465 23rd International Colloquium Tribology - January 2022 465 Effect of Thermal Conductivity of Bearing on the Thermal Wedge in Parallel Slider Bearing Tae-Jo Park School of Mechanical Engineering, Gyeongsang Nation University, Jinju, Korea Corresponding author: tjpark@gnu.ac.kr Jeong-Guk Kang School of Mechanical Engineering, Gyeongsang Nation University, Jinju, Korea 1. Introduction Temperature rise due to viscous shear of the lubricating oil generates hydrodynamic pressure even if the lubri-cating surfaces are parallel [1-2]. This is known as the thermal wedge effect and varies significantly with film-temperature boundary conditions [3]. The bearing con-ducts a part of the heat generated; hence, the film tem-perature varies with the thermal conductivity (ks) of the bearing. This study numerically investigates the effect of thermal conductivity on the thermohydrodynamic (THD) lubrication of parallel slider bearings. 2. Numerical Analysis Figure 1: Schematic of 2D parallel slider bearing. Table 1. Bearing size and operating condition. Symbol Value Bearing length, Effect of Thermal Conductivity of Bearing on the Thermal Wedge in Parallel Slider Bearing Tae-Jo Park 1)* , Jeong-Guk Kang 1) 1) School of Mechanical Engineering, Gyeongsang Nation University, Jinju, Korea * Corresponding author: tjpark@gnu.ac.kr 1. Introduction Temperature rise due to viscous shear of the lubricating oil generates hydrodynamic pressure even if the lubricating surfaces are parallel [1-2]. This is known as the thermal wedge effect and varies significantly with filmtemperature boundary conditions [3]. The bearing conducts a part of the heat generated; hence, the film temperature varies with the thermal conductivity (k s ) of the bearing. This study numerically investigates the effect of thermal conductivity on the thermohydrodynamic (THD) lubrication of parallel slider bearings. 2. Numerical Analysis Figure 1 Schematic of 2D parallel slider bearing. Table 1. Bearing size and operating condition. Symbol Value Bearing length, ㎛ L 450 Pad thickness, ㎛ h s 100 Film thickness, ㎛ c 1 Ambient temperature, K T 0 310 Sliding speed, m/ s U 10 Table 2. Thermal properties of bearing material. k s , W/ m∙K C ps , J/ kg∙K Carbon 167.36 707 Steel 16.27 502.48 SiO 2 1.4 700 Figure 1 shows a 2D micro-bearing model used. The continuity, Navier-Stokes, energy equations, temperature-viscosity-density relations for lubricant, and conduction equations for bearing are analyzed using a commercial CFD software, FLUENT. Tables 1 3. Results and Discussion Figure 2 shows the contour plot of film temperature and pressure distributions for three different pad materials, and Fig. 3 compares load-carrying capacity (LCC) and friction force acting on the slider. The thermal conductivity significantly influences the THD lubrication characteristics of parallel slider bearings. The lower the thermal conductivity, the greater the pressure generation due to the thermal wedge effect, so the LCC increased, and the frictional force decreased. Figure 2 Film-temperature and pressure distributions. (a) h s = 0 ㎛ , (b) Carbon, (c) Steel, (d) SiO 2 . (a) (b) Figure 3 Effect of bearing thermal conductivity on the (a) LCC, (b) friction force. 4. References [1] Cameron, A., "The viscosity wedge", ASLE Trans., 1, 2, 1958, 248-253. [2] Khonsari, M. M., "A review of thermal effects in hydrodynamic bearings. Part I: Slider and thrust bearings", ASLE Trans., 30, 1, 1987. 19-25. [3] Cui, J. et al., "The relation between thermal wedge and thermal boundary conditions for the L 450 Pad thickness, Effect of Thermal Conductivity of Bearing on the Thermal Wedge in Parallel Slider Bearing Tae-Jo Park 1)* , Jeong-Guk Kang 1) 1) School of Mechanical Engineering, Gyeongsang Nation University, Jinju, Korea * Corresponding author: tjpark@gnu.ac.kr 1. Introduction Temperature rise due to viscous shear of the lubricating oil generates hydrodynamic pressure even if the lubricating surfaces are parallel [1-2]. This is known as the thermal wedge effect and varies significantly with filmtemperature boundary conditions [3]. The bearing conducts a part of the heat generated; hence, the film temperature varies with the thermal conductivity (k s ) of the bearing. This study numerically investigates the effect of thermal conductivity on the thermohydrodynamic (THD) lubrication of parallel slider bearings. 