基于STAGE的水下战仿真系统研究

文中首先阐述了STAGE软件的框架结构和功能,构建了水下战系统的结构, 最后实现了某典型作战想定下潜-舰对抗作战仿真系统的可视化演示.     

机载雷达环境仿真系统的软件开发

简要介绍了机载雷达环境仿真系统的开发过程。在开发过程中，借助STAGE软件平台，避免了底层软件，实时仿真控制等基本功能的开发，把精力集中在与应用有关的核心软件编制上，显著提高了整个仿真系统的质量和研制效率。     

STAGE在防空反导作战研究中的作用

介绍了防空反导作战的特点和研究内容，应用STAGE构建舰艇防空反导作战仿真应用平台，给出了一种运用作战仿真手段研究水面舰艇防空反导作战的方法．给出了该仿真平台的仿真模型体系、仿真流程、仿真实现方案和仿真运行机制，并对某型舰艇的防空反导作战决策方案分析进行了研究．在特定的作战想定条件下，经过两轮仿真作战结果统计分析得出了最佳决策方案．     

NEW SCALING METHOD FOR COMPRESSOR MAPS USING AVERAGE INFINITESIMAL STAGE

The estimation of the precise performance of existing multistage axial-flow compressors of gas turbine engines is fast becoming a great concern, as the use of gas turbine engines in the power generation and in the military industry increases. In order to reduce the analysis performance error of the traditional scaling method, a new scaling method for estimating the characteristics of multistage axial flow compressors is proposed. This novel method is based on experimental and partial data provided by engine manufacturers. Taking the effect of density-change into account, we introduce the average infinitesimal stage concept, and thereby divide the compression process into an infinite number of infinitesimal processes corresponding to infinitesimal stages. Subsequently, we adopt the corrected Reynolds analogy method for compressible flow calculation in order to ensure much better compliance with the similarity criterion. Validation checks show that the proposed method has enough precision to predict the off-design performance characteristics of multistage axial flow compressors.     

DESIGN AND CONTROL OF AN ULTRAPRECISION STAGE USED IN GRATING TILING

In petawatt laser system, the gratings used to compose pulse compressor are very large in size which can be only acquired currently by arraying small aperture gratings to form a large one instead, an approach referred to as grating tiling. Theory and experiments have demonstrated that the coherent addition of multiple small gratings to form a larger grating is viable, the key technology of which is to control the relative position and orientation of each grating with high precision. According to the main factors that affect the performance of the grating tiling, a 5-DOF ultraprecision stage is developed for the grating tiling experiment. The mechanism is formed by serial structures. The motion of the mechanism is guided by flexure hinges and driven by piezoelectric actuators and the movement resolution of which can achieve nanometer level. To keep the stability of the mechanism, capacitive position sensors with nanometer accuracy are fixed on it to provide feedback signals with which to realize closed-loop control, thus the positioning precision of the mechanism is within several nanometers range through voltage control and digital PID algorithm. Results of experiments indicate that the performance of the mechanism can meet the requirement of precision for grating tiling.     

COMPARISON OF TWO METHODS TO INCREASE TIP CLEARANCE AND ITS EFFECT ON PERFORMANCE OF TURBOCHARGER CENTRIFUGAL COMPRESSOR STAGE

