Research On Air Resistance When Train Passing Through Tunnel

Whether it is the diesel or the electric locomotive pulling the train through the tunnel, it will have an additional air resistance which is the key element affecting the reduction factor of the slope of the tunnel. At present, the current rail design specification of our country for the procession of the additional air resistance in tunnel is based on the Liangfengya Railway Tunnel and is implemented by analysis, calculation, simplification. However, the Liangfengya tunnel tests is not only old aged, based on low technical standards, but also have a relatively poor equipment and technical conditions. The tested length of the tunnel is a only4270m one-way tunnel, and whether the test results are appliable to those long tunnel still lacks of research and validation. At the same time,as the improvement of technical standards for railways, the increase of effective area of tunnels, a substantial increase in the length of the tunnel, the more complex operating conditions of trains in a tunnel, the raise of the speed of trains and the speed difference increases, the change in flat vertical section of the tunnel line conditions, and the rapid development of traction power, the lessons learned from original Liangfengya tunnel test have been far behind in today’s railway technology.Under this circumstance, this paper combined the theories and computation methods considering different lengths of current tunnels, the clearance area of tunnels within the different sections, different traction conditions, the different marshalling combination of length and quality of traction of trains under the conditions of a separate train, two trains in the tunnel intersection, and the overtaking cases to carry out additional air resistance. Through the study comes to the following conclusions:1, Using the theory of unsteady flow calculation methods for different sections of the tunnel clearance, different length of the tunnel, the train runs at different speed, different grouping of locomotives and trains under a variety of working conditions to carry out calculations on additional tunnel air resistance through which obtains the variation law of additional air resistance in the tunnel.2, It applys theoretical calculation method of the additional air resistancethe to the various staged about the circumstances that two trains in the tunnel operate toward each other and that overtake in the same direction. And it has proposed the resistance change law and the one-dimensional theoretical analysis methods under these two conditions3, It adopts inert test for site tunnel methods to obtain the additional air resistance of a single-train when come through the tunnel, and to validate the theoretical method on the non-constant flow of additional air tunnel resistance.