Optimization of Nozzle Design for Pulse Cleaning of Ceramic Filter

The experimental study was carried out to optimize the nozzle shape and dimension for the pulse cleaning of a ceramic filter candle. A bench scale unit of ceramic filter consisting of four commercial filter elements was used to measure the traces of the transient pressure around the nozzle and the overpressure in the filter cavity during the pulse-jet injection of pulse gas. Overpressure in the filter cavity is related to the pulse cleaning force. Nozzle design is concerned to increase the overpressure at the open end of filter element of pulse cleaning inlet, as well as to minimize the consumption of pulse gas. Convergent nozzle induces more secondary flow and generates higher pulse cleaning effect than straight nozzle. Nozzles of different convergent ratio （ratio of outlet to inlet diameter of nozzle） by changing the convergent angle and height were tested. The outlet diameter of convergent nozzle seriously influences the cleaning effect. The optimum convergent ratio increases with the increase of pulse gas pressure The nozzle position （distance of nozzle tip from the open end of filter inlet） is also important to decide the nozzle dimension. Nozzle of large outlet diameter accepts high pressure of pulse gas to provide large overpressure in the filter cavity of top position by applying long distance.

Numerical Analysis of Flow Field in Ceramic Filter During Pulse Cleaning

In the commercial utilization of rigid ceramic filters, the performance of pulse cleaning has crucial effects on the long-term stable operation. In order to get a clear insight into the nature of this cleaning process and provide a solid basis for industrial applications, the flow in ceramic candle filter was investigated. The flow in the pulse-jetspace and inside the ceramic candle is regarded as two- dimensional, unsteady, compressible flow, and numerical simulation is carried out by computational fluid dynamics. The numerical predictions of flow field are in good agreement with the experimental measurements. Effects of the candle diameter, the separation distance between the nozzle and the candle injector and the length of the candle on the flowfield have been numerically analyzed to provide the basis for the optimum design of the pulse cleaning system.

The Experimental Investigations of Dielectric Barrier Discharge and Pulse Corona Discharge in Air Cleaning

The dielectric barrier discharge (DBD) and pulse corona discharge(PCD) plasma generator was used to remove NH3, H2S, C7H8 etc. from atmosphere. The principle and characteristic of the two ways was discussed in the article. The test shows the result of PCD is better than that of DBD.

Pulse cleaning flow models and numerical computation of candle ceramic filters

Analytical and numerical computed models are developed for reverse pulse cleaning system of candle ceramic filters. A standard turbulent model is demonstrated suitably to the designing computation of reverse pulse cleaning system from the experimental and one dimensional computational result. The computed results can be used to guide the designing of reverse pulse cleaning system, which is optimum Venturi geometry. From the computed results, the general conclusions and the designing methods are obtained.

First Option for Fusion with CPA-Laser Pulses instead of Thermal Pressures with Dozens of Million Degrees Temperature for Laser-Boron-Fusion

To avoid the > 50 million degree temperatures in pressures for fusion,the goal has now been reached that higher pressures from picosecond CPA-laser pulses of more than 10 PW power can ignite nuclear fusion at modest temperatures in a power reactor for generating electricity.Gerard Mourou,who was honoured with the 2018 Physics Nobel Prize,was involved to solve this crucial problem of fusion energy with the reactor design as co-authors(Hora,H.,Korn,G.,Giuffrida,L.,Margarone,D.,Picciotto,A.,Krasa,J.,Jungwirth,K.,Ullschmied,J.,Lalousis,P.,Eliezer,S.,Miley,G.H.,Moustaizis,S.,and Mourou,G.,Laser and Particle Beams 33,2015:607)using the CPA Chirped Pulse Amplification.

Inhomogeneous Dielectric Target Properties for Increased Non-thermal Pressure in Laser Boron Fusion by CPA-Pulses

Based on the documentation of the invited paper and the subsequent discussion at a virtual conference,discoveries are indicated,which are summarized in the following paper for further evaluation on the topic of non-thermal forces using terms of extremely powerful components of Maxwell’s stress tensor at the interaction of CPA(chirped pulse amplification)laser pulses in the fusion plasmas of hydrogen with the isotope 11 of boron.This is caused by a recoil mechanism given by the Fresnel formulas of the suppression of the reflectivity of inhomogeneous plasma given by optical constants of the plasma properties.