2. Numerical Analysis Figure 1 Schematic of 2D parallel slider bearing. Table 1. Bearing size and operating condition. Symbol Value Bearing length, ㎛ L 450 Pad thickness, ㎛ h s 100 Film thickness, ㎛ c 1 Ambient temperature, K T 0 310 Sliding speed, m/ s U 10 Table 2. Thermal properties of bearing material. k s , W/ m∙K C ps , J/ kg∙K Carbon 167.36 707 Steel 16.27 502.48 SiO 2 1.4 700 Figure 1 shows a 2D micro-bearing model used. The continuity, Navier-Stokes, energy equations, temperature-viscosity-density relations for lubricant, and conduction equations for bearing are analyzed 3. Results and Discussion Figure 2 shows the contour plot of film temperature and pressure distributions for three different pad materials, and Fig. 3 compares load-carrying capacity (LCC) and friction force acting on the slider. The thermal conductivity significantly influences the THD lubrication characteristics of parallel slider bearings. The lower the thermal conductivity, the greater the pressure generation due to the thermal wedge effect, so the LCC increased, and the frictional force decreased. Figure 2 Film-temperature and pressure distributions. (a) h s = 0 ㎛ , (b) Carbon, (c) Steel, (d) SiO 2 . (a) (b) Figure 3 Effect of bearing thermal conductivity on the (a) LCC, (b) friction force. 4. References [1] Cameron, A., "The viscosity wedge", ASLE Trans., 1, 2, 1958, 248-253. [2] Khonsari, M. M., "A review of thermal effects in hydrodynamic bearings. Part I: Slider and thrust bearings", ASLE Trans., 30, 1, 1987. 19-25. [3] Cui, J. et al. "The relation between thermal h s 100 Film thickness, Effect of Thermal Conductivity of Bearing on the Thermal Wedge in Parallel Slider Bearing Tae-Jo Park 1)* , Jeong-Guk Kang 1) 1) School of Mechanical Engineering, Gyeongsang Nation University, Jinju, Korea * Corresponding author: tjpark@gnu.ac.kr 1. Introduction Temperature rise due to viscous shear of the lubricating oil generates hydrodynamic pressure even if the lubricating surfaces are parallel [1-2]. This is known as the thermal wedge effect and varies significantly with filmtemperature boundary conditions [3]. The bearing conducts a part of the heat generated; hence, the film temperature varies with the thermal conductivity (k s ) of the bearing. This study numerically investigates the effect of thermal conductivity on the thermohydrodynamic (THD) lubrication of parallel slider bearings. 2. Numerical Analysis Figure 1 Schematic of 2D parallel slider bearing. Table 1. Bearing size and operating condition. Symbol Value Bearing length, ㎛ L 450 Pad thickness, ㎛ h s 100 Film thickness, ㎛ c 1 Ambient temperature, K T 0 310 Sliding speed, m/ s U 10 Table 2. Thermal properties of bearing material. k s , W/ m∙K C ps , J/ kg∙K Carbon 167.36 707 Steel 16.27 502.48 SiO 2 1.4 700 Figure 1 shows a 2D micro-bearing model used. The continuity, Navier-Stokes, energy equations, 3. Results and Discussion Figure 2 shows the contour plot of film temperature and pressure distributions for three different pad materials, and Fig. 3 compares load-carrying capacity (LCC) and friction force acting on the slider. The thermal conductivity significantly influences the THD lubrication characteristics of parallel slider bearings. The lower the thermal conductivity, the greater the pressure generation due to the thermal wedge effect, so the LCC increased, and the frictional force decreased. Figure 2 Film-temperature and pressure distributions. (a) h s = 0 ㎛ , (b) Carbon, (c) Steel, (d) SiO 2 . (a) (b) Figure 3 Effect of bearing thermal conductivity on the (a) LCC, (b) friction force. 