Experimental investigation of the Gibson's method outside standards
2008 (English)In: Hydro technology and the evironment for the new century: 24th IAHR Symposium on Hydraulic Machinery and Systems, October 27 - 31, 2008, Foz do Iguassu, Brazil, Foz do Iguassu, 2008Conference paper (Refereed)
Gibson's method, also known as pressure time method, is used to measure the discharge in hydropower plants. It is an accurate and economical method which is suitable for site efficiency tests. However, it has some limitations. The present paper presents an experimental survey of Gibson's method used outside these limitations, i.e. with a measuring length and an initial flow velocity that are below the criterions stated by the IEC 41. In the experiments pressure is measured with two types of sensors; absolute pressure sensors and differential pressure sensors, to see the influence of the connecting tubing. The measurements are compared to an accurate reference flow meter and also to calculations from 1-D water hammer simulations. The results show, for both types of sensors, a positive bias error of the discharge which increases with decreasing initial velocity. The uncertainty for most of the measurements lies within ±1.5% at a 95% confidence level. The absolute sensors give a slightly larger random error than the differential. The numerical result shows a similar pattern as the experiments but with a smaller magnitude of the error.
Place, publisher, year, edition, pages
Foz do Iguassu, 2008.
Research subject Fluid Mechanics
IdentifiersURN: urn:nbn:se:ltu:diva-27741Local ID: 147c4010-b012-11dd-b677-000ea68e967bISBN: 978-85-60858-13-1 (PDF)OAI: oai:DiVA.org:ltu-27741DiVA: diva2:1000930
IAHR Symposium on Hydraulic Machinery and Systems : 27/10/2008 - 31/10/2008
Godkänd; 2008; Bibliografisk uppgift: CD-ROM; 20081111 (ysko)2016-09-302016-09-30Bibliographically approved