Experimental Study On Ignition Characteristics Of A Valveless Self-excited Pulse Combustor Of The Helmholtz-type

Pulse combustion has the advantages of high combustion efficiency, highcombustion intensity, high mass transfer rate, high heat transfer coefficient, lowpollutant emission, with self suction function and simple structure. The maindisadvantage of pulse combustion is a narrow operating range and unstable operation.Research on the ignition characteristics of pulsating combustion is important forstability control of the pulse combustor and extending operating range of the pulsecombustor.Design and build the experiment platform research on ignition characteristics ofa valveless self-excited pulse combustor of the helmholtz-type. Measured the rangeof ignition of the burner. Depending on the initial conditions, pulse combustionignition can be divided into non ignition, pre ignition over process and successfulignition in three cases. Introduced the development of indoor fire movement and thecombustion pressure oscillation in three cases. Analysis of the ignition process in thecombustion chamber pressure changes of the reasons: in the beginning, the flamesquickly spread, lit the unburned gas combustion chamber. Then, as the gascombustion chamber burns, pressure has fallen to a value near the unburned time.Next, a new gas enters into the combustion chamber and ignited, combustion powergradually increased, the combustion chamber turbulence becomes stronger gradually,finally stabilized.The ignition process of pulse combustor can be divided into4stages: pre ignitionstage、the ignition delay period、 pressure pulsation increasing stage and periodicoscillation phase introduces the characteristics of each stage. Analysis the reasons forpressure change of the ignition process. Because of complexity of the flow of thecombustion chamber, mixed state point of different reasons, pressure amplitude andfrequency of the first3stages are random, the pressure oscillation periodic oscillationphase of the law. This paper studies the relationship between periodic oscillationphase power and excess air coefficient and the amplitude and frequency of thecombustion chamber. Unchanged in the excess air coefficient, with the power of thecombustion chamber pressure increases the amplitude and frequency increase. Inpower under the condition of invariable, with the increase of excess air coefficient,the pressure in the combustion chamber increases the amplitude and frequency issmaller. In the burner ignition process, tail pipe exhaust temperature rises rapidly in theexplosion, then in the ignition delay period and pulse development stage rise rate islow, the temperature reaches the maximum value set in1s.Study on the ignition burner, ignition delay period and pressure fluctuationincreased time usually tens of milliseconds to200ms, from the last to the end of atotal time of deflagration pulse combustion is usually around300ms.