排序方式: 共有39条查询结果,搜索用时 15 毫秒
1.
For the problem that the plume flow field structure of a multi engine parallel rocket is complicated and the bottom thermal environment is extremely harsh, which may cause the failure of the engine structural components, the plume flow field and thermal environment at different altitudes are studied through numerical simulation. The result is compared with the measured results in flight which shows that when the rocket is flying at a low altitude, the plume of the engines do not interfere with each other. As the flight altitude increases, the plumes gradually expand and begin to interfere with each other, and finally there is an obvious backflow at the bottom of the rocket. The maximum heat flux at the moment of take off is basically the same as the measured value in flight. Before the backflow occurs, the heat flux mainly consists of radiant heat, the convective heat flow increases as the flight altitude grows, but it is also much smaller than the peak heat flow at takeoff. The result has certain guiding significance for the optimal design of engine structure thermal protection. 相似文献
2.
Numerical simulations of energy depositions in the middle and upper solar chromosphere result in ejection of chromospheric material into the corona and heating of the chromospheric gas. These simulations may be capable of describing some of the features seen by the soft X-ray telescope on board theYohkoh satellite. 相似文献
3.
Loukas Vlahos 《Space Science Reviews》1994,68(1-4):39-50
The magnetic energy released inside an active region is closely related to its formation and evolution. Following the evolution of a collection of flux tubes inside the convection zone and above the photosphere we can show that many nonlinear structures (current sheets, shock waves, double layers etc.) are formed. We propose in this review that coronal heating, flares and particle acceleration are due to the interaction of the plasma with these nonlinear structures. Approaching active regions as a driven complex dynamical system we can show that several coherent ensembles of the nonlinear structures will appear spontaneously. The statistical analysis of these structures is a major problem in solar physics. We can also show that many observed large scale structures are the result of the convolution of non-observable fragmentation in the energy release process. 相似文献
4.
况森保 《南昌航空工业学院学报》1995,(2):62-66
对带裂纹的30CrMnSiA钢紧头等拉伸试件进行同时加温超载处理,经卸载冷却后,在裂纹端区产生残余压应力塑性场。这一处理方法起到延缓裂纹扩展、抑制起裂的效果。 相似文献
5.
介绍了控制系统在热值比较稳定的前提下,依靠控制加热炉排气中的残氧量以降低空燃比,达到降低排气热损失的目的,实现了加热炉节能降耗. 相似文献
6.
7.
《中国航空学报》2021,34(10):91-102
To meet the needs of preventing information leakage in space engineering and military industry, an efficient method was introduced to obtain layered electromagnetic shielding sealing rubber. The carbon fiber, Ni-Fe coating, and Carbon NanoTube (CNT) were combined by chemical plating and in-situ polymerization to obtain a lightweight (0.14 g/cm2) and thin (1 mm thick) Carbon fiber Fabric (CF)/Ni-Fe/CNT/silicone layered electromagnetic shielding composites. The layered material obtained by adjusting the electroless plating time exhibited a high Shielding Efficiency (SE) of 60.2–85.5 dB in the range of 0–4800 MHz, which can be used for aviation electromagnetic shielding. Carbon fibers and carbon nanotubes mainly attenuated electromagnetic waves through absorption loss, while the nickel-iron alloy coating through reflection loss interacted with the magnetic vector of incident ElectroMagnetic (EM) radiation and magnetic dipoles, therefore, the EM Interference (EMI) shielding composite attenuated EM waves with the “absorption-reflection-absorption” cooperative interaction. Moreover, the flexible fabric substrate adhered with silicone rubber possessed a breaking elongation of 52.3%, which can be utilized as a good sealing material. Simultaneously, the outstanding exothermicity (67.2 °C under the applied voltage of 5 V) makes it possible to be applied in electric heating area. The electromagnetic shielding composites prepared in this paper have good potential in the fields of precision electronic equipment and aviation systems. 相似文献
8.
9.
10.
柔性热防护系统为高超声速充气气动减速器的防热需求而发展,主要为大质量地球再入及未来火星的进入、下降和着陆系统的防热而研发。本文介绍了美国针对高超声速充气气动减速器已经进行和正在策划的飞行试验情况以及火星进入、下降和着陆系统对柔性热防护系统的使用热环境需求。对柔性热防护系统的基本组成进行了介绍,详细描述柔性热防护系统的相关热考核试验。 相似文献