Validation of numerical simulation of a longitudinal ventilated road tunnel by Particle-Image Velocimetry (PIV) in a reduced scale model tunnel

摘要

Longitudinal ventilation is a widely used and appropriate method for ventilating road tunnels. Numerical investigations are an indispensable tool during the design phase of a tunnel. However, the disadvantage is that a validation of the numerical data in the real tunnel is only possible after completed tunnel construction. Therefore, a model tunnel in the scale 1:18 was developed in order to validate the numerical results with experimental measurements. The longitudinal ventilation consisted of two-model jet fans installed in parallel. The experimental measurement of the velocity distribution in the tunnel cross-section was carried out by the use of Particle-Image Velocimetry (PIV). The results show the importance of accurate scaling and modelling of the jet fans and rotors with regard to the interaction of the jet flow, the tunnels basic flow, and the tunnel wall. The numerical results are confirmed qualitatively by the experimental investigations on the model tunnel. Thus, the simulation and the experimental investigation of longitudinal ventilation in a model tunnel represents an adequate method for the validation of numerical results. With this method, it is possible to adapt longitudinal ventilation more precisely to the conditions in a tunnel during the design process.