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Slide 1: D. N. THAKUR SCIENTIST DRDL, HYDERABAD, INDIA
Slide 2: PRESENTATION OVERVIEW  BACKGROUND FOR THE PRESENT STUDY  LATERAL FORCES AND MOMENTS – HOW AND WHEN ARE THEY GENERATED ?  WIND TUNNEL TESTING FOR ALLEVIATION STUDIES CONFIGURATIONS TESTED TESTS RESUTLS  COMPUTATIONAL STUDIES CARRIED OUT  CONCLUSIONS
Slide 3: TEST RESULTS ON ANTI-TANK MISSILE REPEATABILITY OF TEST DATA AT  = 45o NORMAL FORCE COEFFICIENT 2 1 0 -1 -2 -3 -4 -5 -6 -7 -24 -20 -16 -12 -8 -4 0 4 8 Alpha (deg) 0.1 0.0 -0.1 cl -0.2 -0.3 -0.4 4 8 CN 1.5 1.0 0.5 0.0 cn cs -0.5 -1.0 -1.5 -2.0 -2.5 -24 -20 -16 -12 -8 -4 0 Alpha (deg) 4 8 -0.6 -24 -20 -16 -12 -8 -4 0 Alpha (deg) YAWING MOMENT COEFFICIENT 0.4 0.2 0.0 -0.2 -0.4 SIDE FORCE COEFFICIENT ROLLING MOMENT COEFFICIENT -0.5 -24 -20 -16 -12 -8 -4 0 Alpha (deg) 4 8 • REPEATABILITY GOOD FOR LONGITUDINAL CHARACTERISTICS • FOR LATERAL CHARACTERISTICS REPEATABILITY IS GOOD UP TO –160 ALPHA
Slide 4: LATERAL FORCES AND MOMENTS – HOW AND WHEN  LATERAL FORCES AND MOMENTS ARE GENERATED BECAUSE OF ASYMMETRIC SHEDDING OF VORTICES  OCCURS AT HIGH ANGLES OF ATTACK AT SUB / TRANSONIC MACH NUMBERS  HIGHLY DETRIMENTAL BECAUSE OF WASTAGE OF CONTROL POWER TO CORRECT THESE FORCES AND MOMENTS  LITERATURE SURVEY ON EXPERIMENTS SUGGEST THAT ALLEVIATION IS POSSIBLE BY ACTIVE AND PASSIVE MEANS
Slide 5: ASYMMETRIC VORTEX SHEDDING
Slide 6: TWO REASONS WHY THE VORTEX SHEDDING IS ASYMMETRIC:  SEPARATION LINES ON EITHER SIDES OF THE FOREBODY BECOME ASYMMETRIC  ABOVE A CERTAIN ANGLE OF ATTACK, IT IS NO LONGER POSSIBLE FOR TWO STRONG CONTRA-ROTATING VORTICES TO COEXIST SYMMETRICALLY. SO, A VERY SMALL PERTURBATION (SLIGHT GEOMETRICAL DEFECT) IS THEN SUFFICIENT TO CAUSE THE VORTEX SYSTEM TO CHANGE OVER FROM AN UNSTABLE SYMMETRIC STATE TO A STABLE ASYMMETRIC STATE.
Slide 7: PRESENT STUDY OBJECTIVE: TO GENERATE AERODYNAMIC LATERAL FORCES AND MOMENTS AND ALLEVIATE THE SAME  TYPICAL MISSILE CONFIGURATIONS WITH 3 DIFFERENT NOSE SHAPES (OGIVE, CONE, HEMISPHERE) HEMISPHERICAL NOSE 13.0d CONFIGURATION - I d CONFIGURATION -II d OGIVAL NOSE 13.0d CONFIGURATION -III d CONICAL NOSE 13.0d
Slide 8:  WIND TUNNEL TESTS WERE CONDUCTED IN 2’ TUNNEL, NAL, BANGALORE, INDIA  MODEL SCALE  MACH NUMBERS  WIND TUNNEL TESTS: (1) ON CLEAN BODY (WITHOUT WIRE TUNNELS)  EFFECT OF NOSE SHAPE AND ROLL ORIENTATION (2) WITH WIRE TUNNELS  EFFECT OF NOSE SHAPE AND ROLL ORIENTATION  EFFECT OF PROTRUSIONS  EFFECT OF MACH NUMBER (3) TESTS FOR ALLEVIATION OF LATERAL CHARACTERISTICS  FOUR DIFFERENT RINGS WERE TRIED – 1:3.6 – 0.5, 0.7, 1.0, 1.15
Slide 10: NOSE EFFECT: NO Wire Tunnels (φ = 0o) NORMAL FORCE COEFFICIENT AT MACH = 0.5 PITCHING MOMENT COEFFICIENT AT MACH = 0.5 φ = 0 deg.
