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Chemical Engineering 150A Spring Semester, 2009 Homework 10: Turbulence & Intro to Heat Transfer Problem 1 Water flows through a 150 mm diameter diameter pipe with an average velocity of 0.4 m/s. Assuming that the velocity profile in turbulent flow is well-described by the empirical pwer equation: v z v z ,max = 1 " r R # $ % ’ ( 1/ n (Note that n is often set equal to 7; this result is equivalent to equation 16.64a in Denn.) (a) Determine the relationship between v z and v z ,max . (b) At what radial position should a pitot tube be placed if it is to measure the average velocity in the pipe? For the case where n=7? (c) What is the shear stress at this radial position? (d) What fraction of the shear stress at this position is due to the turbulent or Reynolds stresses? Problem 2 Water is flowing at 68 ° F through a smooth, horizontal tube of 2-in ID at an average velocity of 5.0 ft/s. At a point 0.75 inches from the wall, calculate: (a) the time-averaged velocity (b) the total shear stress
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This note was uploaded on 02/05/2010 for the course CHEM 150A taught by Professor Muller during the Spring '10 term at University of California, Berkeley.
- Spring '10