A free-jet experimental study on the performance of a cavity-type ramjet

Free jet experiments have been conducted to evaluate the performance of a cavity-type ramjet. To prevent uncertainty of combustion parameters, a method to calculate internal thrust from cold flow parameters is brought forward. According to this analysis method, the internal thrust of the cavity-type ramjet increases linearly with the stoichiometric ratio while the specific impulse decreases squarely. The aero-propulsive balance of a conceptive missile is also examined, focusing on the effect of attack angle. Considering both efficiency and performance, an attack angle of 3∼6 degrees is recommended. And the free-jet experimental results show that the cavity-type ramjet can supply sufficient thrust for the missile under cruise conditions.