Abstract Liquid metals (LMs) are a special case of metals that exist in a liquid at room temperature, making them one of the most attractive conductive materials in stretchable electronics. In many cases, however, the LM attacks other metals in contact with the LM through penetration, embrittlement, and alloying. To address these critical issues, there have been efforts to introduce robust barriers, which can preserve the underlying metals without degradation. For example, graphene is employed as a flexible barrier owing to its chemical inertness and impermeability. Nevertheless, this material is difficult to utilize in stretchable electronics because its defects result in inevitable fracture, even at a low strain (< 6%). In addition, it is a challenge to pattern the graphene layer on the point‐of‐interest area in a facile manner. Herein, it is shown that the insertion of single‐walled carbon nanotubes (SWCNTs) at the liquid metal–solid metal interface provides a proper barrier for LM under large deformation conditions. A tangled 1D structure of the SWCNTs formed from a solution process greatly suppresses the crack generation/propagation and maintains conductivity even under large strains, which facilitates the use of SWCNTs as stretchable barriers with long‐term reliability through the introduction of a corrugated structure.

Abstract Liquid metals (LMs) are a special case of metals that exist in a liquid at room temperature, making them one of the most attractive conductive materials in stretchable electronics. In many cases, however, the LM attacks other metals in contact with the LM through penetration, embrittlement, and alloying. To address these critical issues, there have been efforts to introduce robust barriers, which can preserve the underlying metals without degradation. For example, graphene is employed as a flexible barrier owing to its chemical inertness and impermeability. Nevertheless, this material is difficult to utilize in stretchable electronics because its defects result in inevitable fracture, even at a low strain (< 6%). In addition, it is a challenge to pattern the graphene layer on the point‐of‐interest area in a facile manner. Herein, it is shown that the insertion of single‐walled carbon nanotubes (SWCNTs) at the liquid metal–solid metal interface provides a proper barrier for LM under large deformation conditions. A tangled 1D structure of the SWCNTs formed from a solution process greatly suppresses the crack generation/propagation and maintains conductivity even under large strains, which facilitates the use of SWCNTs as stretchable barriers with long‐term reliability through the introduction of a corrugated structure.

• Combined approach using pilot injection and outer nozzle fuel staging effectively controls combustion instability. • Two fuel staging methods alter flame structures, affecting time delay characteristics. • MIMO thermoacoustic model successfully predicts experimental trends. • Stability map demonstrates combined fuel staging effects on combustion instability. Hydrogen co-firing and lean premixed combustion technologies in modern gas turbines have significantly increased concerns regarding combustion instability. Although fuel staging has emerged as an effective control method, existing studies have focused on individual staging approaches, limiting our understanding of the combined staging effects. In this study, a comprehensive thermoacoustic stability map was developed by simultaneously applying outer nozzle fuel staging and pilot injection under 30% hydrogen co-firing conditions, providing a predictive framework for multiparameter instability control. An integrated methodology combining experiments, computational fluid dynamics (CFD), and thermoacoustic modeling was employed to investigate the interaction effects between the pilot injection and outer nozzle fuel staging. Experimental investigations revealed that the combined effects of pilot injection and outer nozzle fuel staging on dynamic pressure amplitudes exhibited complex interdependencies that varied with operating conditions. CFD analysis identified the underlying physical mechanisms and showed that different staging parameters modify the flame structure and time delay characteristics of the outer nozzles in distinct ways. A multi-input multi-output (MIMO) thermoacoustic model was developed to construct a stability map that incorporates the time-delay variations of outer nozzles. The stability map successfully captured the effects of pilot injection and outer nozzle fuel staging on the combustion instability characteristics. This integrated framework provides a practical design tool for optimizing fuel staging strategies in hydrogen-compatible gas turbines.

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The purpose of this study was to evaluate the combustion instability characteristics of target aircraft combustors under development using network thermoacoustic (TA) models. The eigenfrequencies of the aeroengine combustor and their mode shapes were calculated using the TA model, and the growth rates of the acoustic resonances were interpreted from a feedback analysis combined with the combustion process. Two different forms of the flame transfer function (FTF) were considered to reflect the flame responses to the incoming flow fluctuations in feedback coupling. To derive the time delay between the velocity fluctuations from the nozzle to the flame surface, a steady-state computational fluid dynamics (CFD) calculation was performed under actual combustor operating conditions. The acoustic analysis results using the current 1D network model showed that both the eigenfrequency and mode distribution of each resonance were reasonably predicted by comparing it with the 3D Helmholtz calculation results. From the feedback instability analysis, it was found that both the frequency and growth rates of the instabilities were significantly affected by the change in gain and time delay of the FTF.