Chapt06

We can compare with eq 683 for laminar flow which

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: length for 1.9 slugs/ft3 and 3 3 (a) 0.00002 ft /s and (b) 0.002 ft /s. Assume smooth walls. Solution Part (a) The viscosity 3.8 10 5 slug/(ft s). The spacing is 2h 4h 0.4 ft. The Reynolds number is VDh ReDh (6.0 ft/s)(0.4 ft) 0.00002 ft2/s 2.4 in 0.2 ft, and Dh 120,000 The flow is therefore turbulent. For reasonable accuracy, simply look on the Moody chart (Fig. 6.13) for smooth walls f 0.0173 hf f L V2 Dh 2g 100 (6.0)2 0.4 2(32.2) 0.0173 2.42 ft Ans. (a) Since there is no change in elevation, p ghf 1.9(32.2)(2.42) 148 lbf/ft2 Ans. (a) This is the head loss and pressure drop per 100 ft of channel. For more accuracy, take Deff 2 3 Dh from laminar theory; then 2 3 Reeff and from the Moody chart read f and p 80,000 0.0189 for smooth walls. Thus a better estimate is 0.0189 hf (120,000) 100 (6.0)2 0.4 2(32.2) 2.64 ft 161 lbf/ft2 1.9(32.2)(2.64) Better ans. (a) The more accurate formula predicts friction about 9 percent higher. Part (b) Compute 0.0038 slug/(ft s). The Reynolds number is 6.0(0.4)/0.002 fore...
View Full Document

Ask a homework question - tutors are online