Therefore, major modifications to the burner design were conducted from Oct. 2023 to Dec. 2024. Thus, the project is well organized and progressing soothingly.
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| Strategy for Future Research Activity |
Plans for the next fiscal year (FY 2024) are as follows:
Experiments: The experimental campaign to investigate the influence of different parameters, such as equivalence ratio, flow rate, and fuel mixture composition on the DCN from both hydrogen and hydrogen/ammonia flames will be continued on the same swirler + bluff-body configuration of the Stanford burner. Through this experimental campaign, conditions that produce the most intense combustion noise will be identified, and the correlation between the time-resolved chemiluminescence signal and the pressure fluctuation signals will be analyzed to understand the physics behind the turbulent flame dynamics of hydrogen/ammonia flames leading to combustion noise generation. In addition, using a Reinforcement Learning-based algorithm, we will attempt to reduce the DCN generated by the turbulent swirling hydrogen and hydrogen/ammonia flames.
Numerical simulations: After validating the LES results of the preliminary swirling hydrogen/ammonia/air premixed flame with the experimental data, a Computational Aero-Acoustics (CAA) simulation will be performed. The CAA results will also be validated using the pressure fluctuation signals measured with the microphones in the experiment. Next, the simulation data will be analyzed to elucidate the DCN generation mechanisms in the confined hydrogen/ammonia/air premixed swirling flame, and also for the predictions of its noise characteristics. Additional hybrid LES/CAA simulations will be performed for the conditions that produce the most intense combustion noise in the experiments.
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| Causes of Carryover |
The amount of 1,086,665 Yen stated under the column "Amount to be used in the next fiscal year (B-A)" is due to the reasons stated below: (1) Burner design modification was carried out from Oct. 2023 to Dec. 2023 to make the burner compatible for operation with ammonia before carrying out the experiments at Stanford. (2) Following the burner design modification, Kyoto University issued a purchase order to Stanford (based on the quotation prepared in consultation with the overseas collaborator at Stanford) to procure Consumable Supplies and Equipment. The final purchase orders were executed through Stanford to local suppliers in the US in the middle of January 2024. (3) However, there were some major delays (up to 2 months) from the suppliers’ side (in the US) in delivering some items needed for the experiments due to which we were unable to use the amount stated in column “「次年度使用額（B-A）」” by 31 March 2023. However, we have now received all the necessary Consumable Supplies and Equipment for the 1st year of experiments, so the amount stated in column “「次年度使用額（B-A）」” will certainly be used together with the grant requested for FY 2024.
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