Train model acceleration and deceleration

Abstract

In order to accelerate a heavy train model with great dimensions to a speed higher than 300 km h 1 in a moving train model testing system, compressed air is utilized to drive the train model indirectly. The gas from an air gun pushes the piston in an accelerating tube forward. The piston is connected to the trailer through a rope, and the trailer pulls the train model to the desired speed. After the testing section, the train model enters the deceleration section. The speed of the train model gradually decreases because of the braking force of the magnetic braking device on the bottom of the train model and the steel plates fixed on the floor of this device. The dissipation of kinetic energy of the trailer is also based on a similar principle. The feasibility of these methods has been examined in a 180 m-long moving train model testing system. The speed of the trailer alone reaches up to 490 km h

A moving model rig with a scale ratio of 1/8 for high speed train aerodynamics

“…An interesting phenomenon is the regular oscillation of acceleration in the acceleration section. Such phenomenon is caused by the towrope between the pistons and the trailer and has been observed in a similar device (Yang et al, 2013). At the beginning of the acceleration, the sudden acceleration of the pistons results in the higher acceleration of the towrope in comparison with the acceleration of the trailer and train model because of the limited elongation of the towrope.…”

“…In the trailer deceleration section, the motion of the permanent magnets on the trailer relative to the deceleration steel plate on the ground induces a brake force (Yang et al, 2013;Jirout et al, 2009;Jou et al, 2006;Maclatchy et al, 1993;Ma et al, 2010). Thus, the trailer slows down and finally stops, as illustrated in Fig.…”

“…Moreover, the aforementioned two processes depend on the driving and braking mechanisms of train models. Yang et al (2013) successfully developed technologies for the acceleration and deceleration of small train models, whose driving power and braking force originate from the release of compressed air and the motion of magnets on the model relative to the steel plates on the ground, respectively.…”

Development of a moving model rig with a large Reynolds number and measurement of aerodynamic drag

“…9 To assess the aerodynamic drag of the model using the Davis equation, the speed and acceleration of the model in the test section must be known. 1 However, from our experimental results, it is easy to find that the model exhibits uniform deceleration in the test section, 9,21 which means that the nonlinear change of the model speed is too small. Therefore, it is not easy to apply the Davis equation to estimate the aerodynamic drag accurately.…”

“…If an MMR can accelerate a model with a large-scale ratio to a required speed, which ensures Re of the model is in the self-simulation region, 3,6,18 and the aerodynamic drag can be exactly estimated by an effective method, the aerodynamic drag of the corresponding real vehicle will be accurately assessed. For this purpose, these principles of acceleration and deceleration and the corresponding improvements made by ourselves are introduced and analyzed in this article on the basis of the developments and upgradation of the MMR, 9,21 in which the acceleration was achieved using the adiabatic expansion of compressed air and the deceleration was achieved by the braking forces from the compression of air in the pipe and the relative motion between the permanent magnets and the iron plates. Using the integral form of the Davis equation and the measured acceleration data from MMT, a novel method for estimating the aerodynamic drag was proposed and demonstrated experimentally using our MMR with a scale of 1/8.…”