Effects of the inlet particle spatial distribution on the performance of a gas-solid cyclone separator

The present study was aimed at the inlet particle spatial distribution of a gas-solid separator with high solid loading and investigated its effects on cyclone performance and the inner flow pattern.The flow fields of a cyclone with different rectangular particle flow areas on the inlet surface were numerically simulated using a four-way coupling method.The simulated results indicate that reducing the inlet particle flow area and lowing the inlet particle position can effectively reduce the scattered particles inside the cyclone separator and enhance the separation performance.Vertically gathering the particles to the centerline can also weaken the particle back-mixing.The particles near the roof account for the swirling particle ceiling phenomenon.The inlet particle spatial distribution affects the pressure drop mainly by affecting the gas tangential velocity in the cylinder body.Moreover,compared to the hori-zontal particle distribution on the inlet surface,the vertical particle distribution has greater effects on cyclone performance.

Serpentine Inlet Performance Enhancement Using Vortex Generator Based Flow Control

In order to provide the line-of-sight blockage of the engine face for an advanced Uninhabited Combat Air Vehicle（UCAV）, a highly curved serpentine inlet is proposed and experimentally studied. Based on the static pressure distribution measurement along the wall, the flow separation is found at the top wall of the second S duct for the baseline inlet design, which yields a high flow distortion at the exit plane. To improve the flow uniformity, a single array of vortex generators （VGs） is employed within the inlet. In this experimental study, the effects of mass flow ratio, free stream Mach number, angle of attack and yaw on the performance of a serpentine inlet instrumented with VGs are obtained. Results indicate： （1） Compared with the baseline serpentine design without flow control, the application of the VGs promotes the mixing of core flow and the low momentum flow in the boundary layer and thus prevents the flow separation. Under the design condition, the exit flow distortion （-↑△σ0） decreases from 11.7% to 2.3% by using the VGs. （2） With the descent of the free stream Mach number the total pressure loss decreases. However, the circular total pressure distortion increases. When the angle of attack rises from - 4° to 8°, the total pressure recovery and the circular total pressure distortion both go down. In addition, with the increase of yaw the total pressure recovery is fairly constant, while the circular total pressure distortion ascends gradually. （3） When Mao = 0.6-0.8, a = -4°-8° and β = 0°-6°, the total pressure recovery varies between 0.936 and 0. 961, the circular total pressure distortion coefficient varies between 1.4 % and 5.4 % and the synthesis distortion coefficient has a ranges from 3.8 % to 7.0 %. The experimental results confirm the excellent performance of the newly designed serpentine inlet incorporating VGs.

Effect of inlet configuration on hydrocyclone performance

Inlet configuration is important parameter of hydrocyclones,which has great impact on the classification performance.The effects of inlet configuration on the precise classification were studied by computational fluid dynamics under variouscombinations of inlet diameter and inlet velocity.The results showed that a high sharpness of classification was achieved withspecific inlet diameter and inlet velocity.The separation efficiency of the coarse particles by underflow significantly decreased wheninlet had an oversize diameter owing to a stronger short-circuit flow.It is resulted from the chaotic flow and the stronger pressuregradient around the vortex finder.Meanwhile,a low separation efficiency of the fine particles by overflow was achieved when inletvelocity was high,which indicated a low sharpness caused by the overlarge centrifugal force.

Study of Structural Parameters of the Inlet of Downhole Hydrocyclones

Three different inlets of hydrocyclone are studied in combination with the construction of a dowrahole system and hydrocyclone. By comparing the relationship between the inlet structure ＆ dimensional parameter of hydrocyclone and separation efficiency ＆ pressure loss, the highest efficiency is obtained from the inlet of an involute curve with increasing depth-width ratio from the three types, in which the separation efficiency and pressure loss all drops slowly, for the length of the channel decreases, while it drops rapidly in the other two. The flow guiding ability of the inlet affects the separation efficiency greatly, so the corresponding involute type of inlet of hydrocyclone fits for downhole oil-water separation is optimized, which serves as a basis for the structural design of downhole hydrocyclone.

ELECTROSTATIC PSEUDO LIQUID MEMBRANE SEPARATION TECHNOLOGY

Electrostatic pseudo liquid membrane（ESPLIM）separation process,developed recently in this laboratory,is a novel chemical separation technology.ESPLIM is an interdisciplinary technology evolved from thecombination of solvent extraction,liquid membrane and electrostatic techniques.It can be used to separate,purify and concentrate specific solutes from aqueous solutions.Therefore,it is suitable for the recovery ofvaluable metals from aqueous solutions in the field of hydrometallurgy（including nuclear fuel cycles）and forthe processes of waste water treatment.This paper discusses the basic principles of this new technology.Taking the extraction of Co2+by D2EHPA as an example,effects on metal extraction of electrical fieldstrength,extractant concentration and the flow ratio of feed to stripping solution have been studied.Exper-iments show that the once through extraction efficiency of Co2+can reach 99% while Co2+can be concen-trated up to 40—50g/L in the stripping solution.