Slide 11: NOSE EFFECT: NO Wire Tunnels (φ = 0o) AXIAL FORCE COEFFICIENT AT MACH = 0.5 ROLLING MOMENT COEFFICIENT AT MACH = 0.5 φ = 0 deg. 17o IS THE SEMI CONE ANGLE
Slide 12: NOSE EFFECT: NO Wire Tunnels (φ = 0o) SIDE FORCE COEFFICIENT AT MACH = 0.5 YAWING MOMENT COEFFICIENT AT MACH = 0.5 φ = 0 deg.
Slide 13: NOSE EFFECT: NO Wire Tunnels (φ = 0o) SIDE FORCE COEFFICIENT AT MACH = 0.7 ROLLING MOMENT COEFFICIENT AT MACH = 0.7 φ = 0 deg.
Slide 14: NOSE EFFECT: NO Wire Tunnels (φ = 0o) SIDE FORCE COEFFICIENT AT MACH = 1.15 ROLLING MOMENT COEFFICIENT AT MACH = 1.15 φ = 0 deg.
Slide 15: NOSE EFFECT: NO Wire Tunnels (φ = 22.5o) SIDE FORCE COEFFICIENT AT MACH = 0.5 ROLLING MOMENT COEFFICIENT AT MACH = 0.5 φ = 22.5 deg.
Slide 16: EFFECT OF ROLL: OGIVAL NOSE NORMAL FORCE COEFFICIENT AT MACH = 0.5 φ = 0 deg. PITCHING MOMENT COEFFICIENT AT MACH = 0.5 φ = 22.5 deg. φ = 45 deg.
Slide 17: EFFECT OF ROLL: OGIVAL NOSE AXIAL FORCE COEFFICIENT AT MACH = 0.5 φ = 0 deg. ROLLING MOMENT COEFFICIENT AT MACH = 0.5 φ = 22.5 deg. φ = 45 deg.
Slide 18: EFFECT OF ROLL: OGIVAL NOSE SIDE FORCE COEFFICIENT AT MACH = 0.5 φ = 0 deg. YAWING MOMENT COEFFICIENT AT MACH = 0.5 φ = 22.5 deg. φ = 45 deg.
Slide 20: EFFECT OF PROTRUSIONS: OGIVAL NOSE (φ = 0o) SIDE FORCE COEFFICIENT AT MACH = 0.5 CONFIGURATION - I d No Wire Tunnel 13.0d 450 d CONFIGURATION -II 1.7 d 13.0d One Wire Tunnel d ROLLING MOMENT COEFFICIENT AT MACH = 0.5 CONFIGURATION -III 450 13.0d Two Wire Tunnels
Slide 21: EFFECT OF PROTRUSIONS: OGIVAL NOSE (φ = 45o) SIDE FORCE COEFFICIENT AT MACH = 0.5 No Wire Tunnel ROLLING MOMENT COEFFICIENT AT MACH = 0.5 45 0 45 0 One Wire Tunnel Two Wire Tunnels
Slide 22: EFFECT OF COMPONENTS: HEMISPHERICAL NOSE (φ = 0o) NORMAL FORCE COEFFICIENT AT MACH = 0.7 PITCHING MOMENT COEFFICIENT AT MACH = 0.7
Slide 23: EFFECT OF COMPONENTS: HEMISPHERICAL NOSE (φ = 0o) SIDE FORCE COEFFICIENT AT MACH = 0.7 ROLLING MOMENT COEFFICIENT AT MACH = 0.7
Slide 24: EFFECT OF MACH NO: CONICAL NOSE WITHOUT WT (φ = 0o) NORMAL FORCE COEFFICIENT PITCHING MOMENT COEFFICIENT
Slide 25: EFFECT OF MACH NO: CONICAL NOSE WITHOUT WT (φ = 0o) AXIAL FORCE COEFFICIENT ROLLING MOMENT COEFFICIENT
Slide 26: EFFECT OF MACH NO: CONICAL NOSE WITHOUT WT (φ = 0o) SIDE FORCE COEFFICIENT YAWING MOMENT COEFFICIENT
Slide 28: ALLEVIATION OF LATERAL CHARACTERISTICS ALLEVIATION ACTIVE DEVICES PASSIVE DEVICES NOSE BLOWING NOSE ROTATION RINGS STRAKES NOSE BLUNTING POROUS TIPS BOUNDARY LAYER TRIPS
Slide 29: DETAILS OF THE RINGS USED FOR ALLEVIATION CONFIGURATION - I d 13.0d Ring A CONFIGURATION -II d Ring B 13.0d CONFIGURATION -III d 13.0d Ring C Ring D
