排序方式: 共有47条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
35.
36.
37.
This study seeks to determine the similarities in plume radiation between reduced and full-scale solid rocket models in ground test conditions through investigation of flow and radiation for a series of scale ratios ranging from 0.1 to 1. The radiative transfer equation(RTE) considering gas and particle radiation in a non-uniform plume has been adopted and solved by the finite volume method(FVM) to compute the three dimensional, spectral and directional radiation of a plume in the infrared waveband 2–6 μm. Conditions at wavelengths 2.7 μm and 4.3 μm are discussed in detail, and ratios of plume radiation for reduced-scale through full-scale models are examined. This work shows that, with increasing scale ratio of a computed rocket motor, area of the hightemperature core increases as a 2 power function of the scale ratio, and the radiation intensity of the plume increases with 2–2.5 power of the scale ratio. The infrared radiation of plume gases shows a strong spectral dependency, while that of Al_2O_3 particles shows spectral continuity of gray media.Spectral radiation intensity of a computed solid rocket plume's high temperature core increases significantly in peak radiation spectra of plume gases CO and CO_2. Al_2O_3 particles are the major radiation component in a rocket plume. There is good similarity between contours of plume spectral radiance from different scale models of computed rockets, and there are two peak spectra of radiation intensity at wavebands 2.7–3.0 μm and 4.2–4.6 μm. Directed radiation intensity of the entire plume volume will rise with increasing elevation angle. 相似文献
38.
高温射流流场计算是尾焰辐射目标特性计算的前提,然而由于缺少可靠实验数据,针对湍流超声速射流的数值模拟多集中于低温射流,高温射流计算与实验的对比工作还很少见。利用k-ωSST双方程湍流模型,模拟了多个典型超声速射流实验的流场速度与温度分布,通过与实验结果进行对比,建立了一种超声速射流计算方法。首先,通过对比多个低温射流的实验与计算结果,探索了湍流模型中可压缩修正以及来流湍动粘性比对超声速射流计算结果的影响;进而,针对火箭发动机尾焰实验,计算尾焰流场与流场红外辐射,流场辐射计算结果与实验观测结果符合较好,进一步验证了计算方法。最终认为经过可压缩修正的k-ωSST双方程湍流模型结合湍动粘性比取值30可以作为超声射流计算中较为典型的湍流计算方法。 相似文献
39.
This paper presents a gaskinetic study on high-speed, highly rarefied jets expanding into a vacuum from a cluster of planar or annular exits. Based on the corresponding exact expressions for a planar or annular jet, it is convenient to derive the combined multiple jet flowfield solutions of density and velocity components. For the combined temperature and pressure solutions, extra attention is needed. Several direct simulation Monte Carlo simulation results are provided to validate these analytical solutions. The analytical and numerical solutions are essentially identical for these high Knudsen number jet flows. 相似文献
40.
Plume aerodynamic effects of cushion engine in lunar landing 总被引:1,自引:0,他引:1
During the second period of China "Tanyue" Project, the explorer will softland on the moon. The cushion engines are used to decelerate the explorer and reduce the impact on the lunar ground. It is necessary to study its plume effects on the explorer component. The self-developed PWS (Plume WorkStation) software based on direct simulation Monte Carlo (DSMC) method is used to simulate the plume effects of two 150 N engines. Due to the complex structure of the explorer, PWS uses a decoupling method to treat the boundary mesh, which mainly interacts with simulation particles, and has no relation with the computational grids. After the analytical expressions of plane surfaces and curved surfaces of each boundary block are given, the particle position within or without the boundary blocks can be easily determined. Finally the 3D plume field of two 150 N engines is simulated. The pressure, temperature and velocity distributions of plume field are clearly presented by three characteristic slices. The aerodynamic effects on the explorer bottom, the landfall legs and antenna are separately shown. The compression influence on the plume flow of four landfall legs can be observed. 相似文献