Numerical study of supercavitating flow around high-speed underwater projectile near different seabed obstacles

Due to the fast development of high-speed rail (HSR) around the world, high-speed trains (HSTs) are becoming a strong competitor against airliners in terms of long-distance travel. Compared with airliner cabins, HST cabins have much larger window sizes. When the big windows provide better lighting and view of the scenery, they also have significant effects on the thermal conditions in the cabins due to the solar radiation through them. This study presents a numerical study on the solar radiation on the thermal comfort in a typical HST cabin. The effect of solar radiation was discussed in terms of airflow pattern, temperature distribution and thermal comfort indices. Parametric studies with seven different daytime hours were carried out. The effect of using the roller curtain was also studied. The overall cabin air temperature, especially near passengers, was found to have significantly increased by solar radiation. Passengers sitting next to windows were recorded to have an obvious thermal comfort variation at different hours of the day. To improve the passengers’ comfort and reduce energy consumption during hot weather, the use of a curtain could effectively reduce the solar radiation effect in the cabin environment.

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Numerical Study of Heat Transfer in High Speed Microflows

36th AIAA Thermophysics Conference ◽

10.2514/6.2003-4051 ◽

2003 ◽

Cited By ~ 1

Author(s):

Reni Raju ◽

Subrata Roy

Keyword(s):

Heat Transfer ◽

High Speed ◽

Numerical Study

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Numerical Study of Volumetric Efficiencies in a High Speed, Four Valve, Four Cylinder, Spark Ignition Engine

10.4271/942533 ◽

1994 ◽

Cited By ~ 6

Author(s):

A. A. Boretti ◽

M. Borghi ◽

G. Cantore

Keyword(s):

High Speed ◽

Numerical Study ◽

Spark Ignition ◽

Spark Ignition Engine

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Numerical study on the mechanism of drag reduction for interceptors on planning boats

Modern Physics Letters B ◽

10.1142/s0217984921400236 ◽

2021 ◽

Author(s):

Lianzheng Cui ◽

Zuogang Chen ◽

Yukun Feng

Keyword(s):

Drag Reduction ◽

High Speed ◽

Degrees Of Freedom ◽

Numerical Study ◽

Dynamic Pressure ◽

Motion Model ◽

Gauge Pressure ◽

Reduction Effect ◽

Pressure Resistance ◽

Viscous Pressure

The drag reduction effect of interceptors on planning boats has been widely proven, but the mechanism of the effect has been rarely studied in terms of drag components, especially for spray resistance. The resistance was caused by the high gauge pressure under the boats transformed from the dynamic pressure, and it is the largest drag component in the high-speed planning mode. In this study, numerical simulations of viscous flow fields around a planning boat with and without interceptors were conducted. A two degrees of freedom motion model was employed to simulate the trim and sinkage. The numerical results were validated against the experimental data. The flow details with and without the interceptor were visualized and compared to reveal the underlying physics. A thinner and longer waterline could be achieved by the interceptor, which made the boat push the water away more gradually, and hence, the wave-making resistance could be decreased. The improved waterline also reduced the component of the freestream normal to the hull surface and led to the less transformed dynamic pressure, resulting in the lowAer spray resistance. Furthermore, the suppression of the flow separation could also be benefited from the interceptor; the viscous pressure resistance was therefore decreased.

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A numerical study of snow accumulation on the bogies of high-speed trains based on coupling improved delayed detached eddy simulation and discrete phase model

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1177/0954409718805817 ◽

2018 ◽

Vol 233 (7) ◽

pp. 715-730 ◽

Cited By ~ 3

Author(s):

Mingyang Liu ◽

Jiabin Wang ◽

Huifen Zhu ◽

Sinisa Krajnovic ◽

Guangjun Gao

Keyword(s):

High Speed ◽

Numerical Study ◽

Snow Accumulation ◽

Phase Model ◽

Detached Eddy Simulation ◽

Discrete Phase Model ◽

Eddy Simulation ◽

Delayed Detached Eddy Simulation ◽

Flow Mechanisms ◽

Discrete Phase

A numerical simulation method based on the improved delayed detached eddy simulation coupled with a discrete phase model is used to study the influence of the snow on the performance of bogies of a high-speed train running in snowy weather. The snow particle trajectories, mass of snow packing on the bogie, and thickness of snow accumulation have been analyzed to investigate the flow mechanisms of snow accumulation on different parts of the bogies. The results show that the snow accumulation on the first bogie of the head vehicle is almost the same as that of the second bogie, but the total accumulated snow on the top side of the second bogie is more than 74% higher than that of the first bogie. Among all the components of the bogies, the motors were found to be strongly influenced by the snow accumulation. The underlying flow mechanisms responsible for the snow accumulations are discussed.

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Numerical Study of Longitudinal Inter-Distance and Operational Characteristics for High-Speed Capsular Train Systems

Vehicles ◽

10.3390/vehicles4010002 ◽

2022 ◽

Vol 4 (1) ◽

pp. 30-41

Author(s):

Bruce W. Jo

Keyword(s):

Error Rate ◽

High Speed ◽

Position Control ◽

Numerical Study ◽

Design Parameters ◽

Maximum Speed ◽

Integer Number ◽

Vehicle Speed ◽

Start Time ◽

Distance Control

High-speed capsular vehicles are firstly suggested as an idea by Elon Musk of Tesla Company. Unlike conventional high-speed trains, capsular vehicles are individual vessels carrying passengers and freight with the expected maximum speed of near 1200 [km/h] in a near-vacuum tunnel. More individual vehicle speed, dispatch, and position control in the operational aspect are expected over connected trains. This numerical study and investigation evaluate and analyze inter-distance control and their characteristics for high-speed capsular vehicles and their operational aspects. Among many aspects of operation, the inter-distance of multiple vehicles is critical toward passenger/freight flow rate and infrastructural investment. In this paper, the system’s equation, equation of the motion, and various characteristics of the system are introduced, and in particular control design parameters for inter-distance control and actuation are numerically shown. As a conclusion, (1) Inter-distance between vehicles is a function of error rate and second car start time, the magnitude range is determined by second car start time, (2) Inter-distance fluctuation rate is a function of error rate and second car start time, however; it can be minimized by choosing the correct second car start time, and (3) If the second car start time is chosen an integer number of push-down cycle time at specific velocity error rate, the inter-distance fluctuation can be zero.

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