Experimental Investigation of a Fixed-geometry Two-dimensional Mixed-compression Supersonic Inlet with Sweep-forward High- light and Bleed Slot in an Inverted ＂X＂-type Layout

A fixed-geometry two-dimensional mixed-compression supersonic inlet with sweep-forward high-light and bleed slot in an inverted ＂X＂-form layout was tested in a wind tunnel. Results indicate： （1） with increases of the free stream Mach number, the total pressure recovery decreases, while the mass flow ratio increases to the maximum at the design point and then decreases; （2） when the angle of attack, a, is less than 6°, the total pressure recovery of both side inlets tends to decrease, but, on the lee side inlet, its values are higher than those on the windward side inlet, and the mass flow ratio on lee side inlet increases first and then falls, while on the windward side it keeps declining slowly with the sum of mass flow on both sides remaining almost constant; （3） with the attack angle, a, rising from 6° to 9°, both total pressure recovery and mass flow ratio on the lee side inlet fall quickly, but on the windward side inlet can be observed decreases in the total pressure recovery and increases in the mass flow ratio; （4） by comparing the velocity and back pressure characterristics of the inlet with a bleed slot to those of the inlet without, it stands to reason that the existence of a bleed slot has not only widened the steady working range of inlet, but also made an enormous improvement in its performance at high Mach numbers. Besides, this paper also presents an example to show how this type of inlet is designed.     

俄罗斯航天工业核心能力的特征

20世纪末,俄罗斯陷入了严峻的危机当中,到2007年俄罗斯经济也才恢复到1990年左右的水平。经济颓势直接影响到俄罗斯航天工业,逐渐降低的先行优势以及资金限制让俄罗斯航天工业体系日渐衰落。直到近年,在俄罗斯政府对航天活动大力投资与发展的支持下,俄罗斯航天部门才获得了新的推进力,诸多雄心勃勃的航天项目计划得到实施,资金危机得到有效解决,航天工业核心能力得到迅速提升,并体现出＂持续性、战略性、集团化、军民一体化、产业化、国际化＂的特征。     

核能就是全能!?

1947年9月,特温林在那封著名的《飞碟是真实的》信中,他指出了关于UFO现象信息的收集被送到一些机构,其中一个就是国家环境政策法计划或者核能飞行器推进力计划。证实某种核动力飞行器存在的可能性对某些追求UFO信息的人来说,可能具有非常强大的吸引力。任何卷入位于田纳西州橡     

两种手形对游泳推进效率影响的数值模拟

针对采用何种手形游泳能产生较高的推进效率,运用计算流体力学(CFD,Computational Fluid Dynamics)方法,建立了国内某女运动员手掌和前臂在五指并拢和五指分开两种手形的三维非结构网格模型;计算了90°攻角划水时两种不同手形的手掌和前臂在不同来流速度下的推进阻力、推进升力及其系数值,依据计算结果对手周围的流场进行了分析,研究了不同手形对游泳推进效率的影响.结果表明压差阻力是推进阻力的主要组成部分,在90°攻角划水时五指并拢具有更高推进效率.