Research Progress On Thermal Protection Materials And Structures Of Hypersonic Vehicles

Hypersonic vehicles represent future trends of military equipments and play an important role in future war. Thermal protection materials and structures, which relate to the safety of hypersonic vehicles, are one of the most key techniques in design and manufacture of hypersonic vehicles. Among these materials and structures, such as metallic temperature protection structure, the temperature ceramics and carbon/carbon composites are usually adopted in design. The recent progresses of research and application of ultra-high temperature materials in preparation, oxidation resistance, mechanical and physical characterization are summarized.

Chemical Nonequilibrium Effects on Flow Field for Reusable Launch Vehicles

High temperature chemical non-equilibrium phenomena have a great effect on the flow field around a reentry vehicle. A set of three dimensional Navier-Stokes equations have been solved by implicit finite volume NND scheme. Both ideal gas viscous flow and chemical non-equilibrium flow are calculated for a spherical-cone at a small angle of attack. The results of the two flows have been compared and the effect of chemical non-equilibrium has been analyzed. The effect of wall material's properties, such as catalysis and radiation were studied. The results are in good agreement with the referenced paper.

Experimental Demonstration Of A New Concept Of Drag Reduction And Thermal Protection For Hypersonic Vehicles

A new idea of drag reduction and thermal protection for hypersonic vehicles is proposed based on the combination of a physical spike and lateral jets for shock-reconstruction. The spike recasts the bow shock in front of a blunt body into a conical shock, and the lateral jets work to protect the spike tip from overheating and to push the conical shock away from the blunt body when a pitching angle exists during flight. Experiments are conducted in a hypersonic wind tunnel at a nominal Mach number of 6. It is demonstrated that the shock/shock interaction on the blunt body is avoided due to injection and the peak pressure at the reattachment point is reduced by 70% under a 4A degrees attack angle.

Configuration optimization of hypersonic vehicles under transitional flow conditions

The rarefied gas effects on several configurations are investigated under hypersonic flow conditions using the direct simulation Mont Carlo method. It is found that the Knudsen number, the Mach number, and the angle of attack all play a mixed role in the aerodynamics of a flat plate. The ratio of lift to drag decreases as the Knudsen number increases. Studies on 3D delta wings show that the ratio of lift to drag could be increased by decreasing the wing thickness and/or by increasing the wing span. It is also found that the waveriders could produce larger ratio of lift to drag as compared with the delta wing having the same length, wing span, and cross section area.

Quantum well infrared photodetector simultaneously working in two atmospheric windows

We have demonstrated a two-contact quantum well infrared photodetector (QWIP) exhibiting simultaneous photoresponse in both the mid- and the long-wavelength atmospheric windows of 3-5 mu m and of 8-12 mu m. The structure of the device was achieved by sequentially growing a mid-wavelength QWIP part followed by a long-wavelength QWIP part separated by an n-doped layer. Compared with the conventional dual-band QWIP device utilizing three ohmic contacts, our QWIP is promising to greatly facilitate two-color focal plane array (FPA) fabrication by reducing the number of the indium bumps per pixel from three to one just like a monochromatic FPA fabrication and to increase the FPA fill factor by reducing one contact per pixel; another advantage may be that this QWIP FPA boasts broadband detection capability in the two atmospheric windows while using only a monochromatic readout integrated circuit. We attributed this simultaneous broadband detection to the different distributions of the total bias voltage between the mid- and long-wavelength QWIP parts.

High power red-light GaInP/AlGaInP laser diodes with nonabsorbing windows based on Zn diffusion-induced quantum well intermixing

The layer structure of GaInP/AlGaInP quantum well laser diodes (LDs) was grown on GaAs substrate using low-pressure metalorganic chemical vapor deposition (LP-MOCVD) technique. In order to improve the catastrophic optical damage (COD) level of devices, a nonabsorbing window (NAW), which was based on Zn diffusion-induced quantum well intermixing, was fabricated near the both ends of the cavities. Zn diffusions were respectively carried out at 480, 500, 520, 540, and 580 Celsius degree for 20 minutes. The largest energy blue shift of 189.1 meV was observed in the window regions at 580 Celsius degree. When the blue shift was 24.7 meV at 480 Celsius degree, the COD power for the window LD was 86.7% higher than the conventional LD.

基于Windows CE的HIRFL-CSR前端控制系统设计与实现

介绍了一个基于WindowsCE的嵌入式分布控制系统,系统基于以太网和现场总线连接,节点用嵌入式平板计算机实现。给出了系统的硬件组成和软件设计,该系统已应用于HIRFL-CSR前端控制系统。

在Windows下PC机作为半双工RS-485网络主机通信程序的设计

描述了一个以PC机作为半双工RS-485网络主机,工作于Windows平台上的通讯程序。该程序特点是通过使用异步通信WIN32API和多线程及多种同步量来实现半双工通信方式。

基于Windows系统的原油水气含量自动监测仪表远程控制系统的设计

本论文主要内容是一种应用于油田的工业用仪表的程序设计。程序体现了当今流行软件基本的设计思想，同时具有积极的现实意义。论文内容主要包括三大部分。第一部分简略地介绍仪表的总体的工作原理。从水含量，气含量两个方面进行了论述。第二部分介绍了仪表的工作过程中，涉及的硬件部分。简略的阐述了硬件部分的探测器结构部分，详细的介绍了第三部分软件编程中用到的计数卡和D／A转换板卡的原理，及编程控制的基本步骤。第三部分是仪表的软件部分，也是核心和重点部分。主要介绍了软件的总体框架，重点地说明了计数卡的驱动程序设计，数据采集，打印部分，数据库部分，实时性的实现方法。同时还有参数拟合功能中，涉及到的数理统计中参数回归法确定参数的具体方法。结合各个具体功能的说明，给出了具体的源代码。程序的其它必不可缺少，但实现起来难度相对较小的部分给出了简略的说明。该程序具有操作简单明了，界面友好，功能齐全等特点。通过对该工业仪表程序的设计，在计算机软件及硬件方面的理解，都能够得到一定水平的提高。特别是在计算机软件的设计方法，设计思想等各个方面都有深入的认识。

CAMAC Windows 2000驱动程序设计

兰州重离子加速器（HIRFL, Heavy Ion Research Facility at Lanzhou）是中国最大的、在国际上享有较高知名度的中、低能量重离子物理基础及其应用研究装置，HIRFL控制系统是这一大型研究装置的重要组成部分。CAMAC是HIRFL控制系统最重要的硬件接口设备，Windows 2000是HIRFL控制系统最理想的软件运行平台，所以设计一个标准的CAMAC Windows 2000驱动程序对HIRFL控制系统有着重要的意义。本文首先介绍了Windows 2000的系统总体结构以及与驱动程序编写密切相关的内核模式I/O组件。在硬件环境方面，简要叙述了CAMAC接口和EISA总线的知识。内核模式I/O处理是编写驱动程序最重要的知识，文章对此作了详细的阐述。驱动程序的各个内核模式对象是驱动程序开发的基本数据结构，是驱动程序的生命线，这部分内容在论文中占有一定的比重。在实际的驱动程序代码中，有很多类和例程，本文就几个关键的类和例程进行了剖析。最后就如何构造和安装驱动程序作了说明。作者用Microsoft Visual C++ 6.0和Windows 2000 DDK作为工具，成功地开发了CAMAC Windows 2000内核模式驱动程序并制作了最终安装版本，取得了比较满意的结果。它的完成，将会对HIRFL控制系统性能以及HIRFL的运行效率产生积极的影响。