Use of Non-uniform Rational B-splines for Discharge Calculation in the Velocity Area Method  

作　　者：Zbigniew Krzemianowski Adam Adamkowski 

机构地区：[1]The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Gdansk 80-231, Poland

出　　处：《Journal of Energy and Power Engineering》2014年第5期911-919,共9页能源与动力工程（美国大卫英文）

摘　　要：The velocity area method belongs to the group of primary methods for discharge measurement in hydropower plants. The measurements require an appropriate application of measuring devices and carrying out correctly the process of data analyzing including integration technique. The authors present their own experiences gathered during many years of utilizing the current meter method for discharge measurement in many hydropower plants. They have developed the special integration techniques using the progressive numerical algorithms. The techniques differ from the recommendations contained in the relevant international standards. The authors＇ own software for calculating the discharge from the measured local velocity distribution （obtained using current meters） adopts advanced spline functions, the so-called NURBS （non-uniform rational B-splines）. Nowadays, this kind of splines is commonly used in modeling of the complex geometrical shapes because of their smoothness. It is assessed that it represents much better quality of interpolation than the classic spline functions （classic cubic spline technique）. Particularly, the better properties of the NURBS splines can be observed for velocity profile area characterized by very strong velocity gradients where boundary layers meet the core regions of the flow （mainstream）. In the developed software the boundary layer thickness and exponent of von Karman function is calculated in accordance with the ISO 3354 standard. The software has been successfully used during many performance tests of the hydraulic turbines in Poland for several years. Paper presents the results of flow rate measurements for two different flow systems of Kaplan turbines. First case concerns the application of the current meters in a long circular penstock whereas the second one in short rectangular turbine intake. A comparative analysis of three flow calculation procedures applied for these two cases is presented in the paper-（1） the integration procedure according to the ISO 3354

关 键 词：HYDROPOWER discharge measurements current meter method pressure-time method. 

分 类 号：TP391.72[自动化与计算机技术—计算机应用技术] TB937[自动化与计算机技术—计算机科学与技术]