Explain the design parameters for a hydrodynamic journal bearing.

Hydrodynamic bearings develop pressure through viscous fluid film. Key parameters: L/D ratio (0.5-1.5), clearance ratio c/r (0.001-0.002), and Sommerfeld number S = (mu.N.D.L/W).(r/c)^2. From Raimondi-Boyd charts using S, determine eccentricity ratio, minimum film thickness h_min, friction coefficient, and oil flow. Ensure h_min > 3x(Ra_shaft + Ra_bearing) for full film. Heat balance: heat generated P_f = f.W.pi.D.N must equal heat dissipated by oil flow. Check for thermal instability (hot oil carryover). Specify lubricant viscosity considering temperature rise. Used in turbines, compressors, and large rotating machinery at L&T, BHEL.