Investigation of Separated Flow around a Curved Air Intake

This paper prcsents an investigation of two-dimensional separated flow in and around a submerged curved intake by experiment and computation. The eniptic Navier-Stokes equations are employed which are discreted in body-fitted coordinate system by the SIMPLE method. The results show that the flow separation exists near and behind the inlet and the duct flow is distorted. Comparison between the computational and experimental data is fairly satisfactory.

Speech Separation Methodology for Hearing Aid

In the design of hearing aids(HA),the real-time speech-enhancement is done.The digital hearing aids should provide high signal-to-noise ratio,gain improvement and should eliminate feedback.In generic hearing aids the perfor-mance towards different frequencies varies and non uniform.Existing noise can-cellation and speech separation methods drops the voice magnitude under the noise environment.The performance of the HA for frequency response is non uni-form.Existing noise suppression methods reduce the required signal strength also.So,the performance of uniform sub band analysis is poor when hearing aid is con-cern.In this paper,a speech separation method using Non-negative Matrix Fac-torization(NMF)algorithm is proposed for wavelet decomposition.The Proposed non-uniformfilter-bank was validated by parameters like band power,Signal-to-noise ratio(SNR),Mean Square Error(MSE),Signal to Noise and Dis-tortion Ratio(SINAD),Spurious-free dynamic range(SFDR),error and time.The speech recordings before and after separation was evaluated for quality using objective speech quality measures International Telecommunication Union-Telecommunication standard ITU-T P.862.

进液量对气举式同向出流旋流器分离特性影响

为了提高旋流器的分离效率,提出一种气举式同向出流水力旋流器结构,通过注气的方式将旋流器轴心的油核举升至溢流口,加速油核向溢流口方向运动,进而提升旋流器的分离性能。基于雷诺应力模型(Reynolds Stress Model,RSM)与多相流模型(Mixture),模拟计算了入口进液量对气举式同向出流旋流器分离性能的影响,分析了进液量对旋流器内气核形态、速度场分布以及分离性能的影响规律。数值模拟结果表明:进液量分布在(3.6~8.4)m^(3)/h范围内时,随着进液量的增加,注气口处压力逐渐增大,混合液内各相介质的轴向速度与径向速度均有显著提高,旋流器轴心处的油相体积分数明显增大,旋流器的分离效率从64%增至77.9%。

直升机整体式惯性粒子分离器研究现状

整体式惯性粒子分离器是一种直升机进气防护装置,其性能优异、应用广泛,对于保护直升机发动机、延长其使用寿命具有重要意义。本文从4个方面对整体式惯性粒子分离器的研究现状进行归纳总结,包括:总结了现有直升机进气防护装置的类型及相关气动参数,梳理了整体式惯性粒子分离器现有的研究方法及取得的相关成果,分析了影响整体式惯性粒子分离器工作性能的因素,并展望了整体式惯性粒子分离器未来的发展方向。研究成果可为今后开展整体式惯性粒子分离器研究及优化设计提供一定参考。

侧式进/出水口偏流出流下的大涡模拟

实际工程中受地形地质条件影响,引水洞在水平上存在转角,导致出流工况来流不均,进/出水口内部紊流特性的复杂程度显著提升。利用大涡模拟对某带水平弯段抽水蓄能电站侧式进/出水口进行数值计算,其流速、概率密度分布与模型试验吻合较好。结果表明:偏流出流下进/出水口各流道分流比分别为0.64、0.81、1.26和1.29,水平方向流速分布极为不均;垂直方向主流靠近中下部,垂向雷诺切应力在扩散段内呈一正一负峰值分布,该现象主要由中上部的流动分离和底部的壁面剪切造成;两中间流道的回流区高度大于两边流道,导致中间流道的拦污栅更易受到反向流速影响;流动分离使拦污栅附近存在三轴漩滚,靠近过水断面中上部和底部产生2处能量集中的低频脉动,且各流道在偏流条件下的紊动强度相比均匀来流的紊动强度分别提高11%、25%、29%、3%,不利的水流流态和较高的紊动强度可能对拦污栅造成威胁。

