Assignment_4 sol

# Assignment_4 sol - (a Total Power Paddle velocity for Inner...

This preview shows pages 1–2. Sign up to view the full content.

Assignment 4 Solutions 1. Q=8.0×10 3 m 3 /d, G=1000 S -1 T= 15 , square basin with a depth equal to 1.25 times width, t d =30 s t d = V/Q V = Qt d = (8.0×10 3 m 3 /d)(30 s)(1d/86400 s) = 2.78 m 3 L = w, D =1.25w V = LwD = w 3 (1.25) = 2.78 m 3 w = 3 3 (2.78m )/1.25 1.31 = m L = w = 1.31 m, D = 1.25 (1.31 m) = 1.64 m G = 1/ 2 P V μ , P = μVG 2 At 15 : μ = 1.139 × 10 -3 N-s/m 2 (kg/m-s), ρ = 999.1 kg/m 3 P= (1.139 × 10 -3 kg/m-s)(2.78 m 3 )(1000 s -1 ) 2 = 3156 kg-m 2 /s 3 = 3156 J/s =3156 W Impeller diameter, d = 0.50w = (0.50)(1.31 m) = 0.66 m 2. A flocculator paddle of the design and dimensions shown below is rotated through water at 20 o C with an angular speed of 4.0 r/min. (a) How much power is dissipated into the water? (b) If the tank in which this paddle is rotating has the dimensions of 4 × 4 × 4 m and the flow through the tank is 5000 m 3 /d, determine the Gt value for the flocculator.

This preview has intentionally blurred sections. Sign up to view the full version.

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

Unformatted text preview: (a) Total Power Paddle velocity for Inner board = x 2 x 4 x 1/60 = 0.419 m/s Paddle velocity for outer board = x 3 x 4 x 1/60 = 0.628 m/s Power for each paddle Paddle tip speed (V p ) = 0.75 x paddle velocity Co-efficient of drag (Cd) = 1.8 for flat blade Density of water ( ) = 998.2 kg/m 3 Viscosity, = 1.002 x10-3 N.s/m 2 P = (C d A p V p 3 )/2 Power, P1 for inner board = [1.8 x (0.1 x3 x 4) x 998.2 x (0.75 x 0.419) 3 ]/2 = 33.46 watt Power, P2 for inner board = [1.8 x (0.1 x3 x 4) x 998.2 x (0.75 x 0.628) 3 ]/2 = 112.64 watt Total power P = P1 + P2 = 33.46 + 112.64 = 146.1 watt (b) Gt Retention Time, t = V/Q = 4x4x4/5000 = 0.0128 days = 1106 sec G = [P/(Vx )] 1/2 = [146.1/(4x4x4x1.002x10-3 )] 1/2 = 47.75 s-1 Therefore, Gt = 1106 x 47.75 = 52811.5...
View Full Document

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern