A sealed portal could significantly alter the flame shape and smoke flow characteristics in inclined tunnel fires.In inclined tunnels,two typical sealing conditions could be defined,namely the upper portal sealed and ...A sealed portal could significantly alter the flame shape and smoke flow characteristics in inclined tunnel fires.In inclined tunnels,two typical sealing conditions could be defined,namely the upper portal sealed and the lower portal sealed.In this study,the effects of tunnel slope on flame shape,flame length,along with smoke mass flow rate and induced velocity at the tunnel portal,are numerically investigated.The results show that,in all scenarios,flames initially rise vertically but tilt toward the sealed portal during the quasi-steady stage,with the largest tilt angle observed in tunnels sealed at the lower portal.The slope significantly affects the flame tilt angle.The flame tilt angle in tunnels with the lower portal sealed varies irregularly with the slope,while it decreases as the slope increases in tunnels with the upper portal sealed.Subsequently,the smoke mass flow rate and induced velocity at the tunnel portal are analyzed in detail.Drawing on the obtained data,the flame length prediction models for impinging flames and non-impinging flames under different sealing conditions are developed,along with dimensionless models for smoke mass flow rate and induced wind velocity.These findings provide a theoretical foundation for the formulation of fire rescue strategies and emergency evacuation plans in inclined tunnels with one portal sealed.展开更多
In this paper, various strategies of spiral irradiating scheme for the flame forming of a bowl shaped surface are investigated experimentally and numerically. Experimental work is performed using a flame torch integra...In this paper, various strategies of spiral irradiating scheme for the flame forming of a bowl shaped surface are investigated experimentally and numerically. Experimental work is performed using a flame torch integrated with a 2-axis CNC workstation. The ABAQUS implicit solver is used in the numerical simulation. Three different strategies of the spiral irradiating scheme are investigated for the flame forming of a bowl shaped surface. The first strategy is the Simple spi- ral irradiating scheme, the second is the Rotational spiral irradiating scheme, and the third is the Symmetrical-Rotational spiral irradiating scheme. The results show that using the Symmetrical- Rotational spiral irradiating scheme, a bowl shaped surface with the maximum deformation can be produced, followed by using the Rotational scheme, and the Simple spiral scheme. It is also concluded from the results that the spiral irradiating scheme with Symmetrical-Rotational, Rota- tional and Simple spiral schemes lead to the maximum symmetries in the produced bowl shaped surface, respectively. All the numerical results are in good agreement with the experimental ob- servations.展开更多
The paper presents a complex method of forming the surface-modified layers of materials with shape memory effect, including high-speed flame spraying of powders based on TiNiCo;subsequent thermal and thermomechanical ...The paper presents a complex method of forming the surface-modified layers of materials with shape memory effect, including high-speed flame spraying of powders based on TiNiCo;subsequent thermal and thermomechanical treatment allows the formation of surface layers of nano-sized state that have a high level of functional, mechanical and performance properties;it is shown that the complex processing with a layer of TiNiCo allows a reduction of the porosity of the coatings and increases the strength of the coating’s adhesion to the substrate. It is found that, after treatment with high-speed flame spraying powder shape memory TiNiCo, steel has an increase in cycle life by 30% - 40% in a cycle fatigue and 3 - 3.5 times durability. Based on comprehensive research into the metallophysical surface-modified layer, new information is obtained about the nanoscale composition.展开更多
基金financially supported by National Natural Science Foundation of China(NSFC)under Grant No.52208115Science and Technology Support Plan for Youth Innovation of Colleges and Universities of Shandong Province of Chain(No.2023KJ122)+2 种基金Leading Researcher Studio Fund of Jinan(No.202333050)Natural Science Foundation of Shandong Province(ZR2024ME027)Young Talent of Lifting engineering for Science and Technology in Shandong,China(SDAST2024QTA077).
文摘A sealed portal could significantly alter the flame shape and smoke flow characteristics in inclined tunnel fires.In inclined tunnels,two typical sealing conditions could be defined,namely the upper portal sealed and the lower portal sealed.In this study,the effects of tunnel slope on flame shape,flame length,along with smoke mass flow rate and induced velocity at the tunnel portal,are numerically investigated.The results show that,in all scenarios,flames initially rise vertically but tilt toward the sealed portal during the quasi-steady stage,with the largest tilt angle observed in tunnels sealed at the lower portal.The slope significantly affects the flame tilt angle.The flame tilt angle in tunnels with the lower portal sealed varies irregularly with the slope,while it decreases as the slope increases in tunnels with the upper portal sealed.Subsequently,the smoke mass flow rate and induced velocity at the tunnel portal are analyzed in detail.Drawing on the obtained data,the flame length prediction models for impinging flames and non-impinging flames under different sealing conditions are developed,along with dimensionless models for smoke mass flow rate and induced wind velocity.These findings provide a theoretical foundation for the formulation of fire rescue strategies and emergency evacuation plans in inclined tunnels with one portal sealed.
文摘In this paper, various strategies of spiral irradiating scheme for the flame forming of a bowl shaped surface are investigated experimentally and numerically. Experimental work is performed using a flame torch integrated with a 2-axis CNC workstation. The ABAQUS implicit solver is used in the numerical simulation. Three different strategies of the spiral irradiating scheme are investigated for the flame forming of a bowl shaped surface. The first strategy is the Simple spi- ral irradiating scheme, the second is the Rotational spiral irradiating scheme, and the third is the Symmetrical-Rotational spiral irradiating scheme. The results show that using the Symmetrical- Rotational spiral irradiating scheme, a bowl shaped surface with the maximum deformation can be produced, followed by using the Rotational scheme, and the Simple spiral scheme. It is also concluded from the results that the spiral irradiating scheme with Symmetrical-Rotational, Rota- tional and Simple spiral schemes lead to the maximum symmetries in the produced bowl shaped surface, respectively. All the numerical results are in good agreement with the experimental ob- servations.
文摘The paper presents a complex method of forming the surface-modified layers of materials with shape memory effect, including high-speed flame spraying of powders based on TiNiCo;subsequent thermal and thermomechanical treatment allows the formation of surface layers of nano-sized state that have a high level of functional, mechanical and performance properties;it is shown that the complex processing with a layer of TiNiCo allows a reduction of the porosity of the coatings and increases the strength of the coating’s adhesion to the substrate. It is found that, after treatment with high-speed flame spraying powder shape memory TiNiCo, steel has an increase in cycle life by 30% - 40% in a cycle fatigue and 3 - 3.5 times durability. Based on comprehensive research into the metallophysical surface-modified layer, new information is obtained about the nanoscale composition.
