Friction Coefficient in Plastic Pipelines
Currently, plastic pipes are beginning to be more used because of its low cost, easy installation, flexibility, durability, low weight, etc. However, this kind of pipes may have a friction coefficient sensitive to variations of flow and temperature, which
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Abstract Currently, plastic pipes are beginning to be more used because of its low cost, easy installation, flexibility, durability, low weight, etc. However, this kind of pipes may have a friction coefficient sensitive to variations of flow and temperature, which can affect in the design of an analytic leak diagnosis system. The variations of friction in a plastic pipeline can be caused by the following: the flow is not in a fully developed regime. In the same way, temperature affects the viscosity of water which affects the value of the Reynolds number and then, the value of the friction coefficient. This work illustrates the sensitivity of the friction coefficient due to changes in flow and temperature with experiments performed in a plastic pipeline prototype located at the Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-Guadalajara).
1 Introduction Water is an essential natural resource for humanity therefore the waste of this vital liquid must be avoided. A way to do that, in pipelines, is by implementing monitoring systems by using algorithms for leak detection and isolation (LDI). E. A. Padilla (&) O. Begovich A. Pizano-Moreno Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Del Bosque 1145, 45019 Guadalajara, Jalisco, Mexico e-mail: [email protected] O. Begovich e-mail: [email protected] A. Pizano-Moreno e-mail: [email protected]
J. Klapp et al. (eds.), Fluid Dynamics in Physics, Engineering and Environmental Applications, Environmental Science and Engineering, DOI: 10.1007/978-3-642-27723-8_41, Ó Springer-Verlag Berlin Heidelberg 2013
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Fig. 1 Moody chart
However, due to several phenomena present in plastic pipelines, robust LDI algorithms are still in via of research, since in this kind of pipes a flow regime that assures a constant friction factor is difficult to obtain. The variations in the friction coefficient in plastic pipes can be caused by: a) A small relative roughness, so that is difficult to reach a complete turbulence zone where the value of the friction factor is almost constant; b) The effect of temperature changes on density and viscosity, these variations affect the flow regime and friction coefficient. This paper is organized as follows: In Sect. 2, we talk about variation of the friction coefficient due to a non-fully developed flow regime. In Sect. 3 we discuss the variation of friction caused by the action of temperature. Section 4 describes the need of friction compensation for models used to the design of LDI algorithms. Section 5 shows some real-time experimental results. Finally, in Sect. 6 the conclusions are stated.
2 Friction Coefficient Variations Due to Flow Changes In the Moody chart, in Fig. 1, it can be seen that for pipes with a relative roughness less than 1 9 10-3, such as plastic, it is difficult to reach a complete turbulent flow, where the friction coefficient can be considered constant. Then, in this kind of pipes, it is
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