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导流管长度和雾化压力对气体回流影响的数值模拟及实验研究
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作者 谭小练 郭振 +3 位作者 李传锋 李传珍 张宏智 苏晓峰 《粉末冶金工业》 CAS 北大核心 2024年第1期30-36,43,共8页
金属3D打印专用球形粉末普遍采用气雾化法制备,无坩埚电极感应气雾化技术(EIGA)制备的金属粉末具有氧增量低、细粉收得率较高、球形度高、流动性好等优点。实验对雾化喷嘴导流管底端的气流场进行了数值模拟,研究导流管长度和雾化压力对... 金属3D打印专用球形粉末普遍采用气雾化法制备,无坩埚电极感应气雾化技术(EIGA)制备的金属粉末具有氧增量低、细粉收得率较高、球形度高、流动性好等优点。实验对雾化喷嘴导流管底端的气流场进行了数值模拟,研究导流管长度和雾化压力对气体回流的影响,并通过雾化实验对模拟结果进行了验证。结果表明:导流管长度存在一临界值,当长度低于临界值时,雾化喷嘴环缝外侧气体的流速高于内侧气体的流速,气体易回流进入导流管内部,导致较多缺陷粉产生;长度高于临界值时,环缝内侧气体的流速高于外侧气体的流速,气体回流现象消失,缺陷粉数量大幅减少。雾化压力主要影响粉末的粒径,雾化压力越大,粉末粒径越小。 展开更多
关键词 金属3D打印 球形粉末 雾化 导流管 气体回流
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气体回流对罗茨风机的损害及预防措施
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作者 高玉新 《小氮肥设计技术》 1998年第1期52-54,共3页
本文针对化肥厂由于气体回流而造成的罗茨风机的损害进行了全面的分析,指出了损害的原因,并提出了预防措施。
关键词 罗茨鼓风机 气体回流 预防措施 通风机 氮肥
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粉煤液态排渣旋风燃烧器回流特性研究
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作者 何屏 蔡乔方 周振刚 《昆明工学院学报》 1995年第4期24-27,共4页
对模化设计好的燃烧器模型内流场回流区特性作了较深入的研究;分别给出了中心回流率和环形回流率沿燃烧器轴线的变化曲线和规律。
关键词 旋风燃烧器 液态排渣 气体回流 粉煤燃烧器
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一种新型无动力除尘系统的研发与应用 被引量:1
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作者 范旭阳 李博 《选煤技术》 CAS 2021年第3期48-52,共5页
选煤厂煤流转载过程中会产生较大扬尘,尤其在一些高差较大、落料点较多的转载点扬尘问题更为突出。为降低选煤厂生产现场粉尘浓度,提高职业卫生水平,开发了一种新型无动力除尘系统,并将之应用于鲍店选煤厂粉尘治理难度较大的231#带式输... 选煤厂煤流转载过程中会产生较大扬尘,尤其在一些高差较大、落料点较多的转载点扬尘问题更为突出。为降低选煤厂生产现场粉尘浓度,提高职业卫生水平,开发了一种新型无动力除尘系统,并将之应用于鲍店选煤厂粉尘治理难度较大的231#带式输送机和356#带式输送机除尘。生产实践表明:无动力除尘系统的应用大大降低了生产现场的粉尘浓度,实现了粉尘的有效治理,降低了除尘系统电耗,节约了生产成本。 展开更多
关键词 粉尘治理 无动力除尘系统 气体回流 势能旋袋降尘 粉尘浓度
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How many cases of laryngopharyngeal reflux suspected by laryngoscopy are gastroesophageal reflux disease-related? 被引量:12
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作者 Nicola de Bortoli Andrea Nacci +10 位作者 Edoardo Savarino Irene Martinucci Massimo Bellini Bruno Fattori Linda Ceccarelli Francesco Costa Maria Gloria Mumolo Angelo Ricchiuti Vincenzo Savarino Stefano Berrettini Santino Marchi 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第32期4363-4370,共8页
AIM:To investigate the prevalence of gastroesophageal reflux disease(GERD) in patients with a laryngoscopic diagnosis of laryngopharyngeal reflux(LPR).METHODS:Between May 2011 and October 2011,41 consecutive patients ... AIM:To investigate the prevalence of gastroesophageal reflux disease(GERD) in patients with a laryngoscopic diagnosis of laryngopharyngeal reflux(LPR).METHODS:Between May 2011 and October 2011,41 consecutive patients with laryngopharyngeal symptoms(LPS) and laryngoscopic diagnosis of LPR were empirically treated with proton pump inhibitors(PPIs) for at least 8 wk,and the therapeutic outcome was assessed through validated questionnaires(GERD impact scale,GIS;visual analogue scale,VAS).LPR diagnosis was performed by ear,nose and throat specialists using the reflux finding score(RFS) and reflux symptom index(RSI).After a 16-d wash-out from PPIs,all patients underwent an upper endoscopy,stationary esophageal manometry,24-h multichannel intraluminal impedance and pH(MII-pH) esophageal monitoring.A positive correlation between LPR diagnosis and GERD was