受限空间内空心锥形喷雾-横流掺混规律

在自建的冷态横流-旋流喷雾两相掺混系统实验台上,采用PIV测量了掺混通道内气液两相掺混过程中液滴群的运动特性,获得了掺混流场中不同位置的液滴分布图像与流场结构特性。实验段结构为方腔（横截面尺寸为95 mm×95 mm）,喷嘴采用空心锥形雾化喷嘴。对影响掺混效果的主要参数（横流速度、喷嘴雾化压力、喷嘴雾化粒径）进行了详细研究,绘出了最佳掺混效果下各参数关系曲线。掺混过程主要受不同尺度的旋涡结构影响,液滴多富集于旋涡边缘,稳定的大尺度涡不利于掺混。提高掺混效果的途径即是避免流场中出现稳定的大尺度旋涡结构,采用喷嘴前倾布置、增加喷嘴个数、确定合适的横流速度均是提高掺混效果的有效途径。分析方法与研究结果为工程实际应用中掺混室结构的设计及掺混性能的改进提供了依据和参考。     

湿法脱硫雾化喷嘴特性实验研究

利用FAM激光颗粒测量仪,以水为工质对撞击流燃煤烟气湿法脱硫装置中采用的旋涡压力喷嘴的雾化特性进行了实验研究,测量了不同压力下液体雾化粒子的平均粒径和粒径分布,讨论了压力对雾化特性的影响,得出了压力和喷片结构尺寸对雾化特性的影响规律。     

旋涡式压力喷嘴雾化性能的研究

本文研究了旋涡式压力喷嘴雾化所得的液滴大小及其分布与压力的关系,流量及雾化角与压力的关系,以及喷雾速度和空气芯的形成和对料雾的影响。     

旋涡压力喷嘴及其在流化床喷雾造粒中的应用

研制了一种旋流室为半空心球形的旋涡压力喷嘴 ,具有结构紧凑、零部件少、旋流效率高、高速流道短、摩擦损耗小、雾炬张角大等优点。应用于流化床喷雾涂布造粒 ,在节省动力和单喷嘴覆盖面积大从而可减少喷嘴数量等方面显示出优越的性能。     

压力喷雾分散模型初探

本文分析了旋涡式压力喷嘴的雾化机理,研究了液膜的受力情况,指出了液膜的分裂条件,推导出计算液滴直径的公式,其计算结果与实验数据较为吻合。     

蒸汽喷射器用双喷嘴结构性能的数值研究

运用CFD数值模拟的方法研究了第二喷嘴进出口截面大小对喷射效率的影响,并对比研究了不同工作流体压力下普通喷嘴结构和双喷嘴结构对蒸汽喷射器操作性能的影响。计算结果表明,在相同的操作条件下,双喷嘴结构能有效地提高喷射器的喷射系数。同时,第二喷嘴进出口截面以及第二喷嘴出口长度存在一最佳值,对应于最大喷射系数。并且这种喷嘴结构能有效改善由于工作流体压力降低而造成的设备操作性能恶化,提高蒸汽喷射器运行的稳定性。     

基于Fluent的喷嘴型式对干冰清洗影响的模拟仿真

喷嘴作为干冰清洗系统的关键部件之一,其形状、结构形式及内部流场的分布对清洗效果都有很重要的影响。通过Fluent模拟软件,针对不同结构形式的喷嘴进行建模计算,模拟研究得到了圆形喷嘴和方形喷嘴的压力场、速度场及粒子分布情况。研究结果表明:喷嘴出口处的压力远大于大气压力,气体在喷嘴出口处产生膨胀,在环境中产生激波现象。通过改变喷嘴结构形式,方形变圆形,气体射流速度在环境中衰减变缓,激波传输距离增加,气体湍动程度增大。     

