d. bottazzi2, d. galloni1, m. milani , l. montorsi...

STAR Global Conference 2014 - Vienna

HYDRAULIC SYSTEMS DESIGN RESEARCH GROUP

DEPT. OF SCIENCES & METHODS FOR ENGINEERING – UNIV. OF MODENA & REGGIO EMILIA

Dept. of Sciences and Methods for Engineering University of Modena and Reggio Emilia, Italy

ANALYSIS OF THE LUBRICATION SYSTEM IN A HIGH PRESSURE PISTON WATER PUMP

D. Bottazzi2, D. Galloni1, M. Milani2, L. Montorsi2

1 - Comet S.p.A. Reggio Emilia, Italy

2 - HYDRAULIC SYSTEMS DESIGN RESEARCH GROUP




- Task: avoid overheating for long time operation -

Comet Product Divisions

Numerical Analysis and

Optimization of the

Lubrication System




– Test rig thermal analysis -

CLW (aluminium crank case) 66 l/min (1000 rpm) @ 140 bar

1 – Oil 2 – Water 3 – Air (ambient) 4 – Needle-bearing on the joint side 5 – Needle-bearing on the other side 6 – Crank case, front position 7 – Crank case, close to the valves

Thermocouple measurements




• spectral range: 7.5 - 13 µm • temperature range: -20 °C - 900 °C • optical resolution: 160 x 120 pixel • picture repetition frequency: 120 Hz

– Test rig thermal analysis - CLW (aluminium crank case) 66 l/min (1000 rpm) @ 140 bar

a) b)

c) d)

Optris PI 160




–Mesh construction, from 3D to 2D -

2D - 300000 cells

1 mm

0.5 mm

3D – millions of cells

Only one piston is simulated




– Moving mesh construction -

• Point B position – Rod big end position

• Generic point J

trx cB sin

trz cB cos

BJvv BBtransJtot

trx cB cos

trz cB sin

t

tB

22 sin1

cos

ttrz cA 22 sin1)/1(cos)/11(

• Point A position – Rod small end position

- Overset mesh (rod motion) -

- Morphing (piston motion) -




– VOF – air&oil-

W. Habchi, P. Vergne, S. Bair, O. Andersson, D. Eyheramendy, G.E. Morales-Espejel - Influence of pressure and temperature dependence of thermal properties of a lubricant on the behaviour of circular TEHD contacts, Tribol. Int. 43 (2010) 1842–1850.

- Oil properties, T & p dependence -

6.73

___10 //101.01/

refoiloilrefoiloilrefoiloiloil VVTTVVCCk

oilrefoiloilrefoiloiloilp VVTTCCc ///4

__32




fringfjbfrsefrbefnbhmhydftot PPPPPPP 321

- Friction evaluation -

hmvol

suc

mech

hyd

totM

ppQ

P

P

max

max

4/23/2

pcvol drQ

- Needle bearings -

2/4/2

max ppnb ndpF

nbnbffnb FdCM 5.0

J.B. Heywood - Internal Combustion Engine Fundamentals, 1st ed., McGraw-Hill, Inc., New York, 1988.

rbe

rberbeoil

rbe

rbe

oilrberbefrbec

ld

c

dldF

22 2/rbefrbefrbe dFM

frbefrbe MP

35% 65%




- Heat transfer -

K.A. Brucker, J. Majdalani - Effective thermal conductivity of common geometric shapes, Int. J.

Heat Mass Transf. 48 (2005) 4779–4796.

wallwallwallextwallwallcond ksSTTW //int__int_ extwallextwallenvextwallconv hSTTW ___

envextwallenvextwallextwallextwall fklhNu Pr,Re/ ____

9/416/9

4/1

_

_

Pr67.01

67.068.0

env

extwall

extwall

RaNu

Dissipated thermal power - Conduction & convection -




– Selected physical models & field functions -

• Eulerian Multiphase → Volume Of Fluid (immiscible fluid mixtures)

• Segregated Multiphase Temperature

• k-ε Turbulence

• Oil thermo-physical properties function of temperature and pressure

oiloilcellcell

oiloilcellcellcell

oiltotVFV

VFVTT

_

_

_

Monitoring field functions

airaircellcell

airaircellcellcell

airtotVFV

VFVTT

_

_

_

Air Oil




– Moving mesh -

- Overset mesh (rod motion) -

- Morphing (piston motion) -




– Temperature -

Oil

Air




– Oil fraction & Dynamic Viscosity -

Oil

Air




– Velocity - Oil

Air




Different oil levels …

High oil level

Std. oil level

Low oil level

Oil

Air




High oil level, 800 rpm



Std. oil level, 1000 rpm



Low oil level, 1200 rpm



… and various operating conditions -













Oil Air … and various operating conditions -




– Work in progress -

… Three pistons …

… From 2D to 3D …

Thank you very much

for your kind attention!

d. bottazzi2, d. galloni1, m. milani , l. montorsi...

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