管道气体助送的加气装置试验研究

针对绞吸式挖泥船排泥输送距离往往不能满足有关于工程需要的情况,采用了管道加气减阻以延长排距的方法,其中的加气方式和装置是影响减阻及排距的重要因素.研究了管道输送加气减阻的机理,对比分析了小孔多孔加气、双级喉管喷射加气、微孔材料渗气加气和旋转射流水气混合喷射加气的试验结果,得到了旋转射流水气混合喷射加气效果最好的结论,并设计了旋转射流水气混合喷射喷嘴.     

水气射流通风器参数对吸风性能影响的实验研究

分析了水气射流通风器的工作原理,介绍了理论确定水气射流通风器结构参数可应用的资料及实验用水气射流通风器的制作,建立了水气射流通风器实验系统,进行了不同吸风管结构、喉嘴距、喷嘴型式及水压对吸风量影响的正交试验,同时对实验结果进行了分析.实验结果表明,与射流泵对照,水气射流通风器最佳优参数既有其共同之处,也有其不同点.     

自激吸气式脉冲射流装置机理的试验和理论研究

为了揭示自激吸气式脉冲射流装置的脉冲产生机理，通过试验获取了装置典型测点压力、靶心冲击压力的时间变化过程和内部水气流动图像，分析了工作压力1.4～1.8 MPa和围压0～0.15 MPa下冲击压力的平均值、脉冲频率和脉冲效果，并结合水气两相流理论研究了装置内部的水气流动结构和水气流动过程。结果表明，围压不变和工作压力越高，冲击压力平均值越大，围压0.1 MPa时，增加幅度为51%；工作压力不变和围压越高，冲击压力平均值越小，工作压力1.8 MPa时，降低幅度为63%；不同工作压力和围压的冲击压力脉冲频率变化不大，在0.5～1.0 Hz之间，但工作压力越高或围压越低，脉冲效果越好；装置内部的碰撞体附近和射流核两侧为亚声速水气流动，下喷嘴入口为超声速水气流动；装置在内部负压区域形成了泡状水气涡团，吸气量、碰撞体测点压力和冲击压力的时间变化过程与典型时间水气涡团的旋转速度和气泡直径之间具有明显的相互影响关系。     

环形水气自激振荡射流泵提高传能效率分析与计算

提出环形自激振荡水射流概念,使用Realizable k-ε湍流模型对环形射流泵和环形自激振荡射流泵内部流动进行了仿真计算,结果表明:环形自激振荡射流泵提高了10%左右的吸气量;对两种射流泵内部流场进行了稳态计算,分析了面积比与吸气量之间的关系;通过瞬态计算阐述了下喷嘴处水气相间不稳定边界层的周期性运动发展过程。根据稳态和瞬态的模拟计算结果,总结出环形自激振荡射流提高对气体的卷吸效果的原因。这为提高射流泵传能效率,研制新型环形自激振荡水气射流泵奠定了理论和应用基础。     

消防水炮喷嘴射流特性分析

消防水炮在现代消防灭火作战中起着越来越重要的作用,喷嘴是消防水炮产生射流的关键部件,其结构参数直接影响消防水炮的射流性能。为研究消防水炮喷嘴结构参数对射流特性的影响,该文设计了一种直流喷雾两用型消防水炮喷嘴。采用数值计算方法,利用Fluent软件对喷嘴直流射流和喷雾射流进行了仿真分析。同时具体分析了喷嘴出口直线段长度、喷嘴出口圆环面积、喷嘴喉管结构以及喷嘴芯结构等结构参数对射流特性的影响,得出了最佳的喷嘴结构参数。所设计的直流喷雾两用型喷嘴安装于移动式消防水炮上,初步实验验证射流效果较好。相关结论为消防水炮灭火提供了一定的理论指导。     

几种异形喷嘴喷射的液气射流泵性能试验研究

液气射流泵常作为一种射流混合设备而广泛应用,为适应不同喷射需要以形成不同的两相混合特性,本文研究了几种异形喷嘴情况下液气射流泵的水力性能,并与当量面积圆形喷嘴喷射情况对比。固定喉管长度及内径不变,更换3种当量面积比的喷嘴进行性能试验,结果表明:对于吸入室形成一定的真空度,圆形喷嘴形式喷射与异形喷嘴喷射比较,需要的工作压力较低。异形喷嘴在较大面积比时,形成的液气射流泵最大气液比大于圆形喷嘴,从射流发散碎裂分析,异形喷嘴能减小喉管长度,本文结论为液气射流泵内气液混合的应用提供了新的射流方法。     