Y型油喷嘴混合孔内压力特性的实验研究

本文以压缩空气和变压器油为工质对Y型油喷嘴混合孔内压力特性进行了实验研究。研究结果表明,对于结构已确定的油喷嘴,影响混合孔内压力的运行因素主要是油压(P1),气压(P2)及两者差值(P1-P2)。实验测得了相同雾化气压下不同油压时混合孔内压力的变化值,并利用数理统计的方法,整理出了这种油喷嘴混合孔内压力随油压变化的关系式。从统计关系式及实验数据相关线图的比较可以看出,两者的变化关系是非线性的。实验还测得了相同油压条件下不同雾化气压时,混合孔压力随气压的变化值,整理出了混合孔压力随气压变化的关系式。从统计规律及实验数据相关线图分析比较看出,两者的关系为线性关系。本文测得的Y油喷嘴混合孔内压力特性变化关系式,为这类喷嘴的流量特性的理论研究及设计应     

空气助力改善气化炉激冷室喷嘴特性的实验研究

设计了4种不同结构的用于气化炉激冷室内喷雾激冷的压力雾化喷嘴,采用马尔文激光粒度分析仪和数码单反照相机分别测量了不同压差、不同水流量等工况参数下的液滴粒径(SMD)D32分布和雾化角变化规律,并对4种喷嘴进行了优化选型。研究结果表明:雾滴粒径随压力的增加而减小,随水流量的减小而减小,空气助力可以明显改善液滴的雾化质量;雾化角随压差的增大先增大后趋于平缓;当压差增大到0.4 MPa时,雾滴粒径、雾化角等参数的变化渐趋平缓。通过比较气化炉激冷室中4种压力式雾化喷嘴的测量结果,1-2号内混式空气雾化喷嘴在4组喷嘴中具有最好的雾化效果,当气压为0.8 MPa,水流量为20 L/h时,SMD极小值为16,因此优选出喷嘴1-2作为气化炉激冷室冷模实验的定型喷嘴。     

喷动床脱硫压力旋流喷嘴的雾化性能

雾化喷嘴是半干式喷动床的关键部件之一,其雾化性能直接影响脱硫效率。为了得到喷嘴雾化的详细信息,用激光粒度测试仪对空心锥压力旋流式喷嘴和实心锥压力旋流式喷嘴雾化性能进行了实验研究,得出不同类型、不同孔径的喷嘴的流量,索太尔直径DSM,雾滴粒径分布DSP等与压力的关系。实验表明:流量与压力平方根成正比关系;DSM与压力为e函数的单调减函数关系;实心锥喷嘴出口直径越大,雾滴粒径平均分布(■)越小,粒径分布范围越窄,雾化性能越好,空心锥喷嘴则变化不明显;压力增大,实心锥喷嘴的DSP变大,雾滴粒径在压力低时分布比较均匀。     

水力旋流器类组合涡分析及节能原理研究

根据旋涡运动基本理论以及水力旋流器流场具有类组合涡结构的特点 ,推导出了关于压力降和能耗系数等的理论公式 ,分析了水力旋流器内各种能耗的产生机理 ,提出了若干节能措施和设想。     

射流撞击过程中的高频压力脉动特性

引　言利用两束射流相互撞击或单射流撞击靶在微细颗粒制备、多相流快速微观混合及团聚颗粒单分散过程中具有特殊优点。用作预混合器或反应器 ,能够强化微细颗粒的成核与生长环境在微观尺度上的均匀性 ,尤其对于快速反应体系 ,可实现液液或液固多相流快速微观混合 ,有效控制反应过程和产物指标 .Ｍａｈａｊａｎ等[1] 利用两束撞击流实现流体的快速微观混合以合成超细微粉 ,并用萘酚与重氮苯磺酸两步反应表征两束撞击流体数十毫秒的微观混合时间 ,关联微观混合时间与射流速度的关系 ,通过控制射流的微观混合时间控制合成超细微粉的粒度分布 .…     

Computational Investigation of an Industrial Cyclone Separator with Helical‐Roof Inlet

An industrial cyclone separator with helical‐roof inlet TsN‐11 has been numerically investigated as to pressure and flow field, pressure drop, fractional efficiency, and particle trajectories inside the cyclone. The turbulence was modeled with Reynolds stresses and large eddy simulations (LES) based on three different subgrid‐scales (SGS). The results with the different setups were compared to experimental data from previous studies. For a proper calculation of the flow field, LES combined with a dynamic SGS model was used for predicting cyclone performance. Individual particles were tracked through the unsteady flow field using the Lagrangian approach. The results of the numerical calculations of the tangential and axial velocity, pressure drop, and cut size are in good agreement with experimental measurements.     

