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Water mist is considered as a potential alternative to halon in fire extinguishing applications. However, penetration is remarkably reduced due to the rapid decay of momentum in the process of water mist movement, which makes it difficult for water mist to reach the flame zone to extinguish the fire. To effectively improve the momentum of the water mist, a novel water mist system namely co-flow jet water mist system was proposed. A configuration in which a co-flow jet was induced to control the motion of water mist. A three-dimensional simulation was performed on the gas–liquid flow in this system. The Realizable k-ε model coupled with the discrete phase model (DPM) was employed for high-speed co-flow jet and laden droplets respectively. Simulations were focused on the interaction of the gas–liquid phase. It was found that the potential core length of the co-flow jet was increased owing to the injection of droplets, but the turbulence intensity and the attenuation of the axial velocity of the co-flow jet were reduced by the broken droplets. In addition, the droplets produced by the atomizer were broken into uniform small ones under the action of co-flow jet, and the spatial distribution of droplets was also changed, more importantly, the momentum of droplets was increased effectively. The droplet size as well as spatial distribution and momentum was related to the gas–liquid mass ratio (GLR). The GLR should be increased as much as possible to enhance the performance of the co-flow jet once the required concentration to extinguish a fire is achieved. This technique is helpful to the popularization and application of a water mist system.
Mingli He; Guang Zhang; Shaohua Hu; Cheng Wang. Assessment of a Method to Enhance the Momentum of Water Mist: Co-Flow Jet Water Mist System. Fire Technology 2021, 1 -21.
AMA StyleMingli He, Guang Zhang, Shaohua Hu, Cheng Wang. Assessment of a Method to Enhance the Momentum of Water Mist: Co-Flow Jet Water Mist System. Fire Technology. 2021; ():1-21.
Chicago/Turabian StyleMingli He; Guang Zhang; Shaohua Hu; Cheng Wang. 2021. "Assessment of a Method to Enhance the Momentum of Water Mist: Co-Flow Jet Water Mist System." Fire Technology , no. : 1-21.
Based on the excavation of Yuelongmen tunnel on ChengLan Railway in China, this paper will probe into the forced ventilation effect of harmful gas generated by drilling and blasting construction, simulate the diffusion process of harmful gas generated during blasting operation on the tunnel face by establishing the finite element model of gas turbulent flow and concentration diffusion in the tunnel, and study the spatial-temporal evolution law of CO concentration field under different air pipe layout locations and tunnel excavation methods. The results show that, compared with corner layout, haunch layout, and central layout, the ventilation effect is the best when the air pipes are arranged near the wall at the tunnel vault, and the CO concentration can be reduced to the concentration limit after 588 s of ventilation; compared with the full-face tunneling method and the lower pilot heading method, the benching tunneling method can effectively reduce the retention time of CO near the tunnel face, and the CO concentration on the tunnel face can be reduced to the standard limit after 326 s of ventilation near the wall of tunnel vault.
Qingsong Pu; Yi Luo; Junhong Huang; Yingwei Zhu; Shaohua Hu; Chenhao Pei; Guang Zhang; Xinping Li. Simulation Study on the Effect of Forced Ventilation in Tunnel under Single-Head Drilling and Blasting. Shock and Vibration 2020, 2020, 1 -12.
AMA StyleQingsong Pu, Yi Luo, Junhong Huang, Yingwei Zhu, Shaohua Hu, Chenhao Pei, Guang Zhang, Xinping Li. Simulation Study on the Effect of Forced Ventilation in Tunnel under Single-Head Drilling and Blasting. Shock and Vibration. 2020; 2020 ():1-12.
Chicago/Turabian StyleQingsong Pu; Yi Luo; Junhong Huang; Yingwei Zhu; Shaohua Hu; Chenhao Pei; Guang Zhang; Xinping Li. 2020. "Simulation Study on the Effect of Forced Ventilation in Tunnel under Single-Head Drilling and Blasting." Shock and Vibration 2020, no. : 1-12.
Uncertain probability distributions and interdependencies of geotechnical parameters have profound impacts on slope reliability analysis, especially under incomplete probabilistic information. In this paper, a copula-based approach coupling information diffusion (ID) distribution is proposed to reduce such uncertainties. Firstly, ID theory is introduced to establish marginal distribution of strength parameter. Copulas are subsequently performed to characterize the corresponding dependence structure and link the proposed ID margins. At last, equivalent samples are simulated and plugged into Monte Carlo simulation (MCS) to estimate slope reliability. The effect of the proposed method is validated by a slope case. Results show that the proposed ID algorithm holds remarkable superiority in estimating the marginal distribution with considering random volatility of geotechnical parameter. For slope reliability, both marginal distributions and interdependencies of geotechnical parameters barely affect the factor of safety (FS) but significantly impact failure probability (pf). Unreasonable estimation of probability distribution may lead to large deviation in calculation of slope failure probability. Comparably, the proposed copula-based approach coupling ID distribution can give a reasonable and robust reliability results with considering random volatility.
