Nozzle effects on pulse detonation engines performance

Pulse detonation engine is a new concept across air-birthing propulsion systems. Today, due to the unsteady behavior of this type of engine, design optimizations are not completed yet. In this regard, recent studies are focused on the effects of nozzle implementation in this propulsion system. In this paper, the effect of nozzle shape (angle & length) on the impulse and frequency of engine cycle performance is studied. Results show that the nozzle increases the impulse which the direct nozzle has the largest effect. In the other words, the greater the divergence angle and the length of the nozzle, the smaller the impulse. On the other hand, results indicate that the presence of a nozzle would increase the cycle frequency; to be exact, the greater the divergence angle and the length of nozzle, the higher would be the frequency. However, since thrust is a function of both the impulse and the cycle frequency, a system optimization has to be performed in order to find out the optimized design conditions. Further, since combustion phenomenon is not considered in the quasi one dimensional code utilized in this work, results do caution some degrees of error. However, a comparison with experimental data validates the trend obtained in this paper