Numerical investigation of the Gibson's method: effects of connecting tubing
2007 (English)In: Proceedings of the 2nd IAHR International Meeting of the Workgroup on Cavitation and Dynamic Problems in Hydraulic Machinery and Systems, Timisoara,Romania, October 24-26, 2007 / [ed] R. Susan-Resiga; S. Bernad; S. Muntean, Timişoara, 2007, 305-310 p.Conference paper (Refereed)
In order to calculate the efficiency of a hydro power plant some quantities needs to be measured. One of them is the flow rate, which can be difficult to measure with good accuracy. There are several methods for that task. Gibson's method is one of them and has the advantage to be economical and easily installed at the site. In order to achieve accurate results with this method, some criterions must be fulfilled. Two of these criterions are the measuring length must be larger than 10 m and the mean initial velocity times the measuring length should be larger than 50 m2/s. These criterions are rarely fulfilled in low head hydro power plants.This paper presents a numerical analysis of the effects of the connecting tubing between the pressure taps at the conduit and the differential pressure sensor. A one dimensional code programmed in Matlab is used for the numerical simulations where the governing equations, continuity and equation of motion, are discretizised with a second order Godunov-type scheme. The simulations are made for different initial flow rates and different valve closures. The result shows that the tubing has an overall small influence on the calculated flow rate error. A positive bias error appears in all tested cases and has a maximum (1.2 to 1.3 % depending on the test case) at the smallest Reynolds number.
Place, publisher, year, edition, pages
Timişoara, 2007. 305-310 p.
, Transaction of Mechanics, Scientific Bulletin of the Politehnica University of Timisoara, Romania, ISSN 1224-6077 ; 52(66)
Research subject Fluid Mechanics
IdentifiersURN: urn:nbn:se:ltu:diva-40452Local ID: f98601c0-86f9-11dc-a4a5-000ea68e967bOAI: oai:DiVA.org:ltu-40452DiVA: diva2:1013974
IAHR International Meeting of the Workgroup on Cavitation and Dynamic Problems in Hydraulic Machinery and Systems : 24/10/2007 - 26/10/2007
Godkänd; 2007; 20071030 (cervante)2016-10-032016-10-03Bibliographically approved