Abstract
Numerical simulations of a spinning projectile with a diameter of 120 mm were conducted to predict the aerodynamic coefficients, and the CFD results were compared with the semiempirical method, PRODAS. Six coefficients or coefficient derivatives, including zero and the quadratic drag coefficient, lift force coefficient derivative, Magnus force coefficient derivative, overturning moment coefficient, and spinning damping moment coefficient, which are important parameters for solving the equations of motion of the spinning projectile, were investigated. Additionally, the nonlinear behavior of these coefficients and coefficient derivatives were analyzed through the predicted flow fields. The considered Mach number ranges from 0.14 to 1.2, and the nondimensional spinning rate (PD/2V) is set to 0.186. To calculate the coefficient derivative of the corresponding force or moment, additional simulations were conducted at the angle of attack of 2.5 degrees. The simulation results were able to predict nonlinear behavior, the especially abrupt change of the predicted coefficients and derivatives at the transonic Mach number, 0.95. The simulation results, including the skin friction, pressure, and velocity field, allow the characterization of the nonlinear behavior of the aerodynamic coefficients, thus, enabling better predictions of projectile trajectories.
Highlights
Common methods to predict the aerodynamic coefficients of a spinning projectile in the design phase are to adopt the semiempirical method and conduct a wind tunnel test of the model
The employed grid generation method and numerical scheme are validated through the numerical simulation of a 155 mm M107 projectile without the spin and the results are compared with the experimental results [10, 11]
Numerical simulations on the geometry of a spinning projectile with a diameter of 120 mm are conducted, and the predicted aerodynamic coefficients are compared with the results of the semiempirical method, PRODAS
Summary
Common methods to predict the aerodynamic coefficients of a spinning projectile in the design phase are to adopt the semiempirical method and conduct a wind tunnel test of the model. The representative software, based on the semiempirical method, is PRODAS [1] and DATCCOM [2], respectively, developed by Arrow Tech Associates Inc., the USAF. These methods very quickly obtain the aerodynamic coefficients with a given geometry and flow conditions, but when the geometry and flow conditions are out of the recommended data range, the prediction accuracy cannot be guaranteed. The wind tunnel test can be an alternative method to obtain the aerodynamic coefficients of the spinning projectile. The CFD methodology is able to accurately predict the aerodynamic coefficient, including static and dynamic load, and improve the performance through the analysis of the flow field around the projectile and its control surfaces
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