FINITE ELEMENT ANALYSIS OF GAS FOIL BEARINGS by IRJET Journal

FINITE ELEMENT ANALYSIS OF GAS FOIL BEARINGS

Abstract - Micro turbomachinery demands gas comportments to be light compact and should operate at varying temperatureconditions.Lowheatgenerationdisunion and lack of lubricant rotation system makes it compact dependable andeco-friendly. still low stiffness and damping portions, high cost and lack of sufficient knowledge and prophetic tools kindly restricts GFBs use in mass produced operation. Current marketable and engineering operation demands further and more aggressive designs with high face speed and unit loads as well as thinner fluid film. Again rotordynamics analysis uses stiffness and damping portions to represent fluid film geste or in other words theseportionsplay the crucial part in determining dynamic characteristics of a rotor shaft. Stiffness portions depend substantially on two factors first the static deviation of antipode due to shaft cargo and second the hydrodynamic effect produced due to the fluid film. Then's an approach to calculate the stiffness measure produced due to static deviation of GFBs due to static cargo using finite element analysis and the stiffness measure has been calculated. Reynold’s equation is to be answered using FDM to gain pressure profile during hydrodynamic action of fluid film and using these pressure values in thebearingmodel dynamic element of stiffness can be produced. Adding both factors will produce the overall stiffness measure of a gas antipode bearing.

Key Words: FEA, gas foil bearing, stiffness coefficients.

1. INTRODUCTION

A bearing is a mechanical device that separates two opposingshellsfullybyasubcasteoffluidlubricant.Plain journalbearingisusedcommerciallyinnearlyallbiasthat hasa rotating part.Compressors,pumpsturbines,motors creatorsaremanyexemplificationsneedtobementioned. Journal bearing is a structure where two cylinders rotate concentrically relative to each other. One being the shaft, rotatingataparticularangularspeed,andotherthebearing. Themainidealistosupporttherotatingstructuresandgive sufficientlubricationtoavoiddisunionthatcauseswearand tear and gash to machine corridor. The fluid film at high pressure provides the hydrodynamic film lubrication and determinesthecargocapacityofthebearing.curiosityisa bearing parameter which is defined as the relegation betweenshaftandbearingcenter.

2. MODELLING PARAMETERS OF BEARING

Table-1: Parametersanddimensionsof3gasfoilbearings tobemodelledandanalyzed

3. FINITE ELEMENT ANALYSIS USING ANSYS

3.1 GENERATION OF MESH

Generatingmeshisthemostimportantandcriticalwork inengineeringsimulationinAnsyssoftware.Largenoofcells may take longer time to produce solutions without increasingaccuracywhereasveryfewnumberofcellsmight produceinaccurateresults.

International Research Journal of Engineering and Technology (IRJET) e-ISSN:2395-0056 Volume: 10 Issue: 05 | May 2023 www.irjet.net p-ISSN:2395-0072 © 2023, IRJET | Impact Factor value: 8.226 | ISO 9001:2008 Certified Journal | Page216

Srinath Ingale1 , Sushant Mane2 , Sanket More3 , Vishal More4, Swaraj Kashid5 , Aditya More6 1Assistant Professor of Mechanical Department, Dr. A. D. Shinde Collage of Engineering, Gadhinglaj-416502, Maharashtra, India 2,3,4,5,6 Student of Mechanical Department, Dr. A. D. Shinde Collage of Engineering, Gadhinglaj-416502, Maharashtra, India

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Serial no. Parameter GFB1 GFB2 GFB3 1 Journaldiameter 28.5mm 25mm 30mm 2 Journallength 28.5mm 25mm 30mm 3 Filmclearance .020mm .020mm .020mm 4 Foilthickness(top& bump) 127μm 150μm 300μm 5 Numberofbumps 40 36 40 6 Bumpheight 580μm 580μm 580μm 7 Bumppitch 1.2mm 1.3mm 1.15mm 8 Bumpdiameter 1mm 1mm 1mm 9 BumpfoilYoung’s modulus 200Gpa 200Gpa 200Gpa 10 BumpfoilPoisson’sratio 0.31 0.31 0.31

Figure- 3:Schematicviewofextendedbumpstripsanda typicalbumpfoilbearing

3.2

to1N/mm2andtemperature10oC.

4. 4.1 CALCULATION OF STIFFNESS

Ansys simulation of all 3 gasfoil bearings for a varying pressure range (0.1-1 N/mm2) is carried out and total deformation,directionaldeformationandvon-Misesstress areobtained.ResultsforGFB1at1280Nareshownhere.

