Leading edge. Leading edge vortex, LE-V. Closed-type Boundary layer separation. Unsteady shedding by axial velocity

Transcription

1 Leeward 8/24/2014 Appendix III. CFDShip-Iowa Analysis of Onset and Separation of Instantaneous Vortical Structures, Instability Analysis and Turbulence Budget for Static Drift Condition Table III.1-1: Summary of additional instantaneous vortices, apart from the dominant mean vortices, predicted by CFDShip-Iowa V4 DES for DTMB 5415 with bilge keels at 20 drift at Re = , Fr = 0.28 Flow side Vortex Onset Separation Progression Sonar Dome surface Leading edge vortex, LE-V Leading edge free-furface vortex LE-FSV Leading edge Sonar dome reconnection vortex LE-SD-R Free-surface vortex FSV Sonar dome-hull reconnection vortex SD-H-R Fore body keel vortex FBKV Leeward bilge keel vortex, BKV Leading edge Vertically aligned in between free-surface and sonar dome Below the free-surface and close to the leading edge Circulation induced by the free-surface Separation on sonar dome surface close to the leading edge (X = 0.008, Z = -0.04) and slighty upstream (X = 0.03, Z = ). Free-surface induced Aligned along axial direction in between hull and breaking waves Flow separation on concave surface of sonar dome (X = 0.068, Z = ) and on the hull (X = X = 0.055, Z = ) Concave section of the sonar dome X = 0.055, Z = Free-surface induced downward flow and upward flow from the concave portion of sonar dome Vortex separation behind blunt body due to incoming cross flow Multiple separations along the bilge keel Closed-type Boundary layer separation Open-closed type Boundary layer separation Closed-type, connects leading edge and sonar dome separation Both Boundary layer and cross flow separation Open-closed type Boundary layer separation Closed-type Both Boundary layer and cross flow separation Connects hull high pressure source and sonar dome saddle point Open-type Boundary layer separation at the sonar domekeel intersection Open-type Shear layer separation Unsteady shedding by axial velocity Advected by the flow streamline underneath the free-surface Needs investigation Advected along the hull by axial velocity and towards free-surface bt the SDTV circulation Needs investigation Advected by streamwise velocity Moves towards the hull due to lifting generted by SDTV Advected by freestream velocity 1

2 Table III.1-2: Vortices and scaling for DTMB 5415 with bilge keels at 20 drift simulation. 8/24/2014 Windward side Leeward side Vortex BKTV Bow free surface vortex FS BW2 Shoulder free surface vortex SDTV Sonar dome separation bubble Instability type Helical Plunging wave breaking Spilling wave breaking Helical Unsteadiness Measurement Location Points are shown in Fig. III.1-13 Points are shown in Fig. III.1-12 Period Frequency (f) Length (L) Analysis required Analysis Required Results shown in Fig. III.1-14 Results shown in Fig. III.1-14 Velocity (U) St=fL/U LW-FBKV Shear-layer X=0.2, Y=-0.11, Z= = Leeward free surface Plunging X=0.16, Y=-0.158, Z= vortex FS BW1 breaking wave Shoulder free surface Spilling wave vortex FS BW3 breaking Analysis Required SDTV induced wave Spilling wave breaking vortex FS 3 breaking Analysis Required Leeward bilge keel vortex Analysis Required Shear-layer, B SL1 X=0.056, Y=-0.168, Z= = Shear-layer, B SL2 X=0.078, Y=-0.176, Z= = Karman-like, B K X=0.088, Y=-0.168, Z= Flapping-like Analysis Required Transom Transom vortices Karman-like Analysis Required Half the distance between B SL1 and B SL2 instabilities. Half wake width H=

