The study of one-dimensional flow analysis model of the combustor in supersonic combustion experiments

对公开发表的用于超声速燃烧流场分析的几种一维模型进行了研究，指出了其中存在的问题，研究结果表明：基于实验静压数据的一维模型，若不借助必要的流场测量数据或分析结果，或借助于经验性的处理方法，单靠一维假设，无法获得较为完整的一维流场分析结果。改进后的一维模型降低了数据处理过程中的不确定性，提高了对一般情况的适应能力。用编制的计算程序SSC-2对两组典型的超燃燃烧室壁面静压实验数据进行了演算，取得了燃烧室出口总压恢复系数的计算值与测量值基本一致的好结果

Development of the facility for model scramjet testing

A hypersonic propulsion test facility has been constructed in IMCAS (Institute of Mechanics, Chinese Academy of Sciences) in order to provide a high enthalpy hypersonic flow for a model scramjet testing. The vitiated air is produced by a hydrogen/air and oxygen replenishment combustion heater with flow rate of 3.5kg/s, total pressure of 5MPa and total temperature of 2000K in maximum, and accelerated up to Mach 5.6 by a two-dimensional nozzle. Test chamber of the facility is evacuated by a one-stage central air ejector. The preliminary facility performance tests showed that the vitiated air heater could provide the high enthalpy flow as expected. A copper model scramjet without cooling is ready for testing. © 2001 The American Institute of Aeronautics and Astronautics Inc. All rights reserved

Catalytic Cracking and Heat Sink Capacity of Aviation Kerosene Under Supercritical Conditions

Catalytic cracking of China no. 3 aviation kerosene using a zeolite catalyst was investigated under supercritical conditions. A three-stage heating/cracking system was specially designed to be capable of heating 0.8 kg kerosene to a temperature of 1050 K and pressure of 7.0 MPa with maximum mass flow rate of 80 g/s. Sonic nozzles of different diameters were used to calibrate and monitor the mass flow rate of the cracked fuel mixture. With proper experiment arrangements, the mass flow rate per unit throat area of the cracked fuel mixture was found to well correlate with the extent of fuel conversion. The gaseous products obtained from fuel cracking under different conditions were also analyzed using gas chromatography. Composition analysis showed that the average molecular weight of the resulting gaseous products and the fuel mass conversion percentage were a strong function of the fuel temperature and were only slightly affected by the fuel pressure. The fuel conversion was also shown to depend on the fuel residence time in the reactor, as expected. Furthermore, the heat sink levels due to sensible heating and endothermic cracking were determined and compared at varying test conditions. It was found that at a fuel temperature of similar to 1050 K, the total heat sink reached similar to 3.4 MJ/kg, in which chemical heat sink accounted for similar to 1.5 MJ/kg

Studies on spray characteristics of barbotaged atomizer

为了研究静止空气中气泡雾化喷嘴的液雾特性，利用粒子多普勒分析仪（PDA）和Mie散射显示法，对气泡雾化喷嘴在水压2.5 MPa和3.4 MPa条件下，较宽气液比范围内的液雾的张角、粒度及速度分布进行了测量，分析了水压、气液比、两股射流相互作用对液雾的影响。结果表明，气泡对液体射流的雾化具有较大的增强作用，同时发现在一临界气液比（介于3% ～ 4%之间），当气液比达到临界值后，射流的雾化突然增强，且运行稳定

Performance of supersonic model combustors with distributed injection of supercritical kerosene

Supersonic model combustors with two-staged injections of supercritical kerosene were experimentally investigated in both Mach 2.5 and 3.0 facilities with the stagnation temperatures of approximately 1750K. Supercritical kerosene at temperatures of approximately 760K and various pressures was prepared using a two-staged heater developed in Ref. 1 and injected at equivalence ratios of 0.98 to 1.46. Two pairs of integrated injector/flameholder cavity models in tandem were used to facilitate the fuel-air mixing and stabilize the combustion. Combustor performances with different fuel injection locations, injector numbers, combinations of injection stages, and combustor entry Mach numbers were investigated systematically and discussed based on the measured static pressure distributions and the specific thrust increments due to combustion. With two-staged fuel injections the overall performance of the combustors was shown to be improved and fuel injections at equivalence ratio higher than unity could be reached without combustor-inlet interaction. Reducing the number of injectors while increased its diameter was very effective to increase the pressure rise in the combustor with single-stage injections but had little effect on the combustor performance with two-staged fuel injections. Increasing the entry Mach number resulted in lower combustion levels, in particular, with fuel injections at locations close to the combustor exit but was balanced with two-staged fuel injections

