Performance of Virtual Current Meters in Hydroelectric Turbine Intakes

Harding, Samuel F.¹  Romero-Gomez, Pedro D. J.¹  Richmond, Marshall C.¹ 

[1] Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Hydrology Group

关键词: hydropower;    CFD;    flow measurement;   

DOI  :  10.2172/1326153
RP-ID  :  PNNL--25319
PID  :  OSTI ID: 1326153
Others  :  Other: WC0102000

学科分类：再生能源与代替技术

美国|英语

来源: SciTech Connect

【 摘 要 】

Standards provide recommendations for the best practices in the installation of current meters for measuring fluid flow in closed conduits. These include PTC-18 and IEC-41 . Both of these standards refer to the requirements of the ISO Standard 3354 for cases where the velocity distribution is assumed to be regular and the flow steady. Due to the nature of the short converging intakes of Kaplan hydroturbines, these assumptions may be invalid if current meters are intended to be used to characterize turbine flows. In this study, we examine a combination of measurement guidelines from both ISO standards by means of virtual current meters (VCM) set up over a simulated hydroturbine flow field. To this purpose, a computational fluid dynamics (CFD) model was developed to model the velocity field of a short converging intake of the Ice Harbor Dam on the Snake River, in the State of Washington. The detailed geometry and resulting wake of the submersible traveling screen (STS) at the first gate slot was of particular interest in the development of the CFD model using a detached eddy simulation (DES) turbulence solution. An array of virtual point velocity measurements were extracted from the resulting velocity field to simulate VCM at two virtual measurement (VM) locations at different distances downstream of the STS. The discharge through each bay was calculated from the VM using the graphical integration solution to the velocity-area method. This method of representing practical velocimetry techniques in a numerical flow field has been successfully used in a range of marine and conventional hydropower applications. A sensitivity analysis was performed to observe the effect of the VCM array resolution on the discharge error. The downstream VM section required 11???33% less VCM in the array than the upstream VM location to achieve a given discharge error. In general, more instruments were required to quantify the discharge at high levels of accuracy when the STS was introduced because of the increased spatial variability of the flow velocity.