附录A
设计与非设计情况下轴流式通风机的处理
摘要
在设计与非设计情况下，轴流式通风机的噪声处理分析是用两个缠绕在叶片上的热传感器试验测量完成的。在不稳定自然因素条件下，精确速度的测量依据是安放在旋转气流区域的两个热传感器，靠相互作用因素和减缓两个波动速度的时间实现的。该结果表明噪声消除的方法包括：离散频率的噪声由周期性速度波动决定，而噪声的波带与叶片上波动速度有关。通过四个谐波叶片上的频率中，旋转气流的最高频率是主要观察的对象。离散频率包括在非设计操作情况下产生的波动速度的频率，同旋转气流区域和反向气流区域相似。当叶片高速旋转时，最高频率一定是一个重要噪声源。旋转气流的波动速度采用螺旋式，目的是在旋转波动时用来描述产生最高频率的机械。总之，噪声的增加由在低速情况下气流的处理决定，分析认为与速度波动的分配有关，而波动速度又由涡流的泄漏和叶片表面相邻的压力决定。
1 引言
现阶段的研究主要关注于产生噪声的机械装置。噪声的产生由轴流式通风机的旋转刷旋
转的不稳定因素引起的。涡流的泄漏主要在旋转刷区域，这是很多研究者所关注的，因为它在流体领域中很重要。例如：Zoue和Kuroumaru、Store和Cumpsty、Lakshminarayana等都从事该方面的研究。他们指出气流的泄漏是三维的、不稳定的自然因素并且影响产品的寿命和噪声的产生。然而，大多数研究主要集中在叶片上与气体动力学有关的旋转气流，没有考虑到因旋转气流的不稳定因素所产生的噪声。
噪声处理水平的提高靠的是Longhouse 、Fukano.etat、Kamier、和Neise在该方面的研究。他们的研究指出频率在中的峰值发生在声谱中，尽管噪声是自然传播的。Kamier和Neise也提出噪声处理与轴流式机械中的不稳定旋转气流有关。然而，以上研究没有详细分析叶片上的气流。对气流结构的理解和叶面上的波动
速度频谱一样对分析产生噪声的机械来说很重要。这与气流的泄漏所产生的不稳定因素有密切的关系。
另一方面，在轴流式机械的叶片上对在固定框架内高频有价值信号的测量几乎是不可能的。因此，对于与旋转有关的框架内精确速度的测量是十分重要的，很容易理解在旋转机械叶面上波动旋转气流的频率特性。现阶段的研究，对于轴流式通风机速度及速度波动的测量是用一个放在旋转框架内的旋转刷附近的一个热传感器来实现的。
Fukano.etat是在旋转框架内气流测量研究的先驱者。他们测量了旋转盘面边缘气流周期性速度波动情况，是通过与最初与设计测量体系相连的传感器来实现的。该结果表明有着重要意义的周期性速度波动是由产生噪声的Kamier涡流通道所决定的。
在现阶段的研究中，旋转刷附近速度波动的频谱是通过连接在轴流式通风机中的热传感器来实现的，这与相对速度和波动速度的分配有关。精确速度不稳定频谱的测量是通过在旋转气流区域的两个热传感器实现的，应用相关系数和两个波动速度的延迟进行调查。总之，峰值处理对旋转气流区域、气流动力学噪声的产生有影响，这也是回顾轴流式通风机的两种不同峰值处理方法。
2试验仪器及过程
2.1测试轴流式通风机
现阶段的研究主要集中在低速轴流式通风机上，一种是2mm、一种是4.5mm。对于叶片是2mmTC设计的具体说明总结。叶片的设计气流参数O=0.39（mean axial velocity divied by rotor tip speed）和设计静压力上升参数Os=0.26（static pressure rise divied by dymanic pressure at rotor tip ）。静压力上升参数Os与声压水平SPL的划分。旋转体叶面NACA65系列轮廓设计由涡流决定。叶面stagger angle和the angle of attack分别是64.2°和4.4°。该测试实验采用非设计操作情况下O=0.33、0.31、0.29（25 per cent than the design flow rate）同设计情况下O=0.39一致，而叶片的旋转速度保持在1000r.p.m。叶片旋转体的顶部截面强度为0.55、长度为129mm。依据旋转刷的速度且旋转刷的长度为2.6*10。
当前的研究中，对于轴流式通风机的设计是分析三维旋转气流结构，通过数据相似性及实验测结果来实现的。三维峰值泄漏涡流结构及泄漏状况，是一种侧
面透视图。涡流鉴别方法与标准化螺旋性Hn的定义详细的在上一层出现。研究发现峰值泄漏涡流的形成与叶片边缘在吸入冲程过程有密切的关系。循环区域的形成导致涡流从叶面内侧溢出。
2.2测试过程
实验仪器的各个尺寸，是一个内径为0.579m的开环设备。该设备由一个进口、一个由带传动的叶片、一个助推叶片组成。按照空气动力学设计的减震器常用作调节气流速率。进口与测试叶片间的距离是0.43m。
测试系统原理图。安放在叶片上的两个热传感器用于介绍现阶段在反面及横跨位置间的相互关系，同时用在旋转叶片内外的三维速度及速度波动情况的介绍。I热传感器应用的是直径为5mm的钨丝，复合探测器直接安装在轮毂上。横跨的探测器用三维跨度系统控制：切向、轴向、径向且安装在轮毂内部—0.3mm。在径向、轴向、切向维跨度系统的最大范围分别是45mm、50mm、50°（45°for one blade passage）。因此，当旋转体正在运动且没有重新安排情况下可能测量到一个叶片。精确波动速度的测量是通过热力风计和与在线电脑相连接的测试仪器来实现的，在线系统是Scientific Corporation通过安装在轮毂内部的水银管是新实现的，来自热探测器的输出是从旋转框架到一个固定框架传送，来自热敏风速计的信号是装置过滤掉超过8.9KHZ的信号。
旋转体叶片内外三维速度及速度波动是用横跨式探测器来测量的，而其确定是通过热敏风速计和在线电脑均值仪器实现的。速度及速度波动整体平均值的测量是通过每个测量位置6000个样品数据实现的。波动速度频谱的分析是Onsokki FFT 完成的。在测试系统中，探测器的校准是通过拆换不同旋转测试叶片及测量到的四个不同旋转频率下的切向速度实现的：300、600、900、1200r.p.m。探测器的变形量是由在实验前旋转体的校准仪器的。当内部设备保持连续运行时，TC 为2、4mm旋转叶片实验的实现是由旋转刷的直径改变实现的。
另一方面，在距旋转叶片上游1m位置处且在旋转轴上，来自旋转叶片上产生的噪声被测量出来。在噪声频谱的测量中，背景噪声一直保持在5dB且在所有频率的声音水平以下。噪声是从测试系统获得的，仅叶片旋转部件被排除在外。
结果讨论
3.1噪声的增加油泄漏气流和相邻旋转叶片决定
声压水平SPL在气流速率O=0.33时急剧上升，之后气流速率则下降。也就是说压力上升Os不是在O=0.29情况下。这就是为什么在低气流速率下、在O=0.29和O=0.35之间SPL上升的原因，这也是以下所讨论的。是在2mTc设计的测试叶片上（O=0.39）和两种非设计操作情况下（O=.33和O=0.29），叶片上99%的范围内测量盘上相对速度的分配情况，这是设备内部的特点。相对速度被计为Vat、瞬时速度则计为Vt：
Vat=Vat+Vt/V(1)
Vat和Vt分别表示轴向速度和切向速度。叶面上的低速区域导致了泄露气流，管壁上形成的峰值泄露气流在管壁的下表面增加，在设计操作情况下没有形成相邻的压力表面界线。然而，当气流速率下降时与O=0.39比较泄露气流边缘向下移动。因此导致了相邻压力表面的分离。
在99%范围内测量盘上波动速度的分配情况，这一情况波动速度用Vf表示，由相对速度Vat所决定。在相互作用的低速区域，每个测量盘上都获得了高速率波动。
在相同气流情况下旋转叶片下部分速度波动的分配情况。在近似于气流方向垂直且距叶片边缘2.7mm的测量盘上。水平轴代表到叶片边缘气流方向的垂直距离为ｈ。在设计操作情况下旋转刷压力表面附近没有获得高波动速度，因为峰值泄露气流在流动。在相邻压力表面没有形成干扰。然而当气流速率下降时，高速度波动区域的移动与压力面有关。峰值泄露气流受压力表面干扰。特别是最高波动速度出现在最低气流情况下且在压力表面附近。在压力表面附近的高速率波动导致了在叶片表面上的高压力波动，这对叶片上噪声的产生有很大影响。是由在固体表面压力波动的奇偶特性所决定。
三种非设计操作情况下在叶片上2mmTC噪声的频谱：O=0.29、0.31、0.33。通过的频率是133Hz，垂直线指的是通过叶片上的有用频率。当前测量的样品频率是5012Hz，仅在1200Hz以下的频率才出现。因为超过1200Hz的声压频率几乎拥有同样的价值。频率最高可达到8400Hz的几乎有相同的声压水平且由叶片驱动马达所产生，在气流速率O=0.33以下的噪声增加有设计操作情况下相同的声压水平。较强的波动速度产生的主要原因即作用在压管内表面和相邻的叶片上。除了有用BFF频率可获得O=0.29、0.31、0.33外，频率最高可达到170、250、
330Hz。该频率特性是由于安装在叶片旋转体上的管路决定的。在距叶片旋转体下游9m处产生白噪声，该噪声是由在旋转轴和叶片旋转体上游1m处测量得到的。在图10中可获得以下频宽，频率最高可达到180、360、970Hz。考虑到高频可达到170、330Hz且受180、360Hz管路所产生的频率的影响可以认为在低气流速率情况下噪声的增加是由于旋转的气流在管路表面和相邻压力表面的高速率波动所引起的。
在这片论文的下一部份我们将讨论产生离散频率的机械装置。
3.2 三维旋转气流的结构
为了研究在旋转刷附近的三维旋转气流结构，在叶片下游的相对速度是通过在非设计和设计操作情况下缠绕在旋转体叶片上的热传感器来实现的。两种操作情况的目的是为了理解TC对旋转气流的影响。旋转气流的结构是用两种不同的TC处理方法分析的。
安装在轮毂内部的热传感器是通过横跨系统来传输得。在长度方向测量位置的间隔大约是5mm而长度方向和径向的距离大约是3mm。径向测量区域时从255mm（76percent span）到280mm（98percent span）。一个实验表格及叶片2mmTC下的被测低速区域。相对速度Vat被旋转刷速度Vt标准化，低速区域：Vat/Vt＜0.75。气流的泄露位置，这就导致了数据的相似性且与低速率区域相一致，也就是说在叶片上的低速区域是由峰值泄露涡流引起的。
为了比较在设计与非设计情况下峰值泄露我流的结构被测低相对速度区域将在叶片上重现。2mm、4.5mmTCs的测量区域内被测的低相对速度，这是来自构件内的透视图的观点。在设计与非设计操作情况下图中白色和黑色区域所描述获得的低相对速度的情况。在图示中速度区域的范围拥有不同的价值。低速率区域与在叶片上所获得的峰值泄露涡流所决定。可以比较在设计与非设计情况下所获得的峰值泄露涡流。大体上可以了解在轴向压缩机旋转体内Znoue et at所描述的情况，也可以理解当气流速率速率下降时低速度区域将向外传播，也就是在低气流速率情况下的峰值泄露涡流有较大的运动情况的原因。当TC上升时，大的旋转气流的产生是由较大的泄露气流所引起的。在设计操作情况下，旋转气流与数字相似性所获得的结果的比较在本篇论文中所表现出来。
3.3在设计操作情况下波动速度频谱的峰值
