Research On Energy Efficiency Optimization Of Ventilation And Pollutant Coordinated Control Of Multi-Ramp Urban Highway Tunnel Based On Traffic Flow State

As an infrastructure for expanding urban land and solving traffic congestion,urban highway tunnels can not only evacuate traffic flow and improve traffic efficiency,but also efficiently connect the central financial circle and surrounding areas to optimize urban comprehensive planning.In order to improve road connectivity and ensure the rapid entry and exit of motor vehicles,urban tunnels usually contain multiple ramps.The existence of ramps evolves different traffic flow characteristics,resulting in more complex airflow organization and pollutant distribution.Therefore,it is of great significance to improve the operation and management level of urban complex highway tunnels to carry out research on energy efficiency optimization of ventilation and pollutant coordinated control of multi-ramp urban highway tunnels based on traffic flow state.In this paper,tunnel engineering,information engineering,fluid mechanics and other interdisciplinary research methods are applied.Through theoretical analysis,numerical simulation,computer experiment,field experiment and other methods,the ventilation characteristics and pollutant distribution law affected by traffic flow and ventilation scheme,local loss mechanism of bifurcated tunnel and energy efficiency optimization of ventilation scheme are studied.The main results are as follows:（1）Based on the traffic flow theory,the traffic state is clustered,and the simultaneous fluid mechanics equation is used to solve the operation ventilation model with only traffic flow.The results show that:When the tunnel structure is fixed,the air volume ratio is greatly affected by the traffic flow ratio and ventilation scheme,and the upstream and downstream air volume ratio caused by the traffic flow ratio does not interfere with each other;the total air volume is greatly affected by traffic conditions and ventilation schemes.The section length has little effect on the air volume ratio and total air volume.With the increase of traffic volume,the wind speed increases first and then decreases,and the wind speed is the highest in crowded flow.（2）Improving the traffic flow ratio is the main means to control the distribution of pollutants,and limiting traffic volume is the primary measure to ensure a good operating environment when traffic volume is high.The ventilation scheme cannot fundamentally change the distribution of CO concentration under different traffic conditions.The CO concentration in the tunnel section increases linearly along the longitudinal direction,and the increase of CO concentration and CO concentration increases with the increase of traffic volume.When the mainline diversion ratio is less than 0.6,the diversion ramp has an inhibitory effect on the mainline CO concentration.（3）The local resistance loss mechanism of bifurcated tunnel is revealed,the sensitivity level and interaction of different factors are explored,and the prediction model of local resistance coefficient is constructed.It is pointed out that the mismatch between branch flow ratio and area ratio is the direct cause of fluid energy loss.When the two are equal,the fluid energy loss is the smallest.Increasing the length of the transition section can delay the confluence or diversion process and reduce the local resistance coefficient,and the influence of the length of the transition section is more significant during the diversion.（4）It is proved that the quadratic term model has good accuracy in fitting the local resistance coefficientζ.The flow ratioβhas a quadratic function relationship withζ,and the ramp angleθand the gradient length L have a linear function relationship withζ.The influence ofβ,θand L onζdecreases successively during confluence.In the process of diversion,the influence ofβ,L andθon the local resistance coefficient of the main line decreases in turn,and the influence ofβ,θand L on the local resistance coefficient of the rampζ₃₂ decreases in turn.The interaction betweenβandθmakes the variation ofζ₃₂ withθon both sides of a certainβvalue completely opposite.When the lane is unbalanced,there is an interaction between the ramp and the transition section near the ramp,so that the influence of the length of the transition section near the ramp onζ₃₂ is greater thanθ.（5）The optimization process of tunnel operation ventilation scheme based on computer test is developed,and the energy efficiency optimization platform of ventilation scheme considering traffic flow characteristics is constructed by combining response surface.The ventilation control scheme under different traffic flow conditions is solved with the guidance of the optimal global or local ventilation quality and the minimum ventilation energy consumption of the tunnel.The feasibility of the ventilation strategy is verified based on field measurement.The results show that the Kriging method is very suitable for studying the optimization problem of operation ventilation scheme,and it is feasible to construct the optimization platform by computer test.