ABE4171 Review

# ABE4171 Review - ABE 4171 Power and Machinery Review Review...

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1 Review ABE 4171 Power and Machinery Review Work = force * distance = lbs * ft z English: ft*lbs z SI: N*m (Joule) Power = (force * distance) / time z English: (lbs * ft) / sec z SI: (N*m) / s = Watt Ex: F = 100 N, v = 4 m/s, P = ? z 100 N * 4m / 1s * 1W / 1Nm/s = 400 W Mechanical Power 2 forms z Linear power – uses linear velocity z Rotary power – uses radial velocity Torque z T = f*d (ft*lbs) or (N*m) Rotary speed z Eng: Rev per min Æ RPM z SI: Rev per sec Æ RPS

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2 Rotary Power P = (F * D) / τ (Linear) C = distance/revolution = 2 π r W (Angular Speed) = Rev/Min Power = F * C * W * (1 HP/33,000 ft*lb/min) Example F = 100 N, R = 0.254 m, w = 2.5 rev/s Power = 100 N * (2 π * 0.254m)/rev * 2.5 rev/s * 1W/(N*m/s) * 1kW / 1000W = 0.4 kW Rotary Power Example Rev = 2 π r = 6.280 ft d/ τ = 6.28 ft/rev * 1000 rev/min = 6280 ft/min P = (100 lb * 6280 ft/min)/ (33000 ft*lb/min) = 19 HP r = 1 ft
3 Example P 1 = (100 lbs * 6.280 * 1000 RPM) / 33,000 = 19 HP P 2 = (100 lbs * 12.56 * 500 RPM) / 33,000 = 19

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## This document was uploaded on 11/21/2011.

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ABE4171 Review - ABE 4171 Power and Machinery Review Review...

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