Figure-2: Optimizationofauto-generatedmesh. APPLYING BOUNDARY CONDITIONS AND LOAD Figure-3: Applyingboundaryconditionsandbearingload toGFB1forpressurecorrespondingto1N/mm2. Figure-4: Applyingboundaryconditions,thermal conditionsandbearingloadtoGFB1forpressure corresponding RESULT AND DISCUSSION Figure 5: Variationoftotaldeformation. Figure 6: Variationofequivalentstress Figure 7: Directionaldeformation(X-axis). Figure 8: Directionaldeformation(Y-axis).

no. F1(GFB1) inN F2(GFB2) inN F3(GFB3 )inN X1(GFB1) inmm X2(GFB2) inmm X3(GFB3) inmm 1 128 98.17 141 4.36×10-8 2.31×10-8 1.04×10-8 2 255 19635 283 869×10-8 461×10-8 209×10-8 3 383 29452 424 131×10-7 692×10-8 312×10-8 4 510 3927 565 174×10-7 922×10-8 416×10-8 5 638 49087 707 218×10-7 115×10-7 521×10-8 6 766 58905 848 261×10-7 138×10-7 625×10-8 7 893 687.22 990 304×10-7 161×10-7 730×10-8 8 1020 7854 1130 348×10-7 184×10-7 833×10-8 9 1150 883.57 1270 3.92×10-7 2.08×10-7 9.36×10-8 10 1280 98175 1410 978×10-7 231×10-7 104×10-7

Table 2: Bearingloadanddirectionaldeformation(along X-axis)foravaryingpressurerange.

4.2 PLOTS FOR BEARING LOAD VS DEFLECTION: Figure -9: Bearingload(N)vsDeflection(mm)forGFB1, (F1vsX1). Figure -10: Bearingload(N)vsDeflection(mm)forGFB2, (F2vsX2) Figure -11: Bearingload(N)vsDeflection(mm)forGFB3, (F3vsX3) 4.3 VARIATION OF STIFFNESS WITH TEMPERATURE Figure 12: Variationoftotaldeformationat10oC. Figure 13: Variationofequivalentstressat10oC. Figure 14: Directionaldeformation(X-axis)at10oC. Figure 15: Directionaldeformation(Y-axis)at10oC.

No Temperature Deformation inGFB1at 1280N Deformation inGFB2at 981.75N Deformation inGFB3at 1410N 1 10 6.68×10-7 8.88×10-7 7.21×10-7 2 20 4.25×10-7 4.63×10-7 1.51×10-7 3 30 5.76×10-7 2.31×10-7 6.59×10-7 4 40 1.29×10-6 6.39×10-7 1.48×10-6 5 50 2.00×10-6 1.28×10-6 2.30×10-6 6 60 2.72×10-6 1.92×10-6 3.12×10-6 7 70 3.43×10-6 2.55×10-6 3.95×10-6 8 80 4.14×10-6 3.19×10-6 4.77×10-6 9 90 4.86×10-6 3.83×10-6 5.59×10-6 10 100 5.57×10-6 4.47×10-6 6.41×10-6

Table-3:Temperatureanddirectionaldeformation(along X-axis).

4.4 5. CONCLUSIONS

Bearingloadisappliedtothreedifferentmodelsofgasfoil bearings.Deflectionsfordifferentloadvaluesobtainedusing finiteelementanalysis.Graphisplottedbetweenloadand deflectionandastraightlineisobtained,theslopeofeach curverepresentsstiffnessofeachbearing.

Graphbetweenstiffnessandtemperatureisplottedandthe variation is obtained. It is observed that the stiffness is maximumasthetemperatureofthebearingcoincideswith the ambient temperature and stiffness reduces as the temperature difference between the bearing and working environmentincreases.

ACKNOWLEDGEMENT

It gives us an immense pleasure to write an acknowledgementtothisPaper,acontributionofallpeople whohelpedusrealizeit.Wetakethisopportunitytoexpress ourrespectfulregardstoourbeloved Principal Prof. K. S. Joshi formotivateustopublishthispaper.Alsoweexpress ourdeepsenseofgratitudeandappreciationtoourbeloved Project Guide Prof. Srinath Ingale for this enthusiastic inspirationandamicableinallphasesofourPaper.

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PLOTS FOR TEMPERATURE VS STIFFNESS: Figure 16: Stiffness(N/mm)vsTemperature(oC)forGFB1. Figure-17: Stiffness(N/mm)vsTemperature(oC)forGFB2. Figure-18: Stiffness(N/mm)vsTemperature(oC)forGFB3.

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