Analysis And Experimental Investigation On The Thrust Performance Of Aero-valve Pulse Detonation Engine

Pulse detonation engine(PDE)is a new propulsion device using detonation combustion.This propulsion device has the advantages of high cycle thermal efficiency,low fuel consumption and relatively simple structure.Thrust is one of the important indexes of PDE.Improving the thrust of PDE is the key of PDE engineering application.With theoretical analysis,simulations and experiments,this paper investigate the flow characteristics and thrust performance for aero-valve PDE,main work and results are follows:(1)The mechanism of PDE thrust formation and the influence factor of thrust are analyzed theoretically.The formula of thrust and operating frequency of PDE is given.The measures to reduce the loss of PDE thrust and to reduce the PDE negative thrust are put forward.There is a contradiction between these measures.(2)In order to reduce the loss of PDE thrust,the design idea of inversing-rotating aero-valve with reducing channel is put forward.It is found that the one-way performance is enhanced but the flow loss is increased when the inlet angle of aero-valve is increased.The best inlet angle of the aero-valve is about 60°.The atomization scheme using double pre-filmed ultrasonic nozzle with central rod is presented,and its atomization characteristics were investigated.The results indicate that the average droplet size SMD is about 6,and it changes in the range of 2 with the change of the fuel pressure,the distance between nozzle and resonator and the measuring location.The nozzle spray angle reduce from about 180° to about 60° with the increase of distance between nozzle and resonator.The fuel supply scheme of three solenoid valves in parallel is given.The investigation on the characteristics of fuel supply shows that the control system can work normally when the frequency varied from 5Hz to 30 Hz.(3)The flow field and fuel distribution of PDE are investigated by numerical simulation.It is found that PDE flow field is greatly influenced by the inlet pressure.Installing the mixers can obviously improve the fuel distribution of detonation tube.Using of the ring and lobed mixers are the best scheme.The influence of nozzle on PDE thrust performance is simulated and analyzed.The result shows that the straight extension nozzle and divergent nozzle make PDE thrust performance improved,and the convergent nozzle makes the PDE thrust performance reduced.For the expansion nozzle,the PDE thrust performance increases with the nozzle angle increasing.For the convergent nozzle,the PDE thrust performance decreases with the nozzle angle increasing.When nozzle expansion ratio is constant,the nozzle has an optimal length,and its thrust performance will be reduced if it is too long or too short.(4)Cold blowing and debugging experiments of aero-valve PDE were carried out.Selection of spiral obstacles and ring and lobed combination mixer is determined.The PDE can operate continuously when the frequency varied from 17 Hz to 22 Hz,but detonations are not initiated successfully.70 N average thrust is got when the PDE operate in 20 Hz.The thrust performance of PDE with solenoid valve was investigated.The PDE can work normally when the opening time of solenoid valve is 4ms ahead of the ignition time.The average thrust of the PDE is 69.3N when there is no solenoid valve,and the average thrust of the PDE is 73.6N when the solenoid valve is operated.The thrust performance of PDE with nozzle is investigated.Both the straight extension nozzle and the convergent nozzle make the PDE thrust performance improved,and the PDE thrust performance is significantly reduced by the divergent nozzle.For the convergent nozzle,the PDE thrust performance increases with the nozzle angle increasing.For the divergent nozzle,the PDE thrust performance decreases with the nozzle angle increasing.