Aerodynamic Design of a Subsonic Evacuated Tube Train System

Theoretical and numerical studies on compressible flow around a subsonic evacuated tube train

“…Evacuated tube trains at different subsonic speeds will exhibit different aerodynamic characteristics, under different blockage ratios. 3,4 The critical criterion for this phenomenon is the isentropic limit. 22 It is expressed bywhere K is the heat capacity ratio of the ideal gas, which has a value of 1.4.…”

“…The blockage ratio is β. The ratio of the area of the tube to the area of the throat can be obtained by equation (3). The relationship between the cross-section and Mach number is described as…”

“…Focusing on research on the aerodynamics of evacuated tube trains, most scholars use CFD methods to study the aerodynamic characteristics of evacuated tube trains and the aerodynamic phenomena inside the tube. Some scholars [1][2][3][4][5][6][7] studied the effects of tube blockage ratio, atmospheric pressure and train speed on the aerodynamic drag of the vehicle, based on the steady compressible Naiver-Stokes equation, KIM et al 2 found the linear relationship between aerodynamic drag and atmospheric pressure, Oh et al 5 found that train speed and blockage ratio significantly affect the drag coefficient. NIU et al 8 and ZHOU et al [9][10] studied the development of shock waves and aero-thermal effects in tubes, by means of a two-dimensional dynamic mesh technique, and described the propagation and reflection of shock waves in the tube.…”

Design and Optimisation of a Virtual Prototype of a Ground Transportation System at Very High-Speeds in Conditions Close to Vacuum

“…This corresponds to 140 times the height h of the capsule, which is considered enough for this case. Other authors used smaller domains, such as Zhang et al [82] who used 27h upstream and 50h downstream, Oh et al [87] who used 1.76L upstream and 5.65L downstream, Bao et al [92] who used 31.25h and 69h, and Li et al [86] who used 34h and 78h respectively. Another input parameter is required to define the tunnel height.…”

“…Taking into consideration the pressure as a variable, the ratio between the cross-sectional area of the capsule and the tunnel (known as Blockage Ratio or BR), and the speed or Mach number of the vehicle, several studies varying these parameters arise [81,85,86,87]. Chen et al [88] added the effect of the levitating gaps in their confined simulations.…”