Measurement of solid propellant burning rates by analysis of ultrasonic full waveforms

The measurement of solid propellant burning rates using ultrasound requires the simultaneous acquisition and analysis of ultrasonic signals and pressure data simultaneously in a wide range of pressure values during the process of propellant burning. Recently, this method has been proposed as an effective approach based on an analysis of full waveforms of ultrasonic signals together with a laboratory prototype system in which the proposed approach has been implemented. However, this prototype system had limitations in terms of data processing speed and signal processing procedures. To overcome such limitations, in the present study, we develop a dedicated, high speed system that can acquire ultrasonic full waveforms and pressure data up to 2,000 times per second. Our system can also estimate the burning rate as a function of pressure using a special software based on ultrasonic full waveform analysis. This paper describes the approach adopted in this high speed system, along with the burning rate measurement results obtained from three propellants with different burning characteristics. This paper was recommended for publication in revised form by Associate Editor Dae-Eun Kim Sung-Jin Song received a B.S. degree in Mechanical Engineering from Seoul National University, Seoul, Korea in 1981, a M.S. degree in Mechanical Engineering from Korea Advanced Institute of Science and Technology in 1983, and a Ph.D in Engineering Mechanics from Iowa State University, Ames, Iowa, USA in 1991. He has worked at Daewoo Heavy Industries, Ltd., Inchoen, Korea for 5 years from 1983, where he has been certified as ASNT Level III in RT, UT, MT and PT. He has worked at Chosun University, Gwangju, Korea as Assistant Professor for 5 years from 1993. Since 1998 he has been at Sungkyunkwan University, Suwon, Korea and is currently Professor of Mechanical Engineering.     

X-ray visualization measurement of slurry flow in solid propellant casting

Simulated solid propellant slurry containing lead sphere tracers is experimentally cast into a double-circular cylindrical container. During the casting, the temperature and the pressure environment has been mimicked to an actual composite solid propellant casting of solid rocket motors. X-rays are projected on to the slurry flow from two directions and penetration images are recorded by a flat-panel detector and an X-ray image intensifier. By suppressing the mutual interference of the X-rays, the two-directional X-ray photography has been successfully conducted. Using the time series data of the X-ray images from the two directions, the identification of each tracer particle in space and time has been done and their three-dimensional paths have been computed. From these procedures, the flow field or the velocity field inside the slurry flow, which is usually invisible, has been estimated.     

微型固体火箭制造与点火技术的研究

介绍了一种新型微型固体火箭的结构特点。首次通过微弧氧化工艺实现了铝合金材料在制造微型固体火箭燃烧室壳体方面的应用,并经数值计算验证微弧氧化层的隔热效果。根据微型固体火箭结构特点选用了半导体桥作为点火装置。为了进一步研究微型固体火箭族在空间中分组点火工作状况,设计了模拟微型固体火箭族(实验设计为180个)空间点火的实验台。实验台实现了通过小型键盘输入火箭代号,同时LED显示器显示以及单片机控制半导体桥点火等工作过程。     

固体火箭推进剂燃烧微粒场的激光全息诊断

大幅度提高金属燃料的含量是实现高能高效推进剂配方的一个发展方向。现针对含铝量2／%,粒度及含铝量6%,粒度15±2μm的两种推进剂展开了一系列的研究工作。应用离轴4F全息技术,进行了固体火箭推进剂燃烧流场的粒子分布研究。在常压、2MPa和4MPa实验工况下,获得了清晰的全息图。     

Tribological performance of some solid lubricants for hot forming through laboratory simulative tests

Tribological research concerning sliding contacts at temperatures of 500–1000 °C has received limited attention. Industrial systems operating under high temperatures can be readily found in sheet metal forming processes. The control of friction during the tool–workpiece interaction and minimisation of tool wear are both crucial in maintaining the products quality. The application of solid lubricants can be a possible approach in accomplishing these goals.The objective of this work is to investigate the reliability of combined model and component tests under solid lubricating conditions. The laboratory tests showed that both methodologies provide consistent results in exploring potential of the solid lubricants.     

Experimental and numerical modelling of the ventriculosinus shunt (El-Shafei shunt)

This study assesses malresorptive hydrocephalus treatment by ventriculosinus shunting with the shunt in the antegrade or retrograde position. First, an experimental model of the cerebral ventricles, the arachnoid villi, the cortical veins, and the superior sagittal sinus was built. For this purpose, the compliance of a human cortical vein was measured and then modelled by means of Penrose tubes. The dimensions of the superior sagittal sinus were determined in vivo by measurements on magnetic resonance imaging scans of 21 patients. Second, a numerical model of the cortical veins and the superior sagittal sinus was built. The numerical results were validated with the results from the experimental model. The experimental and numerical pressure difference between the intracranial pressure and the static sinus pressure was small (0-20 Pa) and corresponded to the theoretically expected values. No overdrainage was found in either the antegrade or the retrograde position of the shunt. Blood reflow was only found while mimicking lumbar puncture or changes in position with the experimental model (lowering the intracranial pressure or increasing the sinus pressure rapidly). Optimal results can be obtained with the shunt positioned in the most downstream half of the superior sagittal sinus. The experimental and numerical results confirm the potential of ventriculosinus shunting as therapy for malresorptive hydrocephalus patients. The ventriculosinus shunt thus proves to be a promising technique.     

Aerospace mechanisms and tribology technology: Case study

The success of many tribological products used or tribological systems operated in vacuum depends on adequate control of adhesion between two or more materials. Adhesion (e.g., in adhesive bonding) is the mechanical force or strength required to separate the surfaces in contact. This foreword is concerned with adhesion, which has greatly contributed, and should continue to contribute, to tribological problems, such as high friction, solid-state welding, scuffing or scoring, high wear, and a short lubricant life, in vacuum.     

