INTEGRALLY GEARED COMPRESSORS Travis A. Cable Karl Wygant Research - PowerPoint PPT Presentation

Proceedings of ASME Turbo Expo 2016: Turbine Technical Conference and Exposition, June 13-17, 2016, Seoul, South Korea Paper GT2016-57888 ON THE PREDICTED EFFECT OF ANGULAR MISALIGNMENT ON THE PERFORMANCE OF OIL LUBRICATED THRUST COLLARS IN INTEGRALLY GEARED COMPRESSORS Travis A. Cable Karl Wygant Research Assistant Director of Engineering Luis San Andrés Hanhwa Techwin Houston, TX 77079,USA Mast-Childs Chair Professor, Fellow ASME Mechanical Engineering Texas A&M University 1 Supported by Hanhwa (formerly Samsung) Techwin

Integrally Geared Compressors Compared to single shaft multistage compressors, industry selects IGCs for their: • increased thermal efficiency, • decreased footprint, & • ease of access for maintenance and overhaul. 2 All pictures & components are a courtesy of Hanhwa (formerly Samsung) Techwin

The Thrust Collar (TC) Lubricated zone in thrust collar transmits axial load from pinion shaft & gear to bull gear shaft. Load is from gas pressure acting on the front and back sides of an impeller plus the axial component of the transmission contact force in a helical gear. 3

Thrust Collars in the Literature  empirical formula for selection of taper angles Sadykov, V.A. and Shneerson, L.M, “Helical and diametral interference fit. Table for selection of Gear Transmissions with Thrust Collars,” 1968 thrust collars given operating speed and load. Russian Engineering Journal. Simon, V., “Thermal Elastohydrodynamic  Hydrodynamic analysis of rider rings (thrust Lubrication of Rider Rings,” ASME J. 1984 collars) with identical taper angles. Tribology.  Hydrodynamic analysis of thrust cones (thrust Barragan de Ling, F., Evans, H.P. and Snidle, R.W., “Thrust Cone Lubrication collars) for heavily loaded, low speed, marine gear 1991 boxes. Only one taper angle. Part 1: Elastohydrodynamic Analysis of Conical Rims,” IMech J. Eng. Trib.  Complete EHD analysis of TCs to optimize Thoden, D., “ Elasto-hydrodynamic 2006, Lubrication of Pressure Ridges,” geometry for largest load at design speed. Only 2009 one taper angle. Clausthal University of Technology . San Andrès, L., Cable, T.A., Wygant, K.D. and Morton, A. , “On the Predicted  Predictions of thrust collar performance Performance of Oil Lubricated Thrust (mechanical power loss, film thickness, etc.) for 2014 Collars in Integrally Geared various thrust collar and bull gear taper angles. Compressors,” ASME J. Eng. Gas Turbines Power. Wygant, K., Bygrave, J., Bosen, W. and  Design considerations for IGCs. One section Pelton, R., 2016, “ Tutorial on the addresses to thrust collars for balancing thrust Application and Design of Integrally 2016 loads on IGC pinion shafts. Geared Compressors,” Proc. of Asia Turbomachinery and Pump Symposium, Feb. 22-26, Singapore.

Kinematics of thrust collar w B : BG speed w B : BG speed w TC : TC speed Film thickness (exaggerated) f : taper angle 5

Static Misalignment of Thrust Collar Thrust Collar: α x α y Angular Misalignment y y y ω TC ω TC ω TC TC z z z r r r θ θ θ x α y x α x x TC TC Angular Misalignment BG BG BG ω B ω B ω B (b) α x (c) α y (a) No misalignment misalignment misalignment 6

Static Misalignment of Bull Gear Bull gear: y y y ω TC ω TC TC ω TC Angular β x TC β y TC Misalignment z z r r z r θ θ θ x x x β x β y BG BG BG ω B ω B ω B Angular Misalignment (b) β x (c) β y (a) No misalignment misalignment misalignment 7

Generation of Hydrodynamic Pressure Assumptions Laminar thin film flow. Incompressible lubricant. Rigid surfaces. Steady state.         3 3 1 h p 1 h p      r        θ r     r r 12 r r 12           1 1 h h       w     w   w          r b sin b cos r       B   θ B TC       r r 2 r 2 w B : BG speed w TC : TC speed  : oil viscosity                        h r θ h R d b φ R  φ r θ β d β , tan tan cos r R 1 B TC y y y 1 1 h : film thickness       θ β r sin x x f : taper angles 8

