## 5 Conclusions  
This paper investigates the SETAI behavior under a hedge premixed combustion condition, focusing on the influence of the asymmetric structure of the air/fuel supply system and the asymmetric combustion condition. To achieve this, experiments were conducted with different \(L_{\mathrm{P}}\) or different \(\varphi\) on each side. The main conclusions are as follows:  
1. The SETAI characteristic under an asymmetric condition is not simply the combination of the states under the two corresponding symmetric conditions. Instead, it is determined by the condition on each side and the cooperation between them in influencing sound pressure oscillation. 2. An asymmetric supply structure has different effects on two sides, potentially promoting oscillation on one side while suppressing it on the other side. The system with an asymmetric supply structure can generate strong oscillation only when the coupling between heat release oscillation and sound pressure oscillation on both sides promotes oscillation. Even so, the promotion effect may be asynchronous between  
Figure 10: The pressure oscillation condition under asymmetric combustion conditions of cases 68–73. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Case**} & \multirow{2}{*}{\(f_{\mathrm{M}}\) **(Hz)**} & \multicolumn{4}{c}{**Premixed Chamber 1**} & \multicolumn{4}{c}{**Premixed Chamber 2**} & \multirow{2}{*}{\(P_{\mathrm{RMS}}\) **(Pa)**} \\ \cline{3-3} \cline{5-8}  & & \(L_{\mathrm{I}}\)/\(\lambda_{\mathrm{P}}\) & \(\varphi_{1}\) & **Effects on Oscillation** & \(L_{\mathrm{J}}\)/\(\lambda_{\mathrm{P}}\) & \(\varphi_{1}\) & **Effects on Oscillation** \\ \hline
68 & 81.0 & 0.452 & 0.7 & Suppression & 0.453 & 0.8 & Suppression & 316 \\
69 & 81.4 & 0.454 & 0.7 & Suppression & 0.456 & 0.9 & Promotion & 731 \\
70 & 82.2 & 0.458 & 0.7 & Suppression & 0.462 & 1.1 & Promotion & 163 \\
71 & 81.8 & 0.456 & 0.7 & Suppression & 0.462 & 1.3 & Promotion & 159 \\
72 & 70.6 & 0.395 & 0.9 & Promotion & 0.397 & 1.1 & Promotion & 3120 \\
73 & 70.4 & 0.394 & 0.9 & Promotion & 0.397 & 1.3 & Promotion & 2947 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Ratio of \(L_{\mathrm{P}}\) to \(\lambda_{\mathrm{P}}\) on each side and the \(P_{\mathrm{RMS}}\) under asymmetric combustion condition of case 68–73. the two sides, partly cancelling each other out and reducing the system's oscillation amplitude. Adopting an asymmetric supply structure allows for control of SETAI by only changing the length of one side of the premixed chamber, which is more convenient than a symmetric structure distribution. 3. Under an asymmetric combustion condition with different \(\varphi\) on two sides, the oscillation of heat release on each side depends on the local \(\varphi\), not the global \(\varphi\). This causes different effects on two sides due to the different phase relation between heat release and sound pressure oscillation. The concepts identified in this paper demonstrate that SETAI can be effectively controlled by adopting an asymmetric \(\varphi\) distribution or an asymmetric structure of the supply system. This provides the potential to control SETAI without changing the fuel feeding rate, global \(\varphi\), and other main combustion parameters, thus preserving the equipment's thermal performance. Further investigation into how asynchronous heat release oscillations are coupled to influence pressure can provide a better understanding of SETAI behavior under asymmetric conditions. In addition, the dependence of SETAI behavior on the supply structure before premixing will be investigated to develop a better asynchronous control technology for SETAI in multi-flame combustion systems. Conceptualization, Y.D. ([PERSON]) and Y.Z. ; formal analysis, J.Z. and X.L. ; funding acquisition, Y.D. ([PERSON]); investigation, Y.Z., Y.J. and J.Z. ; project administration, Y.J. and Y.D. ([PERSON]); supervision, Y.D. ([PERSON]) and D.C.; writing--original draft, Y.D. ([PERSON]) and Y.Z. ; writing--review and editing, Y.D.