为了研究在叶片上气流的波动情况，设计操作情况下的峰自己泄露涡流成准90度的源盘上的速度波动的分配，这与相对速度的分配有关。在叶片上的峰值泄露涡流成准90度的圆盘位置是一个来自箱体的透视图观点。分别位于涡流的上下游且爱圆盘的A、G位置处。从相对速度的分配上看，旋转气流的获得是由峰值泄露涡流所决定的。在低速区域（bellow the velociety of 0.75）旋转气流的中位是在存在最小动能的地方。相反气流区域是灰色区域且在箱壁上所获得。另一方面，在峰值泄露涡流与主要气流之间的相互作用区域内所获得的高速率波动同在涡流中心区域内所获得的高速率波动同在涡流中心一样。
在设计情况下，对于2mmTC的波动速度的频谱的分配情况。FFT分析所获得的频谱，这是在测量位置平均值的64倍。在当前的研究中，对于一种测量情况用表49来测量该频谱。在它们之间，频率在所示12位置处。存在三个径向位置：0.98（RI）、0.96（RII）、0.9（RIII）的范围内。在相反气流区域它们中存在四个位置（RI-E、RI-F、RII-E、RII-F in13（b））。可见，虽然波动速度的频谱的最大值不是转气流的上下游值但是在相反气流区域可见接近400、500Hz的频率峰值。Kamerier和Neise也指出轴流式机械的TC噪声是由于在旋转刷附近的反向气流与旋转气流的不稳定性联系所产生的。
3.4 在非设计操作情况下波动速度的频率最大值
很多研究者重复研究在叶片存在的不期望看到的现象，噪声的增加是由于旋转的不稳定性和在低气流情况吓轴流式通风机的操作所引起的。在现阶段的研究中，非设计情况下：O=0.31存在2mm和4.5mmTCs操作的轴流式风机里，叶面上旋转气流的结构和波动速度的频谱特性已完成调查。
在非设计情况下存在2mmTC操作的轴流式通风机的峰值泄露涡流在三个成准90度的圆盘上相对速度和波动速度的轮廓如。在叶片上测量盘的是箱体的透视图。低相对速度区域自箱体向外传播85%的范围，根据气流速率下降。较大速度区域是由作为旋转气流的阻碍的增加和在叶片上能量的损失引起的。在三个测量盘上相对速度的分配，可以清晰地获得旋转气流的图形。在峰值泄露涡流和主要气流之间的相互作用区域内可获得高波动速率。也就是说当旋转气流朝着切向所移动时，低速度区域将扩大。当气流速率下降时，反向气流区域也将增加，因为旋转气流的扩大是由于它的及时运动引起的。
测量盘II和III上所选择的位置速度波动的频谱。在每个测量盘上三个径向位置0.98（RI）、0.96（RII）、0.9（RIII）范围内，在出现频率的12个位置上计X，就（f）所选择的特征。在设计操作情况下反向气流区域可以获得250Hz附近的频率最大值。可见，高速度波动强度增加大约40%，这与设计情况下相比较。更不必说在本部分的描述中速度波动的强度是噪声产生的重要原因。
在非设计操作情况下是4.5mmTC的相对速度和波动速度的轮廓图。叶片测量盘的位置用同样的方式。上可以看到来自箱提内的旋转气流扩大了0.75。也就是说和2mmTC的较大气流相比在径向的旋转气流的增加大于12%。在峰值泄露涡流和主要气流之间的相互作用区域获得了在测量盘II和III的高波动速度。当TC增大时，速度波动的强度也增大。
测量盘II和III上所选择的位置是速度波动频率的分配情况。包括反向气流区域在内的所有测量位置上可获得的160Hz附近的频谱峰值。在存在4.5mmTC 叶片，频率密度S（f）的强度与2mmTC比较两次。也就是说，160Hz附近的较高频率峰值对噪声水平的增加有较大影响。与在设计情况下相比在非设计操作情况下的离散频率价值较低，这是由于旋转气流的大量增加所至。
3.5 在非设计情况下泄露气流与延缓时间相互作用的分析
在本节的描述中，由波动速度决定的高速率波动以及频率所达到的最大值是在旋转气流区域内获得的。在轴流式风机中，根据TC和在旋转气流中的气流速率，频率的峰值存在不同的价值。为了理解产生频率的机械，在旋转气流中一个参考位置与所选择的参考位置之间有效的分析精确速度的相互作用关系。也就是在旋转气流区域内通过两个热传感器所测量到的精确速度频谱的不稳定因素，该不稳定因素是用相互作用系数以及两个波动速度的延迟时间所界定的。
相互作用系数（c-c）和通过两个热传感器所测得的两个精确速度的例子：一个参考位置计作①，在中的测量盘II所示，另一个计作②，两个所选择的位置都位于旋转气流内部。中的两个波动速度是通过在240和260Hz之间的频率过滤所获得的，是通过两个热传感器测得的精确速度。所选择的过滤器的范围是10Hz —250Hz。在现阶段的测量中，有价值信号的采样频率是5120Hz，这是频率为250Hz的20倍。两个波动速度的测量时间是60s（about 80 fan revolutions）。也就是说250Hz速度不是稳定的，因为考虑到振幅的波动。
两个波动速度的相关系数延迟时间由相关系数的第一次峰值延迟所决定。两个波动速度的周期的延迟时间在相关系数的第一次峰值和第二次峰值之间。
分别说明在2mmTC（O=0.3）时表面II和III上的五个位置相关性的分配情况。在旋转气流区域所分配的五个位置。几乎每个位置相关系数都超过了30.7。在表面II、III上，参考位置的精确速度的测量就是一个例子，它们均有相似的频谱。通过测量盘II、III上的相关系数价值可以看到在旋转气流内的波动速度与上游有着密切的关系。这也暗示旋转气流是由于峰值泄露气流引起的。另一方面，由于管线所引起的延迟时间的存在可以清晰的获得逆时针旋转的气流。在测量盘上波动速度的周期是0.004s（250Hz）。也就是说250Hz的频率是产生旋转气流周期的原因。
对于4.5mmTC（O=0.31）在测量盘II和III上，五个位置相互作用关系的分配情况，具有相同的方式。五个位置在旋转气流区域。超过0.7的有价值的相关系数几乎在相同位置出现。由于管路所引起延迟时间的分配，逆时针旋转气流也被获取。他的周期大约是0.006s。旋转气流的周期与频谱峰值周期一致。
3.6 噪声是由不稳定的旋转气流引起的
本节所描述的是在旋转气流下的峰值频率与低速率的密切关系，而低速率是由峰值泄露涡流所引起的。众所周知，在轴流式风机中峰值泄露涡流是三维的、不稳定的自然因素。，波动速度在240和260Hz之间的频率经过滤获得了旋转气流的不稳定特性，振幅的重复又改变了波动速度。
为了描述在旋转气流中峰值频率的产生机械，作者推荐了一个速度波动源的螺旋式概念。也就是低速率沿着螺旋结构、朝着顺时针方向运动。250Hz的风致频率是在旋转体的相关框架内的复合味指出测量到的并且在该处所产生的。因为对于一个旋转体来说沿着螺旋结构以0.004s的低速度向下游运动。当然，由于峰值泄露涡流所引起的低速度是在低速区域所产生的。以旋转速度是1000r.p.m 的250Hz峰值频率与该噪声有着密切的关系。根据2mmTC（O=0.31）叶片旋转速度的速度波动的频谱。峰值频率成比例的增加是由于叶片旋转体旋转速度的增加。
峰值频率于叶片旋转体在气流速率下与旋转速度的关系。峰值频率随着叶片旋转体在连续旋转速度下气流速率的增加而增加。这也暗示叶片以高速率旋转时，
噪声是由峰值频率引起的，是噪声的重要来源。
最后，在设计（O=0.39）和非设计（O=0.31）情况下，轴流式风机内有两种不同的TCS噪声频谱，通过管路旋转线可以看出叶片上频率的意义。在设计操作情况下两种400、500Hz峰值频率。
当O=0.31时，如图16的250、160Hz峰值频率。在同样的情况下，当TC 增大时，两种噪声的离散频率是由频率峰值和噪声的增加引起的，它们是由较大的旋转气流引起的，而较大的旋转气流又由增加的气流所引起的。可见，噪声是由在轴流式风机中的TC引起的且影响低频宽度。
4 结论
噪声有轴流式风机里的两种不同的TC决定，在设计与非设计情况下通过两个缠绕的热传感器分析获得。结果总结如下：
1 噪声的增加由在低速率情况下的TC决定，是由峰值泄漏涡流和乡邻压力表面、箱体表面间的旋转气流的高速率波动引起的。速度波动强度的增加是由于TC的增加和气流速率的下降引起的。
2 在四个有用频率下，旋转气流中可获得峰值频率。而在设计操作情况下反向气流区域获得的频率同时在旋转气流区域，非设计操作情况将产生速度波动的峰值频率。
3 速度波动的峰值频率成倍的增加是由于叶片的旋转速度的增加引起的。在连续旋转速度下，随着气流速率的增加频率也增加。这就暗示当叶片高速旋转时，噪声是由于峰值频率引起的、是在省的重要来源。
致谢
作者感谢Mr.N.ogata和Mr.D.Sato在本次实验所给予的帮助。
附录B
Tip clearance noise of axial flow fans operating at design and
off-design condition
T. Fukano*, C.-M. Jang
Abstract
The noise due to tip clearance (TC) flow in axial flow fans operating at a design and off-design conditions is analyzed by an experimental measurement usingtwo hot-wire probes rotating with the fan blades. The unsteady nature of the spectra of the real-time velocities measured by two hot-wire sensors in a vortical flow region is investigated by using cross-correlation coefficient and retarded time of the two fluctuating velocities. The results show that the noise due to TC flow consists of a discrete frequency noise due to periodic velocity fluctuation and a broadband noise due to velocity fluctuation in the blade passage. The peak frequencies in a vortical flow are mainly observed below at four harmonic blade passingfrequency .The discrete frequency component of velocity fluctuation at the off-design operating conditions is generated in vortical flow region as well as in reverse flow region. The peak frequency can be an important noise source when the fans are rotated with a high rotational speed. The authors propose a spiral pattern of velocity fluctuation in the vortical flow to describe the generation mechanism of the peak frequency in the vortical flow. In addition, noise increase due to TC flow at low flow rate condition is analyzed with relation to the distribution of velocity fluctuation due to the interference between the tip leakage vortex and the adjacent pressure surface of the blade.
