Heat Load and its Effects on Fluid Friction Factor in Corrugated Pipes.

摘要

In this paper, we investigate the effect of heat load on the fluid friction factor for laminar flow of a 2D axisymmetric straight corrugated pipe. Some clever assumptions are made on the Navier-Stokes equations to derive analytic expressions for computing the friction factor for the flow in terms of average velocity, density of the fluid, pressure drop and Reynolds number. The coupled momentum and energy equations are solved numerically and the effect of the heat load on the friction factor and hence the computed head loss in corrugated pipes/hoses analyzed. A new geometry is introduced for computing quasi-periodicity in pipes whose corrugations are periodically positioned. This has a positive effect of reducing instabilities in the solution and shows interesting features of the periodic pressure profile. Computational time and CPU memory have been drastically reduced as a result of simulating only one period as a true representation of an infinitely long pipe in which the flow is fully developed. We show that the heat load reduces the friction factor in corrugated pipes, this presupposes that pump requirements in the tropics are different from temperate regions for the same work done. The Moody Diagram shows a plot of the friction factor and Reynolds number at different corrugation heights without the effect of varying heat load. In this paper we show a diagram of the friction factor and Reynolds numbers at varying inlet and wall temperatures at a constant corrugation height. Furthermore we show that when flow is fully developed, periodizing the temperature on the boundary does not affect the flow.