3 Inset D Inset A Inset C Inset B (a) 10 M grid URANS (b) 10M grid DES (b) 48M grid DES (c) 250M grid DES Figure III.1-1: Free-surface elevation contour obtained from (a) 10M grid URANS, (b) 10M grid DES, (c) 48M grid DES and (d) 250M grid DES. Contour levels are from to 0.01 with intervals of Figure (a) shows the inset locations used in the figures below. 3

4 Free-surface Vortex, FSV Leading Edge Free- Surface Vortex LE-FSV Leading Edge Vortex, LE-V Leading edge Sonar dome reconnection vortex LE-SD-R Sonar dome- Hull reconnection vortex SD-H-R (a) High pressure source Open Separation Line Sink Open Separation Line Saddle point Closed Separation Low pressure sink Converging streamlines Converging streamlines Saddle point Closed Separation Converging streamlines (b) Figure III.1-2: (a) View of the vortical structures (Q = 2000) on the leeward sonar dome surface. (b) Hull surface streamline for =20 case obtained using CFDShip-Iowa (DES, 10M) instantanesou solution. 4

5 Figure III.1-3: Vortices on the windward side are shown using Q = 300. Surface streamline on the windward sonar dome surface for =20 case obtained using CFDShip-Iowa (DES, 10M) instantanesou solution. 5

6 Boundary layer separates Leading Edge Separation Line Saddle point X=0.035 X=0.025 LE-FSV LE-V Flow-streamline Figure III.1-4: Surface streamline on the leeward leading edge and Q=5000 showing the vortical structures for =20 case obtained using CFDShip-Iowa (DES, 10M) instantanesou solution. 6

7 LE-FSV (a) (b) Figure III.1-5: Flow streamline below the free-surface showing the generation of the LE-FSV for =20 case obtained using CFDShip- Iowa (DES, 10M) instantanesou solution. 7

8 Z = LE-SD-R Z = Z = (a) X=0.03 X=0.03 X=0.035 X=0.035 (b) Figure III.1-6: (a) View of the LE-SD-R vortex using Q = 5000, flow streamline at Z = , and slice X = 0.03 shows the vortex using Q = contours (red line). (b) Cross-flow recirculation associated with LE-SD-R vortex on the sonar dome for =20 case obtained using CFDShip-Iowa (DES, 10M) instantanesou solution. 8

9 Free-surface Vortex, FSV X=0.1 X=0.05 Z= Z= Figure III.1-7: Shoulder free-surface vortex FSV is shown using Q = Slices Z = , X = are shown to analyze the generation of the vortex for =20 case obtained using CFDShip-Iowa (DES, 10M) instantanesou solution. 9

10 Z= Sonar dome- Hull reconnection vortex SD-H-R Connection on hull Figure III.1-8: Sonar dome Hull reconnection vortex is shown by Q = 2000 for =20 case obtained using CFDShip-Iowa (DES, 10M) instantanesou solution. 10

11 Inset A Inset B Inset C Inset D 8/24/2014 (a) 10M grid, URANS (b) 10M grid, DES Windward bow wave breaking scar Leeward bow wave breaking scars (c) 48M grid, DES Windward shoulder breaking wave scar Leeward shoulder breaking wave scar Sonar done vortex induced breaking wave scar Transom breaking wave scar (d) 250M grid, DES Fig. III.1-9: Wave breaking pattern predicted for obtained using CFDShip-Iowa on 10M, 48M and 250M grids. Inset A-D locations are shown in Fig. III

12 Leeward Free-surface Vortex (FSBW1) 8/24/2014 Transom vortices, shown using Q = 100 BSL1 X=0.088 LW-BKV Z=-0.04 BSL2 BK X=0.088 Karman-like Instability (BK) Leeward Forebody Keel Vortex Sonar Dome Vortex (SDTV) Shear-layer Instability (BSL1) Z=-0.04 Shear-layer Instability (BSL2) Windward Forebody Keel Vortex LW-FBKV Fig. III.1-10: Leeward side view of the isosurfaces of Q=300 for an instantaneous solution T=7.5L/U using 10M grid. Isosurfaces are colored using pressure and free-surface using z. 12