超大面积比射流泵性能的数值模拟与流动分析

对超大面积比射流泵进行了三维数值模拟研究。采用Realizable k-epsilon湍流模型和标准壁面函数法,对面积比分别为57.4和60.05的单喷嘴射流泵进行了数值模拟和结构优化。基于数值模拟结果,对泵内压力和速度分布进行了分析。试验研究表明:对于超大面积比射流泵,随着流量比的增加,被吸流体阻力增加较快,导致压力比下降趋势不同于常规面积比射流泵的线性下降,从而呈现抛物线形式;随着面积比的增加,最高效率点右移,所需最优喉管长度也增大;对于超大面积比射流泵,工作流体进入喉管后仍有足够的空间进行径向扩展,其内部流场更近似于无限空间伴随射流。     

基于交互正交设计的射流曝气机吸气性能影响因素研究

针对射流曝气机的吸气性能受多种因素影响且这些因素之间又相互作用的实际情况,以交互正交试验为指导,采用数值模拟的方法对射流曝气机的吸气性能进行了研究。考察了面积比、喉嘴距、喉管长径比、喉管收缩角、吸入角等因素及其交互作用对射流曝气机吸气性能的影响。通过极差分析和方差分析研究了各因素及其交互作用对吸气性能影响的主次顺序和显著性。结果表明,影响射流曝气机吸气性能的因素中,面积比对射流曝气机吸气性能影响程度最大,吸入角对射流曝气机吸气性能影响程度最小。面积比,喉嘴距,喉管长径比以及面积比与喉管长径比的交互作用对射流曝气机吸气性能影响高度显著(置信度P=99%)。研究结果可为新型射流曝气机的设计提供理论和实际参考。     

自循环射流式喷灌泵喷嘴的试验研究

循环射流自吸系统是一种自吸快、对泵外特性影响小的新型射流式自吸装置.其中喷嘴的结构及尺寸直接影响到泵的自吸时间.对不同尺寸参数的喷嘴进行自吸时间性能试验,并探索新结构形式的喷嘴有助于进一步分析问题,改进设计.试验结果表明,喷嘴直径是影响喷嘴自吸效果的主要因素.对同一泵体,喷嘴直径存在最佳值,直径大于或小于最佳值都会增加泵的自吸时间.喷嘴锥角及流道长度对泵的自吸时间略有影响.双流道喷嘴的自吸时间要明显长于单流道喷嘴,泵体自吸时间随流道间距增加而变长.     

高压水除鳞喷嘴结构参数对喷嘴射流性能的影响

为了进一步研究高压水除鳞喷嘴的射流性能,优化喷嘴的结构参数,选取出口扩张角、锥孔深度、入口收缩角作为参考因素,以喷射角和射流流量作为评价指标,对喷嘴各参考因素对射流性能的影响进行了仿真分析。结合正交试验的方法,对喷嘴各结构参数及其交互作用对其性能影响的显著性及重要性次序进行分析,获得最优的参数组合并对其进行了实验验证。结果表明：出口扩张角的增大会使喷射角减小但会使射流流量增加,锥孔深度的增加可以较为全面地提升喷嘴的射流性能,收缩角的增大会使得喷嘴的射流性能减弱,喷嘴的除鳞效果变差;3个参考因素中锥孔深度是对射流性能影响最大的因素;当出口扩张角为80°、锥孔深度为8 mm、入口收缩角为65°时喷嘴的射流性能最优。通过将参数优化后的喷嘴的实验结果与原始喷嘴的实验结果对比发现,优化后喷嘴的喷射角由原始值35.7°提升至44.1°,射流流量的大小由原始值10.17 L/min提升至28.3 L/min。     

