DEVELOPMENT OF GAS-FOIL BEARINGS FOR MINIATURIZED RTB CRYOCOOLERS – PHASE III MATHEMATICAL MODELING AND ANALYSIS – I Presented by  K.V.Krishna Murty MMAE MINIATURE ENGINEERING SYSTEMS GROUP

ISSUES TO BE CONSIDERED FOR ANALYSIS IN PHASE III 1.Thermodynamic and Heat Transfer issues, 2.Fluid flow issues, 3.Mechanical issues.

Thermodynamic and Heat Transfer Issues 1. Heat dissipation and consequent thermal expansion in foils because of friction. 2. Heat transfer to outer and inner journals from foils. 3. Heat transfer between the fluid (gas) and the foils. Present status: Present status: The Tribological Coatings Group is looking into the coatings to be deposited on foils to provide lubrication The foils are being thermally analyzed for Heat Transfer and dissipation effects in software IDEAS.

Fluid Flow Issues Dynamic behavior of gas/fluid in the annular space between the shaft and the foils. Dynamic behavior of gas/fluid in the annular space between the shaft and the foils. Present Status: Present Status: Not being dealt presently.

Mechanical Issues Effect of shaft ‘Vibrations’ and ‘Critical Speed’ on the fluid dynamics and the foil geometry. Effect of shaft ‘Vibrations’ and ‘Critical Speed’ on the fluid dynamics and the foil geometry. ‘Stiffness’ and ‘Damping’ in foils. ‘Stiffness’ and ‘Damping’ in foils. Present Status: Present Status: 1. The ‘Vibrations’ and ‘Critical Speed’ issue is integrated with shaft/rotor design for motor and is being analyzed. Some results were already presented. 2. Mathematical modeling to analyze ‘Shaft Whirl’ using some ‘Finite Element’ methods is being done and the corresponding algorithms are being computer coded using ‘MATLAB’.

Future Work To continue ‘Mechanical-Thermal Analysis’ in IDEAS. To continue ‘Mechanical-Thermal Analysis’ in IDEAS. To do the ‘Fluid Flow Analysis’ using CFD software. To do the ‘Fluid Flow Analysis’ using CFD software. Mathematical modeling of foil ‘Stiffness’ and ‘Damping’. Mathematical modeling of foil ‘Stiffness’ and ‘Damping’.