The invention provides a multi-tube pulse knocking engine with a stable exhaust device. The engine comprises a knocking
combustion chamber, a pressure stabilizing section and an exhaust
nozzle. According to the engine,
fuel gas is exhausted from knocking pipes and then enters the exhaust
nozzle through the pressure stabilizing section, the pulsation characteristic of the
fuel gas is weakened by the buffering effect of a pressure stabilizing cavity in the pressure stabilizing section, and thrust loss caused by exhaust over-expansion or under-expansion when a fixed geometric
nozzle is adopted is reduced. The pressure stabilizing cavity has the specific effects that firstly, the section area of a flow channel of the pressure stabilizing cavity is larger than that of the knocking pipes, the
fuel gas expands and decelerates after entering the pressure stabilizing cavity, then the pressure gradient in the fuel gas is reduced, in addition, when a
shock wave structure generated by knocking
combustion enters the pressure stabilizing cavity,
diffraction occurs at the sudden expansion position of the section of the flow channel, the strength of shock
waves is greatly weakened, and therefore pressure oscillation caused by the shock
waves is abated; and secondly, the pressure stabilizing cavity is the confluence of the flow directions of the fuel gas in all the knocking pipes, and under the condition that all the knocking pipes work cooperatively, the pressure in the cavity can be always kept near the
peak value. On the basis of the two points, the purposes of stabilizing the incoming flow pressure of the nozzle and improving the working efficiency of the nozzle are achieved. The engine can be applied to the fields of knocking propulsion and the like.