Numerical study on the influence of initial ambient temperature on the aerodynamic heating in the tube train system

The evacuated tube transportation has great potential in the future because of its advantages of energy saving and environmental protection. The train runs in the closed tube at ultra-high speed. The heat quantity generated by aerodynamic heating is not easy to spread to external environment and then accumulates in the tube, inducing the ambient temperature in the tube to rise gradually. In this paper, a three-dimensional geometric model and the Shear Stress Transport (SST) κ-ω turbulence model are used to study the influence of initial ambient temperature on the structure of the flow field in the tube. Simulation results show that when the train runs at transonic speed, the supersonic flow region with low temperature and low-pressure is produced in the wake. The structure of the flow field of the wake will change with the initial ambient temperature. And the higher the initial ambient temperature is, the shorter the low temperature region in the wake will be. The larger temperature difference caused by the low temperature region may increase the temperature stress of the tube and affect the equipment inside the tube. Consequently, the temperature inside the tube can be maintained at a reasonable value to reduce the influence of the low temperature region in the wake on the system.

Numerical study on the influence of initial ambient temperature on the aerodynamic heating in the tube train system

The evacuated tube transportation has great potential in the future because of its advantages of energy saving and environmental protection. The train runs in the closed tube at ultra-high speed. Because the heat quantity generated by aerodynamic heating is not easy to spread to external environment and will accumulate in the tube, the phenomenon that the ambient temperature in the tube will gradually rise will be induced. In this paper, a three-dimensional geometric model and the Shear Stress Transport (SST) κ-ω turbulence model are used to study the influence of initial ambient temperature on the structure of the flow field in the tube. Simulation results show that when the train runs at transonic speed, the supersonic flow region with low temperature and low-pressure is produced in the wake. The structure of the flow field of the wake will change with the initial ambient temperature. And the higher the initial ambient temperature, the shorter the low temperature region in the wake. The larger temperature difference caused by the low temperature region may increase the temperature stress of the tube and affect the equipment inside the tube. Consequently, the temperature inside the tube can be maintained at a reasonable value to reduce the influence of the low temperature region in the wake on the system.

Numerical study on the influence of initial ambient temperature on the aerodynamic heating in the tube train system

The evacuated tube transportation has great potential in the future because of its advantages of energy saving and environmental protection. The train runs in the closed tube at ultra-high speed. Because the heat quantity generated by aerodynamic heating is not easy to spread to external environment and will accumulate in the tube, the phenomenon that the ambient temperature in the tube will gradually rise will be induced. In this paper, a three-dimensional geometric model and the Shear Stress Transport (SST) κ-ω turbulence model are used to study the influence of initial ambient temperature on the structure of the flow field in the tube. Simulation results show that when the train runs at transonic speed, the supersonic flow region with low temperature and low-pressure is produced in the wake. The structure of the flow field of the wake will change with the initial ambient temperature. And the higher the initial ambient temperature, the shorter the low temperature region in the wake. The larger temperature difference caused by the low temperature region may increase the temperature stress of the tube and affect the equipment inside the tube. Consequently, the temperature inside the tube can be maintained at a reasonable value to reduce the influence of the low temperature region in the wake on the system.

Numerical study on the influence of initial ambient temperature on the aerodynamic heating in the tube train system

The evacuated tube transportation has great potential in the future because of its advantages of energy saving and environmental protection. The train runs in the closed tube at ultra-high speed. Because the heat quantity generated by aerodynamic heating is not easy to spread to external environment and will be accumulate in the tube, the phenomenon that the ambient temperature in the tube will gradually rise will be induced. In this paper, a three-dimensional geometric model and the Shear Stress Transport (SST) κ-ω turbulence model are used to study the influence of initial ambient temperature on the structure of the flow field in the tube. Simulation results show that when the train runs at transonic speed, the supersonic flow region with low temperature and low-pressure is produced in the wake. The structure of the flow field of the wake will change with the initial ambient temperature. And the higher the initial ambient temperature, the shorter the low temperature region in the wake. Considering that the larger temperature difference caused by the low temperature region may increase the temperature stress of the tube and affect the equipment inside the tube. Consequently, the temperature inside the tube can be maintained at a reasonable value to reduce the influence of the low temperature region in the wake on the system.

Study of a Null-Flux Coil Electrodynamic Suspension Structure for Evacuated Tube Transportation

This paper focuses on the study of a null-flux coil electrodynamic suspension structure for evacuated tube transportation (ETT). A Maglev system in evacuated tubes is a promising concept for high speed transportation systems, and the design of levitation structure is a critical part among the subsystems. The whole system with functions of levitation, guidance, and propulsion is proposed in this paper, and the utilization of magnetic fields from both sides of magnets makes the system simple. The figure eight shaped null-flux coil suspension structure is adopted to provide a high levitation-drag ratio. The equivalent circuit model of the null-flux coil structure is established by employing the dynamic circuit theory. Based on the determination of the mutual inductance between the null-flux coil and the moving magnet, electromagnetic forces are calculated through an energy method. The validity of the dynamic circuit model is verified by comparing the calculation with the 3D finite element analysis (FEM) results, and the working principle of the null-flux coil structure is described. The effects of vehicle speed and the time constant of the coil on the electromagnetic forces are studied at the bottom level of force impulses in one coil and verified by FEM simulation. The characteristics of electrodynamic forces as functions of the magnet speed, the vertical displacements, and the lateral displacements are investigated based on the dynamic circuit theory, and the levitation-drag ratio is compared with that of plate type structure. The results show that the proposed structure is a promising option for application in ETT, and the following study will focus on the dynamic research of the electrodynamic suspension (EDS) system.

Main Technologies of Life Support System of Evacuated Tube Transportation Vehicle Passenger Cabin

The passenger cabin of evacuated tube transportation vehicle is the airproof shell. In order to ensure the safety of passengers, riding comfort and good health, the cabin should be offered with the right pressure, oxygen and temperature-humidity environment, while eliminating carbon dioxide and impurities, providing clean air, retaining a reasonable proportion of inert gas by the life support systems. Passenger cabin pressure system is specified to a mix of oxygen-nitrogen atmospheres, close to 1 atm, the oxygen partial pressure is slightly higher than the value outside the tube, and carrying amount of compressed air decided by the oxygen demand standard 0.038kg/ (person • h); drying phenomenon does not occur in the cabin, but dehumidifying to control the humidity is needed; Sorbent dosage and purification device design is based on carbon dioxide emissions 24L/ (person • h). These functions are attained respectively by some technologies such as cabin pressure controlling, gas supplying, temperature and humidity controlling, air purification and security technology.

Numerical Research of Thermal-Pressure Coupling Effect on Blockage Ratio in the Evacuated Tude Transportation System

According to the three-dimensional mathematical model and physical model of evacuated tube transportation(ETT) system, thermal-pressure coupling equations based on viscous fluid Navier-Stokes equation and k- ε turbulence model are established for the first time. The numerical simulation is carried out to investigate the inherent laws for different blockage ratios of ETT system. The simulation results show that: when the speed of the train and the pressure of the system are constants, in the temperature field, the aerodynamic heating is getting more as the blockage ratio increases, and its trend grows exponential. In the pressure field, with the increase of the blockage ratio, the stagnation pressure is gradually increased, but the growth is getting slower; vortex region pressure reduces gradually, and has accelerated the decreasing trend; the pressure difference between the head and the end of the train is linear increment.