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361.
第四代歼击机发动机加力燃烧室的技术特点 总被引:3,自引:0,他引:3
本文着重介绍了第四代歼击机发动机加力燃烧室的发展,内容包括对最高加力温度、组织燃烧和进气方案等的分析与研究。鉴于第四代歼击机发动机发展的需要,加力燃烧室已由单一功能发展成具有多种功能,采用了许多新技术。文中介绍了包括红外隐身、超音速巡航和推力矢量等新技术,还介绍了金属间化合物如Ni_3Al,Ti_3Al等新材料和新工艺。最后作者提出了八项建议。 相似文献
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An Event Horizon Imager(EHI) Mission Concept Utilizing Medium Earth Orbit Sub-mm Interferometry
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KUDRIASHOV V MARTIN-NEIRA M ROELOFS F FALCKE H BRINKERINK C BARYSHEV A HOGERHEIJDE M YOUNG A POURSHAGHAGHI H KLEIN-WOLT M MOSCIBRODZKA M DAVELAAR J BARAT I DUESMANN B VALENTA V PERDIGUES ARMENGOL J M DE WILDE D MARTIN IGLESIAS P ALAGHA N VAN DER VORST M 《空间科学学报》2021,41(2):211-233
Submillimeter interferometry has the potential to image supermassive black holes on event horizon scales, providing tests of the theory of general relativity and increasing our understanding of black hole accretion processes. The Event Horizon Telescope (EHT) performs these observations from the ground, and its main imaging targets are Sagittarius A* in the Galactic Center and the black hole at the center of the M87 galaxy. However, the EHT is fundamentally limited in its performance by atmospheric effects and sparse terrestrial (u,v)-coverage (Fourier sampling of the image). The scientific interest in quantitative studies of the horizon size and shape of these black holes has motivated studies into using space interferometry which is free of these limitations. Angular resolution considerations and interstellar scattering effects push the desired observing frequency to bands above 500 GHz.
This paper presents the requirements for meeting these science goals, describes the concept of interferometry from Polar or Equatorial Medium Earth Orbits (PECMEO) which we dub the Event Horizon Imager (EHI), and utilizes suitable space technology heritage. In this concept, two or three satellites orbit at slightly different orbital radii, resulting in a dense and uniform spiral-shaped (u,v)-coverage over time. The local oscillator signals are shared via an inter-satellite link, and the data streams are correlated on-board before final processing on the ground. Inter-satellite metrology and satellite positioning are extensively employed to facilitate the knowledge of the instrument position vector, and its time derivative. The European space heritage usable for both the front ends and the antenna technology of such an instrument is investigated. Current and future sensors for the required inter-satellite metrology are listed. Intended performance estimates and simulation results are given. 相似文献
This paper presents the requirements for meeting these science goals, describes the concept of interferometry from Polar or Equatorial Medium Earth Orbits (PECMEO) which we dub the Event Horizon Imager (EHI), and utilizes suitable space technology heritage. In this concept, two or three satellites orbit at slightly different orbital radii, resulting in a dense and uniform spiral-shaped (u,v)-coverage over time. The local oscillator signals are shared via an inter-satellite link, and the data streams are correlated on-board before final processing on the ground. Inter-satellite metrology and satellite positioning are extensively employed to facilitate the knowledge of the instrument position vector, and its time derivative. The European space heritage usable for both the front ends and the antenna technology of such an instrument is investigated. Current and future sensors for the required inter-satellite metrology are listed. Intended performance estimates and simulation results are given. 相似文献
364.
基于声学黑洞的盒式结构全频带振动控制 总被引:2,自引:1,他引:1
声学黑洞(ABH)作为一种新型高效的波动控制技术,被广泛应用于梁板结构的振动控制中。传统声学黑洞结构存在局部强度和刚度较弱、特征尺寸较大、有效作用频率较高等问题,限制了声学黑洞技术的进一步应用和推广。针对盒式结构振动控制问题,设计了一种新型的声学黑洞阻尼(ABHD)振子。运用有限元仿真方法研究了附加ABHD振子的盒式结构的动态特性,结果表明附加声学黑洞阻尼振子的盒式结构具有高效的能量聚集和耗散能力。通过对盒式结构上下主梁中间不同位置处振子参数的优化,在不改变原有主结构强度和刚度的前提下,实现了对主梁全频带的减振效果。实验结果表明,传统盒式结构在附加多个ABHD振子后全频带的共振峰均有5~30 dB的削减,且附加振子的质量占系统总质量的7.8 %。 相似文献
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IntroductionExpensive turbine parts like HPT(HighPressure Turine)blades or vanes are replaced bynew parts in case of damage.For example theburn through of the inner side of a blade or vane(Figure 1)is a frequently appearing damage,which cannot be repaired… 相似文献
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Mission to Mars using integrated propulsion concepts: considerations, opportunities, and strategies 总被引:1,自引:0,他引:1
The aim of this paper is to evaluate the feasibility of a mission to Mars using the Integrated Propulsion Systems (IPS) which means to couple Nuclear-MPD-ISPU propulsion systems. In particular both mission analysis and propulsion aspects are analyzed together with technological aspects. Identifying possible mission scenarios will lead to the study of possible strategies for Mars Exploration and also of methods for reducing cost. As regard to IPS, the coupling between Nuclear Propulsion (Rubbia's engine) and Superconductive MPD propulsion is considered for the Earth-Mars trajectories: major emphasis is given to the advantages of such a system. The In Situ Resource Utilization (ISRU) concerns on-Mars operations; In Situ Propellant Utilization (ISPU) is foreseen particularly for LOX-CH4 engines for Mars Ascent Vehicles and this possibility is analyzed from a technological point of view. Tether Systems are also considered during interplanetary trajectories and as space elevators on Mars orbit. Finally strategic considerations associated to this mission are considered also. 相似文献
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