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Exterior Ballistics

Complex Aerodynamics Behavior of High Spin APFSDS Projectile

[+] Author and Article Information
Roxan Cayzac

Head of Aerodynamics Technical Direction Nexter Munitions,
7 Route de Guerry,
18023 Bourges Cedex, France;
Associate Professor of the Universities,
ENSIB/PRISME,
88 Boulevard Lahitolle, 18020 Bourges Cedex, France
e-mail: r.cayzac@nexter-group.fr

Eric Carette

Research Associate in Aerodynamics
Technical Direction
e-mail: e.carette@nexter-group.fr

Settie Heddadj

Head of Flight Dynamics
Technical Direction
e-mail: s.heddadj@nexter-group.fr
Nexter Munitions,
7 Route de Guerry,
18023 Bourges Cedex, France

1Corresponding author.

Contributed by the Applied Mechanics Division of ASME for publication in the JOURNAL OF APPLIED MECHANICS. Manuscript received June 28, 2012; final manuscript received September 12, 2012; accepted manuscript posted January 9, 2013; published online April 19, 2013. Assoc. Editor: Bo S. G. Janzon.

J. Appl. Mech 80(3), 031601 (Apr 19, 2013) (7 pages) Paper No: JAM-12-1271; doi: 10.1115/1.4023337 History: Received June 28, 2012; Revised September 12, 2012; Accepted January 09, 2013

The supersonic aerodynamics of a high spin armor-piercing fin-stabilized discarding sabot projectile (APFSDS) is numerically and experimentally investigated. Classically, using a 120 mm smooth bore gun, the value of the nondimensional steady spin rate of the inflight APFSDS projectile is about 0.01. In our case, a medium caliber APFSDS projectile is fired using a rifled barrel gun. The initial nondimensional spin rate, which is, with the Mach and the Reynolds numbers, the third similitude parameter governing the projectile aerodynamics, is significantly greater and about 0.09. Complex aerodynamics and flight dynamics were found and are detailed in the paper. In particular, the side force and moment evolutions with spin rate and angle of attack reflect a highly nonlinear behavior of the Magnus effect. The numerical predictions are mainly based on Reynolds-averaged Navier–Stokes (RANS) and URANS (Unsteady RANS) equations. Flight tests have been performed in an aeroballistics corridor. The exterior ballistics of the projectile was investigated using a yaw cards method, the experimental results are analyzed using a 6DOF flight dynamics model. The comparison between computational fluid dynamics (CFD) computations and flight tests results is satisfactory. CFD computations show, for the first time at our knowledge, that a roll-pitch coupling may appear.

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References

Platou, A. S., 1960, “Magnus Characteristics of Finned and Nonfinned Projectiles,” AIAA J., 3(1), pp. 83–90. [CrossRef]
Weinacht, P., and Sahu, J., 1994, “Navier–Stokes Predictions of Missile Aerodynamics,” Special Course on Missile Aerodynamics, AGARD Report No. 804.
Péchier, M., 1999, “Numerical Predictions of Magnus Effects Over Ammunition Configurations,” Ph.D. thesis, Department of Mechanical Engineering, University of Poitiers, Poitiers, France.
Cayzac, R., and Carette, E., 2000, “Intermediate Ballistics and Aeroballistics Overview,” Proceedings of the European Forum on Ballistics of Projectiles, ISL, Saint-Louis, France, April 11–14, pp. 259–274.
Péchier, M., Guillen, P., and Cayzac, R., 2001, “Magnus Effect Over Finned Projectiles,” J. Spacecr. Rockets, 38(4), pp. 542–549. [CrossRef]
Cayzac, R., and Carette, E., 2004, “CFD Computations of Projectile Unsteady Aerodynamics,” Proceedings of the 55th Meeting of the Aeroballistic Range Association, Freiburg, Germany, September 27–October 1.
Cayzac, R., Carette, E., and Thepot, R., 2005, “Recent Computations and Validations of Projectile Unsteady Aerodynamics,” Proceedings of the 22nd International Symposium on Ballistics, Vancouver, Canada, November 14–18, Vol. 1, pp. 29–37.
Cayzac, R., Carette, E., Denis, P., and Guillen, P., 2011, “Magnus Effect: Physical Origins and Numerical Prediction,” ASME J. Appl. Mech., 78, p. 051005. [CrossRef]

Figures

Grahic Jump Location
Fig. 2

Mach number fields (Mach = 4.1, p* = 0, α = 2 deg, 4 deg, and 10 deg)

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Fig. 3

Mach number fields (Mach = 4.1, p* = 0.00375 and p* = 0.0877, α = 4 deg)

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Fig. 4

Pressure fields (Mach = 4.1, p* = 0.00375 and p* = 0.0877, α = 4 deg)

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Fig. 5

Velocity vector fields (Mach = 4.1, p* = 0.00375 and p* = 0.0877, α = 4 deg)

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Fig. 6

Cy and Cn distributions (Mach = 4.1, p* = 0.00375 with ▪ and p* = 0.0877 with □, α = 4 deg)

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Fig. 7

Mean CAn and Cm coefficients with spin rate in rev/s and angle of attack (Mach = 4.1)

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Fig. 8

Mean Cy, Cn, and Cl coefficients with spin rate in rev/s and angle of attack (Mach = 4.1)

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Fig. 9

Stagnation pressure in different cross-planes (Mach = 4.1, p* = 0.0877, α = 4 deg on the left/Mach = 4.1, p* = 0.00375, α = 10 deg on the right)

Grahic Jump Location
Fig. 10

Unsteady Cm and Cn evolutions with angle of attack (Mach = 4.1)

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Fig. 11

Angles of attack versus range (yaw cards)

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Fig. 12

Yaw cards/calculations fittings for a low AoA (left) and a high AoA (right)

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Fig. 13

Cnpα Magnus moment coefficient derivative evolutions with spin rate (rev/s) and angle of attack (deg)

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