SEMINAR REPORT ONSEMINAR REPORT ONINTRODUCTION TO HYDROSTATIC JOURNAL INTRODUCTION TO HYDROSTATIC JOURNAL BEARING WITH COAXIAL FLOATING SLEEVEBEARING WITH COAXIAL FLOATING SLEEVE

A NEW CONCEPT A NEW CONCEPT

Submitted by :- Guided by :-Submitted by :- Guided by :-

# WHY NEED TO APPLY THIS NEW CONCEPT ?# WHY NEED TO APPLY THIS NEW CONCEPT ?

(a) Today market demand (a) Today market demand

- high productivity,- high productivity,

- high power and high speed range m/c tools.- high power and high speed range m/c tools.

(b) Current available speed only 40-50 k-rpm at 40kw power but (b) Current available speed only 40-50 k-rpm at 40kw power but some manufacture ask for 100 k-rpm.some manufacture ask for 100 k-rpm.

(c)(c) We can not achieve 100 k-rpm with We can not achieve 100 k-rpm with

- ball bearing- ball bearing

- conventional hydrostatic bearing- conventional hydrostatic bearing

# # TYPES OF BEARING:TYPES OF BEARING: (1) ROLLING CONTACT BEARING(1) ROLLING CONTACT BEARING

(a) Basic four elements – inner and outer race,(a) Basic four elements – inner and outer race, rolling element like ball and roller,rolling element like ball and roller, cage.cage.

(b) Classification.(b) Classification. (c) Antifriction bearing.(c) Antifriction bearing. (d) It is more noisy, low resistance to shock, wear of the balls, (d) It is more noisy, low resistance to shock, wear of the balls,

not suitable for high load and high rpm. not suitable for high load and high rpm.

(2) HYDRODYNAMIC BEARING(2) HYDRODYNAMIC BEARING (a) It having thick film between journal and bearing.(a) It having thick film between journal and bearing. (b)(b) Load carryingLoad carrying by pressure without any actual contact by pressure without any actual contact betweenbetween journal journal and bearing.and bearing. (c) Used for high speed and low load(c) Used for high speed and low load..

(3) HYDROSTATIC BEARING(3) HYDROSTATIC BEARING

(a) Load is supported by fluid film(a) Load is supported by fluid film

(b) Lubricant supply under the pressure – externally (b) Lubricant supply under the pressure – externally pressurized bearing.pressurized bearing.

(c) Advantage – high load, even low speed.(c) Advantage – high load, even low speed.

no starting friction.no starting friction.

no rubbing action.no rubbing action.

(d) Application – used in turbo generator and centrifuge.(d) Application – used in turbo generator and centrifuge.

(4)FLOATING BEARING(4)FLOATING BEARING

(a) Floating sleeve located between the journal and bearing (a) Floating sleeve located between the journal and bearing surface.surface.

(b) Operated at wide range speed for shaft.(b) Operated at wide range speed for shaft.

(c) Used in turbines and compressors.(c) Used in turbines and compressors.

(5) SQUEEZE FILM JOURNAL (5) SQUEEZE FILM JOURNAL

BEARINGBEARING

(a) Suitable for oscillate or rotate (a) Suitable for oscillate or rotate

slowly instruments.slowly instruments.

(b) Sufficient capacity to carry dynamic(b) Sufficient capacity to carry dynamic

load.load.

Difference between conventional Difference between conventional

bearing and full-floating bearingbearing and full-floating bearing

# MAGIC OF COAXIAL FLOATING SLEEVE:# MAGIC OF COAXIAL FLOATING SLEEVE:

(1) (1) For high speed/power use –In bearing putting sleeve between For high speed/power use –In bearing putting sleeve between shaft and housing so splitting total relative speed in two shaft and housing so splitting total relative speed in two contribution.contribution.

(2) Hydrostatic bearing keep all advantage – contactless, no wear (2) Hydrostatic bearing keep all advantage – contactless, no wear phenomenon, no maintenence required.phenomenon, no maintenence required.

Source of friction is only viscosity of lifting fluid.Source of friction is only viscosity of lifting fluid.

(3)(3) Sleeve saving half of the friction power because of relation for Sleeve saving half of the friction power because of relation for friction power and relative speed is quadratic.friction power and relative speed is quadratic.

(4) Because of sleeve improved damping performance because of (4) Because of sleeve improved damping performance because of reduce the stiffness characteristics.reduce the stiffness characteristics.

(5) Disadvantage of high cost compensate by -High productivity, (5) Disadvantage of high cost compensate by -High productivity,

-Less maintenance,-Less maintenance,

-New market -New market opportunities, opportunities,

due to high due to high speed speed

capacity.capacity.