1.Introduction
The present study is focused on the mechanism of sound generation due to unsteady behavior of vortical flow near the rotor tip in axial flow fans. The nature of a tip leakage vortex observed in a rotor tip region has been studied by many researchers because of its important role on the flow field; for example, Inoue and Kuroumaru [1], Storer andCumpsty [2], and Lakshminarayana et al. [3]. They showed that the tip leakage flow has a three-dimensional and an unsteady nature, and effect on a loss production and a noise generation. However, most studies are mainly
focused on the
vortical flow in a blade passage with relation to aerodynamic performance without considering the sound generation due to the unsteady behavior of the vortical flow.
Noise level increase by enlarging a tip clearance (TC) is studied by Longhouse [4], Fukano et al. [5], and Kameier and Neise [6]. Their studies showed that the spectral peaks occurred in sound spectra although a TC noise is broadband naturally. Kameier and Neise [6] also reported that the TC noise associated with a rotatingflow instability in axial turbomachines was generated under reverse flow conditions in a TC gap. However, the above studies were performed without detailed flow analysis in the blade passage. The understanding of the detailed flow structure as well as the spectrum of a fluctuating velocity in the blade passage is important to analyze the generation mechanism of the TC noise, which is closely related to the unsteady behavior of the tip leakage vortex.
On the other hand, the measurement of the real-valued signal with a high sampling frequency in the stationary frame is nearly impossible in the blade passage of axial turbomachines. Therefore, it is essential to measure a real-time velocity in the relative frame of reference rotatingwith a rotor to readily understand the frequency characteristics of a fluctuatingvortical flow in the rotor blade. Detailed measurements of a velocity and a velocity fluctuation in the axial flow fans are made usinga rotatinghot-wire sensor near the rotor tip in the rotatingframe in the present study.
The pioneer study of the flow measurement in the rotational frame was performed by Fukanoetal. [7]. They measured the periodic velocity fluctuation in the downstream of the trailingedg e of a rotating flat-plate blade using a hot-wire sensor attached to the originally designed measuring system. The result showed the important role of the periodic velocity fluctuation due to Karman vortex street in the generation of broadband noise.
In the present study, spectra of the velocity fluctuation near rotor tip were measured using the rotatinghot-wire sensor to elucidate the TC noise in the axial flow fans with relation to the distribution of the relative velocity and the velocity
fluctuation. The unsteady nature of the spectra of the real-time velocities measured by two hot-wire sensors in the vortical flow region is also investigated by using cross-correlation coefficient and retarded time of the two fluctuating velocities. The present study was performed at off-design operating conditions as well as a design flow condition. In addition, the TC effects on the vortical flow field and the aerodynamic noise generation are also reviewed by introducing two different TCs to the axial flow fans.
2.Experimental apparatus and procedures
Test axial flow fan
The present study was performed on low speed axial flow fans in two cases of the TC of 2mm (1.6 per cent tip chord) and 4.5mm (3.5 per cent tip chord). Its design specifications for the fan having2 mm TC are summarized in Table 1. The fan has a design flow coefficient F (mean axial velocity divided by rotor tip speed) of 0.39 and a design static pressure rise coefficient CS (static pressure rise divided by dynamic pressure at rotor tip) of 0.26. Fig. 1 shows the pressure rise CS and the sound pressure level SPL plotted against flow rate of the test fan. The rotor blade has NACA 65 series profile sections designed by free vortex operation. The blade stagger angle and the angle of attack at the rotor tip are 64.2_ and 4.4_, respectively. The experimental measurements were carried out at the off-design operating conditions of F=0.33, 0.31 and 0.29 (25 per cent lower than the design flow rate) as well as at the design condition of F=0.39 while rotational speed of the fan rotor was kept constant, 1000 r.p.m. The blade tip section of the rotor has the solidity of 0.55 and the chord length of 129 mm. Reynolds number based on the rotor tip speed and the rotor tip chord length is 2.6_105.