13 Leeward After-body keel Vortex (ABKV) Windward After-body keel Vortex (ABKV) Windward Free-surface Vortex (FSBW2) Leeward SDTV induced freesurface Vortex (FS3) Bilge keel Tip Vortex (BKTV) Fig. III.1-11: Windward side view of the isosurfaces of Q=300 for an instantaneous solution T=7.5L/U using 10M grid. Isosurfaces are colored using pressure and free-surface using z. 13

14 SDTV P4 P5 P3 P2 P1 X=0.12 X=0.125 X=0.13 X=0.16 X=0.20 SDTV inception Fig. III.1-12: Instantaneous solution streamlines at several X planes show the inception of SDTV at X=0.125, Y= , Z= and advection on leeward side. Contours are for pressure. 14

15 BKTV P6 P5 P4 P3 P2 P1 X=0.375 X=0.6 X=0.75 X=0.85 X=1.0 BKTV Fig. III.1-13: Instantaneous solution streamlines at several X planes show Bilge keel tip vortex (BKTV) formation at X=0.375, Y= , Z= , which is advected to the port side. Contours are for pressure. 15

16 (a) (b) Fig. III.1-14: Variation of (a) dimensionless frequency and (b) product frequency and distance from origin as a function of stream wise distance along vortex core for SDTV and BKTV. 16

17 X=0.088 Z= /24/2014 Z=0.04 X=0.056 Karman-like Instability (BK) X=0.078 Shear-layer Instability (BSL1) Shear-layer Instability (BSL2) Shear-layer Instability (BSL1) Inception (P1) X=0.056 X=0.078 X=0.084 X=0.088 BSL1 FSBW1 Shear-layer Instability (BSL2) Inception (P2) Karman-like Instability (BK) (P3) X=0.092 X=0.096 X=0.1 Fig. III.1-15: Slices of instantaneous flow field shows inception of B SL1 at X=0.056, Y=-0.168, Z= and B SL2 at X=0.078, Y=-0.176, Z= Counter rotating KH B1 and KH B2 merge at shown at X=0.084 slice and are advected away from the sonar dome bulb as shown in X= slices. Contours are for pressure. 17

18 (a) (b) (c) Fig. III.1-16: Dominant frequency for (a) BSL1, (b) BSL2 and (c) BK. 18

19 X=0.2 X=0.3 X=0.4 X=0.5 X=0.6 KSL inception (P4) (a) (b) Fig. III.1-17: (a) Instantaneous solution streamlines at several X planes show boundary layer flow separation at X=0.2, Y=-0.11, Z= , which eventually forms K SL at X=0.6. Contours are for pressure. (b) K SL dominant frequency. 19

20 Amplitude 8/24/ (a) M Grid 48M Grid 10M Grid (b) Period Fig. III.1-18: (a) FS BW1 dominant frequency and (b) FS BW2 dominant frequency. 20

21 BK (a) 10M Grid 21

22 (b) 48M Grid Fig. III.1-19: TKE budget at x/l=

23 SDTV KSL (a) 10M Grid 23

24 (b) 48M Grid Fig. III.1-20: TKE budget at x/l=

25 SDTV BKK (a) 10M Grid 25

26 (b) 48M Grid Fig. III.1-21: TKE budget at x/l=

27 SDTV KSL BKK (a) 10M Grid 27

28 (b) 48M Grid Fig. III.1-22: TKE budget at x/l=

29 FS3 SDTV KTV (a) 10M Grid 29

30 (b) 48M Grid Fig. III.1-23: TKE budget at x/l=

31 SDTV KTV (a) 10M Grid 31

32 (b) 48M Grid Fig. III.1-24: TKE budget at x/l=

33 KTV SDTV (a) 10M Grid 33

34 (b) 48M Grid Fig. III.1-25: TKE budget at x/l=