To provide an engine capable of generating a swirling flow in the air flowing on an external wall outside a cowling of the turbo-jet engine, smoothening the air flow, and promoting mixture of jet exhaust and ambient air.

Swirl vanes 35 projecting outwardly in the radial direction of an exhaust duct (exhaust nozzle) 23 of the turbo-jet engine are spirally provided along an external wall part outside the exhaust duct (exhaust nozzle) 23 to generate the swirling flow in fluidizing air flowing at high speed around the exhaust duct (exhaust nozzle) 23 and to exhaust the flow of the fluidizing air flowing on the external wall outside the exhaust duct (exhaust nozzle) 23 smoothly backwards.