Experimental and modeling studies of a multi-tailpipe on a pulse combustor system

The effect of a multi-tailpipe structure on a pulse combustor with an exhaust decoupler and a vent pipe is investigated. A nonlinear theoretical model is established, and corresponding experiments are made to verify the theoretical model. The results show that the multi-tailpipe structure has two effects: It enhances the exhaust gas resistance and decreases exhaust gas velocity in the tailpipe; it also expands the tailpipe heat dissipation area and increases the heat loss. The amplitude of pressure fluctuations in the combustion chamber and exhaust decoupler is determined by competition between the strengthening effect of tailpipe resistance and the weakening effect of heat loss from the tailpipe. Frequency and pressure characteristics are dominated by tailpipe resistance and tailpipe heat loss. The working region is divided into three parts for different structure parameters: low frequency inphase zone, unstable zone, and high-frequency antiphase zone. Tailpipe resistance only affects the unstable zone, and the necessary value of tailpipe friction exists to minimize the unstable zone. Heat loss from the tailpipe can reduce the unstable zone and cause it to squeeze the inphase zone, resulting in shrinkage of the inphase zone. Copyright © 2016 John Wiley & Sons, Ltd.