基于CLEAN思想的互补码信号脉冲压缩算法

互补码信号具有理想的零旁瓣非周期自相关函数,特别适用于高频地波雷达。然而高频地波雷达常采用高占空比波形,近距离目标回波遮挡严重,遮挡时原互补码不再互补,脉压旁瓣很高。针对这一问题,提出基于CLEAN算法思想的互补码脉冲压缩方法,该算法利用互补码的子码互补特性,在不同遮挡程度使用不同长度的子码作为脉压系数;同时,引入了CLEAN算法的思想,由远距离段至近距离段依次进行脉压和CLEAN操作,在保留互补码零旁瓣特性的同时消除了不同子码段之间的相关性造成的距离栅瓣。多目标环境下的计算机仿真实验表明,这种算法在距离盲区内保持了互补码的零旁瓣特性,且无距离栅瓣。

Nonlinear temporal pulse cleaning techniques and application

Two different pulse cleaning techniques for ultra-high contrast laser systems are comparably analysed in this work.The first pulse cleaning technique is based on noncollinear femtosecond optical-parametric amplification(NOPA)and second-harmonic generation(SHG)processes.The other is based on cross-polarized wave(XPW)generation.With a double chirped pulse amplifier(double-CPA)scheme,although temporal contrast enhancement in a high-intensity femtosecond Ti:sapphire chirped pulse amplification(CPA)laser system can be achieved based on both of the techniques,the two different pulse cleaning techniques still have their own advantages and are suitable for different contrast enhancement requirements of different laser systems.

基于CLEAN算法的HFM脉压信号研究

双曲调频(HFM)信号对多普勒频移不敏感,但其脉压结果时宽较大,距离分辨力较低,难以实现邻近多目标的检测。利用CLEAN算法对HFM信号的多目标脉压结果进行处理,将估计出的最强目标的理想脉压输出逐步抵消,使得相邻弱目标依次显现,改善了邻近多目标脉压输出,提高了距离分辨力。仿真结果验证了本文所提方法的有效性。

Pseudo-Random Coding Side-Lobe Suppression Method Based on CLEAN Algorithm

A pseudo-random coding side-lobe suppression method based on CLEAN algorithm is introduced.The CLEAN algorithm mainly processes pulse compression results of a pseudo-random coding,and estimates a target＇s distance by a method named interpolation method,so that we can get an ideal pulse compression result of the target,and then use the adjusted ideal pulse compression side-lobe to cut the actual pulse compression result,so as to achieve the remarkable performance of side-lobe suppression for large targets,and let the adjacent small targets appear.The computer simulations by MATLAB with this method analyze the effect of side-lobe suppression in an ideal or noisy environment.It is proved that this method can effectively solve the problem due to the side-lobe of pseudo-random coding being too high,and can enhance the radar＇s multi-target detection ability.

Understanding the beam self-cleaning behavior of ultrashort laser pulse filamentation

In this paper we report a recent study on the beam self-cleaning behavior occurred during the ultrashort laser pulse filamentation process. The propagation of a Gaussian beam with distorted beam profile is numerically simulated based on the nonlinear wave equation. Our results demonstrate that when the power is not too high so that multiple filaments are not yet induced, the intensity perturbation con-tained in the initial beam profile could be treated as high order spatial modes su-perpositioning on a fundamental mode. Then the self-focusing of the laser beam acts as a spatial filter. It focuses the fundamental mode toward the propagation axis, and produces a fundamental mode profile at the self-focus. While the strong diffraction of higher order modes could not be counteracted by the self-focusing. Therefore their propagation is mainly governed by the divergence without de-stroying the high profile quality at the self-focal region. These lead to the observa-tion of beam profile self-cleaning behavior.

床旁脉冲预处理对流产吸引管清洗质量的影响

目的通过对流产吸引管预处理方法进行改进,探索预处理时机与方法对管腔器械清洗质量的影响。方法选取2020年7月至2022年7月梧州市红十字会医院使用的600件流产吸引管为研究对象,按照抽签分组法分为A组(n=200)、B1组(n=200)和B2组(n=200)。A组预处理采用在流产吸引管使用后马上床旁使用负压吸引恒温多酶清洗剂进行脉冲冲洗管腔内壁方式进行处理;B1组和B2组预处理采用在流产吸引管使用后马上采用流动水下冲洗管腔内壁进行处理。经预处理的器械均放置3 h后集中回收到供应室进行进一步处理,A组直接放入超声波清洗机超声清洗5 min;B1组在常温多酶洗剂内浸泡20 min后再放入超声波清洗机超声清洗5 min;B2组在常温多酶清洗剂内浸泡15 min后用毛刷在液面下贯通管腔来回刷洗5次后再放入超声波清洗机超声清洗5 min。比较三组器械清洗质量。结果A组残留蛋白检测合格率、隐血试验合格率、白色通条检查合格率、带光源放大镜检查合格率均高于B1组和B2组,差异有统计学意义(P<0.001)。结论改进预处理方法将器械有效预处理的地点前移至使用科室,预处理时间前移至术后即时,既践行行业标准,又改进预处理方法,抓住污染管腔器械最佳处理时间以及酶洗剂最强效果,利用脉冲原理使污物从管腔内壁剥离达到理想的预处理效果,进而提高器械清洗质量。

