Study on afterbody-effects of multi-stage separation at high-speed

The stage separation of high-speed vehicle is complicated at high dynamic pressure, usually accompanied by strong shock and vortex interaction. There exists a strong interaction between first stage and second stage, which called “afterbody-effects”. The aerodynamic mechanism of “afterbody-effects” is studied in this paper based on numerical simulation. The aerodynamic characteristics of a simplified three-dimensional projectile model at different distances between stages at 0° angle of attack is researched with structural mesh. The results show that the vortexes of stages have a significant impact on the aerodynamic characteristics of different stages, As the distance between stages increases, the drag coefficient of the first stage increases, and the drag coefficient of the second stage increases first and then decreases.

Low Pressure Tube Transport—An Alternative to Ground Road Transport—Aerodynamic and Other Problems and Possible Solutions

This paper presents the concept of one possible but unconventional implementation of a Low Pressure Tube Transport (LPTT) system for a network with station-to-station distances of 300 km, based on the use of circular tunnels in which modular vehicles consisting of three interconnected functional segments move on wheels with airless tires. The physical limitations associated with high-speed vehicle travel in tunnels are presented. The reasons for the expected inconvenience in the travel system, compensated by short travel times, are justified. Assumptions for the use of locomotion, safety, and passenger segments in the construction of a vacuum modular vehicle are presented, as well as systems to ensure the efficient conversion of serial traffic in tunnels to parallel traffic in station areas. Schemes of station construction and traffic organization in the station area are presented, as well as assumptions for a number of systems increasing the safety of vehicle traffic used in emergency situations. Visualizations of some solutions are presented. Details of the construction of a locomotive segment based on a multi-wheel system of airless wheels with the use of a system of linear motors for acceleration and an inertial drive system between them to reduce its weight are presented. Some conclusions from tests conducted on built simulators, mechanical and virtual, of the passenger segment of a vacuum vehicle are discussed.

Effect of airfoil thickness on cargo carrying capacity for high speed ship with aerodynamic unloading

В последние несколько лет, высокоскоростные суда с аэродинамической разгрузкой вызывают интерес, как в гражданском, так и военно-морском транспорте. Было проведено много исследований аэродинамических профилей около границы раздела. Но исследований грузоподъемности крыла для этого типа судов было мало. В данной работе численно оценивалось влияние толщины профиля на грузоподъемность высокоскоростного суда с аэродинамической разгрузкой. Для изучения влияния толщины аэродинамического профиля в диапазоне от 10% до 60% хорды, были проведены расчеты на движущемся экране при углах атаки от 0° до 8° и (h/c = 0,1). Все аэродинамические профили имели хорду 1 м. Профили были модифицированы и имели плоскую нижнюю поверхность, чтобы избежать присасывания на малых углах атаки при малом отстоянии от границы раздела. Поскольку это является нежелательным явлением. Модель турбулентности k-ω SST использовалась для моделирования обтекания крыла при числах Рейнольдса (R_e = 〖1×10〗^6). Для проверки результатов расчетов результаты CFD профиля NACA 4412 при движении над землей были сопоставлены с экспериментальными данными. В данной статье показано, какой тип толщины крылового профиля следует использовать для получения эффективной грузоподъемности высокоскоростного суда с аэродинамической разгрузкой при его проектировании. In the past few years, high-speed aerodynamic unloading vessels have attracted interest in both civilian and naval transport. There have been many studies of airfoils near the interface. But there has been little research on wing loading for this type of vessel. In this study, the effect of the profile thickness on the carrying capacity of a high-speed vehicle with aerodynamic unloading was numerically estimated. To study the effect of the thickness of the airfoil in the range from 10% to 60% of the chord, calculations were carried out on a moving screen at angles of attack from 0 ° to 8 ° and (h / c = 0.1). All airfoils had a chord of 1 m. The airfoils were modified to have a flat bottom surface to avoid suction at low angles of attack with a small distance from the interface. As this is an undesirable phenomenon. The k-ω SST turbulence model was used to simulate the flow around the wing at Reynolds numbers (R_e = 〖1×10〗^6). To check the calculation results, the CFD results of the NACA 4412 profile when moving above the ground were compared with the experimental data. This article shows what type of airfoil thickness should be used to obtain the effective carrying capacity of a high-speed aerodynamic craft in its design.