Contents CHAPTER 1 Properties of gases 1 Gas equations 1 Ideal gas equations 2 Gas index equation 3 Actual gas equation 5 Degree of gas molecular freedom 5 Specific heat capacity 7 Viscosity 7 Property of wet gas 11 Pressure 12 Humidity. 13 Dew point temperature. 14 References 14 CHAPTER 2 Gas lubrication equations 15 Reynolds equation 15 Derivation of Reynolds equation 16 Reynolds equation in the polar coordinate system 19 Reynolds equation in the cylindrical coordinate system 19 Lubrication parameters 20 Energy equation 22 Chang of gas inner energy 23 External work on gas and energy loss 24 Solid heat conduction equation and the interface equation 26 Numerical analysis method 27 Finite difference method 27 Flow conservation 28 Friction force balance 34 References 35 CHAPTER 3 Isothermal gas lubrication 37 Sliders 37 Lubrication equation 38 Pressure boundary condition 40 Lubrication performance parameters 40 V VI Contents Hydrodynamic lubrication characteristics of sliders 41 Hydrodynamic lubrication characteristics of divergent sliders 43 Lubrication characteristics of the magnetic head slider 45 Journal bearing and radial seal 51 Lubrication equations 52 Boundary conditions 52 Lubrication parameters 53 Lubrication characteristics 55 Spiral groove thrust bearing 56 Gas lubrication equations. 59 Pressure boundary conditions 60 Lubrication parameters 60 Lubrication characteristics 61 Spiral groove face seal 64 Lubrication equations 65 Pressure boundary conditions 65 Seal performance parameters 66 Lubrication regularity 66 References 71 CHAPTER 4 Gas thermohydrodynamic lubrication of rigid surfaces 73 Sliders 73 Gas lubrication equations. 73 Boundary conditions 75 Thermal lubrication characteristics 75 Journal bearing and radial seal 79 Lubrication equations 79 Thermal boundary condition 80 Lubrication property 80 Spiral groove thrust bearing 83 Lubrication equations 83 Boundary conditions 85 Lubrication property 86 Spiral groove face seal 86 Temperature characteristics of gas film 91 Lubrication property 94 References 99 Contents _x00E_VII CHAPTER 5 Gas thermoelastohydrodynamic lubrication of face seals 101 Fundamental equations 101 Lubrication equations 101 Boundary conditions 104 Choked fluid effect 107 Model validation 107 Pressure distribution characteristics 109 Characteristics of thermoelastic distortions of seal faces 109 Characteristics of gas thermoelastohydrodynamic lubrication 111 Mechanical distortions 111 Thermal distortions 115 Thermoelastic distortions 117 References 120 CHAPTER 6 Transient thermoelastohydrodynamic gas lubrication of face seals 121 Fundamental equations 121 Dynamic equations 122 Lubrication equations 122 Boundary conditions 123 Dynamic characteristic parameter 123 Dynamic characteristics of isothermal gas lubrication 124 Axial stiffness and damping 124 Angular stiffness and damping 126 Amplitude-frequency characteristics of gas film 129 Dynamic characteristics of thermal gas lubrication of rigid surfaces 130 Axial stiffness and damping 131 Angular stiffness and damping 134 Amplitude-frequency characteristics of gas film 137 Dynamic characteristics of gas thermoelastohydrodynamic lubrication 137 Axial stiffness and damping 137 Angular stiffness and damping of gas film 139 Amplitude-frequency characteristics of gas film 140 References 141 VIII Contents CHAPTER 7 Vapor-condensed gas lubrication of face seals 143 Fundamental equations 143 Wet gas equations 143 Vapor-condensed parameter 145 Characteristics of vapor condensation in gas lubrication film 145 Laws of vapor condensation in gas lubrication film 146 Humidity 146 Seal clearance 147 Seal pressure 148 Rotational speed 148 Movement of liquid drops on gas lubrication surfaces 150 Surface wetting model 150 Surface-texture geometry parameters and wettability 152 Droplet motion 158 Drop adsorption on seal surface 164 References 164 CHAPTER 8 Cryogenic gas lubrication of face seals 167 Fundamental equations 167 Lubrication equations 168 Boundary conditions 171 Phase change in gas lubrication film 172 Characteristics of thermoelastic distortions of seal faces 173 Characteristics of cryogenic gas lubrication 173 Ambient temperature 174 Rotation speed 174 References 177 CHAPTER 9 Surface grooves of gas face seals and testing technology 179 Surface grooves of gas face seals 179 Testing technology of gas face seals 185 Experimental setup 185 Face groove machining 185 Face morphology test 187 Experimental characteristics of gas face seals 188 Seal opening characteristic 188 Hydrodynamic characteristics 190 Contents IX Surface wear 192 References 195 CHAPTER 10 Design of gas face seals 197 Force analysis of gas seals 197 Opening force 198 Closing force 198 O-ring friction force 199 Geometric parameters of gas face seals 199 Seal clearance 199 Seal face width 199 Balance diameter 200 Seal face and shaft (shaft sleeve) clearance 200 Performance parameters of gas face seals 201 Leakage rate 201 Gas film stiffness 201 Materials of the seal couple 202 Dimension design of seal rings 202 Design of rotor dimension 202 Design of stator dimension 203 Design of the face groove 204 Design of the secondary seal 205 Process of seal design and illustration 205 Process of seal design 205 Design conditions 206 Design steps 206 References 218 Index 219