潜艇气动发射系统能量储备设计及气量控制分析

鱼雷气动发射时,储备空气以很高的速度流入发射管,强烈搅动发射管的海水,导致气流和海水之间会存在强烈的热交换。该文对不同发射深度的能量储备进行计算,以便合理地确定了发射系统的气动参数。     

小体积长焦距激光指向监测装置研制

为了实现可见光波段多路不同波长激光的高精度合束与发射,设计了一套用于激光指向误差监测的紧凑型光学监测装置.根据光电跟瞄发射系统对激光合束与发射精度的应用需求,提出了光束指向监测装置的设计指标.在明确监测装置应用空间的基础上,分别对装置的光电探测器、光学系统和机械结构进行了详细设计,采用上下分层多次折叠的光学设计有效压缩...     

大口径宽波段高能激光发射窗口的设计与测试

由于大口径宽波段高能激光发射系统使用环境复杂、激光发射间歇时间长,晶体窗口难于满足使用要求,本文设计了一套用于发射系统的快门式机械窗口。该机械窗口由防尘罩压紧机构和防尘罩的驱动机构两部分组成。压紧机构通过丝杠、钢丝绳和同步带等传动方式实现单电机驱动多目标同步运动,利用柔性铰链补偿安装误差。采用柔索的非线性分析法和积分原理求解了防尘罩的风压载荷与锁紧机构所需的压紧力间的解析关系,通过逆推法建立了正压风载与电机负载扭矩间的解析表达式。根据电机的矩频特性计算了机构的转速范围和防尘罩能承受的最大风载。实际测试表明,电机输出扭矩达到0.34Nm时,防尘罩可以抵御10m/s风载作用,开启与关闭的最小时间稳定在3s左右,正压风载与电机负载间表达式的计算误差不超过15%,窗口的运行可靠,符合设备使用要求。     

激光共聚焦扫描显微镜的光学设计

为获得较高分辨率的细胞图像,设计了激光共聚焦光学系统。通过较复杂结构物镜实现了照明光路系统和发射光路系统的设计。用Zemax对照明光路和发射光路进行了设计,仿真过程中照明光路的聚焦弥散斑直径小于1μm,照明针孔处的聚焦弥散斑直径小于20μm,发射光路的聚焦弥散斑直径小于20μm,同时照明光路和发射光路的MTF曲线接近衍射极限,达到较理想的情况。     

水平式激光发射系统指向误差的修正

为修正由轴系误差引起的水平式激光发射系统的指向误差,借鉴经纬仪视轴指向误差的修正方法--单项差法和坐标变换法,建立了激光发射系统指向误差的修正模型,得到了轴系误差在激光发射光路中的传递规律.介绍了系统光机结构及建模理论,导出了反射镜的作用矩阵.通过建立水平式跟踪架笛卡尔坐标系,将激光光束看作空间内一单位矢量,并借助矢量...     

机动车载快速反射镜激光指向修正量的解算

为了提高机动车载跟瞄发射系统的瞄准精度,提出在其发射光路中引入快速反射镜来修正发射激光的方向。研究了快速反射镜激光指向修正量和粗红外跟踪脱靶量以及反射镜空间实时绝对角度的关系,结合激光发射光路和红外跟踪光路的结构特点,提出了将船摇坐标变换理论应用到快速反射镜激光指向修正量的解算中。建立了快速反射镜激光指向修正量与粗红外跟踪、快速反射镜空间位置的关系,并通过MATLAB编写了M函数,建立了SIMLINK仿真模型。基于仿真模型得出了激光指向修正量与快速反射镜转角的关系数据以及在快速反射镜工作范围(±6′)内的简化公式。试验结果表明:该解算算法正确,解算精度较高,最大静态解算误差为2.9″;载车在三级公路上以20km/h的速度跑车时,激光指向的控制精度为方位角11.65″、俯仰角15.38″,均满足项目指标要求。     