(6) We have to focus on radial expansion when working with 100 (6) We have to focus on radial expansion when working with 100 k-rpm. Because of neglecting centrifugal deformation prevent k-rpm. Because of neglecting centrifugal deformation prevent to reach at request performance to reach at request performance

# THE RIGID MODEL:# THE RIGID MODEL:

The model is based on the following hypothesis:The model is based on the following hypothesis:

(a) the viscosity of the lifting fluid does not depend on temperature,(a) the viscosity of the lifting fluid does not depend on temperature,

(b) fluid viscosity has a constant value inside each of the two (b) fluid viscosity has a constant value inside each of the two clearances,clearances,

(c) there is no slip of the fluid at the walls,(c) there is no slip of the fluid at the walls,

(d) the lifting fluid is uncompressible; corrections on this hypothesis (d) the lifting fluid is uncompressible; corrections on this hypothesis are required when using air or gas.are required when using air or gas.

(e) laminar flow: velocity profile across the clearances is linear and (e) laminar flow: velocity profile across the clearances is linear and shear stress is constant.shear stress is constant.

(f) local effects of curvature on fluid flows are neglected as the gap (f) local effects of curvature on fluid flows are neglected as the gap height is negligible with respect to its radius.height is negligible with respect to its radius.

(g) all eccentricities e are zero.(g) all eccentricities e are zero.

If torque TIf torque T11 and T and T22 acting on opposite surface of floating elements acting on opposite surface of floating elements are force equal So by intergrating the viscous shear stress are force equal So by intergrating the viscous shear stress over the over the whole bearing friction areas S:whole bearing friction areas S:

S = NS = NPP.A.Aff = N = NPP.(A.(APP –3/4A –3/4ARR) N) Npp = no. of pads = no. of pads

TT11 = =S1S1 R R11..11.dS, A.dS, Aff = pad friction area = pad friction area

TT22 = =S2S2 R R22..22.dS, A.dS, App = area of single pad = area of single pad

AArr = area of recess = area of recess

According to hypothesis (e), considering the viscous shear stress in According to hypothesis (e), considering the viscous shear stress in COUETTE FLOW COUETTE FLOW

= ( = ( µ) / h = (µ µ) / h = (µ.R)/h.R)/h

So the expressions of the viscous torques can be rewritten as followsSo the expressions of the viscous torques can be rewritten as follows::

TT11= (µ= (µ11 (R (R11))22 S S11 ( (11 - - 22))/h))/h11

TT22= (µ= (µ22 ( R ( R22))22 S S22 22)/h)/h22

Now, take TNow, take T11 = T = T22, the angular speed ratio , the angular speed ratio 11//22 can be written as can be written as

((11 / / 22) = 1 + [(µ) = 1 + [(µ22 / µ / µ11) (Af) (Af22 /Af /Af11) (h) (h11/h/h22) (R) (R11/R/R22))22]]

Since the shaft speed is the independent parameter, speed ratio is Since the shaft speed is the independent parameter, speed ratio is

expressed as expressed as = = 22//11..

# EXPERIMENTAL RESULT:# EXPERIMENTAL RESULT:

(1)(1) Experimental data available for hydrostatic bearing with Experimental data available for hydrostatic bearing with floating coaxial bush:floating coaxial bush:

Shaft supported by two bearing having 30mm dia. and 4 Shaft supported by two bearing having 30mm dia. and 4 pads, and external bearing are 39mm dia and 4 pads.pads, and external bearing are 39mm dia and 4 pads.

Height of hHeight of h11 and h and h22 are 17 are 17m and 32m and 32m, working fluid 5cts m, working fluid 5cts oil, pressure is 5.5 MPaoil, pressure is 5.5 MPa

Tested up to 50000 rpm. Tested up to 50000 rpm.

# THE DEFORMABLE BEARING:# THE DEFORMABLE BEARING:

(1) In high speed range bearing, due centrifugal force produce the (1) In high speed range bearing, due centrifugal force produce the

radial expansion which cannot be neglectedradial expansion which cannot be neglected..

(2) In figure we can see the FEM analysis.(2) In figure we can see the FEM analysis.

(3)(3) Radial expansion for any speed obtain from Radial expansion for any speed obtain from R - R - diagram diagram and that convert in parabolic polynomial use to be input to and that convert in parabolic polynomial use to be input to matlab program.matlab program.

