14_ch 12 Mechanical Design budynas_SM_ch12

# 14_ch 12 Mechanical Design budynas_SM_ch12 - Repeat the...

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Chapter 12 317 12-16 Continue to build a skill with pressure-fed bearings, that of ﬁnding the average tempera- ture of the ﬂuid ﬁlm. First examine the case for c = c min Trial #1 : • Choose an initial T f . • Find the viscosity. • Find the Sommerfeld number. • Find fr / c , h o / c , and ± . • From Eq. (12-24), ﬁnd ² T . T a v = T s + ² T 2 • Display T f , S , ² T , and T a v . Trial #2 : • Choose another T f . Repeat the drill, and display the second set of values for T f , S , ² T , and T a v . • Plot T a v vs T f : Trial #3 : Pick the third T f from the plot and repeat the procedure. If ( T f ) 3 and ( T a v ) 3 differ by more than 0 . 1°F, plot the results for Trials #2 and #3 and try again. If they are within 0 . 1°F,de- termine the bearing parameters, check the Trumpler criteria, and compare H loss with the lubricant’s cooling capacity.
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Unformatted text preview: Repeat the entire procedure for c = c max to assess the cooling capacity for the maxi-mum radial clearance. Finally, examine c = ¯ c to characterize the ensemble of bearings. 12-17 An adequacy assessment associated with a design task is required. Trumpler’s criteria will do. d = 50 . 00 + . 00 − . 05 mm, b = 50 . 084 + . 010 − . 000 mm SAE 30, N = 2880 rev/min or 48 rev/s, W = 10 kN c min = b min − d max 2 = 50 . 084 − 50 2 = . 042 mm r = d / 2 = 50 / 2 = 25 mm r / c = 25 / . 042 = 595 l ± = 1 2 (55 − 5) = 25 mm l ± / d = 25 / 50 = . 5 p = W 4 rl ± = 10(10 6 ) 4(0 . 25)(0 . 25) = 4000 kPa T av 2 1 T f ( T f ) 1 ( T f ) 2 ( T f ) 3 T av ± T f...
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## This note was uploaded on 12/13/2011 for the course EML 3013 taught by Professor Shingley during the Fall '11 term at UNF.

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