A STUDY OF THE HEAT TRANSFER CHARACTERISTICS OF HOT GAS IGNITION.
ROCKETDYNE CANOGA PARK CA RESEARCH DIV
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Solid propellant rocket motors are frequently ignited by hot gas sources such as smaller, burning solid propellant charges or pyrotechnic grains which exhaust their products of combustion into the motor grain port through convergent or convergent-divergent nozzles located in the head-end or aft-end of the motor. The results of an experimental program to develop correlations for predicting when and where such hot gas ignition occurs are discussed based on a preignition transient convective heat transfer model. The hot gas source was nitrogen supplied to thin copper-walled test sections at pressures from 570 to 620 psig and temperatures from 550 to 950 F. A variety of geometrical configurations was studied including canted head-end igniter nozzles and circumferentially slotted motor ports. In all cases the motor ports had cylindrical cross sections. Accordingly, the results are correlated with reference to established relationships for turbulent flow heat transfer in pipes including effects of flow development and time transients. Significant differences in heat transfer characteristics between head-end and aft-end configurations were observed. Author