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| Analysis of outlet flow state of firefighting monitor rotary main structure |
| XUE Lin1,2, YUAN Shouqi1, XIANG Qingjiang1*, XU Jie1 |
| 1. National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2. Shanghai Fire Research Institute of Ministry of Public Security(MPS), Shanghai 200032, China |
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Abstract The main structure of firefighting monitor has rotary forms that cause the water swirl in the pipe and has great influence on thefirefighting monitor performance. The rotary structure is the combinations of straight pipes and different angle elbows. Numerical simulations were done with standard k-ε turbulence model for inner flow of three kinds of rotary structure, which diameter was 180 mm. Three rotary structures were named traditional rotary, half rotary and large rotary respectively. The outlet flow state and hydraulic losses were compared and analyzed. The outlet parameters include the average turbulence kinetic energy, velocity distribution curves and Dean vortex. The results show that the hydraulic loss of three types rotary structure are reduced with the curvature R/d increasing. As the R/d is 1.4, the traditional rotary has the smallest hydraulic loss and the half rotary is the largest. The outlet velocity curves show that the largest velocity occurs near the wall not near the center of pipes, this means that the flow has swirl characteristic at the outlet. When the R/d is 1.4, the large rotary structure has smallest average turbulence kinetic energy at the outlet, and streamline has one clockwise basic vortex which is consistent with traditional rotary structure, but the vortex intensity which is obtained after integral the outlet vorticity is smaller. The format of large rotary structure is better for subsequent flow in tube and nozzle of firefighting monitor.
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Received: 29 May 2018
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