EHTC2010 Oil Bearing Calculations In Ship Diesel Engines Using MotionSolve


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EHTC2010 Oil Bearing Calculations In Ship Diesel Engines Using MotionSolve

  1. 1. Oil Bearing Calculations in ShipDiesel Engines Using MotionSolve Steen Cosmus Thaning Senior Research Engineer LDD1 / MAN-DK © MAN Diesel <1>
  2. 2. MAN GroupGlobally active supplier of vehicles, engines and machineryApprox. €15,5 billion in sales, over 55,000 employees in 120 countriesFour leading business areas Commercial Vehicles Trucks Buses Engines Services Diesel Engines Industrial 2-stroke 4-stroke Propulsion Services Turbochargers Services Packages Contracting Logistics Service Turbomachinery platform Compressors Turbines Reactors Services © MAN Diesel <2>
  3. 3. MAN Diesel Group Locations in Europe Employees worldwide: 7,500 Great Britain MAN Diesel Ltd. Denmark After-sales services Frederikshavn MAN Diesel A/S, Two- and four-stroke engines, propellers and propulsion Copenhagen packages, after-sales Holeby services Stockport Rostock Hamburg Colchester Villepinte/Paris France Czech Republic Augsburg Velká Bìteš PBS Turbo s.r.o. MAN Diesel SAS Saint-Nazaire Turbochargers Four-stroke engines, after- sales services Germany MAN Diesel SEStatus: 12/05 Headquarters, four-stroke engines, turbochargers, after-sales services © MAN Diesel <3>
  4. 4. Low-speed Licensees China Croatia Japan HHM 1980 Uljanik 1954 Mitsui 1926 DMD 1980 Split 1967 Makita 1981 YMD 1989 Hitachi 1951 CMD 2007 Kawasaki 1923 STX 2007 JAD 2007 ZJCME 2008 ZHD 2008 RPM 2008 Korea Poland Hyundai 1976 Cegielski 1959 Doosan 1983 STX 1984 Russia Vietnam Bryansk 1959 Vinashin 2004 L/1442-5.11/2009.08.06 (LL/JBB) © MAN Diesel
  5. 5. Introduction: The Product Large Two-Stroke Diesel Engines Two-stroke10K98MC-C Crossheadand Turbo charged6S35MC Low speed, 61-250 RPM Bore from 26 to 108 cm Stroke from 0.98 to 3.45 m Engine height from 5 to 16 m 4 to 14 cylinders Engine weight from 32 to 2800 tonnes Engines range from 2.100 to 132.000 BHP Continuous demand for cost reduction Reliability is crucial © MAN Diesel 5
  6. 6. © MAN Diesel <6>
  7. 7. Illustration of crankshaft revolutions © MAN Diesel <7>
  8. 8. Motionsolve Crankshaft to bedplate interface Traditional crankshaft to bedplate interface Crankshaft dynamics are evaluated with few boundary conditions to bedplate. The dynamics are calculated in frequency domain on a discrete model. Inhouse build The interface to the bedplate is handled by a 3D FEM Elasto Hydrodynamic oilfilm calculation program. Forces and rotations of journal are used as input. Inhouse build New approach• Two major non-linearities from the bedplate behaviour and from the oilfilm are included into the main-bearing calculation. FEM–model time-domain. © MAN Diesel
  9. 9. MotionsolveBasic model Piston and connecting rod and crankshaft is made from flexible bodies Translational joint Linear stiffness bushings Variable stiffness of bedplate Redistribution of load from movement of crankshaft inside bearing clearance © MAN Diesel
  10. 10. MotionsolveForces Gasforce applied at piston from curve interpolation and function AZU which returns unwrapped angle. © MAN Diesel
  11. 11. MotionsolveForces Non-symmetric thrust bearing Load approx. 500 tons Revolution dependent torque at aftend of engine © MAN Diesel
  12. 12. Motionsolve Stiffness variation of bedplateStiffness of bedplate varies withload angle.FEM contact analysis has beenmade to give variation curve invertical and horisontal direction. © MAN Diesel
  13. 13. MotionsolveForces of bushings without oil interface nonlinear main bearing stiffness. Force response in horisontal and vertical direction of bushing is calculated with regard to actual deformation size and angle. © MAN Diesel
  14. 14. Reynolds Equation1 ∂ ⎛ h3 ∂p ⎞ ∂ ⎛ h3 ∂p ⎞ ω ∂h ∂h ⎜ ⎟+ ⎜ ⎟= +r ∂θ ⎝ 12η ∂θ ⎠ ∂z ⎝ 12η ∂z ⎠ 2 ∂θ ∂t 2h : Oil Film Thickness (Distance between bearing surfaces)ω : Sliding velocity of bearing surface Air Oilp : Pressure in bearing Journalη : Viscosity Shell Y∂h : Inclination of bearing surface X θ∂θ Z∂h : Squeeze of bearing surface (dynamics)∂t ω © MAN Diesel
  15. 15. Model ConsiderationsSimplifications to Reynolds Equation Assume Short width bearing theory applies 1 ∂ ⎛ h3 ∂p ⎞ ∂ ⎛ h3 ∂p ⎞ ω ∂h ∂h ⎜ ⎟+ ⎜ ⎟= + r ∂θ ⎝ 12η ∂θ ⎠ ∂z ⎝ 12η ∂z ⎠ 2 ∂θ ∂t 2 Half Sommerfeld solution applies p ≥ 0 for ϕ1 ≤ θ ≤ ϕ2 where ϕ 2 = ϕ1 + π Y p = 0 otherwiseResult θ X Z Model can be set up analytically ω © MAN Diesel
  16. 16. Coupled CalculationOil Film vs. Structure Fx Fy VFOSUB(MAN-BEAST) x y dx/xt dy/dt © MAN Diesel 16
  17. 17. Motionsolve Application of user subroutine User subroutine is included by a DLL Calling of user subroutine Width radius,clearance,viscosity,angular velocity and deformation and velocityOil film calculation subroutine VFOSUB © MAN Diesel
  18. 18. MotionsolveResults for 11 cylinder engine Journal movement Inside clearance MB3 Bedplate movement MB10 © MAN Diesel
  19. 19. MotionsolveThe loading of engine structure Main bearing loads along with other loads are used to optimise the engine structure © MAN Diesel
  20. 20. Motionsolve Conclusive remarks• A model of the interface between crankshaft mechanism and bedplate structure has been made in MOTIONVIEW.• Takes into account the variable stiffness of bedplate as well as the redistribution of load from the movement of crankshaft journal inside the clearance.• Model will improve the Elastohydrodynamic evaluation of mainbearings and thereby make loading of the bedplate structure more accurate. © MAN Diesel
  21. 21. © MAN Diesel < 21 >