Chapt06

There are two alternatives to iteration for problems

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Unformatted text preview: le 5.7, we could change the scaling variables to ( , , d) and thus arrive at dimensionless head loss versus dimensionless velocity. The result is4 fcn(Red) gd3hf L2 where f Re2 d 2 (6.65) 1.75 Example 5.7 did this and offered the simple correlation 0.155 Red , which is valid for turbulent flow with smooth walls and Red 1 E5. A formula valid for all turbulent pipe flows is found by simply rewriting the Colebrook interpolation, Eq. (6.64), in the form of Eq. (6.65): (8 )1/2 log Red /d 3.7 gd3hf L2 1.775 (6.66) Given , we compute Red (and hence velocity) directly. Let us illustrate these two approaches with the following example. EXAMPLE 6.9 Oil, with 950 kg/m3 and 2 E-5 m2/s, flows through a 30-cm-diameter pipe 100 m long with a head loss of 8 m. The roughness ratio is /d 0.0002. Find the average velocity and flow rate. Direct Solution First calculate the dimensionless head-loss parameter: gd3hf L2 4 | v v The parameter | (9.81 m/s2)(0.3 m)3(8.0 m) (100 m)(2 E-5 m2/s)2 5.30 E7 was suggested by H. Rouse in 1942. e-Text Main Menu | Textbook Table of Contents | Study G...
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This note was uploaded on 10/27/2009 for the course MAE 101a taught by Professor Sakar during the Spring '08 term at UCSD.

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