超声速进气道出口弯段的阻力特性数值研究

推阻匹配设计是吸气式飞行器设计的核心问题,为了获取进气道的阻力特性并降低内流阻力,提高吸气式飞行器的总体性能,采用数值方法对超声速双侧布局进气道的冷流阻力特性开展研究,对比分析了不同转弯长度、转弯角度、扩张比下的弯段流态和阻力特性;获得了进气道内阻的分配比例及关键几何参数对弯段流场结构和进气道内阻的影响特性。结果表明:对于双侧布局的进气道,冷流条件下弯段内容易发生流动分离,存在较大的流动损失,在不产生溢流的情况下,弯段内阻占整个进气道内阻的大部分。分析发现,减小转弯角度或增加弯段扩张比均可降低进气道弯段内阻,而转弯长度与转弯半径相互影响,在给定的设计条件下,弯段内阻随转弯长度的增加先减小后增大。

翼身融合布局机体对发动机进气品质影响

为评估发动机安装后,机体是否对发动机进气存在不利影响,本文通过数值模拟方法,研究了高低速情况下BWB300机体对发动机进气品质的影响。结果表明:高速情况下,发动机前高速气流能完全满足BWB300进气需求,故BWB300机体不会对发动机进气品质造成明显影响;而低速时,由于发动机进气流量需求大且其前方气流流速低,机体表面若存在流动分离,分离气流会较易被发动机吸入,从而降低其进气品质。故对类似BWB300的上置式发动机布局飞机而言,飞发一体化设计时应避免机体表面流动分离首先发生在发动机位置附近处。

3D打印模具钢粉末处理系统的设计与模拟分析

设计了一种面向金属3D打印全过程的粉末处理系统,完成了系统整体结构设计,通过相关参数计算设计了动力装置、输送管道、供料器、分离器、筛分装置等组成部分。采用FLUENT软件模拟分析了18Ni-300模具钢粉末在系统中的流动情况。结果表明:提高粉末供应管道入口气流速度可以改善粉末在管道中的流动状态和输送效果。随着弯管弯径比的增大,粉末输送率会增加,压力损失会随之降低。减小分离器锥角会导致分离器分离效率提高,内部压力损失减小。提高废料回收管道入口气流速度可以增大筛分装置中废料的回收率。

进口雷诺数和湍流度对压气机叶栅流动特性影响

针对高空条件下,无人机发动机的压气机气动性能明显下降的问题,本文以某高亚声速压气机叶型V103为研究对象,采用数值模拟方法研究了3种雷诺数(Re=1.5×10^(5),4.5×10^(5),1.2×106)条件下,不同来流湍流度(Tu=1%,3%,5%,6%,7.5%,10%)对压气机叶栅内部流动特性的影响,分析了流动分离和转捩之间的变化关系,以及由此引起的叶型损失变化规律。研究结果表明:当湍流度不变时,随着雷诺数减小,分离泡长度增加,但分离点位置不变;当雷诺数不变,湍流度减小,层流分离点位置会提前,并且前移现象在低雷诺数下更明显;当湍流度增加,叶片表面分离泡消失,但损失仍然呈现出随着湍流度增加而增大的趋势;在不同雷诺数条件下,都存在一个对应于最小叶型损失的来流湍流度,且该湍流度随着雷诺数的减小而略有增大。本文为修正低雷诺数条件下压气机叶型损失模型和发展预测压气机高空低雷诺数效应的数值模型提供理论指导。

连续重整装置再生循环气干燥系统腐蚀分析与对策

对于催化剂再生采用干冷循环的连续重整技术,再生循环气干燥是连续重整装置中不可或缺的系统,近年来多次发生腐蚀泄漏问题,严重影响装置的长周期运行。针对4个连续重整装置再生循环气干燥系统发生的腐蚀案例,分析了系统内冷却器、分离器以及相连管道的腐蚀原因。结果发现腐蚀原因主要是酸性气露点腐蚀和循环水腐蚀。针对腐蚀现状,提出了一系列延长操作周期的控制措施:工艺设计上增加换热器壳程进出口安装倾斜角度,增加过滤器;选材上分离器及相连管道增加玻璃钢或PTFE(聚四氟乙烯)衬里,水冷器碳钢管束增加涂层防腐;操作上控制循环水水质,加强工艺参数和腐蚀情况监测。