硬岩掘进机高压水耦合破岩影响因素实验研究

硬岩掘进机(TBM)在硬岩甚至超硬岩段掘进时,采用高压水射流辅助破岩成为一种有效提高破岩效率的新的研究方向。由于高压水射流破岩受诸多因素影响,作用规律复杂,其破岩机理一直未能被准确揭示。主要利用正交实验方法研究水射流压力、喷嘴直径、喷嘴移动速度对破岩沟槽深度与沟槽宽度的影响,同时结合刀盘贯入度优化水射流压力、喷嘴直径、移动速度等关键参数,探索高压水射流与岩石耦合破岩规律,为进一步揭示破岩机理提供依据。     

Effect of suction nozzle modification on the performance and aero-acoustic noise of a vacuum cleaner

The suction nozzle of a vacuum cleaner was modified to enhance the power performance and to reduce the airflow-induced acoustic noise. The suction power efficiencies of the vacuum cleaner were measured for various nozzles: (1) original nozzle, (2) original nozzle with modified trench height, (3) original nozzle with modified connecting chamber, and (4) a combination of (2) and (3). In addition, the suction pressure and sound pressure level around the suction nozzle were measured to validate the reduction of acoustic noise. The power efficiency and mean suction pressure increased when the trench height of the suction nozzle was increased. This was attributed to the suppression of the flow separation in the suction channel. Modification of the connecting chamber in the original nozzle, which had an abrupt contraction from a rectangular chamber into a circular pipe, into a smooth converging contraction substantially improved the suction flow into the connecting pipe. When both modifications were applied simultaneously, the resulting suction nozzle was more effective from the viewpoints of aerodynamic power increase and sound pressure level reduction.     

基于CCD激光测微传感器的螺旋焊管周长在线检测技术

针对大尺寸螺旋焊管周长在线检测的难题,提出了一种基于CCD激光测微传感器的技术方案.该方案利用4组CCD测微传感器对螺旋焊管截面2个正交外径进行数据采集,结合螺旋焊管卷焊速度,构造截面点坐标,通过最小二乘椭圆算法对焊管截面圆进行拟合,计算出截面椭圆的周长,作为该段螺旋焊管中心截面周长的最优估计值.搭建了一套实验系统,对...     

An experimental investigation on the pressure characteristics of high speed self-resonating pulsed waterjets influenced by feeding pipe diameter

The destructive power of a continuous waterjet issuing from a nozzle can be greatly enhanced by generating self-resonance in the nozzle assembly to produce a Self-resonating pulsed waterjet (SRPW). To further improve the performance of SRPW, effects of feeding pipe diameter on the pressure characteristics were experimentally investigated by measuring and analyzing the axial pressure oscillation peaks and amplitudes. Four organ-pipe nozzles of different chamber lengths and three feeding pipes of different diameters were employed. Results show that feeding pipe diameter cannot change the feature of SRPW of having an optimum standoff distance, but it slightly changes the oscillating frequency of the jet. It is also found that feeding pipe diameter significantly affects the magnitudes of pressure oscillation peak and amplitude, largely depending on the pump pressure and standoff distance. The enhancement or attenuation of the pressure oscillation peak and amplitude can be differently affected by the same feeding pipe diameter.

     

Research on a new type of squirt gun for cleaning

A new type of squirt gun, which is similar to a jet pump and can better induce formation of cavitating water jet, is presented. The scheme of design of this new squirt gun is discussed. An investigation of effect of different area ratio, length of throat pipe, standoff distance, nozzle type, and suction air amount on decontamination ability was made by experiments. This new squirt gun is experimentally compared with conventional one. Test data indicate that under the same operating condition the new type of squirt gun have the advantages of better decontamination ability, lower energy consumption and less water consuming over conventional one. The optimum operating parameters of this new device are put forward on the basis of test results. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju Korea, October 16–19, 2007.     

一种内螺旋管道机器人

提出了一种内螺旋管道机器人(简称内螺旋机器人）。设计了该机器人的结构,建立了机器人的动力学方程,数值计算了机器人在管道内运行时管道内壁所受的压力、机器人的轴向推进力和液体对机器人的周向阻力矩。结果表明,当驱动为外磁场驱动时,内螺旋机器人轴向推进力和周向阻力矩都会增大,但对管道壁的损伤也会增大。以机器人轴向推进力和能效指标为优化目标,采用正交优化方法得到一组最优的内螺旋槽几何参数。根据内螺旋机器人的工作原理,设计制造了内螺旋驱动样机,该样机在充满201甲基硅油管道中的运行实验证明了内螺旋机器人的可行性。提出的内螺旋机器人表面光滑,能悬浮运行,对管壁的损伤小,可用于人体内腔的微细管道中。     