4. References [1] Cameron, A., "The viscosity wedge", ASLE Trans., 1, 2, 1958, 248-253. [2] Khonsari, M. M., "A review of thermal effects in hydrodynamic bearings. Part I: Slider and thrust c 1 Ambient temperature, K T 0 310 Sliding speed, m/ s U 10 Table 2. Thermal properties of bearing material. k s , W/ m∙K C ps , J/ kg∙K Carbon 167.36 707 Steel 16.27 502.48 SiO 2 1.4 700 Figure 1 shows a 2D micro-bearing model used. The continuity, Navier-Stokes, energy equations, temperature-viscosity-density relations for lubricant, and conduction equations for bearing are analyzed using a commercial CFD software, FLUENT. Tables 1 & 2 show bearing size and operating condition, and thermal properties of bearing material used. The ther-mal properties of oil used are nearly the same as Ref. [3]. 3. Results and Discussion Figure 2 shows the contour plot of film temperature and pressure distributions for three different pad mate-rials, and Fig. 3 compares load-carrying capacity (LCC) and friction force acting on the slider. The thermal conductivity significantly influences the THD lubrication characteristics of parallel slider bearings. The lower the thermal conductivity, the greater the pressure generation due to the thermal wedge effect, so the LCC increased, and the frictional force decreased. 466 23rd International Colloquium Tribology - January 2022 Effect of Thermal Conductivity of Bearing on the Thermal Wedge in Parallel Slider Bearing Figure 2: Film-temperature and pressure distributions. (a) hs = 0 cating surfaces are parallel [1 2]. This is known as the thermal wedge effect and varies significantly with filmtemperature boundary conditions [3]. The bearing conducts a part of the heat generated; hence, the film temperature varies with the thermal conductivity (k s ) of the bearing. This study numerically investigates the effect of thermal conductivity on the thermohydrodynamic (THD) lubrication of parallel slider bearings. 2. Numerical Analysis Figure 1 Schematic of 2D parallel slider bearing. Table 1. Bearing size and operating condition. Symbol Value Bearing length, ㎛ L 450 Pad thickness, ㎛ h s 100 Film thickness, ㎛ c 1 Ambient temperature, K T 0 310 Sliding speed, m/ s U 10 Table 2. Thermal properties of bearing material. k s , W/ m∙K C ps , J/ kg∙K Carbon 167.36 707 Steel 16.27 502.48 SiO 2 1.4 700 Figure 1 shows a 2D micro-bearing model used. The continuity, Navier-Stokes, energy equations, temperature-viscosity-density relations for lubricant, and conduction equations for bearing are analyzed using a commercial CFD software, FLUENT. Tables 1 & 2 show bearing size and operating condition, and thermal properties of bearing material used. The thermal properties of oil used are nearly the same as Ref. [3]. rials, and Fig. 3 compares load carrying capacity (LCC) and friction force acting on the slider. The thermal conductivity significantly influences the THD lubrication characteristics of parallel slider bearings. The lower the thermal conductivity, the greater the pressure generation due to the thermal wedge effect, so the LCC increased, and the frictional force decreased. Figure 2 Film-temperature and pressure distributions. (a) h s = 0 ㎛ , (b) Carbon, (c) Steel, (d) SiO 2 . (a) (b) Figure 3 Effect of bearing thermal conductivity on the (a) LCC, (b) friction force. 4. References [1] Cameron, A., "The viscosity wedge", ASLE Trans., 1, 2, 1958, 248-253. [2] Khonsari, M. M., "A review of thermal effects in hydrodynamic bearings. Part I: Slider and thrust bearings", ASLE Trans., 30, 1, 1987. 19-25. [3] Cui, J. et al., "The relation between thermal wedge and thermal boundary conditions for the load-carrying capacity of a rectangular pad and a slider with parallel gaps", ASME J. Tribology, 138, 2, 2016, 024502-1~6. , (b) Carbon, (c) Steel, (d) SiO2. Figure 3: Effect of bearing thermal conductivity on the (a) LCC, (b) friction force. References [1] Cameron, A., „The viscosity wedge“, ASLE Trans., 1, 2, 1958, 248-253. [2] Khonsari, M. M., „A review of thermal effects in hydrodynamic bearings. Part I: Slider and thrust bearings“, ASLE Trans., 30, 1, 1987. 19-25. [3] Cui, J. et al., „The relation between thermal wedge and thermal boundary conditions for the load-carrying capacity of a rectangular pad and a slider with parallel gaps“, ASME J. Tribology, 138, 2, 2016, 024502-1~6.