Lubricant Temperature Rise Assumptions Bulk-temperature ~ T(r, θ ). Steady state.     1 1                ρc rq T q T h T T h T T   B TC   θ B TC P  r r θ  r r Convection + diffusion of lubricant thermal energy = Mechanical power loss. c p : Lubricant specific heat at constant pressure h : Heat convection coefficient q : Lubricant flow rate (per unit length) T B , T TC : Bull gear and thrust collar temperatures  : Energy dissipation         h p p function             b ω ε rω bω ε  sin cos    B TC B TC B r θ   2 r         9     w 2  w  w  2 r ω b 2 b cos r   B B TC TC h

Forces and Moments on a Thrust Collar Equilibrium and first-order pressure fields cause an axial force and moments on the Thrust Collar (and BG):       F   θ TC z , z R     max 1               w rdrd θ      i t β β M p p p p p p p e     z        TC x , 0 a z y x x y X x x y y       θ r M     max left  TC y , Y Equilibrium First order force and force & moments moments Gives:    z           H H H H H F   F         zz z z z z TC z ,   TC z , x x y y  x     0 w       i t   β M M H H H H H e            TC x , TC x , z x    0 x x x x x x y x y        M   M     H H H H H     TC y , y          TC y , z 0 y y x y x y y y y    β   y H = K + i ω C defines the fluid film stiffness and damping coefficients 10

Validation of the Predictive Tool Operating Conditions Simon Load W 5 kN [1984] R 1 ω TC / R 2 ω BG Speed Ratio 1.5 Geometry R 1 33.5 mm R 2 318.5 mm d 336 mm φ TC = φ BG 5 ° Material Young E TC = E BG 210 GPa modulus Lubricant Supply 60 ° C T s Temperature μ Dynamic Viscosity 0.135 Pa.s Ambient Pressure p a 100 kPa θ max 56 ° Max. angle Width at θ = 0 16 mm l 6.23 cm 2 Area A lub 11

Validation of the Predictive Tool Simon [1984] • Results show good agreement with data from Simon [1984] • Differences due to elastic deformation of the TC and BG surfaces 12

Parametric Study on Effect of Static Angular Misalignments on TC Performance 13

Average axial load and speed selected from existing machines W  W * W W/A =55 bar w w  TC w BG 14

Operating Conditions & Normalized Parameters Operating Conditions Load W 1.0 w Speed (BG/TC) 10 Geometry R 2 / R 1 7.14 d/R 1 7.78 Lubricant ISO VG 32 Supply Temperature T s 49 °C μ Dynamic Viscosity (49°C) 0.0204 Pa.s Ambient Pressure p a 100 kPa Constant load, speed and surface taper angles θ max Max. angle 47.3° Length c/R 1 1.47 Width at θ = 0 l/R 1 0.36  2 Area 0.12 A R lub 1 Normalized thrust load, pressure, film thickness, friction factor, temperature rise and lubricant flow rate:     w * W p h T         TC  W , P , h , f , T , Q Q  * * * * 3   w  R W p h W R T 2 1 TC 15

Contour Plots for Misalignments About x Axis φ B = φ TC • Location and magnitude of min. film shift with increasing TC misalignment α x . 16

Contour Plots for Misalignments About x Axis φ B = φ TC • Location and magnitude of peak pressure (and min film) shift with increasing TC misalignment α x . 17

Contour Plots for Misalignment About y Axis φ B = φ TC • Location and magnitude of min. film shift with increasing TC misalignment α y . 18

Contour Plots for Misalignment About y Axis φ B = φ TC • Location and magnitude of peak pressure (and min film) shift with increasing TC misalignment α y . 19

Minimum film thickness   W = 1.0 h h h / • Only one misalignment angle varies (either α x or α y ) cavitation area reduces • Misalignment of the TC about horizontal ( x ) axis produces different film thickness for           0.2 0.2, 0 positive and negative rotations. x y x y • Minimum film thickness is nearly symmetric for misalignments of the TC about vertical ( y ) axis. 20           0.2 0.2, 0 y x x y