Table 1
Design specifications of axial flow fan
Flow coefficient 0.39
Pressure coefficient 0.26
Rotational speed 1000 r.p.m.
Tip radius 287.5mm
Hub-tip ratio 0.52
Blade profile NACA65
Number of blade 8
The three-dimensional vortical flow structure in the axial flow fans operatingat the design condition was analyzed by numerical simulation and experimental measurement in the previous study [8]. Three-dimensional tip leakage vortex structure and leakage streamlines surrounding the tip leakage vortex obtained by the numerical simulation for the axial flow fan having 2mm TC are shown in Fig. 2, which is a perspective view from the casingside. The vortex core identification method and the definition of normalized helicity Hn were presented in detail in the previous paper [8]. It was found that the tip leakage vortex formed close to the leading edge of the blade tip on suction side grew in the streamwise direction, and formed a local recirculation region resulting from a vortex breakdown inside the blade passage as shown in Fig. 2.
2.2. Measuring procedures
Fig. 3 shows the experimental set-up alongwith its major dimensions. It was an open-loop facility havingthe duct inner diameter of 0.579 m. The facility consisted of a bellmouth inlet, a fan drivingmotor connected by the belt, a damper and a booster fan. The aerodynamically designed damper was used to adjust the flow rates. The distance between the bellmouth inlet and the test fan was 0.43 m.
A schematic view of the measuringsystem is shown in Fig. 4. Two hot-wire sensors rotating with the fan rotor were introduced for the present study to obtain the cross-correlation between a reference position and target (traversing) positions, as well as the three-dimensional velocity and velocity fluctuation inside and downstream of the rotor blade. The I-type sensor of the hot-wire probe was a tungsten filament wire of 5-mm diameter. The wires of the both probe sensors were set parallel to the radial direction of the rotor blade. The supporter of the fixed probe as shown in Fig. 4 was directly installed on the hub. The traversingprobe was controlled by the threedimensional traversingsystem, i.e., radial, axial and rotational directions, installed inside of the hub with traverse resolution of 0.3 mm. The
maximum traversingspan of the traversing system in radial, axial and tangential directions was 45 mm, 50mm and 50_ (45_ for one blade passage),respectively. Therefore, it could measure one blade passage of the tip region without rearranging the traversingsystem while the rotor was in motion. The real-valued velocity fluctuations were measured by usingconstant-temper ature hot-wire anemometer and interfacingtechnique with an on-line computer. The diagram of the on-line system is shown in Fig. 5. The output from the hotwire probe was carried from a rotating frame to a stationary frame through Michigan Scientific Corporation mercury slip-ringunit installed inside of the hub as shown in Fig. 3. The signal obtained from the hot-wire anemometer was filtered out the frequency above 8.9 kHz usingthe low pass filter as shown in Fig. 5.
Three-dimensional velocity and velocity fluctuation inside and downstream of the rotor blade were measured by the traversingprobe, and determined by usinga constant-temperature hot-wire anemometer and averaging technique with an on-line computer. Ensemble averaged values of the velocity and the velocity fluctuation were obtained by 6000 samplingdata at each measuring position. The spectrum analysis of the velocity fluctuation was performed usingOnosokki FFT analyzer. The calibration of the probe at the measuringsystem was performed by detachingthe rotor blade from the test fan and measuringthe tangential velocity for the four different rotational frequencies: 300, 600, 900 and 1200 r.p.m. In addition, the magnitude of the deformation of the probe supporter caused by the rotor rotation was calibrated prior to the experiments. The experiments with rotor blade havingthe TC of 2 and 4.5mm were conducted by changingthe rotor tip diameter while the inner diameter of the casingwas kept constant.
On the other hand, the noise generated from the rotor blades was measured at the position of 1m upstream from the fan rotor and on the rotational axis. In the measurement of the noise spectrum, the background noise kept 5 dB below the sound level of all frequencies. It is noted that the noise is obtained from the measuringsystem that only the fan rotor is excluded.
3.Results and discussion
Noise increase due to the interaction of a leakage flow and an adjacent rotor blade
As shown in Fig. 1, the sound pressure level SPL is sharply increased from the flow rate of F 0:33 as a flow rate is decreased. It is noted that the flow condition is not in a stall at F 0:29 from the pressure rise CS shown in Fig. 1. The reason why the SPL is increase at the low flow rate between F 0:33 and F 0:29 will be discussed in the following.
Fig. 6 shows the distribution of the relative velocity on the plane of 99 per cent span of the blade in the test fan having2 mm TC for the design (F 0:39) and the two off-design operating conditions (F=0.33 and 0.29), which is a perspective view from the casing. The relative velocity V at is defined and normalized by the circumferential
velocity of the blade tip, Ut:
at t V =Where Va and Vt denote axial velocity and tangential (circumferential) velocity, respectively. In Fig. 6, the low velocity region in the blade passage results from the tip leakage vortex as shown in Fig. 2 [8]. The tip leakage vortex formed on suction side grows in the downstream direction without interference with the adjacent pressure surface in the design operating condition. However, the tip downstream side of the leakage vortex is moved upstream compared to the case of the F 0:39 as the flow rate is decreased, thus resultingin interference with the adjacent pressure surface as shown in Fig. 6.
Fig. 7 shows the distribution of the velocity fluctuation on the plane of 99 per cent span, which is presented in the same condition as shown in Fig. 6. The velocity
fluctuation Vf is defined by
f t V =，
where V0 at is the fluctuatingcomponent of the relative velocity defined by Eq.
(1). The high velocity fluctuation on the each plane is observed near the correspondinglow velocity region shown in Fig. 6. It is well known that the high
velocity fluctuation is closely related to the aerodynamic noise generation. It should be noted that the high velocity fluctuation region in the blade passage is enlarged as the flow rate is decreased. The increase of the broadband noise in the low flow rate conditions is mainly caused by the high velocity fluctuation as shown in Fig. 7.
Figs. 8(a)–(c) shows the distribution of the velocity fluctuation downstream of the rotor blade having2 mm TC for the same flow conditions shown in Figs. 6 and 7. The measuringplane, which is nearly perpendicular to streamwise direction, is located 2.7mm downstream from the blade trailing edge. In the figure, the horizontal axis represents the perpendicular distance Z to the streamwise direction from the blade trailing edge. The high velocity fluctuation near the pressure surface of the rotor tip is not observed in the design operating condition as shown in Fig. 8(a) because the tip leakage vortex is moved downstream without interference with the adjacent pressure surface as described in Fig. 6(a). However, the high velocity fluctuation region moves
closer to the pressure side as the flow rate decreases, and the tip leakage vortex interferes with the pressure surface as clearly shown in Figs. 8(b) and (c). Especially, the highest velocity fluctuation presents near the pressure surface (J in Fig. 8(c)) in the lowest flow condition (F=0.29). The high velocity fluctuation near the pressure surface induces high pressure fluctuation on the bladesurface, which has strongly effect on the fan noise generation because of the dipole characteristic of the pressure fluctuation on the solid surface [9].
Fig. 9 shows the spectra of noise in the fan having2 mm TC for the three off-design operating conditions: F=0.29, 0.31 and 0.33. In the figure, vertical dashed lines indicate the harmonic frequencies of blade passingwhere the fundamental blade passing frequency BPF is 133 Hz. The samplingfrequency of the present measurement is 5012 Hz, and the frequency below 1200 Hz is only presented because the sound pressure level over the 1200 Hz has almost same value irrespective of the flow rate F: The spectral peaks at the 840 Hz, which have almost same sound pressure level, are generated by the fan driving motor shown in Fig. 3. The noise increase below the flow rate F 0:33; which has a same sound pressure level
of the design operating condition as shown in Fig. 1, is mainly caused by the stronger velocity fluctuation as described in the Fig. 7 which interacts with the duct inner surface and the adjacent blade. The spectral peaks at 170, 250 and 330 Hz exceptingthe harmonic of BPF are also observed at F=0.29, 0.31 and 0.33. To investigate spectral characteristics due to the duct installed downstream of the fan rotor, a speaker generating a white noise was installed 9m downstream from the fan rotor, and spectrum of the noise was measured at the position of 1m upstream from the fan rotor and on the rotational axis. The spectral peaks of 180, 360 and 970 Hz havinga relatively wide frequency band are observed in Fig. 10. It can be considered that the high peaks at the 170 and the 330 Hz shown in Fig. 9 are influenced by frequencies caused by the duct, 180 and 360 Hz. It should be noted that the noise increase at the low flow rate condition is mainly caused by the high velocity fluctuation in the vortical flow interactingwith the duct surface and the adjacent pressure surface.