Slide 30: ALLEVIATION TESTS: CONICAL NOSE WITHOUT WT (φ = 0o) NORMAL FORCE COEFFICIENT AT MACH = 0.7 d 2.0d 13.0d PITCHING MOMENT COEFFICIENT AT MACH = 0.7
Slide 31: ALLEVIATION TESTS: CONICAL NOSE WITHOUT WT (φ = 0o) AXIAL FORCE COEFFICIENT AT MACH = 0.7 ROLLING MOMENT COEFFICIENT AT MACH = 0.7
Slide 32: ALLEVIATION TESTS: CONICAL NOSE WITHOUT WT (φ = 0o) SIDE FORCE COEFFICIENT AT MACH = 0.7 YAWING MOMENT COEFFICIENT AT MACH = 0.7
Slide 33: ALLEVIATION STUDIES ON ANTI-TANK MISSILE CONFIGURATION EFFECT OF RING ON REPEATABILITY CHARACTERISTICS • INTRODUCING THE RING HELPS IN IMPROVING THE REPEATABILITY • ROLLING MOMENT VALUES ARE ALSO REDUCED WITHOUT RING 0.1 0.0 -0.1 cl cl -0.2 -0.3 -0.4 -0.5 -24 -20 -16 -12 -8 -4 0 Alpha (deg) 4 8 ROLLING MOMENT COEFFICIENT 0.20 0.15 0.10 0.05 0.00 -0.05 -24 -20 -16 -12 -8 -4 0 Alpha (deg) 4 8 WITH RING ROLLING MOMENT COEFFICIENT
Slide 34: ALLEVIATION OF LATERAL FORCE ON A OGIVE-CYLINDER-FLARE MODEL CONFIGURATION WITH STRAKE-A WHTV CONFIGURATION WITH STRAKE- A d 10° STRAKE DETAILS TYPE OF STRAKE 45° h L 2.5 STRAKE - A 5.0d h 2.5 2.5 WHTV CONFIGURATION WITH STRAKE- B SIDE FORCE COEFFICIENT d 10° YAWING MOMENT COEFFICIENT 20 L STRAKE - B STRAKE TYPE STRAKE - B L/d 0.24, 0.4, 0.56 0.16, 0.2 h/d 0.02, 0.04 0.02, 0.04, 0.06 5.0d STRAKE - A STRAKE - B
Slide 35: 45° h 2.5 ALLEVIATION OF LATERAL FORCE ON A OGIVE-CYLINDER-FLARE MODEL L 5.0d STRAKE - A h WHTV CONFIGURATION WITHSTRAKE-B CONFIGURATION WITH STRAKE- B d 10° 2.5 2.5 20 L 5.0d STRAKE TYPE STRAKE - A STRAKE - B STRAKE DETAILS STRAKE - B L/d 0.24, 0.4, 0.56 h/d 0.02, 0.04 SIDE FORCE COEFFICIENT YAWING MOMENT COEFFICIENT 0.02, 0.04, 0.06 0.16, 0.2 STRAKE - B
Slide 36: CFD RESULTS ON CONICAL NOSE CONFIGURATION MESH STRUCTURE No Wire Tunnel Coeff. CN Cs Cm Cn Cl Expt. 6.46 0.94 - 43.74 -7.35 0.19 CFD 6.68 0.91 With Wire Tunnel Expt. 6.43 0.95 CFD 6.25 0.93 - 40.61 -8.1 0.35 - 44.25 - 41.84 -7.15 0.14 -8.42 0.46 M = 0.7, α = 20o, φ = 22.5o PRESSURE DISTRIBUTION OVER THE CONFIGURATION
Slide 37: SUMMARY  AN UNDERSTANDING OF HOW AND WHEN THE LATERAL FORCES AND MOMENTS ARE GENERATED AND POSSIBLE MEANS OF ALLEVIATION  LATERAL FORCES AND MOMENTS START PICKING UP WHEN THE ANGLE OF ATTACK IS EQUAL TO THE SEMI-CONE ANGLE  IT HAS BEEN INFERRED FROM THE EXPERIMENTS THAT STRAKES / CIRCULAR TRIPS ALLEVIATE/REDUCE THE LATERAL FORCES AND MOMENTS  FEW CFD RUNS HAVE BEEN CARRIED OUT AND THE COMPUTATIONAL RESULTS ARE FAIRLY MATCHING WELL WITH THE EXPERIMENTS  FURTHER INVESTIGATION CAN BE CARRIED OUT AFTER IMPROVED FLOW DIAGNOSTICS (LDV) ARE AVAILABLE WITH THE FACILITY