Equivalent Fire Heat Release Rate of Double Fires with Different Separating Distances in the Longitudinal Ventilated Road Tunnel

Equivalent fire heat release rate of double fires under different separating distances is proposed based on the theoretical analysis of smoke back-layering. Through a series of numerical simulations, the characteristics of equivalent fire heat release rate of double fires are investigated, and the results show that the curvy of equivalent fire heat release rate of double fires presents a “stair” shape with the increase of separating distance, which can be divided into three regions, namely the stable region, quickly decrease region and fluctuation region. Based on the equivalent fire heat release rate, a new model to predict the smoke back-layering length of double fires under different separating distances is developed. The model of equivalent fire heat release rate is verified by the experimental results.