Tip clearance between the blade tip and casing of a centrifugal compressor can be varied through two methods:by changing the blade height(M1)or by changing the casing diameter(M2). Numerical simulations are carried out to compare these two methods and their effect on the stage and impeller performance.The impeller and diffuser are connected through rotor stator boundary using frozen rotor approach.Overall stage performance and the flow configuration have been investigated for nine tip clearance levels from no gap to 1 mm.Impeller and diffuser performances are also pre- sented separately.It has been found that the overall and impeller performance are comparatively better for M1 below tip clearance of 0.5 mm whereas M2 is found advantageous above 0.5 mm of tip clear- ance.Both M1 and M2 show performance degradation with the increase in tip clearance.Two models have been proposed for the stage total pressure ratio and efficiency,which are found to be in agree- ment with experimental results.The impeller efficiency and the pressure ratio are found to be maxi- mum at tip clearance of 0.1 mm for both the cases however minimum diffuser effectiveness is also observed at the same clearance level.Diffuser effectiveness is found to be maximum at zero gap for both cases.As it is practically impossible to have zero gap for unshrouded impellers so it is concluded that the optimum thickness is 0.5 mm onwards for M1 and 0.5 mm for M2 in terms of diffuser effec- tiveness.Mass averaged flow parameters,entropy,blade loading diagram and relative pressure fields are presented,showing the loss production within the impeller passage with tip clearance.     

Construction and validation of master sintering curve for TiO2 for pressureless sintering

Abstract

One of the ultimate objectives for sintering research is to predict densification results under different thermal profiles for a given processing method. This paper studies the construction and validation of the master sintering curve (MSC) for rutile TiO₂ for pressureless sintering. The MSC was constructed using dilatometry data at two heating rates and was then validated using isothermal holds at three different temperatures. The scanning electron microscopy (SEM) observation shows that the partially sintered samples have the same density under different heating procedures, which demonstrates that the assumptions of the model are reliable. The concept of the MSC could be used to predict the sintering shrinkage and final density and calculate the activation energy. A value of 105 kJ mol^-1 for TiO₂ was obtained. The MSC could be applied to predict the sintering profile to prepare ceramics with required density and a minimum of grain growth.     

基于STAGE的电子对抗环境下地空导弹武器系统仿真软件研制

介绍仿真平台软件STAGE工作机理及使用STAGE开发电子对抗环境下地空导弹武器系统仿真软件的设计思想和基于STAGE的仿真软件实现方法     

Comparison of flow and shear band structures in oriented,columnar tungsten,single crystal tungsten-tantalum ands intered tungsten heavy alloy ballistic penetrators

Abstract

The penetration of long rods (L/D10) into standard RHA targets differs with rod failure and flow, which produces erosion and deceleration. Oriented, columnar grained W and [001] single crystal W-4%Ta rods exhibit dense shear/shear band flow phenomena consisting of overlapping bands ofpredominantly dynamically recrystallised (DRX) grain structures observed by optical metallography and transmission electron microscopy. This flow is contrasted withWHA (93%W, 5%Ni, 2%Fe) sintered rod penetration characterised by penetrator nose failure in blocks which move on narrow shear bands between the blocks and function like microstructural lubricants. From these comparative observations of residual, penetrated rods, strategies to promote rod penetration seem to involve the development of wide, overlapping bands or layers of equiaxed or preferentially oriented, refined microstructures, which facilitate material flow at high strain rates. Microstructural precursors, such as deformation twinning or the enhancement of recrystallisation or related microstructural issues, promoting frequent or overlapping shear bands, either through alloying or processing routes to control the shear instabilities, seem to provide the best strategies to enhance long rod penetration.     

Effect of minor change in composition on toughness of weldmetal for repair of turbine blades made of martensitic stainless steel

Abstract

Repair welding procedure for cracked turbine blades, made of 13Cr–2˙6Ni–1˙1Mo martensitic stainless steel, has been developed using gas tungsten arc welding process and a twin wire filler metal. The twin wire consists of a 1˙5 mm diameter ER 16-8-2 and a 2˙0 mm diameter ER 410 filler wires tack welded along the length of the two filler wires. A two stage post-weld heat treatment at 675°C for 2 h and 615°C for 4 h, such that the first heat treatments is above the Ac ₁ temperatures of the weld metal and the second is just below its Ac ₁ temperature; has been found to be suitable for obtaining good mechanical properties for the weldment. The weldment has a good combination of transverse weldment strength and weldmetal toughness, with its room temperature yield strength and Charpy V notch impact toughness being similar to that of the turbine blade material.