hamburger menu
All Coursesall course arrow
adda247
reward-icon
adda247
    arrow
    arrow
    arrow
    A journal bearing of radius ‘r1’‘r_1’‘r1​’​ and radial clearance ‘c1’ has a sommerfeld number ‘s1’‘s_1’‘s1​’​. Another journal bearing of r
    Question

    A journal bearing of radius r1‘r_1’​ and radial clearance ‘c1’ has a sommerfeld number s1‘s_1’​. Another journal bearing of radius r2‘r_2’​ and radial clearance c2‘c_2’ has a sommerfeld number s2‘s_2’​. All the other parameters remain the same for both bearings. If r2r_2​= 2 r1r_1​ and c2c_2 = c1c_1​/2, then s2/s1s_2/s_1​​

    A.

    4

    B.

    8

    C.

    16

    D.

    32

    Correct option is C

    Sommerfeld Number Formula:S=(rc)2μNPWhere: r=journal radius c=radial clearance μ=dynamic viscosity N=rotational speed P=unit load (pressure)Since μ,N,P remain constant for both bearings, the Sommerfeld number is proportional to (rc)2.Given:r2=2r1c2=c12So,s2s1=(r2/c2r1/c1)2=(2r1/(c1/2)r1/c1)2=(2r12r1)2=(4)2=16\textbf{Sommerfeld Number Formula:} \\S = \left( \frac{r}{c} \right)^2 \cdot \frac{\mu N}{P} \\\\\text{Where:} \\\bullet \ r = \text{journal radius} \\\bullet \ c = \text{radial clearance} \\\bullet \ \mu = \text{dynamic viscosity} \\\bullet \ N = \text{rotational speed} \\\bullet \ P = \text{unit load (pressure)} \\\\\text{Since } \mu, N, P \text{ remain constant for both bearings, the Sommerfeld number is proportional to } \left( \frac{r}{c} \right)^2. \\\\\textbf{Given:} \\r_2 = 2r_1 \\c_2 = \frac{c_1}{2} \\\\\text{So,} \\\frac{s_2}{s_1} = \left( \frac{r_2 / c_2}{r_1 / c_1} \right)^2 = \left( \frac{2r_1 / (c_1 / 2)}{r_1 / c_1} \right)^2 = \left( \frac{2r_1 \cdot 2}{r_1} \right)^2 = (4)^2 = 16​​

    test-prime-package

    Access ‘ISRO Mechanical Engineering’ Mock Tests with

    • 60000+ Mocks and Previous Year Papers
    • Unlimited Re-Attempts
    • Personalised Report Card
    • 500% Refund on Final Selection
    • Largest Community
    students-icon
    353k+ students have already unlocked exclusive benefits with Test Prime!
    test-prime-package

    Access ‘ISRO Mechanical Engineering’ Mock Tests with

    • 60000+ Mocks and Previous Year Papers
    • Unlimited Re-Attempts
    • Personalised Report Card
    • 500% Refund on Final Selection
    • Largest Community
    students-icon
    353k+ students have already unlocked exclusive benefits with Test Prime!
    Our Plans
    Monthsup-arrow