大口径激光发射系统卷帘式密封结构优化设计

为满足某车载大口径高能激光发射系统密封要求,设计了一种采用卷帘覆盖压紧密封原理的密封结构,以密封窗口整体重量、一阶频率和卷帘中心挠度三者为优化目标,应用集成优化方法,依托ANSYS workbench软件平台对密封窗口结构尺寸进行优化,优化后的密封窗口整体重量为7. 25 kg,一阶频率为1 356. 8 Hz,卷帘中心挠度变形为6. 075 9mm。密封窗口轻量化效果明显,各项指标均满足设计要求。该密封窗口设计可为同类型大口径激光发射系统的密封结构设计提供思路和参考。     

一种大功率激光输出功率低频波动的直接测量法

提出一种新的对大功率激光低频波动的测量技术.它的传感器是一根细小的探针,探针上面有一直径为20～500μm的微孔,光通过微孔对激光进行采样,由探针内通道将该采样光传输到探测器.探针可抗高功率激光损伤.由恒速电机带动探针高速扫描光束截面,最终获得激光输出功率随时间的变化信息.该仪器既可进行在位测量又可进行在线测量,既可测量CO2激光又可测量YAG激光.介绍了测量原理、仪器结构和实验结果.     

风选通道分析及优化设计

为了提高城市生活垃圾中废塑料在风选通道内的分选率,分析了轻质垃圾在分选通道内理想化运动形式,运用流体力学知识以及fluent软件对通道内的气流速度,气流分布形式进行了仿真分析。根据仿真分析以及物料在气流场中的运动规律,对通道形状进行改进,并对改进后的通道内的气流场进行仿真分析。对筛面上方通道出口端的风速及方向进行了分析,这对筛面上物料的运动分析有很大意义。经过通道气流场的分析,以及通道形状的改进,对提高废塑料分选率以及研究筛面上物料的运动状态有重大社会意义、经济意义。     

基于纤维空气分布系统的置换通风的热舒适性研究

以常州大学人工环境室为载体,建立了基于纤维空气分布系统的置换通风气流流动换热数学模型,利用FLUENT软件对人工环境室内气流速度场、温度场和热舒适性进行了仿真研究。结果表明:基于纤维空气分布系统的置换通风策略能创造出传统置换通风的效果,室内空气温度分层现象明显;工作区内垂直温度梯度小于ISO7730限值,人体无明显吹风感,热舒适性较好。研究还发现,房间底部存在部分区域气流速度过高,可能造成吹风威胁,有必要对纤维空气分布系统孔口设计进一步优化。     

室内污染物扩散的通风优化数值模拟

为了减小房屋装修后室内甲醛对人体的危害,了解不同通风方式及通风速度下室内甲醛浓度的分布特征是关键。本文采用CFD方法,模拟2种基本通风方式室内气流组织的流动形式,研究了不同通风方式、不同送风速度对室内甲醛的浓度分布的影响,数值模拟表明:与异侧送回风通风方式相比,同侧送回风形式更能有效减小室内甲醛的浓度,因而室内通风方式应优先选择同侧送回风。在同侧送回风气流组织形式下,送风速度过小或过大均致使人站或坐高度平面上甲醛浓度增大,因而应根据甲醛的散发强度,选择合适的送风速度,如在本文中送风速度以2m/s左右为宜。优化室内污染物扩散的通风形式,对室内通风设计和气流组织的研究具有一定的指导意义。     

Reproduction of air velocity in the entrance region of the test pipe in a wind tunnel

