热喷流红外辐射特性的测试实验研究

以模型实验方法对热喷流的红外辐射特性进行了测试实验研究．着重介绍了以通用红外仪器组成的红外探测系统，对热喷流的红外辐射进行实验的测试方法和实测结果。得出了热喷流的红外辐射能的空间分布，热喷流的红外辐射光谱，热喷流辐射能按波段分布比例以及二元喷管与圆喷管的热喷流辐射特征比较等一系列测试结果。测试实验结果表明，测试系统和测试方法是有效的，由实测数据进行综合分析，得出了有意义的结果，并与理论分析相吻合。本文为热喷流的红外辐射特性测试，提供了一种可供借鉴的探测系统和测试技术。     

DD3单晶高温剪切试验研究

设计了新的剪切试验件和剪切夹具,首次开展了ＤＤ３单晶的剪刀试验研究,分别在７００℃,８５０℃和９５０℃下进行瞬时剪切和恒定剪应力下的蠕变试验,试验结果表明,大部分试验的重复性很好,ＤＤ３单晶存在剪切应变硬化和饱和现象〈００１〉方向的剪切强度比拉伸强度的小一半,同时剪切非弹性变形很大,瞬时剪切行为存在加载速率,温度相关性剪切蠕变曲线形状和蠕为寿命与温度及应力大小有关。     

强驻波声场对微小颗粒群作用的实验研究

用实验手段研究了以空气为介质的强驻波声场 (声压级大于 1 5 0dB)对其中微小颗粒群 (颗粒直径小于 30 μm)的作用。实验中观察到了颗粒有规律地向波节点运动的现象 ,并发现聚集颗粒群中含有周期性长大、破裂而喷发的气泡。这些现象与声流及声辐射压力有关。对这些现象的观察和分析有助于加深对高声强下一些基本效应的认识     

激发跃迁速率对热力学非平衡氮气紫外辐射的影响

基于氮气的碰撞-辐射（CR）模型,计算了速度为6.2 km/s、初始压力为133 Pa的高超声速流动激波中N₂和N₂+分子电子能级的分布情况,分析了不同激发跃迁速率模型对电子能级分布及辐射光谱模拟的影响。针对流动中热力学非平衡区域和平衡区域,在300~440 nm的辐射光谱开展了逐线法的数值模拟,并与激波管实验测量光谱进行了对比。结果表明,目前的激发跃迁速率均存在偏差,综合Park模型的爱因斯坦系数和Johnston模型的碰撞激发速率可以得到与实验结果最为接近的辐射光谱。      

Numerical study on similarity of plume infrared radiation between reduced-scale solid rocket motors

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.     

IR radiation characteristics of rocket exhaust plumes under varying motor operating conditions

The infrared(IR) irradiance signature from rocket motor exhaust plumes is closely related to motor type,propellant composition,burn time,rocket geometry,chamber parameters and flight conditions.In this paper,an infrared signature analysis tool(IRSAT) was developed to understand the spectral characteristics of exhaust plumes in detail.Through a finite volume technique,flow field properties were obtained through the solution of axisymmetric Navier-Stokes equations with the Reynolds-averaged approach.A refined 13-species,30-reaction chemistry scheme was used for combustion effects and a k-e-Rtturbulence model for entrainment effects.Using flowfield properties as input data,the spectrum was integrated with a line of sight(LOS) method based on a single line group(SLG) model with Curtis-Godson approximation.The model correctly predicted spectral distribution in the wavelengths of 1.50–5.50 lm and had good agreement for its location with imaging spectrometer data.The IRSAT was then applied to discuss the effects of three operating conditions on IR signatures:(a) afterburning;(b) chamber pressure from ignition to cutoff;and(c) minor changes in the ratio of hydroxyl-terminated polybutadiene(HTPB) binder to ammonium perchlorate(AP) oxidizer in propellant.Results show that afterburning effects can increase the size and shape of radiance images with enhancement of radiation intensity up to 40%.Also,the total IR irradiance in different bands can be characterized by a non-dimensional chamber pressure trace in which the maximum discrepancy is less than 13% during ignition and engine cutoff.An increase of chamber pressure can lead to more distinct diamonds,whose distance intervals are extended,and the position of the first diamond moving backwards.In addition,an increase in HTPB/AP causes a significant jump in spectral intensity.The incremental rates of radiance intensity integrated in each band are linear with the increase of HTPB,and the growth rates of radiance intensities in some bands reach up to 50% as HTPB weight increases by 3%.     

Deterministic pion and muon transport in Earth’s atmosphere

An accurate understanding of the physical interactions and transport of space radiation is important for safe and efficient space operations. Secondary particles produced by primary particle interactions with intervening materials are an important contribution to radiation risk. Pions are copiously produced in the nuclear interactions typical of space radiations and can therefore be an important contribution to radiation exposure. Charged pions decay almost exclusively to muons. As a consequence, muons must also be considered in space radiation exposure studies. In this work, the NASA space radiation transport code HZETRN has been extended to include the transport of charged pions and muons. The relevant transport equation, solution method, and implemented cross sections are reviewed. Muon production in the Earth’s upper atmosphere is then investigated, and comparisons with recent balloon flight measurements of differential muon flux are presented. Muon production from the updated version of HZETRN is found to match the experimental data well.     

晴空环境下的地基面天线多场耦合分析及试验

大口径高频段的地基面天线在晴空环境下的热变形对电性能影响明显。针对这一问题,首先     

宽温度范围大口径高精度变温标准黑体辐射源研制

红外成像探测系统的应用环境越来越复杂,工作适应温度范围低温可达到-50 ℃以下,高温可达到70 ℃以上。为满足相应要求,研制宽温度范围大口径高精度变温标准黑体辐射源,采用细分均匀加热、模糊PID自整定控制算法、双路配气保护等技术,满足高低温需求,同时开展腔型设计、超黑高发射率涂层等相应研究,保证了黑体辐射源的整体性能,确保完成相应功能。研制完成后,在高低温环境下进行了验证试验,可达到以下指标：有效发射率≥0.999,空腔开口直径≥60 mm,温度测量不确定度10 mK（k=2）。经验证,可满足宽温度范围条件红外探测系统的计量要求。