基于高频激光除漆的LIBS监测平台设计与应用研究

基于激光诱导击穿光谱(LIBS)技术的飞机漆层清洗监测,需要对峰值功率密度范围进行限定,以确保等离子体激发和漆层清洗的稳定性。然而,对于广泛使用的高频(kHz级)脉冲激光除漆技术,其峰值功率密度相对偏低,除漆过程中等离子体激发受到限制;且高频激光烧蚀材料产生的强连续背景光谱干扰了等离子体光谱采集。论文依据蒙皮功能漆层可控清洗需求,基于LabVIEW嵌入式开发系统的控制软件编写及激光清洗、光谱采集、控制与显示模块的集成,设计了一款适用于高频激光除漆的LIBS监测平台。选取2024-T3铝合金双漆层试样作为研究对象,采集波长介于360~700nm范围内的漆层/基体体系光谱(面漆层:Tc;底漆层:Pr;基体:As)。采用平滑滤波,基线校正和归一化对原始光谱进行预处理,并选取12条特征谱线进行主成分分析(PCA),其降维数据作为线性判别分析(LDA)的输入变量,以此建立PCA-LDA判别模型。最后将所建模型导入LIBS监测平台,通过试验验证了高频激光除漆LIBS监测平台的分类准确性。结果表明:仅以累积方差解释率大于85%作为主成分选取原则,不能满足除漆过程LDA的分类需要;通过优化LDA的主成分个数,最终选取前9个主成分作为LDA的输入,显著提升了LIBS平台的检测准确率,此时基于LIBS光谱的PCA-LDA模型分类准确率达92.5%。由此可见,设计的高频激光除漆LIBS监测平台能够完成漆层/基体体系不同结构层的材料识别,从而实现了高频脉冲激光可控除漆的有效监测。

卧式三角型滤筒的脉冲喷吹清灰性能

【目的】为优化卧式三角型滤筒除尘器的清灰性能,探究不同喷吹气流对滤筒内部压力分布的影响,获得不同喷吹孔型式对三角型滤筒的清灰性能的影响规律。【方法】分别采用直管喷吹孔、文氏里管、散射喷嘴、新型曲面诱导引射器共4种喷吹孔型式的诱导引流装置对卧式三角型滤筒开展冷态脉冲实验,以侧壁压强峰值和相对标准偏差作为评价清灰性能的技术指标,分别探讨不同条件下的喷吹射流对滤筒内壁压力分布的影响。【结果】在喷吹压强分别设为0.3、0.4、0.5 MPa的条件下,采用直管、文丘里管、新型曲面诱导引射器时喷吹距离分别设为150、200、250、300、350、400 mm,采用散射喷嘴时喷吹距离分别设为25、50、75、100、125、150、175 mm,则采用直管、文丘里管、散射喷嘴、新型曲面诱导引射器时的平均侧壁压强峰值分别为1037、1758、952、1533 Pa,相对标准偏差分别为0.76、0.58、0.09、0.16;采用新型曲面诱导引射器喷吹孔时,比采用散射喷嘴时的清灰强度高61%,比采用文丘里管时的相对标准偏差小0.47。【结论】新型曲面诱导引射器同时兼顾对侧壁压强峰值和相对标准偏差的要求,在4种喷吹孔型式中清灰性能最佳。