We will discuss the mechanism of the generation of the discrete frequency component more in the later part of this paper.
3.2. Three-dimensional vortical flow structure
To investigate the three-dimensional structure of the vortical flow near the rotor tip, the relative velocity in the blade passage and downstream was measured by the hot-wire sensor (traversing probe in Fig. 4) rotatingwith rotor blade in the off-design operatingcondition (F=0.31) and in the design condition (F=0.39). The structure of the vortical flow was also analyzed for the two different TCs (2 and 4.5mm) at the both operatingconditions to understand the TC effect on the vortical flow.
The hot-wire sensor mounted inside of the hub was moved by the traversingsystem as already shown in Fig. 4. The interval of measuringpositions is about 5mm in the pitchwise direction, and 3mm in the streamwise direction and in the spanwise direction. The measuringarea in the radial direction is from 255mm (76 per cent span) to 280mm (98 per cent span). Fig. 11 shows an experimental grid and a measured low velocity region in the blade passage for the fan having 2mm TC. In the figure, the relative velocity Vat is normalized by the rotor tip speed Ut; and only
the low relative velocity region with Vat=Uto0:75 is shown. The position of the leakage streamlines shown in Fig. 2, which are the result of the numerical simulation [8], correspond well to that of the low velocity region. It should be noted that the low velocity region in the blade passage is caused by the tip leakage vortex [8].
To compare the structure of the tip leakage vortex in the cases of the design and the off-design conditions, the measured low relative velocity region is reproduced in the blade passage. Fig. 12 shows the distributions of the low relative velocity with the measuringreg ion for the 2 and the 4.5mm TCs, which are the perspective view from the casing. The regions colored with white and black in Fig. 12 represent the low velocity area obtained in the off-design and the design operating condition, respectively. In the figure, the scale of the velocity region has a different value. The low velocity region due to the tip leakage vortex is clearly observed in the blade passage. It is found that the tip leakage vortex obtained at the off-design condition is located upstream compared to that at the design condition for the both TCs. This is generally acknowledged as described by Inoue et al. [1] in the axial compressor rotor. It can also be understood that the low velocity region spreads out as the flow rate is decreased, which is caused by the larger movement of the tip leakage vortex in this low flow rate condition. A large vortical flow is generated due to the larger leakage flow as the TC is increased. The detailed vortical flow and its comparison to the result obtained by numerical simulation in the design operating condition was performed in the previous paper [8].
3.3.Spectral peaks of fluctuating velocity at a design operating condition
To investigate the behavior of the flow fluctuation in the blade passage, distributions of the velocity fluctuation on a quasi-orthogonal plane to the tip leakage vortex at the design operating condition are shown in Fig. 13 with relation to the distribution of the relative velocity. The position of the quasi-orthogonal plane to the tip leakage vortex in the blade passage, which is a perspective view from casing, is shown in Fig. 13(c). In the figure, positions of A and G in the plane are located upstream and downstream of the vortex, respectively. From the distribution of the relative velocity as shown in Fig. 13(a), it can be clearly observed the vortical flow
due to the tip leakage vortex. The vortical flow is formed at a low velocity region (below the velocity of 0.75) and a main flow is surrounded the vortical flow. The center of vortical flow is the position having a minimum kinetic energy. A reverse flow region presented by gray color in Fig. 13(a) is also observed near the casingwall. On the other hand, the high velocity fluctuation is observed in the interference region between the tip leakage vortex and the main flow as well as in the vortex core as shown in Fig. 13(b).
Fig. 14 shows the spectral distributions of the velocity fluctuation at the positions selected near the rotor tip on the quasi-orthogonal plane of Fig. 13 for the fan havingthe 2mm TC operatingin the design condition. The spectra are obtained by a FFT analyzer, which averages each value 64 times at a measuringposition. In the present study, the spectra are measured at 49 grid points for one operatingcondition. Amongthem, the spectra at 12 positions shown by _ symbols in Fig. 13(b) are selected at the three radial positions of 0.98(RI), 0.96(RII) and 0.9(RIII) span. Four positions (RI-E, RI-F, RII-E, and RII-F in Fig. 13(b)) of them exist in the reverse flow region. It
is found that spectral peaks near the 400 and 500 Hz are found in the reverse flow region, although the peak of the velocity fluctuation spectrum is not clear upstream and downstream of the vortical flow. Kameier and Neise [6] also reported that TC noise of an axial turbomachine is caused by reverse flow in relation to the rotatingflow instability near the rotor tip.
3.4. Spectral peaks of fluctuating velocity at an off-design operating condition
It has been reported by many researchers that undesired phenomena on the fan performance and noise increase due to a rotatinginstability and stall in the axial fans operating in a low flow condition. In the present study, the vortical flow structure and the spectral characteristics of the fluctuating velocity in the blade passage are investigated in the axial flow fans having the 2 and the 4.5mm TCs operatingat the off-design condition of F=0.31.
Fig. 15 shows the contour of relative velocity and velocity fluctuation on the three quasiorthogonal planes to the axis of the tip leakage vortex of the axial flow
fan having the 2mm TC operatingat the off-design condition. The positions of the measuringplanes (I, II and III) in the blade passage are shown in Fig. 15(b), which is a perspective view from casing. The low relative velocity region spreads out to 85 per cent span from the casing according to decrease of flow rateas shown in Figs. 13(c) and 15(b). The larger velocity region is caused by as a result of the increase of the blockage of the vortical flow and the loss production in the blade passage. From the distributions of the relative velocity on the three planes as shown in Figs. 15(a), (c) and (e), vortical flow pattern is again clearly observed. High velocity fluctuation is observed in the interference region between the tip leakage vortex and the main flow as shown in Figs. 15(d) and (f). It is also noted that the low velocity region is expanded out as the vortical flow is moved to the streamwise direction. The reverse flow region is also increased as the flow rate is decreased because of the expansion of the vortical flow due to its large movement in time.
Fig. 16 shows the spectra of the velocity fluctuation at the positions selected on planes II and III of Fig. 15(b). At each plane, the spectra at 12 positions presented by _ symbols in Figs. 15(d) and (f) are selected at the three radial positions of 0.98(RI), 0.96(RII) and 0.9(RIII) span. Spectral peaks near the 250 Hz are mainly observed in the reverse flow region like in the design operating condition. It should be noted that the intensity of the high velocity fluctuation is increased about 40 per cent compared to that at the design operating condition. Needless to say, the higher intensity of the velocity fluctuation is the important source of the broadband noise increase asdescribed in the previous section.