Large eddy simulation of flow through a streamwise-periodic structure

We present a dynamic large eddy simulation of flow in a periodic open-cell structure in the turbulent regime. The flow domain is represented by a tube with inner diameter of 7 mm with integrated highly porous media. Simulations were performed for three different Reynolds numbers ranging from 1200 to 4500 based on the empty tube diameter. The obtained results were compared to experimental data for which measurements were performed downstream of the same periodic geometry manufactured from a transparent material by stereolithography. The measured pressure drop and turbulence statistics compare well to the results of the large eddy simulations. The numerical results give an insight into the forced convection mechanism within the porous media and enhance the understanding of flow through foamlike structures. Furthermore specific geometric details like the influence of the ligament shape of the porous material can be investigated applying this technique.     

电涡流制动器在卧螺离心机差转速定值控制中的应用

介绍了电涡流制动器的结构和特性，以及由电涡流制动器、数字转速表、ＰＩＤ调节器和程控稳压稳流电源构成的卧螺离心机差转速定值控制装置。     

浅谈涡流检测技术在承压特种设备检验中的应用

涡流检测技术与射线检测、超声波检测、磁粉检测、渗透检测，同属JB／T4730-2005《承压设备无损检测》标准里的五大常规无损检测技术。受技术条件的制约，涡流检测按术并未在承压特种设备检验中广泛应用。文章通过结合涡流检测按术的特点与承压特种设备检验的实际，探讨涡流检测技术在锅炉、压力容器、压力管道等承压特种设备检验中的应用。     

预测气液分层流含气率及压降的模型

The time-dependent liquid film thickness and pressure drop were measured by using parMlel-wire conductance probes and capacitance differential-pressure transducers. Applying the eddy viscosity theory and an appropriate correlation of interfacial sear stress,a new two-dimensional separated model of holdup and pressure drop of turbulent/turbulent gas-liquid stratified flow was presented. Prediction results agreed well with experimental data.     

Mass transfer and pressure drop performance of turbulence promoters in electrochemical cells

Mass transfer and pressure drop behavior of turbulence promoters in rectangular channel is determined using the electrochemical method at the macroscopic and microscopic scales simultaneously.The local mass transfer and fluid shear stresses experimental distributions are presented for different types of cylindrical and mesh-type eddy promoters located in the middle of the channel or against an electrode in an electrochemical cell, and show the quantitative dependence between both distributions.The average mass transfer and pressure drop results are used to test the validity of a model based on application of a mass-momentum transfer analogy to flow over a rough surface.     

Investigation of flow structures and transport phenomena in bubble columns using particle image velocimetry and miniature pressure sensors

The bubble column reactors are usually operated in a heterogeneous regime where the liquid phase turbulence is generated by the bubble motion and the velocity gradients in the mean motion. The turbulent flow comprises of fluid elements moving in a random fashion with different sizes and energies, called ‘flow structures’. Both the large and small scale flow structures within a reactor play an important role in governing the local momentum, heat and mass transfer. The current work is focused on the estimation of the time averaged flow pattern and flow structures. The experimental data has been collected using miniature pressure sensors, PIV+shadowgraphy and LDA. The data was subjected/analyzed to/with multipoint linear stochastic estimation (MLSE), wavelet transforms, image processing and eddy isolation (EIM) to identify the flow structures. Two bubble columns have been used: a narrow rectangular (2D) column and a cylindrical (3D) column. Wavelet transforms (WT) were applied to isolate individual structures from PIV data to get their shape, size and energy in the 2D column. MLSE has been used to obtain the velocity profiles from pressure fluctuation signals. This data, augmented by PIV and LDA data, is subjected to WT and EIM to get the eddy age and its energy distribution. The data of the eddy shape size and energy was used to predict the mass transfer coefficient in the cylindrical bubble column as a test case. Overall, in this work we present a methodology to utilize the experimental data to get a better insight of the dynamics of flow structures, and propose a path forward for the deeper understanding of transport phenomena in bubble columns.