Study On Ballistic Optimization Design Launching Process For A Small Airborne Guided Ammunition

Airborne active defense system has not obtained sufficient research during the development of the weapon systems due to the particularity of airborne platform.It is urgent to design a small airborne defense system while the large air platforms are facing increasing threats.However,there are still many obstacles during its design and launching process.A small airborne active defense system is studied in this paper.The aerodynamic shape and launch system structure are designed by theoretical analysis and numerical simulation.Besides,the design scheme is optimized using intelligent optimization algorithm.The rationality and feasibility of the design scheme are proved through numerical simulation.The initial launch process of the system is simulated using numerical method.The content is as follows:A)The aerodynamic shape is analyzed and designed theoretically based on the overall requirements of a small guided ammunition.Appropriate aerodynamic layout and reasonable aerodynamic parameters are selected.An in-house aerodynamic software is developed based on engineering experience method.The aerodynamic software is evaluated and improved by comparing its results with numerical simulations.It shows that the engineering method is reliable.Besides,the influence of pneumatic device installation position and shape parameters on the aerodynamic performance of the missile are studied based on numerical simulations.B)A high and low pressure launch method is selected based on the overall requirements of the small guided ammunition and the particularity of airborne platform.The high-low pressure internal ballistic of the system is designed based on the principle of high-low pressure internal ballistic ejection.The classical internal ballistic model of high-low pressure ejection for small guided ammunition is established and a numerical calculation code is developed.C)A new intelligent optimization method is proposed in this paper.The inspiration comes from the physical phenomenon that crystals gradually crystallize in supersaturated solution.Firstly,the convergence and feasibility of the algorithm are confirmed mathematically.Secondly,different test functions are used to test and analyze the key parameters in the algorithm.The performance of the new intelligent optimization method is compare the algorithm with several classical intelligent optimization algorithms.A multi-objective optimization calculation model for complex engineering design is developed.D)The internal ballistic design model and aerodynamic design model established are studied using the intelligent optimization method and the established multi-objective optimization design method.The optimal combination of internal ballistic loading parameters and structural parameters is obtained and a series of aerodynamic shape optimization schemes based on different evaluation criteria are obtained.In order to validate the aerodynamic shape optimization design scheme,the overall motion model of the three elements(the carrier,the target and the missile)is established based on the integrated guidance and control technology.It is found that the whole interception trajectory curve is smooth,the minimum overload is needed during the whole interception and the minimum requirement is needed for the steering gear when considering the best maneuverability.The trajectory of the interception scheme takes the longest time and the steering gear is in the position of maximum rudder deflection for a long time when the best stability is considered.Besides,there is a big gap between the available overload and the required overload,resulting in a most curved trajectory of the whole process,which is not conducive to the effective interception.E)For the vertical high-low pressure launch system,the flow field at the bore is quite different from that at the general launcher due to the influence of initial inflow.In order to study the development process of the flow field and its impact on carrier aircraft and small guided munition motion,a model considering the initial flow field and pressure distribution of powder gas in tube is established and the finite volume method is adopted.The results show that because of the movement of carrier aircraft,the flow field out bore is asymmetry obvoiously and shock wave at the windward side of projectile is superior to than that at the leeward side.At the same time,due to the pressure in chamber is low for the high-low pressure launch system,the gunpowder gas has no negative effect on the carrier,which proves that its safe for the carrier craft in the initial launching system.F)In order to study the motion of small guided munition influenced by intial flow field in the separation process,a vertical launch movement model of separation process is established,using the finite volume method combined six degree of movement model to simulate the movement of the small guided ammunition at different carrier craft's speeds and different launch speeds.The results show that while the carrier craft's speeds is larger,the influence of intial field on the guided munition is more obvoious.While the guided munition is ejected slowly,its movement is easily interfered by the gunpowder gas so that the projectile is wiggled by the muzzle flow and intial flow.The results also comfirm that if the lauching velocity is large enough,the guided ammunition could escape from the muzzle flow field and being separated with carrer carft as soon as possible,having a little pitch angle and pitch velocity,which is conducive to the stability of the launch process.