淹没式喷嘴反推力测量及其系柱试验装置设计

喷水推进具有噪声低、空泡性能好、易于矢量调节等优点，已成为水下机器人（ROV）推进技术的研究热点。喷水推进依靠喷嘴将泵产生的压力能转化为高压水动能，产生的反推力是压力和黏性阻力作用在高压腔以及喷嘴上的综合效果，该反推力的大小是推进性能研究的重点。对几种不同形状和参数的喷嘴反推力进行仿真和试验对比。采用Fluent软件对喷嘴进行流场内部仿真，并且通过后处理文件计算出喷嘴的反推力大小。现有测量喷嘴反推力的相关试验装置与实际工况存在较大差异，根据螺旋桨系柱推力试验方法，提出并设计一种新的喷嘴反推力测试装置。该试验装置动力由岸基高压海水泵源供给，通过溢流阀调节喷嘴入口压力，喷嘴固定在ROV框架上，利用拉力传感器测量ROV框架在喷嘴射流驱动下的系柱拖力，进而得到喷嘴射流反推力与输入压力的关系。该试验装置为在水淹没条件下研究喷水推进系统提供了试验条件。     

Performance curve available for non-steady flow through Venturi-like reverse flow diverter

A reverse flow diverter (RFD) consists of a driving nozzle, a diffuser, and a suction gap that separates the nozzle and diffuser. Thus, the RFD is a Venturi-like fluidic component with three ports. The jet flow emanating from the driving nozzle exit can entrain the ambient fluid and transport it to a high elevation. During this time, the flow through the RFD is non-steady, which makes it difficult to measure the flow depending on the pressure drop. In this study, a series of tests was carried out to evaluate this fluid flow with different contraction ratios, suction gap lengths, fluid properties, inlet flow rates, and inlet pressures. A performance curve was formulated that can be expressed as an exponential equation correlating the non-dimensional Euler number, pressure ratio, and suction factor. The performance curve is not affected by the driving nozzle exit diameter and suction length of the RFD. The performance curve makes it possible to measure the flow out of a RFD depending on the pressure drop.     

磨料水射流切割混凝土的深度预测模型

在对磨料水射流切割混凝土分析基础上,应用BP人工神经网络理论,建立磨料水射流切割基于射流压力、靶距、磨料粒径、磨料流量、磨料喷嘴直径、磨料喷嘴长度及横移速度等射流参数的深度模型,通过模型预测结果与实验结果的比较,验证模型具有一定的精度,为实际运用和进一步研究提供参考。     

Experiment and Numerical Simulation of Free Water Jet by a Central-body Nozzle

The recent research about cavitation jet mainly focuses on the organ-pipe nozzle and triangular nozzle.The research content mainly includes the optimized design about the structure of nozzles,the observation and flow analysis about the cavitation jet in the water,and the theory of rock attacked by the cavitation jet,while the energy characteristic of the free jet is not studied yet.In China,the research about the central-body nozzle is almost empty.For the purpose of studying the energy characteristic and the structure of free water jet discharged from central-body nozzle,an experiment with phase Doppler particle anemometry(PDPA) technology is carried out to measure the free water jet flow,which is produced by a central-body nozzle under the jet pressure of 15 MPa.While five sections with different axial distances from the nozzle outlet are selected for data process and analysis,the axial and radial velocity and the droplets of the particle size are studied.Meanwhile,numerical calculation of corresponding flow field is conducted by using volume of fluid(VOF) multiphase model,and the jet flow feature is discussed.The experimental and calculating results show that the axial velocity of high speed jet flow dissipates slowly in the air,and the core area and diffused area are discovered.The diameter of droplet in the core area is small,and jet energy is concentrated,while in the diffusion area,water is mingled with ambient air and radial velocity is relatively large.Obvious low-pressure area exists behind the central body and potential cavitation may occur in that area.The proposed research reveals the energy characteristic of free jet discharged from central-body nozzle,provides the theoretical basis for preestimating erosion feature of the central-body nozzle and also the theoretical foundation for revealing the mechanism of erosion.