A new concept stratospheric aerostat is investigated which consists of a saucer-shaped hull, multi-vectored thrusters, and an under-slung nacelle. The design of this aerostat involves tradeoffs between conventional ai...A new concept stratospheric aerostat is investigated which consists of a saucer-shaped hull, multi-vectored thrusters, and an under-slung nacelle. The design of this aerostat involves tradeoffs between conventional airship and high altitude balloon. The sling connection simplifies structure design significantly, but brings challenges for dynamics analysis. Dynamics modeling for this aerostat is a kind of double-body problem with geometric constraint. Nonlinear dynamics model is established by considering the effects of under-slung nacelle. Oscillation behavior of this double-body system is superposed by a long-period oscillation of the hull and a short-period oscillation of the nacelle. The length of sling only influences the short-period oscillation but the mass ratio of nacelle to main body determines the stability of system. Finally, an envelope about mass ratio and maximal open loop forward thrust as well as speed is presented, where the system is stable.展开更多
An extensive suite of igneous sills was intruded into the Tertiary sedimentary section of the Jiaojiang sag, East China Sea. This suite has been well imaged offshore through 2D and 3D seismic surveys, showing a close ...An extensive suite of igneous sills was intruded into the Tertiary sedimentary section of the Jiaojiang sag, East China Sea. This suite has been well imaged offshore through 2D and 3D seismic surveys, showing a close relationship with CO2 content in nearby gas discoveries. A new observational model, which incorporates simple upward propagation, simple horizontal propagation, and transgressive propagation, was proposed to interpret these sill intrusions. In this model, the source magma of the saucer-shaped sills was injected from their lowest points near the center. The transgressive propagation can be interpreted as a combination of the vertical and horizontal propagation. Most shallow sub-volcanic intrusions in the Jiaojiang sag exhibit fingered characteristics, both vertically and horizontally. The vertical fingered propagation produced saucer-shaped sills arranged in the flower style. Along the brims of lower sills could usually be found the upper sills, which are interpreted to have formed simultaneously with or later than the lower feeder sills. In the second type, the chilled paths of the older sills were reutilized by subsequent intrusions. The horizontal fingered propagation formed sheet intrusions that exhibit groove, lobate, tubular, and crevasse splay- like geometry in plan view. In 3D view, the sheet intrusions have still preserved the lower center and higher rim that similar with the sub-rounded saucer-shaped sills. Although fracture propagation may be important, flow inflation was the key mechanism of magma intrusion. Further consideration of the mechanisms underlying sill formation may help explain the fingered characteristics of sill propagation.展开更多
Saucer-shaped aircraft adopts a novel aerodynamic configuration of blending fuselage with wing. In contrast to the ordinary aircraft configurations, this kind of configuration can totally eliminate the drag resulted f...Saucer-shaped aircraft adopts a novel aerodynamic configuration of blending fuselage with wing. In contrast to the ordinary aircraft configurations, this kind of configuration can totally eliminate the drag resulted from fuselage, bringing many advantages such as simple structure, compact scale, high load capability. But its small aspeet ratio makes the induced drag higher. Through wind tunnel experiments, it is discovered that a type of sweepback fin-shaped winglet can efficiently reduce the induced drag of this kind of aircraft. When this winglet is mounted to a model in wind tunnel experiment, the maximal ratio of lift to drag of the model can be increased by 75% as compared with the model without winglet at the speed of 30 m/s, and reached 15 at the speed of 50 m/s. In order to investigate the performance of this aircraft with winglet at low speed, test flights were processed. The results of test flights not only verify the conclusions of experiments in wind tunnel but also indicate that the load capability of the aircraft with winglet is increased and its lateral stability is even better than that of the aircraft without winglet.展开更多
基金Projects(61175074,11272205)supported by the National Natural Science Foundation of China
文摘A new concept stratospheric aerostat is investigated which consists of a saucer-shaped hull, multi-vectored thrusters, and an under-slung nacelle. The design of this aerostat involves tradeoffs between conventional airship and high altitude balloon. The sling connection simplifies structure design significantly, but brings challenges for dynamics analysis. Dynamics modeling for this aerostat is a kind of double-body problem with geometric constraint. Nonlinear dynamics model is established by considering the effects of under-slung nacelle. Oscillation behavior of this double-body system is superposed by a long-period oscillation of the hull and a short-period oscillation of the nacelle. The length of sling only influences the short-period oscillation but the mass ratio of nacelle to main body determines the stability of system. Finally, an envelope about mass ratio and maximal open loop forward thrust as well as speed is presented, where the system is stable.
基金supported by National Basic Research Program of China (973) under grant No.2009CB219400
文摘An extensive suite of igneous sills was intruded into the Tertiary sedimentary section of the Jiaojiang sag, East China Sea. This suite has been well imaged offshore through 2D and 3D seismic surveys, showing a close relationship with CO2 content in nearby gas discoveries. A new observational model, which incorporates simple upward propagation, simple horizontal propagation, and transgressive propagation, was proposed to interpret these sill intrusions. In this model, the source magma of the saucer-shaped sills was injected from their lowest points near the center. The transgressive propagation can be interpreted as a combination of the vertical and horizontal propagation. Most shallow sub-volcanic intrusions in the Jiaojiang sag exhibit fingered characteristics, both vertically and horizontally. The vertical fingered propagation produced saucer-shaped sills arranged in the flower style. Along the brims of lower sills could usually be found the upper sills, which are interpreted to have formed simultaneously with or later than the lower feeder sills. In the second type, the chilled paths of the older sills were reutilized by subsequent intrusions. The horizontal fingered propagation formed sheet intrusions that exhibit groove, lobate, tubular, and crevasse splay- like geometry in plan view. In 3D view, the sheet intrusions have still preserved the lower center and higher rim that similar with the sub-rounded saucer-shaped sills. Although fracture propagation may be important, flow inflation was the key mechanism of magma intrusion. Further consideration of the mechanisms underlying sill formation may help explain the fingered characteristics of sill propagation.
文摘Saucer-shaped aircraft adopts a novel aerodynamic configuration of blending fuselage with wing. In contrast to the ordinary aircraft configurations, this kind of configuration can totally eliminate the drag resulted from fuselage, bringing many advantages such as simple structure, compact scale, high load capability. But its small aspeet ratio makes the induced drag higher. Through wind tunnel experiments, it is discovered that a type of sweepback fin-shaped winglet can efficiently reduce the induced drag of this kind of aircraft. When this winglet is mounted to a model in wind tunnel experiment, the maximal ratio of lift to drag of the model can be increased by 75% as compared with the model without winglet at the speed of 30 m/s, and reached 15 at the speed of 50 m/s. In order to investigate the performance of this aircraft with winglet at low speed, test flights were processed. The results of test flights not only verify the conclusions of experiments in wind tunnel but also indicate that the load capability of the aircraft with winglet is increased and its lateral stability is even better than that of the aircraft without winglet.