火箭推进剂搅拌罐清洗系统

提出一种火箭推进剂搅拌罐的清洗系统。该系统可实现搅拌罐的翻转、残药的刮除、液态清洗等工作,并对刮削过程中的刮削力进行在线监测,防止意外事故。     

MEMS固体化学推进器设计与建模研究

研制了一种基于MEMS(微机电系统)技术的固体化学微推进器。给出了推进器的结构设计、工艺流程,以及推进剂加注方法。建立了推进器点火过程热传导模型,利用该模型分析了不同因素对点火延迟时间的影响。同时,通过建立推进器性能模型,进行了推进单元推力和冲量的预测,给出了仿真结果。结果表明:减小点火电阻衬底材料的密度、热导率和比热可以减小点火延迟时间和点火功率;在一定条件下,增大喷管出口与喉部面积比能够提高推进器真空推力和冲量;MEMS在推进系统中的应用,能够满足微小型卫星对星载推进系统小型化、微推力、高精度的要求。     

Experimental and numerical investigations on development of cavitation erosion pits on solid surface

Polished, grinded, and milled samples made of 40Cr stainless steel were prepared for the cavitation erosion experiment. A typical phenomenon of “pits chain”, which consisted of two contact pits and a smaller pit on the ridge between them, was found on the sample surfaces after 15-minute experiment. Numerical simulation indicated that the pressure fluctuation caused by the sequentially formed pits on the solid surface was the main reason for the formation of the “pits chain”. It proves that the early-formed pits affect the formation of the subsequent erosion pits, and the whole cavitation erosion process is not a probability event. Based on the numerical analyses, the development of erosion is divided into four stages, which describe how a pit develops vertically and horizontally under the effect of the pressure perturbation. The development was validated by the characteristics of the damaged surface observed at different experimental time.     

纳米氧化物燃烧催化剂在固体推进剂中的应用

纳米氧化物包括单一纳米过渡金属氧化物（纳米Fe2O3和Fe3O4,纳米CuO和Cu2O,纳米PbO、Bi2O3、NiO）、单一纳米稀土氧化物和纳米复合金属氧化物。文中旨在研究纳米氧化物燃烧催化剂在固体推进剂中的应用.     

低功率水工质脉冲等离子体推进器的工作特性

为了解决Teflon脉冲等离子体推进器存在的性能低、有污染等问题,设计了以水为工质的脉冲等离子体推进器系统,并研究了它的主要工作指标的能量阈值.分析了水工质脉冲等离子体推进器系统的放电类型形成条件及原因,通过放电电压和电流测试实验,对工作能量阈值进行了实验研究,得到了稳定运行能量对应的储能电容值.实验结果表明:在足够高...     

锥蜗杆副的精确实体造型

阐述了利用VB语言和AutoCAD编制的应用软件 ,完成了锥蜗杆副加工的动态模拟仿真和精确的三维参数化实体造型 ,其结果可用于其它CAD/CAM软件的设计分析和加工程序中     

AZ31镁合金热轧制工艺及数值模拟研究

针对AZ31镁合金平板的轧制过程进行试验研究,通过控制温度及不同道次的压下率等工艺条件,最终将36mm厚的镁合金铸锭,压制成厚度为1mm的板材.同时运用MSC.Marc软件,采用显式弹塑性有限元法对AZ31镁合金平板的轧制过程进行热-机耦合三维数值模拟.对轧件在轧制过程的金属流动、温度、应力及应变分布等特点进行分析,并与实际试验结果进行对比,验证了模拟结果的准确性.     

Solid Works在螺杆空压机主机设计中的应用

介绍了一种螺杆空压机主机整个产品设计周期中Solid Works在三维造型、应力分析、动态仿真方面的应用。     

多缸内燃机缸套-活塞系统摩擦学与动力学耦合问题的研究

从理论上对多缸内燃机缸套-活塞系统摩擦学与动力学的耦合问题进行了研究。在纠正了到日前为止被广泛引用的活塞二阶运动方程中的错误的基础上,给出了多缸内燃机缸套-活塞系统摩擦学与动力学耦合问题的数学模型。在该模型中,首次在计算活塞二阶运动时考虑了连杆惯性力的影响。并对影响缸套-活塞系统摩擦学行为的主要动力学因素做了深入的论述。最后讨论了缸套-活塞系统摩擦学与动力学之间的耦合作用对活塞侧推力、作用在连杆和主轴承上的力的影响进行了讨论,并据此对它们的传统计算模型作了修正。     

气缸套二维非线性磨损过程的数值模拟及试验研究

为了解气缸套的二维非线性磨损特性,在活塞环-气缸套二维润滑特性分析的基础上,建立了适合于工程实际应用的磨损模型,计算了气缸套的二维磨损量分布,对气缸套的寿命作了预测,并用试验对理论分析作了验证。计算结果表明,气缸套的磨损量受多种运行参数的影响,对其进行磨损过程的数值模拟分析是十分必要的;采用基于润滑分析的粘着磨损模型预测气缸套最大磨损有适当的精度,可以满足工程设计的需要。     

立体车库发展的现状与挑战

立体车库可以在很大程度上解决中国停车拥挤现状，但是立体车库在现实发展中还有许多发展限制因素。这里介绍了立体车库发展的挫折与机遇。     

Solid Edge中标准件的二次开发方法

介绍了用Visual Basic作为开发工具，在Solid Edge平台三维实体参数化建模的二次开发方法。结合数据库技术，具体阐述了机械设计中标准件三维建模基本原理，完成了标准件库软件开发。