Study on the Effects of Air Temperature Distribution by Flow State inside Cold Region Tunnel

Utilizing the basic theory of heat transfer and computational fluid dynamics and considering the coupling influence of air in the channel and tunnel surrounding rock, the paper deduced control equation of hydrokinetics, calculated the formulas and made secondary development program applying UDF language on ANSYS FLUENT as a basis. Based on materials of Fenghuo Mountain tunnel, the paper analysis for coupled problem of heat transfer of surrounding rock and heat convection between air in cold region tunnel and surrounding rock, and comparative analysis of the annual average temperature between the calculation result and the actual observation records in 2004. The results demonstrated: in the laminar flow condition, the annual average temperature of the cross-section of tunnel entrance and exit is the same as or higher than the tunnel inside. In the turbulence fluid condition, the annual average temperature diminishes from entrance to exit, and there exists mutation between the cross-section of entrance and exit and other cross-section. When air flow state is assumed to be laminar inside Fenghuo Mountain tunnel, the calculation result and the actual observation records are the same. Assumed to be turbulent, both of result are different. Therefore, the calculation depend on the actual corresponding air flow state in tunnels in cold regions designs. The paper results will be providing the theory base and reference of design, construction and study of tunnels in cold regions.