激光一次性去除铝合金飞机蒙皮涂层实验与数值研究

目的研究激光的频率、功率及扫描速度等参数对脉冲激光清洗航空铝合金表面S06-0215油漆涂层的影响,分析脉冲激光清洗的机制,优化工艺参数组合,并设计航空铝合金表面涂层一次性去除方法。方法以航空铝合金2A12为基材,开展脉冲激光的频率、功率和扫描速度等参数对基材表面涂层烧蚀深度的影响研究,以及烧蚀过程中基材表面最高温度的模拟研究。同时,以表面粗糙度和去除深度为评价指标,对2A12铝合金飞机蒙皮表面涂层进行清洗实验,对采用优化参数清洗后的蒙皮表面进行粗糙度测量、元素含量以及组成成分分析。结果脉冲激光的扫描速度和频率变大,以烧蚀为主导作用的去除机制逐渐减弱,同时振动机制逐渐增强,并最终转变为主导地位。影响激光去除深度的参数,按权重大小依次为扫描速度、功率、频率。结合模拟与实验结果发现,激光频率125kHz、功率70W和速度50mm/s为表面涂层S06-0215最佳的一次性去除工艺参数组合,此时能量密度大小为1.47J/cm^(2),清洗过程中,不损伤2A12铝合金飞机蒙皮基材。通过XRD、SEM以及EDS表征分析表明,氧化膜仅被部分去除。结论激光清洗铝合金表面油漆涂层采用合适的参数组合可以保留氧化膜,可以实现一次性地去除铝合金表面油漆涂层,同时对基材不会造成损伤。

在线生产橡胶模具激光干式清洗机理及工艺探索

基于在线生产过程中橡胶模具激光干式清洗的机理,选取一定硫化温度下的在线生产模具,通过调整不同功率及脉冲频率等工艺参数进行激光干清洗验证,得出了该硫化温度下橡胶模具激光清洗的最佳工艺参数,为后续其他硫化温度下橡胶模具清洗奠定了一定的工艺基础。

煤磨袋收尘器超洁净排放改造实践

石家庄某水泥厂煤磨袋除尘器由气箱脉冲式袋除尘器改造为行喷吹式袋除尘。改造要求袋除尘器出口颗粒物标况下排放≤5 mg/m^(3),设备阻力≤1 500 Pa。改造利用原气箱脉冲袋除尘器的壳体、灰斗及进出气管道等,新制作整体式净气室,袋室和烟道加高3 m,采用Φ130 mm×5 500 mm的拒水、防油、防静电涤纶覆膜滤袋,根据需要适当增加泄爆阀的面积,采用新的脉冲清灰系统。改造后顺利通过了业主和当地环保部门的检测,经过1年的运行,设备达到了低阻力、超洁净排放的改造目标。

纳秒脉冲激光清洗紧固件表面污垢试验

针对锈蚀油垢易导致紧固件表面局部腐蚀问题,采用正交试验法对紧固件表面污垢进行纳秒脉冲激光清洗试验。利用极差分析得出激光功率、扫描速度、激光频率及扫描间距与试样清洗效果的显著性关系及最优参数组合,并将清洗前后试样宏观与微观表面形貌、粗糙度大小、元素成分3方面进行对比分析,验证试验的合理性。结果表明,当激光功率为20 W、扫描速度为300 mm·s^(-1)、激光频率为75 kHz、扫描间距为0.04 mm时,能有效去除紧固件表面锈蚀油垢的同时不损伤基底,表面粗糙度由清洗前的8.342μm降至2.972μm,表面Fe元素含量由清洗前的27.5%升至75.7%。

垃圾坑擦窗机伺服控制系统设计与应用

介绍了智能擦窗机的工作原理及伺服控制系统的控制思想,着重阐述了以上位机西门子SMART 1000 V3触摸屏,下位机西门子S7-200/S7-200 Smart PLC及三菱MR-JE-40A伺服放大器、三菱HG-KN43J-S100电机,以及阀门、水泵构成的伺服电控系统。通过擦窗速度的设定和擦窗距离来计算出脉冲频率和脉冲数,从而精准地控制擦窗机运动。

滤料脉冲喷吹清灰效果评价指标的试验研究

为定量分析袋式除尘器脉冲喷吹清灰性能,进一步优化清灰系统的结构及参数,针对目前清灰机理研究尚不明晰,且清灰效果评价指标存在局限性等问题,提出冲量密度评价指标的概念。通过试验测试方法,确定不同清灰系统对应的清灰参数(滤料两侧压差和脉冲喷吹气流作用时间),计算滤料的冲量密度,建立一种新型清灰效果评价方法。并利用德国工程师协会(VDI)脉冲喷吹试验装置进行试验。结果表明:喷吹压力越大,相应的冲量密度越大,清灰后残余压降越小,清灰能力越强,利用冲量密度指标评价结果与脉冲喷吹清灰过程实际运行结果一致。