Numerical investigation on the characteristics of lateral smoke extraction in the immersed road tunnel

Self Cite

To investigate the improvement induced by horizontal smoke baffles during lateral smoke exhaust, an immersed road tunnel with various horizontal smoke baffles positioned below the lateral exhaust vent was studied numerically. Together with the velocity field characteristics, the temperature distribution was investigated near the lateral smoke exhaust vent, followed by the analysis of lateral smoke exhaust efficiency under different horizontal smoke baffles. Results showed that after installing the horizontal smoke baffle, there was a significant decrease in the extracted cold air, while the high‐temperature smoke in the exhaust vent increases, indicating the plug‐holing is effectively suppressed. It is known that the efficiency of smoke exhaust increases when the length exceedance ratio of the horizontal smoke baffle is smaller than 100%, while it changes slightly when the baffle length continues to increase. When the width ratio of horizontal baffle is smaller than 40%, the efficiency of smoke exhaust increases with the baffle width and then changes slightly with a wider smoke baffle. With a larger aspect ratio, the wider and shorter lateral exhaust vent is beneficial for improving the lateral smoke exhaust. Under the current conditions, the case shows the optimal smoke exhaust performance with a horizontal baffle length exceedance ratio of 100%, a baffle width ratio of 40%, and exhaust vent aspect ratio of 3:1. Finally, an empirical model is developed to describe the improvement of smoke exhaust efficiency caused by horizontal smoke baffle. These outcomes are helpful to the design of lateral smoke extraction system in road tunnels.

Section: Fire Scenariomentioning

confidence: 99%

“…Also, it was proven that when the smoke barrier's inclined angle is 30 < θ ≤ 75 , a significantly improved smoke extraction efficiency can be achieved. 26 On the other hand, it is known that the immediate cause for plugholing is the adherent flow of fresh air, 21 as presented in Figure 1B.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on smoke control with new‐style horizontal smoke baffle in an immersed road tunnel

Zhang,

Diao,

Shi

et al. 2024

Self Cite

“…This study used FDS simulation software, which is widely used in the field of fire simulation. 22,23 In practical engineering applications, the use of shield tunneling to construct circular tunnels has gradually replaced the early rectangular cross-section shape as a common phenomenon. Wu and Bakar 24 showed that the influence mechanism of tunnel section on fire smoke transport characteristics cannot be well demonstrated using only the physical parameter of tunnel height.…”

Section: Fds Modelmentioning

confidence: 99%

“…This study used FDS simulation software, which is widely used in the field of fire simulation 22,23 . In practical engineering applications, the use of shield tunneling to construct circular tunnels has gradually replaced the early rectangular cross‐section shape as a common phenomenon.…”

Section: Numerical Simulationmentioning

confidence: 99%

Study on the influence of air supply and smoke exhaust on full transverse exhaust of long highway tunnel

Peng,

Zhou,

Ming

et al. 2023

This study investigated the efficacy of the full transverse exhaust method for smoke extraction in tunnel fires. It examines factors such as the number and layout of air supply and exhaust outlets, analyzing their impact on smoke spread, tunnel temperature, visibility, and airflow. The results demonstrate that the full transverse exhaust method effectively controls smoke emissions in raised highway tunnels. It limits smoke spread, reduces tunnel temperature, and effectively controls the fire‐affected area. The number and layout of outlets significantly influence smoke dispersion, with fewer exhaust outlets providing better smoke control and optimizing the tunnel environment. However, insufficient outlets disrupt gas flow stability. The position of exhaust outlets affects smoke distribution, and caution is advised to prevent directing fresh air flow toward the fire. Opening an equal number of exhaust outlets on one side of the fire source yields superior smoke extraction results, reducing tunnel ceiling temperatures and minimizing risks to personnel and structures. Though stabilization may take longer, this configuration proves advantageous. The study offers valuable insights and practical guidelines for implementing the full transverse smoke control method in real‐world scenarios.

“…In the FDS simulation, propane was selected as the fuel. According to the FDS manual and the research results of others, 26,27 the combustion heat of propane was set to 44715 kJ/kg, and the soot yield and CO yield were both set to 0.05. The soot yield and CO yield were directly affected by combustion and ventilation conditions, and a constant value was used here for simplicity 28 …”

Section: Fds Simulationmentioning

confidence: 99%

Experimental and simulation study on the combustion fire spreading characteristics of aluminum composite panels with different thicknesses

Zhang

Zhou

et al. 2022

To study the effect of thickness on the fire spreading characteristics of aluminum composite panels, a reduced‐scale test bench was built to simulate the development of an overflow fire in a high‐rise building. Analysis of the fire spreading characteristics was performed in terms of the flame shape, flame height, fire spread rate, and temperature change. Then, an Fire Dynamics Simulatior model was established to verify the accuracy of the experiment using numerical simulations. The results showed that the flame shape of the 3 and 4 mm aluminum composite panels was a triangular cone, while the flame shape of the 5 and 6 mm aluminum composite panels was approximately rectangular. By establishing the dimensionless flame height, the flame height increased with the panel thickness. The fire spread rate of the aluminum composite panels increased first and then decreased upon increasing the thickness, which was consistent with the simulation results. The temperature change curves all showed a rapid initial increase and then a stable temperature in the later period. The simulation results conformed well to the experimental results.