Xinlong Zhou; Guang Zhang; Shaohua Hu; Junzhe Li; Dequan Xuan; Chang Lv. Copula-based approach coupling information diffusion distribution for slope reliability analysis. Bulletin of Engineering Geology and the Environment 2020, 79, 2255 -2270.
AMA StyleXinlong Zhou, Guang Zhang, Shaohua Hu, Junzhe Li, Dequan Xuan, Chang Lv. Copula-based approach coupling information diffusion distribution for slope reliability analysis. Bulletin of Engineering Geology and the Environment. 2020; 79 (5):2255-2270.
Chicago/Turabian StyleXinlong Zhou; Guang Zhang; Shaohua Hu; Junzhe Li; Dequan Xuan; Chang Lv. 2020. "Copula-based approach coupling information diffusion distribution for slope reliability analysis." Bulletin of Engineering Geology and the Environment 79, no. 5: 2255-2270.
In geotechnical reliability analysis, random volatility in marginal distributions of shear strength parameters has been rarely considered. Unfortunately, conventional marginal distribution models cannot characterize real probability distribution accurately, leading to considerable dispersion with incomplete probabilistic information. In this paper, an estimation methodology is proposed based on copula theory coupling information diffusion technique. Firstly, information diffusion distribution is extended to represent one-dimensional marginal distributions of shear strength parameters. Secondly, copula theory is employed to characterize the dependence structures among the parameters. Eventually, equivalent sample is yielded by information diffusion distribution that has been already established. A case study in Singapore is implemented to enunciate and validate the competence of the proposed method. The performances of the candidate copulas coupling different marginal distributions are further discussed. Results indicate that information diffusion distribution can efficiently capture the random volatility of real distributions of shear strength parameters and hold remarkable superiority in modeling marginal distributions. The equivalent sample, estimated by information diffusion technique in conjunction with Gaussian copula, has considerable consistency with original data. The proposed method can provide a reference to reliability analysis in geotechnical engineering.
Xinlong Zhou; Guang Zhang; Shaohua Hu; Junzhe Li. Optimal Estimation of Shear Strength Parameters Based on Copula Theory Coupling Information Diffusion Technique. Advances in Civil Engineering 2019, 2019, 1 -18.
AMA StyleXinlong Zhou, Guang Zhang, Shaohua Hu, Junzhe Li. Optimal Estimation of Shear Strength Parameters Based on Copula Theory Coupling Information Diffusion Technique. Advances in Civil Engineering. 2019; 2019 ():1-18.
Chicago/Turabian StyleXinlong Zhou; Guang Zhang; Shaohua Hu; Junzhe Li. 2019. "Optimal Estimation of Shear Strength Parameters Based on Copula Theory Coupling Information Diffusion Technique." Advances in Civil Engineering 2019, no. : 1-18.
Due to high water pressure in the concrete reinforced hydraulic tunnels, surrounding rocks are confronted with nonlinear seepage problem in the pumped storage power station. In this study, to conduct nonlinear seepage numerical simulation, a nonlinear seepage numerical model combining the Forchheimer nonlinear flow theory, the discrete variational inequality formulation of Signorini’s type and an adaptive penalized Heaviside function is established. This numerical seepage model is employed to the seepage analysis of the hydraulic tunnel surrounding rocks in the Yangjiang pumped-storage power station, which is the highest water pressure tunnel under construction in China. Moreover, the permeability of the surrounding rocks under high water pressure is determined by high pressure packer test and its approximate analytical model. It is shown that the flow in the surrounding rocks is particularly prone to become nonlinear as a result of the high flow velocities and hydraulic gradients in the nearby of the seepage-control measures and the high permeability fault. The nonlinear flow theory generates smaller flow rate than the Darcy flow theory. With the increase of nonlinear flow, this observation would become more remarkable.
Shaohua Hu; Xinlong Zhou; Yi Luo; Guang Zhang. Numerical Simulation Three-Dimensional Nonlinear Seepage in a Pumped-Storage Power Station: Case Study. Energies 2019, 12, 180 .
AMA StyleShaohua Hu, Xinlong Zhou, Yi Luo, Guang Zhang. Numerical Simulation Three-Dimensional Nonlinear Seepage in a Pumped-Storage Power Station: Case Study. Energies. 2019; 12 (1):180.
Chicago/Turabian StyleShaohua Hu; Xinlong Zhou; Yi Luo; Guang Zhang. 2019. "Numerical Simulation Three-Dimensional Nonlinear Seepage in a Pumped-Storage Power Station: Case Study." Energies 12, no. 1: 180.