A centrifugal fan with the high speed and compact dimensions is studied numerically and experimentally. The centrifugal fan consists of a shrouded impeller rotating at 34 000 r/min with a small tip clearance 0.7 mm to...A centrifugal fan with the high speed and compact dimensions is studied numerically and experimentally. The centrifugal fan consists of a shrouded impeller rotating at 34 000 r/min with a small tip clearance 0.7 mm to the fixed outer casing. Computational models with/without the tip clearance are built and the κ-ω shear stress transport （SST） turbulence model and the unstructured mesh are applied to the numerical simulation for unsteady solutions. The overall performance is measured on a standard experimental bench and the major flow feature of each component inside the centrifugal fan is numerically investigated. In the presence of the tip clearance due to the difference of static pressure between leading and trailing edges of the clearance, i. e. , leading and trailing edges of the impeller, a strong return flow exists inside the clearance passage and re-circulates the main stream inside the impeller passage, and produces the strong flow interaction, thus changing the flow field and influencing the overall performance.展开更多
目的:观察高血压脑出血患者应用神经内镜微创手术治疗的疗效及并发症情况。方法:回顾性收集2021年2月至2023年2月期间本院内收治的82例高血压脑出血患者的临床资料。根据患者手术方法不同将其分为开颅手术组(40例)与微创手术组(42例)。...目的:观察高血压脑出血患者应用神经内镜微创手术治疗的疗效及并发症情况。方法:回顾性收集2021年2月至2023年2月期间本院内收治的82例高血压脑出血患者的临床资料。根据患者手术方法不同将其分为开颅手术组(40例)与微创手术组(42例)。分析对比两组的血肿清除率、术后并发症、围术期相关指标、神经功能以及日常生活能力。结果:微创手术组的血肿清除率明显高于开颅手术组(P<0.05)。微创手术组的术后并发症发生率明显低于开颅手术组(P<0.05)。微创手术组的出血量明显少于开颅手术组,手术时间及切口长度、重症监护室观察时间与整体治疗时间均明显短于开颅手术组(P<0.05)。术后1m,微创手术组的美国国立卫生研究院卒中量表(National institute of health stroke scale,NIHSS)评分与日常生活活动能力表(Barthel index,BI)评分均显著优于开颅手术组(P<0.05)。结论:神经内镜微创术治疗高血压脑出血,能提高血肿清除率,减少术后并发症,改善围术期相关指标,提升神经功能以及日常生活能力。展开更多
文摘A centrifugal fan with the high speed and compact dimensions is studied numerically and experimentally. The centrifugal fan consists of a shrouded impeller rotating at 34 000 r/min with a small tip clearance 0.7 mm to the fixed outer casing. Computational models with/without the tip clearance are built and the κ-ω shear stress transport （SST） turbulence model and the unstructured mesh are applied to the numerical simulation for unsteady solutions. The overall performance is measured on a standard experimental bench and the major flow feature of each component inside the centrifugal fan is numerically investigated. In the presence of the tip clearance due to the difference of static pressure between leading and trailing edges of the clearance, i. e. , leading and trailing edges of the impeller, a strong return flow exists inside the clearance passage and re-circulates the main stream inside the impeller passage, and produces the strong flow interaction, thus changing the flow field and influencing the overall performance.
文摘目的:观察高血压脑出血患者应用神经内镜微创手术治疗的疗效及并发症情况。方法:回顾性收集2021年2月至2023年2月期间本院内收治的82例高血压脑出血患者的临床资料。根据患者手术方法不同将其分为开颅手术组(40例)与微创手术组(42例)。分析对比两组的血肿清除率、术后并发症、围术期相关指标、神经功能以及日常生活能力。结果:微创手术组的血肿清除率明显高于开颅手术组(P<0.05)。微创手术组的术后并发症发生率明显低于开颅手术组(P<0.05)。微创手术组的出血量明显少于开颅手术组,手术时间及切口长度、重症监护室观察时间与整体治疗时间均明显短于开颅手术组(P<0.05)。术后1m,微创手术组的美国国立卫生研究院卒中量表(National institute of health stroke scale,NIHSS)评分与日常生活活动能力表(Barthel index,BI)评分均显著优于开颅手术组(P<0.05)。结论:神经内镜微创术治疗高血压脑出血,能提高血肿清除率,减少术后并发症,改善围术期相关指标,提升神经功能以及日常生活能力。
