检索结果-南通市图书馆

维普期刊数据库

Effects of measuring Positions on the Measured Aerodynamic Performance of a Centrifugal Compressor

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2010年第2期19卷 110-114页

作者： Hongwei MA Jun ZHANG School of Jet Propulsion Beihang University Beijing 100191 China National Key Laboratory of Science and Technology on Aero-Engines Beijing 100191 China

This paper performs a numerical simulation of three-dimensional flow field in a centrifugal compressor with long inlet and outlet pipes using CFX *** arranging virtual probes at different positions in both inlet and outlet planes,the aerodynamic performance of the centrifugal compressor is measured and compared with each *** effects of measuring positions on measurement results are *** results show that it will generate notable measuring errors of the pressure ratio and efficiency if the inlet total pressure is measured using a single-point *** inlet total pressure data can be accurate when they are measured using a 3-point *** outlet total pressure and total temperature data can not be accurate if they are respectively measured at one circumferential position even using a multi-point *** tangential measuring positions at the outlet is effective to improve the test *** the outlet total pressure and total temperature are respectively measured at 3 tangential positions,the data can be almost accurate.

关键词： centrifugal compressor aerodynamics performance measuring error measurement position probe.

维普期刊数据库

Study of errors in ultrasonic heat meter measurements caused by impurities of water based on ultrasonic attenuation

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2015年第1期27卷 141-149页

作者：石硕刘正刚孙建亭张敏杜广生李冬 School of Energy and Power Engineering Shandong University Key Laboratory of Renewable Energy Utilization Technology of National Education Ministry Shandong Jianzhu University

Impurity is one of the main factors that affect the measurement accuracy of an ultrasonic heat meter. To study the effects of different impurity species and concentrations on the accuracy of heat meters, flow tests were carried out for the suspending of calcium carbonate and yellow mud. By analyzing the attenuation characteristics of the ultrasound amplitude in different impurity concentrations and species, the influence of the impurities on the heat meter measurement accuracy is evaluated. In order to avoid the inaccuracy caused by the sediment of the reflective bottom surface, a vortex generator is put ahead of the reflective surface. According to the test, the calcium carbonate suspension with a mass concentration of 1%, which influences the heat meter accuracy severely, is used as the flow media. The influence of the vortex generator on the calcium carbonate suspension flow field in the heat meter body is studied with numerical simulations. The results of this paper provide some theoretical guide on improving the heat meter measurement accuracy when the water contains impurities.

关键词： impurities ultrasonic heat meter amplitude attenuation measuring error experiment study

维普期刊数据库

ADVANCES IN measuring TECHNIQUES OF BED LOAD

在线全文

学校读者我要写书评

暂无评论

泥沙研究 1997年第1期 40-47页

作者： ZHOU Gangyan 1 ZOU Jiazhong 2

ＡＤＶＡＮＣＥＳＩＮＭＥＡＳＵＲＩＮＧＴＥＣＨＮＩＱＵＥＳＯＦＢＥＤＬＯＡＤＺＨＯＵＧａｎｇｙａｎ１ＺＯＵＪｉａｚｈｏｎｇ２ＡＢＳＴＲＡＣＴＢｅｄｌｏａｄｉｓａｎｉｍｐｏｒｔａｎｔｃｏｍｐｏｎｅｎｔｏｆｔｏｔａｌｌｏ... 详细信息

ＡＤＶＡＮＣＥＳＩＮＭＥＡＳＵＲＩＮＧＴＥＣＨＮＩＱＵＥＳＯＦＢＥＤＬＯＡＤＺＨＯＵＧａｎｇｙａｎ１ＺＯＵＪｉａｚｈｏｎｇ２ＡＢＳＴＲＡＣＴＢｅｄｌｏａｄｉｓａｎｉｍｐｏｒｔａｎｔｃｏｍｐｏｎｅｎｔｏｆｔｏｔａｌｌｏａｄｔｒａｎｓｐｏｒｔａｔｉｏｎ．...

关键词： Bed load measurement Sampling efficiency measuring error Sediment discharge Transport rate

ADVANCES IN measuring TECHNIQUES OF BED LOAD

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sediment Research 1997年第1期 34-41页

作者： ZHOU Gangyan ZOU Jiazhong (1 The English text is edited and altered by Mr. Long Yuqian. 2 Senior engineer, Hydrology Bureau, Changjiang Water Resources Comm., Wuhan 430010, P. R. China. 3 Senior engineer (High grade), Hydrology Bureau, Changjiang Water Re

Bed load is an important component of total load transportation. The accuracy of bed load measurement depends on the measuring equipment and sampling method. In this paper, the present situation of bed load measurement is introduced, the structure features and the sampling performance of bed lead samplers currently used in the world is evaluated. Results of field comparison of HS and TR2 type samplers used in USA, Don type sampler used in former USSR, and Chinese made Y78-1, Y80, AWT160, MB2 samplers have been summarized. From statistical point of view, selection of sampling verticals, and duration and number of repetitions in a vertical in the bed load measurement were studied. The error might be minimized if the sampling verticals were selected on the basis of equal partial bed load discharge. Finally, some data processing methods are recommended, which have been applied to the Changjiang River.

关键词： Bed load measurement Sampling efficiency measuring error Sediment discharge Transport rate

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

国外信息

大气与环境光学学报 1995年第1期 38-45+11页

国外信息检验光掩模的共焦激光芯片的多步骤光刻工艺过程需密切加以监测，以提高生产的经济效益。其中最重要的是光掩模的质量，因为有毛病的光掩模将在发现它的缺陷之前导致生产出许多不合格的半导体晶片．采用共焦显微技术直接测量光... 详细信息

国外信息检验光掩模的共焦激光芯片的多步骤光刻工艺过程需密切加以监测，以提高生产的经济效益。其中最重要的是光掩模的质量，因为有毛病的光掩模将在发现它的缺陷之前导致生产出许多不合格的半导体晶片．采用共焦显微技术直接测量光掩模特征，用紫外或蓝色光激光器作光...

关键词： itinerant decting instrument synchronization asynchronization sampler A/D translator measuring error