The nozzle structural constraints of solid rocket motors significantly affect the response process of propellants under cook-off stimuli.To study the influence of nozzle throat diameter on the cook-off response of GAP-based solid propellants,a ther-mal load loading and control system for nozzle structural test pieces was designed and constructed.Using high-speed laser schlie-ren imaging technology,the entire cook-off response process of GAP-based propellants under the constraints of motor nozzle structures was observed.Additionally,the temperature of test pieces and the shock wave overpressure generated upon the igni-tion response were measured.The results indicate that the cook-off response of GAP-based solid propellant specimens with noz-zle constraints can be divided into the following stages:softening and expansion of the propellant before ignition,and flame ac-celeration,deflagration-to-detonation transition(DDT),casing failure,and deflagration process after ignition.The post-ignition response lasts only 0.5-2 milliseconds.From the pressure curve,it is evident that during the flame acceleration phase,the pres-sure grows slowly.When the nozzle throat diameter is relatively small,flow choking is more likely to occur.Once choking oc-curs,pressure and burning rate rapidly increase and reinforce each other,ultimately leading to deflagration-to-detonation transi-tion.In contrast,for test pieces with large nozzle throat diameters,the rapid pressure rise cannot occur or be sustained,reduc-ing the likelihood of deflagration-to-detonation transition and maintaining the structural integrity of test pieces.
GAP solid propellantcook-off responsehigh-speed schlieren imagingnozzle structural constraint
维普
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