Research On Aerodynamic And Flight Characteristics Of Tandem EFP Formed By Double-layered Liner

Tandem EFP formed by double-layered liner shaped charge is an effective way to improve the penetration ablility of the warhead.The design require tandem EFP have better flight stablility,relatively low grag coefficient and proper spacing.This paper combines theoretical analysis and numerical simulation,and focused on the aerodynamic and flight characteristics of tandem EFP.The main contents are as follows:1.The engineering calculation method and its application aerodynamic characteristics of EFP which can be obtained around the bus rotation were studied.Based on the MATLAB software,the paper used the quadrilateral instead of the EFP surface.And using the theory of Newton and Prandtl-Meyer,combined the empirical formula of friction and bottom resistance,a set of practical EFP aerodynamic characteristics engineering calculation method has been established,which can quickly obtain the resistance coefficient,static stability and other parameters of any axisymmetric EFP.The aerodynamic characteristics of EFP with different structures were studied by using this method.The aerodynamic parameters of quasi-sphere,rod and single-skirt EFP were obtained.The reasonable range of the parameters was obtained.2.The numerical simulation of the influence of the initial position parameters of tandem EFP on the aerodynamic characteristics was carried out.Using the Pro/e software to achieve the tandem EFP shape data from the LS-DYNA software to the CFD-FASTRAN software,the paper established the numerical simulation method of forming and flight integration of the double-layered liner.Based on the CFD-FASTRAN software,the influence of the intial position parameters on the aerodynamic characteristics of the rear EFP was simulated,and the influence of the pre-attack angle,the offset distance and the pitch between the front and the back EFP on the aerodynamic characteristics were obtained.3.The flight trajectory for tandem EFP was studied.Based on the numerical simulation results,the velocity attenuation formula of the back EFP was modified,and the calculation model of tandem EFP flight trajectory was established.Based on this model,the influence of intial conditions on the flight characteristics of tandem EFP was analyzed.The influence of the mass,windward area and initial velocity on the time-history curves of velocity difference and displacement difference between the front and rear EFP was carried out.Finally,the results of calculation and numerical simulation agreed well.The results of this paper have some reference meaning in the structure design,fuze warhead matching and application of the double-layered liner warhead.