(4)(4) Calculation of speed ratio is not linear problem because of Calculation of speed ratio is not linear problem because of 2 depends on clearance height.2 depends on clearance height.

unlinear problem solve by step integration if unlinear problem solve by step integration if 1(t) and 1(t) and 2(t)2(t) time time step, step, 1 is angular speed then next time step 1 is angular speed then next time step (t + (t + t)t)

2(t + 2(t + t)= t)= 2(t) + [(T1(t)-T2(t)) 2(t) + [(T1(t)-T2(t)) t]/Jt]/J

From the graph From the graph

Angular speed – time. Angular speed – time.

We see behavior of rigid We see behavior of rigid

and deformable bearing.and deformable bearing.

# RESULT AND ANALYSIS:# RESULT AND ANALYSIS:

Ideal speed ratio is 0.5, but we cannot achieve. Why?Ideal speed ratio is 0.5, but we cannot achieve. Why?

(1) Minor change in height, viscosity and bearing (1) Minor change in height, viscosity and bearing diameter can be change the performance.diameter can be change the performance.

(2) (2) Viscosity is affected by temperature – as warm oil Viscosity is affected by temperature – as warm oil flows across the sills. For 1 cst oil we get the flows across the sills. For 1 cst oil we get the

difference in speed ratio 0.4 to 0.33difference in speed ratio 0.4 to 0.33

(3)(3) Value of Value of for rigid model we take constant for all for rigid model we take constant for all working speed.working speed.

(4)(4) As per hypothesis (g) we take eccentricity zero but in real As per hypothesis (g) we take eccentricity zero but in real condition it never become true.condition it never become true.

(5)(5) Clearance height no longer constant. It become a function of Clearance height no longer constant. It become a function of angular coordinate h = h(angular coordinate h = h(). ).

(6) From the graph, (6) From the graph, Speed ratio- shaft speedSpeed ratio- shaft speedwe get the performancewe get the performanceunder different conditions.under different conditions.

From bottomFrom bottom 1. Experimental.1. Experimental.2. Low tolerance limit.2. Low tolerance limit.3. Numerical deformable.3. Numerical deformable.4. Numerical rigid.4. Numerical rigid.5. High tolerance limit. 5. High tolerance limit.

# FUTURE DEVELOPMENT AND CONCLUSION:# FUTURE DEVELOPMENT AND CONCLUSION:

(1) Main consult with height of clearance (h) and viscosity ((1) Main consult with height of clearance (h) and viscosity () for ) for further design improvement in full floating hydro-static further design improvement in full floating hydro-static bearing.bearing.

(2) All ball bearing replaced with this one – but very careful (2) All ball bearing replaced with this one – but very careful finishing and closed tolerance is required.finishing and closed tolerance is required.

(3) Floating sleeve used only when rotating speed becomes nearly (3) Floating sleeve used only when rotating speed becomes nearly half the one of the shaft means speed ratio (half the one of the shaft means speed ratio () is equal to 0.5) is equal to 0.5

(4) Result from proposed method shown good accordance with (4) Result from proposed method shown good accordance with experimental data.experimental data.

# REFREENCES:# REFREENCES:

(1) (1) A Textbook of Machine Design by R.S.Khurmi and J. K. A Textbook of Machine Design by R.S.Khurmi and J. K. Gupta Gupta (S. CHAND)(S. CHAND)(2) (2) Design of Machine Elements by V.B.Bhandari (TATA Design of Machine Elements by V.B.Bhandari (TATA McGRAW McGRAW HILL) HILL) (3) (3) Hydraulics and Fluid Michanics by Dr.P.N.Modi and Hydraulics and Fluid Michanics by Dr.P.N.Modi and

Dr.S.M.Seth. A standard book of houseDr.S.M.Seth. A standard book of house(4) (4) Ambrosoni, L., Poli, M., 2002. Theory and experimental Ambrosoni, L., Poli, M., 2002. Theory and experimental tests tests on a free-floating journal bearing. In: 3rd AIMETA on a free-floating journal bearing. In: 3rd AIMETA International Tribology Conference, Vietri, Italy.International Tribology Conference, Vietri, Italy.(5) (5) Bassani, R., Piccigallo, B., 1992. Hydrostatic Bassani, R., Piccigallo, B., 1992. Hydrostatic Lubrication. Lubrication. Elsevier, London.Elsevier, London.(6)(6) Powell, J.W., 1970. Design of Aerostatic Bearings. The Powell, J.W., 1970. Design of Aerostatic Bearings. The

Machinery Publishing Co.Ltd., London.Machinery Publishing Co.Ltd., London.(7) (7) Luca ambrosoni, Mario poli, Insitute of Industrial Luca ambrosoni, Mario poli, Insitute of Industrial Technology Technology and Automation,Italian National Research and Automation,Italian National Research Council,Viale Council,Viale Lombradia,201A,20131 Milano,ItalyLombradia,201A,20131 Milano,Italy

THANK YOUTHANK YOU