The airflow development in the pipe, in the entrance region of the wind tunnel located in the Lithuanian Energy Institute, the laboratory of Heat Equipment Research and Testing is investigated to analyze the conditions for the reproduction of air velocity values. The analysis is performed to reveal undeveloped flow conditions where the calibration of the devices is usually made, the entrance region of the pipes, or free stream from the nozzles. In this study, different flow regimes have been investigated using different air velocity measurement methods. Experimental and numerical results clearly show the features of the developing flow. They both demonstrate the stable core of the velocity profile up to 5 D in the pipe and ≤1 D from the entrance into the free stream in the testing chamber. Ultrasonic anemometer (UA) installed in the aerodynamic test facility shows reliable and highly comparable results with another non-intrusive device – laser Doppler velocimeter (LDA) in a range of velocities from 0.05 m/s up to 30 m/s. UA integrated into the wind tunnel is not found to be used for metrological issues for air velocity. Due to the fast response, they both enabled to analyze fluctuations in the flow. Local vortices identified in the flow have influenced the low-frequency fluctuations and the scatter of measurement results. Moreover, high-frequency fluctuations found in the flow originated from the flow turbulence and might be due to the electronic or acoustic noise. The stabilization of the entrance region in the pipe influences the mean value of air velocity, the transversal distribution of velocity and the development of axial velocity in different test sections of the pipe in a wind tunnel. Along with the recirculation zones in cavities of ultrasonic transducers, these factors are essential that make an impact on the reproduction of air velocity value.     

切向气流作用下激光辐照对尼龙材料的热烧蚀规律

为了研究切向气流对激光毁伤低慢小目标的影响,采用仿真分析和实验相结合的方法研究了在激光辐照典型低慢小目标材料尼龙66过程中切向气流对激光烧蚀作用的影响。建立了激光烧蚀尼龙的简化物理模型,利用红外热像仪分别研究了1.5s和4s两个时刻激光辐照下尼龙材料的温度场分布和烧蚀形貌,并与无气流条件下的结果进行对比。实验表明,切向气流对激光烧蚀尼龙材料过程的影响主要分两个阶段,在辐照前段时间切向气流减缓了激光辐照下尼龙66材料的温升,抑制了激光对尼龙材料的烧蚀作用;但随着温度的升高,热分解产物增多使激光屏蔽作用增强,切向气流减轻了目标材料表面热分解产物对激光的衰减,并为尼龙材料的氧化烧蚀提供更多氧气,促进了烧蚀作用。最后对切向气流下激光烧蚀尼龙的过程进行了ANSYS仿真,实验结果和仿真结果基本一致,从而验证了理论的可靠性。     

A computational analysis of the airflow in a twin-track subway tunnel with a sliding-curtain to improve ventilation performance

A computational model of an actual Seoul subway tunnel was analyzed in this study. The computational model was comprised of one natural ventilation shaft, two mechanical ventilation shafts, one mechanical air supply, a twin-track tunnel and a train. The natural ventilation shaft discharges and supplies air due to the train’s movement. The mechanical ventilation shaft and the mechanical air supply discharges and supplies, respectively, the airflow from the axial flow fans in the middle of the ducts of the shafts. A sliding-curtain was installed in the tunnel. The objective of this study was to numerically investigate train-induced airflow in the twin-track subway tunnel with natural and mechanical ventilation shafts and an installed curtain. The numerical analysis characterized the aerodynamic behavior and performance of the ventilation system by solving three-dimensional turbulent Reynolds-averaged Navier-Stokes equations. ANSYS CFX software was used for the computations. The airflow velocity from the computational results was validated by experimental results. Understanding the flow pattern of the train-induced airflow in the tunnel is necessary to improve ventilation performance. The ventilation and aerodynamic characteristics in the tunnel, including train-induced airflow, were investigated by analyzing the volume flowrate at the exits of the ventilation shafts and the velocity in the tunnel. The computational results were compared to cases with and without a curtain installed in the twin-track tunnel. As the train passed the mechanical ventilation shafts, the quantity of discharged-air in the ventilation shafts decreased rapidly. The flowrate at the exits of the ventilation shafts was gradually recovered with time, after the train passed the ventilation shafts. The airflow at the natural shaft and mechanical ventilation shaft 2, which was closest to the curtain, was increased. The computational results showed that the installed curtain can improve ventilation performance in the tunnel.     

