Measuring flows in partially-filled pipes in siphonic roof drainage systems
Tóm tắt
While a variety of flow measurement devices are available to measure the flow of water through closed pipe systems, these devices generally only function correctly when the pipes are completely full of water. Accurate measurement of water flows in partially-filled pipes is extremely difficult. In siphonic drainage systems, this problem is further compounded by the unsteady flow conditions that occur in the pipework during the priming process. This has been a major obstacle to understanding the performance of these systems in practice. In order to accurately model the priming process in multioutlet siphonic roof drainage systems, a method of estimating the instantaneous flows through the partially-filled individual pipes needs to be developed. This paper describes an experimental method of determining flows in partially-filled pipes using a propeller-type current meter to measure flow velocity and a pressure transducer to measure water depth and a modified version of the continuity equation. A computational model is presented which estimates the unsteady flows passing through partially-filled pipework. Overall, the experimental results are promising and correspond well with the model. The results of this study will ultimately be used to develop an unsteady flow model of the priming process in multi-outlet siphonic roof drainage systems.
Tài liệu tham khảo
R. May, Design of Conventional and Siphonic Roof Drainage Systems, in Proceedings of Public Health Services in Buildings — Water Supply, Quality and Drainage, IWEM Conference, London (1995).
S. Arthur, G.B. Wright and J.A. Swaffield, Operational Performance of Siphonic Roof Drainage Systems, Building and Environment, 40 (2005) 788–796.
G.B. Wright, J.A. Swaffield and S. Arthur, The Performance Characteristics of Multi-Outlet Siphonic Rainwater Systems, Building Services Engineering Research and Technology, 23 (2002) 127–141.
S. Arthur and J.A. Swaffield, Siphonic Roof Drinage System Analysis Utilising Unsteady Flow Theory, Building and Environment, 36 (2001) 939–948.
T. Lucke and S. Beecham, Cavitation, Aeration and Negative Pressures in Siphonic Roof Drainage Systems, Building Services Engineering Research and Technology, 30 (2009) 103–119.
T. Lucke and S. Beecham, Capacity Loss of Siphonic Roof Drainage Systems Due to Aeration, Journal of Building Research and Information, 38 (2010) 206–217.
G.F. Hewitt, Measurement of Two Phase Flow Parameters, Academic Press London (1978), 294.
P.P. Kremlevsky, Flowrate Measurement in Multiphase Flows, Begell House USA, (1999), 232.
S. Arthur and J. Swaffield, Siphonic Roof Drainage: Current Understanding, Urban Water, 3 (2001), 43–52.
R. May, Design Criteria for Siphonic Roof Drainage Systems, in Report SR 6542004: Wallingford, England (2004).
C. Rohwer, The Rating and Use of Current Meters, in Technical Bulletin 3, Colorado Agricultural College, USA (1933).
R.J. Goldstein, ed., Fluid Mechanics Measurements, Hemisphere Publishing corporation: New York (1983), 701.
ABB, MagMaster Electromagnetic Flowmeter. 2011 Available from: http://www.abb.com/product/seitp330/05d2d070fe77f6f0c1256d32002bffcd.aspx?productLanguage= us&country=AU, [accessed: 10th July, 2011]