supposed based on the presence of esophagitis(ERD),pathological acid exposure time(AET) in the absence of esophageal erosions(NERD),and a positive correlation between symptoms and refluxes(hypersensitive esophagus,HE).RESULTS:The male/female ratio was 0.52(14/27),the mean age ± SD was 51.5 ± 12.7 years,and the mean body mass index was 25.7 ± 3.4 kg/m 2.All subjects reported one or more LPS.Twenty-five out of 41 patients also had typical GERD symptoms(heartburn and/or regurgitation).The most frequent laryngoscopic findings were posterior laryngeal hyperemia(38/41),linear indentation in the medial edge of the vocal fold(31/41),vocal fold nodules(6/41) and diffuse infraglottic oedema(25/41).The GIS analysis showed that 10/41 patients reported symptom relief with PPI therapy(P < 0.05);conversely,23/41 did not report any clinical improvement.At the same time,the VAS analysis showed a significant reduction in typical GERD symptoms after PPI therapy(P < 0.001).A significant reduction in LPS symptoms.On the other hand,such result was not recorded for LPS.Esophagitis was detected in 2/41 patients,and ineffective esophageal motility was found in 3/41 patients.The MII-pH analysis showed an abnormal AET in 5/41 patients(2 ERD and 3 NERD);11/41 patients had a normal AET and a positive association between symptoms and refluxes(HE),and 25/41 patients had a normal AET and a negative association between symptoms and refluxes(no GERD patients).It is noteworthy that HE patients had a positive association with typical GERD-related symptoms.Gas refluxes were found more frequently in patients with globus(29.7 ± 3.6) and hoarseness(21.5 ± 7.4) than in patients with heartburn or regurgitation(7.8 ± 6.2).Gas refluxes were positively associated with extraesophageal symptoms(P < 0.05).Overall,no differences were found among the three groups of patients in terms of the frequency of laryngeal signs.The proximal reflux was abnormal in patients with ERD/NERD only.The differences observed by means of MII-pH analysis among the three subgroups of patients(ERD/NERD,HE,no GERD) were not demonstrated with the RSI and RFS.Moreover,only the number of gas refluxes was found to have a significant association with the RFS(P = 0.028 andP = 0.026,nominal and numerical correlation,respectively).CONCLUSION:MII-pH analysis confirmed GERD diagnosis in less than 40% of patients with previous diagnosis of LPR,most likely because of the low specificity of the laryngoscopic findings. 展开更多
关键词 Laryngopharyngeal reflux Gastroesophageal reflux Multichannel impedance and pH monitoring Extra-esophageal reflux syndromes Chronic laryngitis
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离心压气机稳态及过渡态轮盘侧泄漏的研究
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作者 郭云鹏 席光 王志恒 《工程热物理学报》 EI CAS CSCD 北大核心 2020年第8期1903-1910,共8页
本文面向高压比离心压气机系统开机启动及加速过程中轴承润滑油气泄漏问题,建立了包含叶轮、无叶扩压器及蜗壳、轮盘侧密封流道和管路系统的集成参数模型,并运用三维CFD模型获得了压气机各主部件及轮盘侧密封流道的气动性能。研究得到... 本文面向高压比离心压气机系统开机启动及加速过程中轴承润滑油气泄漏问题,建立了包含叶轮、无叶扩压器及蜗壳、轮盘侧密封流道和管路系统的集成参数模型,并运用三维CFD模型获得了压气机各主部件及轮盘侧密封流道的气动性能。研究得到了压气机流量-压升特性曲线上的轮盘侧回流临界线和各转速下的阀门开度的最大阈值,并预测了过渡态下压气机性能及回流线与稳态的差别。研究工作为解释高速离心压气机开机启动及加速过程中轴承润滑油气泄漏提供了理论参考,同时对此类过程中压气机的流量提出了控制方案。 展开更多
关键词 离心压气机 轮盘侧泄漏 集成参数模型 气体回流
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