空调器室外机流场和噪声特性

针对分体空调室外机空气侧流场和声场的特点,采用计算流体动力学(CFD)的方法对该系统的气体流动进行数值模拟。详细分析了轴流风扇流道内部和出口的速度分布,并利用激光微粒图像测速(PIV)手段,验证数值模拟结果,模拟结果与PIV测量值吻合较好。在CFD数值模拟的基础上,运用Lowson模型预估系统的离散频率噪声,预估值与测量值吻合较好。CFD技术能够有效地分析室外机空气侧流场特性,并为进行气动声学分析提供依据。     

冷却塔风筒内流速场分布的研究

在分析冷却塔构成的基础上，建立了描述冷却冷却塔风筒内流场分布的数学模型，进而利用MATLAB语言求出了偏微分方程组的数值解，绘出了风筒内的流场。经研究发现，在风筒的中心处，存在一个空气倒吸的区域。最后，提出了消除空气倒吸现象的措施。     

Analytical and Experimental Study on Complex Compressed Air Pipe Network

To analyze the working characteristics of complex compressed air networks, numerical methods are widely used which are based on finite element technology or intelligent algorithms. However, the effectiveness of the numerical methods is limited. In this paper, to provide a new method to optimize the design and the air supply strategy of the complex compressed air pipe network, firstly, a novel method to analyze the topology structure of the compressed air flow in the pipe network is initially proposed. A matrix is used to describe the topology structure of the compressed air flow. Moreover, based on the analysis of the pressure loss of the pipe network, the relationship between the pressure and the flow of the compressed air is derived, and a prediction method of pressure fluctuation and air flow in a segment in a complex pipe network is proposed. Finally, to inspect the effectiveness of the method, an experiment with a complex network is designed. The pressure and the flow of airflow in the network are measured and studied. The results of the study show that, the predicted results with the proposed method have a good consistency with the experimental results, and that verifies the air flow prediction method of the complex pipe network. This research proposes a new method to analyze the compressed air network and a prediction method of pressure fluctuation and air flow in a segment, which can predicate the fluctuation of the pressure according to the flow of compressed air, and predicate the fluctuation of the flow according to the pressure in a segment of a complex pipe network.     

A numerical simulation of train-induced unsteady airflow in a tunnel of Seoul subway

This study has been conducted to investigate numerically the characteristics of train-induced unsteady airflow in a subway tunnel. A three-dimensional numerical model using the dynamic layering method for the moving boundary of a train is applied. The validation of the present study has been carried out against the experimental data obtained by Kim and Kim [1] in a model tunnel. After this, for the geometries of the tunnel and subway train which are very similar to those of the Seoul subway, a three-dimensional unsteady tunnel flow is simulated. The predicted distributions of pressure and air velocity in the tunnel as well as the time series of mass flow rate at natural ventilation ducts reveal that the maximum exhaust mass flow rate of air through the duct occurs just before the frontal face of a train reaches the ventilation duct, while the suction mass flow rate through the duct reaches the maximum value just after the rear face of a train passes the ventilation duct. The results of this study can be utilized as basic data for optimizing the design of tunnel ventilation systems.     

回转式空气预热器流场仿真分析

为分析某电厂1 000 MW锅炉机组的双密封回转式空气预热器漏风问题,建立局部流体仿真模型。通过理论计算和仿真模拟相结合的方法分析了密封间隙对回转式空气预热器内部流场压力分布、密封压差及漏风率的影响,并针对"三密封"特殊时刻下的流场压力及漏风率变化做了研究。结果表明,密封间隙从2mm到8mm的变化过程中,密封片受到的最大压差小于7 000 Pa;为使空预器漏风率小于5%,其漏风间隙需要控制在3 mm以内;"三密封"时刻下的漏风率达到了最小值,为3.98%。经过分析总结,为密封片的载荷计算及密封片的改进提供一定的参考。     

辛烷值测试仪发动机进气道三维仿真与分析

利用CFD软件Fluent对CFR发动机进气道进行了三维仿真，在不同的大气压下，对进气系统的气体流场、空气流量和汽油流量进行了定量分析，得出了进气量、进油量和空燃比随外界大气压的变化规律，为辛烷值测试仪的改进提供了依据。