BackgroundReynoldsPipeFlow

BackgroundReynoldsPipeFlow - AAE 333L Spring 2012 Lab 2:...

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AAE 333L Spring 2012 Lab 2: Reynolds Pipe Flow Background 1.1. Objectives At the completion of this experiment you will be able to: 1. Distinguish between laminar, transitional, and turbulent pipe flow. 1. Calculate pressure loss in a pipe using friction factors. 2. Explore the affect of streamwise pressure gradients on transition. 1.2. Specific Applications Liquid propellant feed systems in satellites and boosters, turbine engine oil systems for lubrication and cooling of critical engine seals, hydraulic systems in aircraft controls, life- support systems in spacecraft, duct flows in aerodynamics, HVXC flows for aircraft, other vehicles, and buildings, etc. 1.3. Reynolds Pipe Flow In pipe flow, viscous effects become important, and the behavior of the boundary layer must be taken into account. At the entrance of a pipe the boundary layer is generally so thin that the flow in this region can be considered non-viscous, except near the pipe walls. However, as the flow progresses down the pipe, there is a thickening of the boundary layer until it encompasses the whole pipe cross-section, and can no longer be considered a boundary layer. Fully developed flow is a flow that no longer changes in the streamwise direction (see Figure 1). Figure : Boundary Layer Development In laminar flow fluid layers slide smoothly over one another in a well-ordered pattern. In the pipe, after the flow becomes fully developed, laminar flow is purely axial, and the velocity profile is independent of the coordinate along the direction of flow. Laminar instability can readily be seen in the classic Reynolds experiment on viscous flow, in which dye is injected into the flow of water through a glass pipe. The thread-like form of the moving dye indicates the laminar behavior. When the velocity of the water is increased a fluctuating motion appears in the dye, indicating a transition to an unsteady flow. At higher velocities the thread of dye becomes mixed with the fluid; irregular radial velocity fluctuations are superimposed upon the axial motion, and the flow is said to be turbulent (see Figure 3). Another method of determining the flow regime involves observation of the fluid
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This note was uploaded on 02/10/2012 for the course AAE 333L taught by Professor Sally during the Fall '11 term at Purdue University.

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BackgroundReynoldsPipeFlow - AAE 333L Spring 2012 Lab 2:...

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