Study On Influence Of Deployable Flare On Longitudinal Static Stability Of Slender Body And Prototype Design

The complex future aerial combat will put the projectile forward higher request of quicker response,further distance and better accuracy.The stability of the aircraft provides safety protection for this purpose.However,stability is contrary to mobility.The demanding for mobility means to reduce the stability,and good stability suppresses the mobility.A good balance should be founded to meet with different demands.Longitudinal static stability refers to the capacity of a projectile to contend disturbance on attack angle.It is an important part of the static stability.Improving the static stability could reduce the dependence on the control system as well as keep the stabilization.In conclusion,the study of static stability means a lot to the design and optimization of an aircraft.Deployable flare takes account of longitudinal static stability and mobility.It's one of the active control method in stability control.To remove the surplus influence factors,the projectile was be simplized to a slender body with a flare.The thesis was exactly regarding this as the object,discussed the contribution of the flare to the longitudinal static stability of the slender body via theoretical calculation and simulation analysis.To get a better balance between stability and mobility,the thesis designed a deployable flare.Simulation test and prototype experiments were carried out to verify the unfolding characteristics.Based on classical slender body theory and the small-perturbation theory,the thesis studied on the influence of the outer configuration of the slender body,especially the flare,to the center of pressure which is the key indicator of the longitudinal static stability.With the condition of small angle of attack and small perturbation hypothesis,the thesis inferred the relationship between axial force and normal force with the coefficient of the center of pressure,proposed a macro impact prediction discriminant of the influence of the outer configuration and flight condition to the the coefficient of the center of pressure.According to the impact prediction,the CFD fluid simulation software was used to simulate the constant fluid flow in a slender in vitro flow field.The pressure center coefficient and the lift drag ratio were taken as the main assessment index.The simulation result verified the macro impact prediction discriminant and led to the influence law of the the outer configuration and flight condition to the coefficient of the center of pressure.The thesis summarized the optimal geometric configuration design boundary and the applicable flight conditions to significantly improve the stability,and provided a reference for the design and optimization of the deployable flare.The thesis proposed a uniformed deployable flare and took it into dynamic and static mechanical anslysis,the dynamic simulation and prototype test were used to verify the unfolding characteristics.