Thermal cracking of aviation kerosene for scramjet applications

Thermal cracking of China No.3 aviation kerosene was studied experimentally and analytically under supercritical conditions relevant to regenerative cooling system for Mach-6 scramjet applications. A two-stage heated tube system with cracked products collection/analysis was used and it can achieve a fuel temperature range of 700-1100 K, a pressure range of 3.5-4.5 MPa and a residence time of approximately 0.5-1.3 s. Compositions of the cracked gaseous products and mass flow rate of the kerosene flow at varied temperatures and pressures were obtained experimentally. A one-step lumped model was developed with the cracked mixtures grouped into three categories: unreacted kerosene, gaseous products and residuals including liquid products and carbon deposits. Based on the model, fuel conversion on the mass basis, the reaction rate and the residence time were estimated as functions of temperature. Meanwhile, a sonic nozzle was used for the control of the mass flow rate of the cracked kerosene, and correlation of the mass flow rate gives a good agreement with the measurements

Heat Transfer of Aviation Kerosene at Supercritical Conditions

The heat transfer characteristics of China no. 3 kerosene were investigated experimentally and analytically under conditions relevant to a regenerative cooling system for scramjet applications. A test facility developed for the present study can handle kerosene in a temperature range of 300-1000 K, a pressure range of 2.6-5 MPa, and a mass How rate range of 10-100 g/s. In addition, the test section was uniquely designed such that both the wall temperature and the bulk fuel temperature were measured at the same location along the flowpath. The measured temperature distributions were then used to analytically deduce the local heat transfer characteristics. A 10-component kerosene surrogate was proposed and employed to calculate the fuel thermodynamic and transport properties that were required in the heat transfer analysis. Results revealed drastic changes in the fuel flow properties and heat transfer characteristics when kerosene approached its critical state. Convective heat transfer enhancement was also found as kerosene became supercritical. The heat transfer correlation in the relatively low-fuel-temperature region yielded a similar result to other commonly used jet fuels, such as JP-7 and JP-8, at compressed liquid states. In the high-fuel-temperature region, near and beyond the critical temperature, heat transfer enhancement was observed; hence, the associated correlation showed a more significant Reynolds number dependency

图书馆员网络社区信息交流行为实证研究——“大旗底下”QQ群个案分析

以"大旗底下"QQ群为个案,通过对聊天记录文本和在线问卷调查的定量分析,展现了图书馆员在网络社区中的信息交流行为特征规律,并探讨了网络社区信息交流对图书馆员精神世界的影响。论文认为,可以充分利用Web2.0技术所带来的信息交流的便利和迅捷,让更多的图书馆员融入到各种专业社区中,在跨地域、跨部门的信息交流中分享专业工作经验和成功的喜悦,在信息交流中不断汲取图书馆职业精神的养分,从而有效培育起对图书馆现代理念和核心价值观的社会认同,以此推动图书馆事业的健康发展

当代中国知识分子的图书馆认同变迁研究——基于《读书》杂志(1979-2009)的文本分析

以书为媒,知识分子与图书馆有着深厚的不解之缘。通过对《读书》杂志30年来所刊载的与图书馆相关的1047篇文章进行分析,发现"阅读情结"一直是维系知识分子图书馆认同的核心因素。随着时代发展和社会思潮变迁,在不同的发展阶段,当代中国知识分子图书馆认同的内涵也随之发生变化:从"思想自由的认同",到"以人为本的认同",再到"民主保障的认同"。在与社会互动推进图书馆事业发展的进程中,展示出当代中国知识分子群体勇于解放思想、兼济天下、敢为人先的时代精神