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Journal of ZheJiang University (Engineering Science)  2023, Vol. 57 Issue (12): 2401-2411    DOI: 10.3785/j.issn.1008-973X.2023.12.007
    
Representation of combustion thermochemical manifolds via multi-gate mixture of experts
Yi-cun WANG1(),Chang-xiao SHAO2,Tai JIN3,Jiang-kuan XING1,Kun LUO1,4,*(),Jian-ren FAN1,4
1. State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
2. Center for Turbulence Control, Harbin Institute of Technology, Shenzhen Campus, Shenzhen 518055, China
3. School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, China
4. Shanghai Institute for Advanced Study of Zhejiang University, Shanghai 200120, China
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Abstract  

The multi-gate mixture of experts (MMoE) for multi-task learning was applied to better implement the representation of combustion thermochemical manifolds in the framework of flamelet-based combustion models. Detailed chemistry (DC) simulation of a three-dimensional laminar spray jet flame was conducted to generate the original dataset. The original dataset was preprocessed by Box-Cox transformation and Z-score normalization to deal with the multi-scale distributions of combustion data. Correlation analysis was performed on the dataset using the Pearson correlation coefficient, and the results showed that there was no significant correlation between some chemical species. The MMoE and feedforward neural network (FNN) models were constructed respectively, and the comparison and analysis showed that although both models achieved similar loss values and coefficients of determination, the MMoE model was more stable during the training process and achieved more accurate quantitative prediction results than FNN model.



Key wordsmulti-gate mixture of experts (MMoE)      feedforward neural network (FNN)      flamelet model      laminar spray flame      numerical simulation of combustion     
Received: 15 April 2023      Published: 27 December 2023
CLC:  TK 4  
Fund:  国家杰出青年科学基金资助项目(51925603);国家自然科学基金资助项目(52236002)
Corresponding Authors: Kun LUO     E-mail: wangyicun@zju.edu.cn;zjulk@zju.edu.cn
Cite this article:

Yi-cun WANG,Chang-xiao SHAO,Tai JIN,Jiang-kuan XING,Kun LUO,Jian-ren FAN. Representation of combustion thermochemical manifolds via multi-gate mixture of experts. Journal of ZheJiang University (Engineering Science), 2023, 57(12): 2401-2411.

URL:

https://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2023.12.007     OR     https://www.zjujournals.com/eng/Y2023/V57/I12/2401


基于多门控混合专家网络的燃烧热化学流形表征

为了更好地在小火焰燃烧模型框架内实施燃烧热化学流形表征,采用多任务学习领域中的多门控混合专家网络(MMoE). 通过对三维层流喷雾射流火焰构型进行详细化学(DC)模拟,构建原始数据集. 原始数据集经过Box-Cox转换和标准化处理,以应对燃烧数据的多尺度分布问题. 对数据集进行Pearson相关系数分析,结果表明部分化学组分之间无明显的相关性. 分别构建同等参数量规模的MMoE和前馈神经网络(FNN)模型,对比分析结果表明,2种模型取得的损失值和决定系数相近,但相比FNN模型,MMoE模型在训练过程中更加稳定,且取得的定量预测结果更加准确.


关键词: 多门控混合专家网络 (MMoE),  前馈神经网络(FNN),  小火焰模型,  层流喷雾火焰,  燃烧数值模拟 
Fig.1 Schematic of configuration of spray jet flame
类型 wk T/K
N2 O2 CH3OH H2O
射流 0.754 0.228 0.018 0 283
伴随流 0.758 0.142 0 0.100 1 430
Tab.1 Inflow parameters of spray jet flame
Fig.2 Schematic of neural network
层类型 专家网络 塔网络
激活函数 输出类型 激活函数 输出类型
Input (None, 3) (None, 32)
Dense tanh (None, 8) tanh (None, 16)
Dense tanh (None, 16) tanh (None, 8)
Output tanh (None, 32) (None, 1)
Tab.2 Structure of expert network and tower network in multi-gate mixture of experts
Fig.3 Contour plots of thermochemical quantities
Fig.4 Heatmap of correlation coefficients for different species
网络模型 L
训练集 测试集
FNN 2.694×10?4 2.728×10?4
MMoE 2.616×10?4 2.634×10?4
Tab.3 Final loss values for different neural network models
Fig.5 Loss values versus iterations for different neural networks
Fig.6 Scatter plots of true and predicted values using FNN model
Fig.7 Scatter plots of true and predicted values using MMoE model
组分 R2
FNN训练集 FNN测试集 MMoE训练集 MMoE测试集
CH2OH 0.999 564 0.999 562 0.999 508 0.999 504
H2O 0.999 951 0.999 949 0.999 983 0.999 982
O 0.999 633 0.999 631 0.999 699 0.999 701
CH3O 0.999 608 0.999 608 0.999 631 0.999 631
HO2 0.999 430 0.999 429 0.999 470 0.999 470
CO2 0.999 850 0.999 846 0.999 851 0.999 847
OH 0.999 759 0.999 758 0.999 749 0.999 752
O2 0.999 900 0.999 900 0.999 925 0.999 924
HCO 0.999 664 0.999 668 0.999 635 0.999 635
H2O2 0.999 481 0.999 471 0.999 459 0.999 444
CH4 0.999 796 0.999 792 0.999 826 0.999 821
CH2O 0.999 686 0.999 681 0.999 694 0.999 688
CH3 0.999 744 0.999 742 0.999 777 0.999 776
CH3OH 0.999 872 0.999 871 0.999 905 0.999 905
H2 0.999 823 0.999 820 0.999 841 0.999 840
H 0.999 834 0.999 835 0.999 766 0.999 767
CO 0.999 805 0.999 800 0.999 831 0.999 825
Tab.4 Coefficients of determination for FNN and MMoE models
Fig.8 Comparisons of detailed chemistry results and solutions using different neural networks at axial location of x/D = 15
Fig.9 Comparisons of detailed chemistry results and solutions using different neural networks at axial location of x/D = 25
Fig.10 Comparisons of detailed chemistry results and solutions using different neural networks at axial location of x/D = 30
Fig.11 Contour plots of gas temperature for mew case
网络模型 L
训练集 测试集
FNN 2.415×10?4 2.383×10?4
MMoE 2.279×10?4 2.269×10?4
Tab.5 Final loss values of different neural network for new case
Fig.12 Loss values versus iterations of different neural networks for new case
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