Fig. 17 shows the contour of relative velocity and the velocity fluctuation for the 4.5mm TC at the off-design operating condition. The positions of the measuring planes in the blade passage are shown in Fig. 17(b), which are presented in the same manner as shown in Fig. 15. As shown in Fig. 17, the vortical flow is expanded to 0.75 span from the casing. That is, the vortical flow is increased about 12 per cent in the radial direction compared to that for the 2mm TC due to the larger TC flow. High velocity fluctuation on planes II and III is observed at the interference region between the tip leakage vortex and the main flow. The intensity of the velocity
前言 在目前激烈的市场竞争中，产品投入市场的迟早往往是成败的关键。模具是高质量、高效率的产品生产工具，模具开发周期占整个产品开发周期的主要部分。因此客户对模具开发周期要求越来越短，不少客户把模具的交货期放在第一位置，然后才是质量和价格。因此，如何在保证质量、控制成本的前提下加工模具是值得认真考虑的问题。模具加工工艺是一项先进的制造工艺，已成为重要发展方向，在航空航天、汽车、机械等各行业得到越来越广泛的应用。模具加工技术，可以提高制造业的综合效益和竞争力。研究和建立模具工艺数据库，为生产企业提供迫切需要的高速切削加工数据，对推广高速切削加工技术具有非常重要的意义。本文的主要目标就是构建一个冲压模具工艺过程，将模具制造企业在实际生产中结合刀具、工件、机床与企业自身的实际情况积累得高速切削加工实例、工艺参数和经验等数据有选择地存储到高速切削数据库中，不但可以节省大量的人力、物力、财力，而且可以指导高速加工生产实践，达到提高加工效率，降低刀具费用，获得更高的经济效益。 1.冲压的概念、特点及应用 冲压是利用安装在冲压设备（主要是压力机）上的模具对材料施加压力，使其产生分离或塑性变形，从而获得所需零件（俗称冲压或冲压件）的一种压力加工方法。冲压通常是在常温下对材料进行冷变形加工，且主要采用板料来加工成所需零件，所以也叫冷冲压或板料冲压。冲压是材料压力加工或塑性加工的主要方法之一，隶属于材料成型工程术。 冲压所使用的模具称为冲压模具，简称冲模。冲模是将材料（金属或非金属）批量加工成所需冲件的专用工具。冲模在冲压中至关重要，没有符合要求的冲模，批量冲压生产就难以进行；没有先进的冲模，先进的冲压工艺就无法实现。冲压工艺与模具、冲压设备和冲压材料构成冲压加工的三要素，只有它们相互结合才能得出冲压件。 与机械加工及塑性加工的其它方法相比，冲压加工无论在技术方面还是经济方面都具有许多独特的优点，主要表现如下； (1) 冲压加工的生产效率高，且操作方便，易于实现机械化与自动化。这是
附录 科技译文： Numerical Control Numerical Control(NC) is a method of controlling the movements of machineComponents by directly inserting coded instructions in the form of numerical data(numbers and data ) into the system.The system automatically interprets these data and converts to output signals. These signals ,in turn control various machine components ,such as turning spindles on and off ,changing tools,moving the work piece or the tools along specific paths,and turning cutting fluits on and off. In order to appreciate the importer of numerical control of machines ,let’s briefly review how a process such as machining has been carried out traditionally .After studying the working drawing of a part, the operator sets up the appropriate process parameters(such as cutting speed ,feed,depth of cut,cutting fluid ,and so on),determines the sequence of operations to be performed,clamps the work piece in a workholding device such as chuck or collet ,and proceeds to make the part .Depending on part shape and the dimensional accuracy specified ,this approach usually requires skilled
附录一英文科技文献翻译 英文原文： Experimental investigation of laser surface textured parallel thrust bearings Performance enhancements by laser surface texturing (LST) of parallel-thrust bearings is experimentally investigated. Test results are compared with a theoretical model and good correlation is found over the relevant operating conditions. A compari- son of the performance of unidirectional and bi-directional partial-LST bearings with that of a baseline, untextured bearing is presented showing the bene?ts of LST in terms of increased clearance and reduced friction. KEY WORDS: ?uid ?lm bearings, slider bearings, surface texturing 1. Introduction The classical theory of hydrodynamic lubrication yields linear (Couette) velocity distribution with zero pressure gradients between smooth parallel surfaces under steady-state sliding. This results in an unstable hydrodynamic ?lm that would collapse under any external force acting normal to the surfaces. However, experience shows that stable lubricating ?lms can develop between parallel sliding surfaces, generally because of some mechanism that relaxes one or more of the assumptions of the classical theory. A stable ?uid ?lm with su?cient load-carrying capacity in parallel sliding surfaces can be obtained, for example, with macro or micro surface structure of di?erent types. These include waviness [1] and protruding microasperities [2–4]. A good literature review on the subject can be found in Ref. [5]. More recently, laser surface texturing (LST) [6–8], as well as inlet roughening by longitudinal or transverse grooves [9] were suggested to provide load capacity in parallel sliding. The inlet roughness concept of Tonder [9] is based on ??e?ective clearance‘‘ reduction in the sliding direction and in this respect it is identical to the par- tial-LST concept described in ref. [10] for generating hydrostatic e?ect in high-pressure mechanical seals. Very recently Wang et al. [11] demonstrated experimentally a doubling of the load-carrying capacity for the surface- texture design by reactive ion etching of SiC
外文出处： 《Exploiting Software How to Break Code》By Greg Hoglund, Gary McGraw Publisher : Addison Wesley Pub Date : February 17, 2004 ISBN : 0-201-78695-8 译文标题： JDBC接口技术 译文： JDBC是一种可用于执行SQL语句的JavaAPI（ApplicationProgrammingInterface应用程序设计接口）。它由一些Java语言编写的类和界面组成。JDBC为数据库应用开发人员、数据库前台工具开发人员提供了一种标准的应用程序设计接口，使开发人员可以用纯Java语言编写完整的数据库应用程序。 一、ODBC到JDBC的发展历程 说到JDBC，很容易让人联想到另一个十分熟悉的字眼“ODBC”。它们之间有没有联系呢？如果有，那么它们之间又是怎样的关系呢？ ODBC是OpenDatabaseConnectivity的英文简写。它是一种用来在相关或不相关的数据库管理系统（DBMS）中存取数据的，用C语言实现的，标准应用程序数据接口。通过ODBCAPI，应用程序可以存取保存在多种不同数据库管理系统（DBMS）中的数据，而不论每个DBMS使用了何种数据存储格式和编程接口。 1．ODBC的结构模型 ODBC的结构包括四个主要部分：应用程序接口、驱动器管理器、数据库驱动器和数据源。应用程序接口：屏蔽不同的ODBC数据库驱动器之间函数调用的差别，为用户提供统一的SQL编程接口。 驱动器管理器：为应用程序装载数据库驱动器。 数据库驱动器：实现ODBC的函数调用，提供对特定数据源的SQL请求。如果需要，数据库驱动器将修改应用程序的请求，使得请求符合相关的DBMS所支持的文法。 数据源：由用户想要存取的数据以及与它相关的操作系统、DBMS和用于访问DBMS的网络平台组成。 虽然ODBC驱动器管理器的主要目的是加载数据库驱动器，以便ODBC函数调用，但是数据库驱动器本身也执行ODBC函数调用，并与数据库相互配合。因此当应用系统发出调用与数据源进行连接时，数据库驱动器能管理通信协议。当建立起与数据源的连接时，数据库驱动器便能处理应用系统向DBMS发出的请求，对分析或发自数据源的设计进行必要的翻译，并将结果返回给应用系统。 2．JDBC的诞生 自从Java语言于1995年5月正式公布以来，Java风靡全球。出现大量的用java语言编写的程序，其中也包括数据库应用程序。由于没有一个Java语言的API，编程人员不得不在Java程序中加入C语言的ODBC函数调用。这就使很多Java的优秀特性无法充分发挥，比如平台无关性、面向对象特性等。随着越来越多的编程人员对Java语言的日益喜爱，越来越多的公司在Java程序开发上投入的精力日益增加，对java语言接口的访问数据库的API 的要求越来越强烈。也由于ODBC的有其不足之处，比如它并不容易使用，没有面向对象的特性等等，SUN公司决定开发一Java语言为接口的数据库应用程序开发接口。在JDK1．x 版本中，JDBC只是一个可选部件，到了JDK1．1公布时，SQL类包（也就是JDBCAPI）
机械设计理论 机械设计是一门通过设计新产品或者改进老产品来满足人类需求的应用技术科学。它涉及工程技术的各个领域，主要研究产品的尺寸、形状和详细结构的基本构思，还要研究产品在制造、销售和使用等方面的问题。 进行各种机械设计工作的人员通常被称为设计人员或者机械设计工程师。机械设计是一项创造性的工作。设计工程师不仅在工作上要有创造性，还必须在机械制图、运动学、工程材料、材料力学和机械制造工艺学等方面具有深厚的基础知识。如前所诉，机械设计的目的是生产能够满足人类需求的产品。发明、发现和科技知识本身并不一定能给人类带来好处，只有当它们被应用在产品上才能产生效益。因而，应该认识到在一个特定的产品进行设计之前，必须先确定人们是否需要这种产品。 应当把机械设计看成是机械设计人员运用创造性的才能进行产品设计、系统分析和制定产品的制造工艺学的一个良机。掌握工程基础知识要比熟记一些数据和公式更为重要。仅仅使用数据和公式是不足以在一个好的设计中做出所需的全部决定的。另一方面，应该认真精确的进行所有运算。例如，即使将一个小数点的位置放错，也会使正确的设计变成错误的。 一个好的设计人员应该勇于提出新的想法，而且愿意承担一定的风险，当新的方法不适用时，就使用原来的方法。因此，设计人员必须要有耐心，因为所花费的时间和努力并不能保证带来成功。一个全新的设计，要求屏弃许多陈旧的，为人们所熟知的方法。由于许多人墨守成规，这样做并不是一件容易的事。一位机械设计师应该不断地探索改进现有的产品的方法，在此过程中应该认真选择原有的、经过验证的设计原理，将其与未经过验证的新观念结合起来。 新设计本身会有许多缺陷和未能预料的问题发生，只有当这些缺陷和问题被解决之后，才能体现出新产品的优越性。因此，一个性能优越的产品诞生的同时，也伴随着较高的风险。应该强调的是，如果设计本身不要求采用全新的方法，就没有必要仅仅为了变革的目的而采用新方法。 在设计的初始阶段，应该允许设计人员充分发挥创造性，不受各种约束。即使产生了许多不切实际的想法，也会在设计的早期，即绘制图纸之前被改正掉。只有这样，才不致于堵塞创新的思路。通常，要提出几套设计方案，然后加以比较。很有可能在最后选定的方案中，采用了某些未被接受的方案中的一些想法。