MTO装置再生器旋风分离器操作优化模拟研究

旋风分离器是甲醇制烯烃(MTO)装置常用的气固两相分离设备,其分离效率对装置的长周期稳定运行非常重要。某0.6 Mt/a MTO装置采用高活性催化剂后,再生器烧焦主风量低于设计值,导致一级旋风分离器入口气速低,20μm以下细粉催化剂跑损量增大,催化剂消耗量增大。为此,采用计算颗粒流体力学(CPFD)软件模拟再生器四组二级旋风分离器的不同操作工况,调整旋风分离器入口面积与烟气流量改变入口气速,研究入口气速对旋风分离器压降和分离效率的影响规律。结果表明:烟气流量为42241 m^(3)/h时,封闭一组一级入口,旋风分离器入口气速提高3 m/s,旋风分离器总效率提高0.501百分点。依据模拟结果对旋风分离器提出了优化操作建议,可推广应用于其他MTO装置的操作调整。

交替静叶布局对轴流压气机气动稳定性的影响

为揭示交替静叶布局控制角区分离的流动机理,提升压气机性能,实现压气机的扩稳,采用了数值模拟方法对某高负荷跨声速压气机展开交替静叶设计研究。通过改变静叶叶尖进口几何角,调整叶片的布局方式,得到一种改叶型弯角交替静叶,在此基础上结合叶片弦长进一步优化,得到另一种改弦长交替静叶。数值研究表明:改叶型弯角交替静叶布局压气机的稳定裕度相对原型提升了34.7%,改弦长交替静叶使改叶型弯角交替静叶的压气机稳定性进一步提高,但会造成压比和效率的小幅下降,即以损失部分性能的代价换取了压气机稳定性的提升,改弦长交替静叶压气机在前者基础上将稳定裕度进一步提升了9.7%。新型的静叶布局使得相邻流道的流场结构产生差异,在周向上形成上、下角区分离交替分布的格局,促进了相邻流道出口流体的汇聚。叶型弯角的改变使角区低能流体区引入了更多高能流体,抑制了低能流体在角区堆积,提升了静叶的扩压能力。而弦长改变的同时增加了叶片前掠,阻隔了部分气流,实现了气流的重新分配,一定程度上平衡了两侧气流流量的不均匀性,从而改善了该压气机的气动稳定性。

主动流动控制下载荷分离对进气道流场的影响研究

该文针对由于工程约束载荷舱布置在进气道前方的内外流耦合载荷投放分离问题,运用计算空气动力学耦合六自由度模型和动态嵌套网格技术模拟载荷投放分离过程,并使用主动流动控制方法改善流场,分析评估有无主动流动控制时内外流耦合一体的载荷投放分离运动特性及对内流进气道流场的影响。结果表明,主动流动控制可将进气道畸变指数DC(60)由0.5612降至0.4658,主动流动控制对改善进气道流场品质有较大收益。

非轴对称静子对压气机气动性能的影响

为降低进气畸变对压气机气动性能的影响,设计了1种压气机非轴对称静子,并对设计方案开展数值模拟研究。仿真结果表明:在最高效率工况下,非轴对称静子能减小畸变区静叶的流动分离,缩小叶尖低密流区域,提升通道的流通能力,压气机的最高效率约增加0.46%,此外,畸变区叶片进口气流角得到改善,在90%叶高处的峰值气流角降低2.5°;在近失速工况下,非轴对称静子能降低畸变区静叶上半叶高的扩压因子,缩小分离范围,虽略微恶化了叶根区域流场,但压气机整体气动性能与流通能力有所提升,能够在更低的流量下工作,稳定裕度增加31.5%。

连片养殖池塘进排水分离及尾水治理设计思路

池塘养殖在我国水产养殖产业地位举足轻重,是保障我国优质动物蛋白供给、促进农业增效及农民增收的关键一环。随着社会经济高速发展,传统的、粗放式的池塘养殖模式凸显出一系列问题,对该产业的改良升级提出要求与挑战。以湖北省某集中连片2050亩养殖池塘为例,梳理了进排水分离改造和尾水治理的设计思路,通过新建沟渠和功能划分实现项目区进排水分离,解决了上游尾水排放对下游池塘用水的污染,降低养殖塘鱼害传染风险和灾害。同时以生态沟渠和藕塘湿地为主要净化单元,养殖尾水经处理后COD_(Mn)、总氮和总磷指标稳定达到《淡水池塘养殖水排放要求》(SC/T 9101-2007)二级标准,极大程度上避免养殖尾水对汉江水体水质与水环境的影响。同时本文对该类池塘进排水分离及尾水治理未来的设计、施工方向进行了展望,并提出一种适合湖北省养殖特征的尾水治理模式,以期为类似项目的设计、施工提供新的参考。