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Firefighting considerations for timber buildings
Published in Andrew Buchanan, Birgit Östman, Fire Safe Use of Wood in Buildings, 2023
Ed Claridge, Christian Dagenais, Andrew Dunn, Claudius Hammann, Kamila Kempna, Martin Milner, Jan Smolka
Water is still the most common extinguishing agent used in fire suppression. Water has a much higher heat capacity than other extinguishing agents and is generally readily accessible. Some fire services use a Compressed Air Foam System (CAFS) for better wettability, cooling effect and minimal water damages.
Experimental and numerical investigation on optimization of foaming performance of the kenics static mixer in compressed air foam system
Published in Engineering Applications of Computational Fluid Mechanics, 2023
Huan Li, Xiaoyang Yu, Yuqing Song, Qian Li, Shouxiang Lu
Compared with the typical aspirated foam system, a compressed air foam system (CAFS) provides higher foaming efficiency and lower water consumption, and the expansion ratio of foam made by CAFS can be adjusted expediently to meet the needs of different industrial applications (Laundess et al., 2011, 2012). The foam generator is the core part of the CAFS. Many scholars have studied the optimization of the structure of foam generators in CAFS and they have mostly focused on baffle-type, mesh-type, and pore-type foam generators. Wang et al. (2012) analyzed the key structural characteristic of baffle-type foam generators and they studied the speed and pressure distribution of the foam generator under different parameters. The results showed that when the vortex generator was 24 mm away from the throat and the baffle angle was 45°, the gas–liquid mixing strength in the foam generator reached the maximum. Lu et al. (2015) designed a new spiral mesh foam generator and found that the pressure gradient gap between the top and bottom of the two ends of the foam generator strongly affected the foaming performance. Parikh (2017) studied the foaming properties and pressure drop loss of chamber containing glass beads with different diameters and found that the bubble size decreased by increasing the chamber pressure. However, the above mentioned foam generators (baffle-type, mesh-type, and pore-type) used to make liquid foam have low gas–liquid mixing strength and high flow resistance. In addition, although the accuracy in simulating the ability to capture the flow field has been significantly improved with the development of CFD (Cao et al., 2022; Christafakis & Tsangaris, 2008; Sarmiento-Laurel et al., 2022; Stec & Synowiec, 2017), the structural optimization of foam generator was rarely studied by CFD simulation due to the vastly complex two-phase mixing of gas and foaming liquid involved. Therefore, it is necessary to explore a high-efficiency foam generator and use CFD software to simulate the turbulence characteristics of the flow field and foaming performance of the foam generator.