附录 INTEGRATION OF MACHINERY （From ELECTRICAL AND MACHINERY INDUSTRY）ABSTRACT Machinery was the modern science and technology development inevitable result, this article has summarized the integration of machinery technology basic outline and the development background .Summarized the domestic and foreign integration of machinery technology present situation, has analyzed the integration of machinery technology trend of development. Key word：integration of machinery ，technology，present situation ，product t，echnique of manufacture ，trend of development 0. Introduction modern science and technology unceasing development, impelled different discipline intersecting enormously with the seepage, has caused the project domain technological revolution and the transformation .In mechanical engineering domain, because the microelectronic technology and the computer technology rapid development and forms to the mechanical industry seepage the integration of machinery, caused the mechanical industry the technical structure, the product organization, the function and the constitution, the production method and the management system has had the huge change, caused the industrial production to enter into “the integration of machinery” by “the machinery electrification” for the characteristic development phase. 1. Integration of machinery outline integration of machinery is refers in the organization new owner function, the power function, in the information processing function and the control function introduces the electronic technology, unifies the system the mechanism and the computerization design and the software which constitutes always to call. The integration of machinery development also has become one to have until now own system new discipline, not only develops along with the science and technology, but also entrusts with the new content .But its basic characteristic may summarize is: The integration of machinery is embarks from the system viewpoint, synthesis community technologies and so on utilization mechanical technology, microelectronic technology, automatic control technology,
本科毕业论文(设计) 外文翻译 学院：机电工程学院 专业：机械工程及自动化 姓名：高峰 指导教师：李延胜 2011年05 月10日 教育部办公厅 Failure Analysis，Dimensional Determination And
Analysis，Applications Of Cams INTRODUCTION It is absolutely essential that a design engineer know how and why parts fail so that reliable machines that require minimum maintenance can be designed．Sometimes a failure can be serious，such as when a tire blows out on an automobile traveling at high speed．On the other hand，a failure may be no more than a nuisance．An example is the loosening of the radiator hose in an automobile cooling system．The consequence of this latter failure is usually the loss of some radiator coolant，a condition that is readily detected and corrected．The type of load a part absorbs is just as significant as the magnitude．Generally speaking，dynamic loads with direction reversals cause greater difficulty than static loads，and therefore，fatigue strength must be considered．Another concern is whether the material is ductile or brittle．For example，brittle materials are considered to be unacceptable where fatigue is involved． Many people mistakingly interpret the word failure to mean the actual breakage of a part．However，a design engineer must consider a broader understanding of what appreciable deformation occurs．A ductile material，however will deform a large amount prior to rupture．Excessive deformation，without fracture，may cause a machine to fail because the deformed part interferes with a moving second part．Therefore，a part fails(even if it has not physically broken)whenever it no longer fulfills its required function．Sometimes failure may be due to abnormal friction or vibration between two mating parts．Failure also may be due to a phenomenon called creep，which is the plastic flow of a material under load at elevated temperatures．In addition，the actual shape of a part may be responsible for failure．For example，stress concentrations due to sudden changes in contour must be taken into account．Evaluation of stress considerations is especially important when there are dynamic loads with direction reversals and the material is not very ductile． In general，the design engineer must consider all possible modes of failure，which include the following． ——Stress ——Deformation ——Wear ——Corrosion ——Vibration ——Environmental damage ——Loosening of fastening devices
外文翻译 专业机械设计制造及其自动化学生姓名刘链柱 班级机制111 学号1110101102 指导教师葛友华
外文资料名称： Design and performance evaluation of vacuum cleaners using cyclone technology 外文资料出处：Korean J. Chem. Eng., 23(6), (用外文写) 925-930 (2006) 附件： 1.外文资料翻译译文 2.外文原文
应用旋风技术真空吸尘器的设计和性能介绍 吉尔泰金，洪城铱昌，宰瑾李， 刘链柱译 摘要：旋风型分离器技术用于真空吸尘器 - 轴向进流旋风和切向进气道流旋风有效地收集粉尘和降低压力降已被实验研究。优化设计等因素作为集尘效率，压降，并切成尺寸被粒度对应于分级收集的50％的效率进行了研究。颗粒切成大小降低入口面积，体直径，减小涡取景器直径的旋风。切向入口的双流量气旋具有良好的性能考虑的350毫米汞柱的低压降和为1.5μm的质量中位直径在1米3的流量的截止尺寸。一使用切向入口的双流量旋风吸尘器示出了势是一种有效的方法，用于收集在家庭中产生的粉尘。 摘要及关键词：吸尘器; 粉尘; 旋风分离器 引言 我们这个时代的很大一部分都花在了房子，工作场所，或其他建筑，因此，室内空间应该是既舒适情绪和卫生。但室内空气中含有超过室外空气因气密性的二次污染物，毒物，食品气味。这是通过使用产生在建筑中的新材料和设备。真空吸尘器为代表的家电去除有害物质从地板到地毯所用的商用真空吸尘器房子由纸过滤，预过滤器和排气过滤器通过洁净的空气排放到大气中。虽然真空吸尘器是方便在使用中，吸入压力下降说唱空转成比例地清洗的时间，以及纸过滤器也应定期更换，由于压力下降，气味和细菌通过纸过滤器内的残留粉尘。 图1示出了大气气溶胶的粒度分布通常是双峰形，在粗颗粒（>2.0微米）模式为主要的外部来源，如风吹尘，海盐喷雾，火山，从工厂直接排放和车辆废气排放，以及那些在细颗粒模式包括燃烧或光化学反应。表1显示模式，典型的大气航空的直径和质量浓度溶胶被许多研究者测量。精细模式在0.18?0.36 在5.7到25微米尺寸范围微米尺寸范围。质量浓度为2?205微克，可直接在大气气溶胶和 3.85至36.3μg/m3柴油气溶胶。
机械类外文翻译 塑料注塑模具浇口优化 摘要:用单注塑模具浇口位置的优化方法，本文论述。该闸门优化设计的目的是最大限度地减少注塑件翘曲变形，翘曲，是因为对大多数注塑成型质量问题的关键，而这是受了很大的部分浇口位置。特征翘曲定义为最大位移的功能表面到表面的特征描述零件翘曲预测长度比。结合的优化与数值模拟技术，以找出最佳浇口位置，其中模拟armealing算法用于搜索最优。最后，通过实例讨论的文件，它可以得出结论，该方法是有效的。 注塑模具、浇口位臵、优化、特征翘曲变形关键词: 简介 塑料注射成型是一种广泛使用的，但非常复杂的生产的塑料产品，尤其是具有高生产的要求，严密性，以及大量的各种复杂形状的有效方法。质量ofinjection 成型零件是塑料材料，零件几何形状，模具结构和工艺条件的函数。注塑模具的一个最重要的部分主要是以下三个组件集:蛀牙，盖茨和亚军，和冷却系统。拉米夫定、Seow(2000)、金和拉米夫定(2002) 通过改变部分的尼斯达到平衡的腔壁厚度。在平衡型腔充填过程提供了一种均匀分布压力和透射电镜,可以极大地减少高温的翘曲变形的部分～但仅仅是腔平衡的一个重要影响因素的一部分。cially Espe,部分有其功能上的要求,其厚度通常不应该变化。 pointview注塑模具设计的重点是一门的大小和位臵,以及流道系统的大小和布局。大门的大小和转轮布局通常被认定为常量。相对而言,浇口位臵与水口大小布局也更加灵活,可以根据不同的零件的质量。 李和吉姆(姚开屏,1996a)称利用优化流道和尺寸来平衡多流道系统为multiple 注射系统。转轮平衡被形容为入口压力的差异为一多型腔模具用相同的蛀牙,也存
信工学院毕业设计外文 翻译封面 Document serial number【NL89WT-NY98YT-NC8CB-NNUUT-NUT108】
毕业设计外文资料翻译 专业名称网络工程 班级学号 学生姓名吕帅 指导教师胡硕 填表日期 2015 年 04 月 02 日 Cryptography isone ofthe maintraditional technology andinformation security technology,it is theShannoninformation theory andcryptography theory andtechnology based on thedigital content protection,theuse ofencryptionmethod to complete,i.e.themultimediadata fileis encrypted into ciphertextafter the release,theillegal attackerappearsin the transmission processcannot obtainconfidentialinformation from thetext,so as to achievethe purpose ofcopyright protection andinformation security.Butthis does not completely solve the problem: the spread ofanencrypted filebecause it is notcomprehensibleand hinderthe multimedia information;on the other hand,through themultimedia informationencryptionis easy to causethe attacker'sattention and curiosity,andthere isthe possibility of cracking,and when theinformation isreceivedanddecrypted,theencryptionthe documentandthe document,will no longer be protected,not spared frompiracy.In other words,cryptographycan protectthe transmissionofcontent,and the contentoncedecryptionwill no longer have theprotection.Therefore,there is an urgent need for areplacementorsupplement thecryptographytechnology,itevencan continue to protect thecontent is decryptedincontent.In this way,people put forward thenewconcept ofdigital watermarking,information hiding.Digital watermark isa new direction in thefield of information security technology,is anewtechnologyto protectcopyright and authentication source andintegrality in theopen network environment,the creation ofinformation andpersonal logocreatorthrough digitalwatermarking system toembed the watermarkcan not be perceivedbypeoplein themedia,peoplecan not perceiveon the face ofthe watermark,onlyspecial detector orcomputer softwarethatcan detect thedigital watermarkhidden.
