Multi-loop Two-phase Detonation Theory, Experiment And Numerical Simulation

Pulse detonation engine (PDE) is a new concept of propulsive device, which use high temperature and pressure gas produced by intermittent or pulsed detonation wave to generate thrust. PDE has many desirable advantages, including high thermodynamics cycles efficiency, simple configurations, and large range of usage, etc. so various research plans about PDE have been laid and carried out. Air breathing two phase PDE which more approaches engineering application now is the current foucs of worldwide PDE research.Firstly history and current status of detonation and pulse detonation engine have been reviewed, analysis according to author's understand, on detonation initiation, DDT(deflagration-to-detonation transition) process, nonideal detonation, spray detonation is established roughly. Also different mechanisms of self-adapting valveless gas-phase and two-phase PDE were detected through different purge gas. Large amount of experiment investigations have been carried out: characteristics of multi cycle spray detonation was studied through multi channel parallel pressure measurement, that result in discovery of many factors which defines PDE's maximal cycle frequency. Among the factors ignition delay time may has the most powerful effect on frequency. A new concept described in the paper: pulsed detonation cycle can be divided into hot time and cool time. Based on the analysis above, a series of explorers were tried including modification of injector, ignition zone, air supply mode and other structures, And now the maximal frequency of spray detonation cycle can reach 67Hz. A proof PDE of 500-800N thrust was defined and tested. Another investigation is on different nozzles such as convergent, divergent, combination of convergent and ejector, and it's concluded that combination nozzle has the highest performance. In another side, numerical simulation is a cheapest method to look inside the detonation wave, a 2D axisymmetrical model was used to simulate and analyse detonation initiation, propagation and interaction with obstacles, DDT processhas been simulated successfully. In multi cycle simulation, 3 different ejecting mechanism of PDE with a simple cylindrical ejector was found which is called: (1) air compression and acceleration by Shockwave; (2) shearing and dragging; (3) inertia and pressure grads.