The Numerical Simulation And Experimental Research Of Pulse Jet Engine

With the advantages of high combustion intensity, high combustion efficiency and low pollution, the pulse fogger, which takes the pulse jet engine as power, becomes significant for forestry pest control, sanitary disinfection and so on. Nowadays, as the energy and environmental problems become serious, the pulse jet engine becomes important with its huge potential. However, as the lack of the understanding of the pulse-combustion mechanism, the new products can only be developed with experience and experiments with the disadvantage of high cost. In this paper, as the foundation for the future low-cost development of the Helmholtz pulse jet engine, the method of using the CFD simulation to develop the Helmholtz pulse jet engine is studied. It is the first time to use the CFD simulation to develop the Helmholtz pulse jet engine in China. 24 different types of combustion chamber-exhaust tube (the C.E.T) are simulated with CFD on the basis of large number of experimental data.The C.E.T is simulated through controlling the rate of fuel and air entering the combustion chamber every cycle. The rate changing with the time is implemented through secondary development of CFD. A half-sine curve is designed. The simulation result of pressure waveform is similar with the experimental result. The phase relationship between the simulation result of pressure waveform and the simulation result of temperature waveform is close to the key rule of the pulse combustion-the Rayleigh criterion.According to the experiment data, the half-sine curve is modified. Meanwhile, the pressure of the combustion chamber is set to be negative at the beginning of the unsteady simulation, which leads to the increasing of the simulated pressure and the pressure is close to the experimental result.Two pulse jet engine with different size are made to test the accuracy of the CFD model. Both of them can be started and operated regularly with stable pressure waveform. According to the experiment result, the pressure and temperature of combustion chamber and the flow velocity of exhaust tube got from the experiment are close to the simulating result. It comes to the conclusion that the CFD model designed is accurate and need to be further improved.