沈阳工业大学工程学院 毕业设计（论文）外文翻译 毕业设计（论文）题目：工具盒盖注塑模具设计 外文题目：Friction , Lubrication of Bearing 译文题目：轴承的摩擦与润滑 系（部）：机械系 专业班级：机械设计制造及其自动化0801 学生姓名：王宝帅 指导教师：魏晓波 2010年10 月15 日
外文文献原文： Friction , Lubrication of Bearing In many of the problem thus far , the student has been asked to disregard or neglect friction . Actually , friction is present to some degree whenever two parts are in contact and move on each other. The term friction refers to the resistance of two or more parts to movement. Friction is harmful or valuable depending upon where it occurs. friction is necessary for fastening devices such as screws and rivets which depend upon friction to hold the fastener and the parts together. Belt drivers, brakes, and tires are additional applications where friction is necessary. The friction of moving parts in a machine is harmful because it reduces the mechanical advantage of the device. The heat produced by friction is lost energy because no work takes place. Also , greater power is required to overcome the increased friction. Heat is destructive in that it causes expansion. Expansion may cause a bearing or sliding surface to fit tighter. If a great enough pressure builds up because made from low temperature materials may melt. There are three types of friction which must be overcome in moving parts: (1)starting, (2)sliding, and(3)rolling. Starting friction is the friction between two solids that tend to resist movement. When two parts are at a state of rest, the surface irregularities of both parts tend to interlock and form a wedging action. To produce motion in these parts, the wedge-shaped peaks and valleys of the stationary surfaces must be made to slide out and over each other. The rougher the two surfaces, the greater is starting friction resulting from their movement . Since there is usually no fixed pattern between the peaks and valleys of two mating parts, the irregularities do not interlock once the parts are in motion but slide over each other. The friction of the two surfaces is known as sliding friction. As shown in figure ,starting friction is always greater than sliding friction . Rolling friction occurs when roller devces are subjected to tremendous stress which cause the parts to change shape or deform. Under these conditions, the material in front of a roller tends to pile up and forces the object to roll slightly uphill. This changing of shape , known as deformation, causes a movement of molecules. As a result ,heat is produced from the added energy required to keep the parts turning and overcome friction. The friction caused by the wedging action of surface irregularities can be overcome
毕业设计（论文） 外文翻译 题目西安市水源工程中的 水电站设计 专业水利水电工程 班级 学生 指导教师 2016年
研究钢弧形闸门的动态稳定性 牛志国 河海大学水利水电工程学院，中国南京，邮编210098 nzg_197901@https://www.doczj.com/doc/2e12184295.html,，niuzhiguo@https://www.doczj.com/doc/2e12184295.html, 李同春 河海大学水利水电工程学院，中国南京，邮编210098 ltchhu@https://www.doczj.com/doc/2e12184295.html, 摘要 由于钢弧形闸门的结构特征和弹力，调查对参数共振的弧形闸门的臂一直是研究领域的热点话题弧形弧形闸门的动力稳定性。在这个论文中，简化空间框架作为分析模型，根据弹性体薄壁结构的扰动方程和梁单元模型和薄壁结构的梁单元模型，动态不稳定区域的弧形闸门可以通过有限元的方法，应用有限元的方法计算动态不稳定性的主要区域的弧形弧形闸门工作。此外，结合物理和数值模型，对识别新方法的参数共振钢弧形闸门提出了调查，本文不仅是重要的改进弧形闸门的参数振动的计算方法，但也为进一步研究弧形弧形闸门结构的动态稳定性打下了坚实的基础。 简介 低举升力，没有门槽，好流型，和操作方便等优点，使钢弧形闸门已经广泛应用于水工建筑物。弧形闸门的结构特点是液压完全作用于弧形闸门，通过门叶和主大梁，所以弧形闸门臂是主要的组件确保弧形闸门安全操作。如果周期性轴向载荷作用于手臂，手臂的不稳定是在一定条件下可能发生。调查指出:在弧形闸门的20次事故中，除了极特殊的破坏情况下，弧形闸门的破坏的原因是弧形闸门臂的不稳定;此外，明显的动态作用下发生破坏。例如:张山闸，位于中国的江苏省，包括36个弧形闸门。当一个弧形闸门打开放水时，门被破坏了，而其他弧形闸门则关闭，受到静态静水压力仍然是一样的，很明显，一个动态的加载是造成的弧形闸门破坏一个主要因素。因此弧形闸门臂的动态不稳定是造成弧形闸门(特别是低水头的弧形闸门)破坏的主要原是毫无疑问。
近几年，我厂和英国、西班牙的几个公司有业务往来，外商传真发来的图纸都是英文标注，平时阅看有一定的困难。下面把我们积累的几点看英文图纸的经验与同行们交流。 1标题栏 英文工程图纸的右下边是标题栏（相当于我们的标题栏和部分技术要求），其中有图纸名称（TILE）、设计者（DRAWN）、审查者（CHECKED）、材料（MATERIAL）、日期（DATE）、比例（SCALE）、热处理（HEAT TREATMENT）和其它一些要求，如： 1)TOLERANCES UNLESS OTHERWISE SPECIFIAL 未注公差。 2)DIMS IN mm UNLESS STATED 如不做特殊要求以毫米为单位。 3)ANGULAR TOLERANCE±1°角度公差±1°。 4)DIMS TOLERANCE±0.1未注尺寸公差±0.1。 5)SURFACE FINISH 3.2 UNLESS STATED未注粗糙度3.2。 2常见尺寸的标注及要求 2.1孔（HOLE）如： （1）毛坯孔：3"DIAO+1CORE 芯子3"0+1; （2）加工孔：1"DIA1"; （3）锪孔：锪孔(注C＇BORE=COUNTER BORE锪底面孔); （4）铰孔：1"/4 DIA REAM铰孔1"/4; （5）螺纹孔的标注一般要表示出螺纹的直径，每英寸牙数（螺矩）、螺纹种类、精度等级、钻深、攻深，方向等。如： 例1.6 HOLES EQUI-SPACED ON 5"DIA (6孔均布在5圆周上（EQUI-SPACED=EQUALLY SPACED均布） DRILL 1"DIATHRO＇ 钻1"通孔（THRO＇=THROUGH通） C/SINK22×6DEEP 沉孔22×6 例2.TAP7"/8-14UNF-3BTHRO＇ 攻统一标准细牙螺纹，每英寸14牙，精度等级3B级 （注UNF=UNIFIED FINE THREAD美国标准细牙螺纹） 1"DRILL 1"/4-20 UNC-3 THD7"/8 DEEP 4HOLES NOT BREAK THRO钻 1"孔，攻1"/4美国粗牙螺纹，每英寸20牙，攻深7"/8,4孔不准钻通（UNC=UCIFIED COARSE THREAD 美国标准粗牙螺纹）