Abstract: An anti-icing system for a nose cowl of an aircraft jet engine. An improved injection nozzle is provided to enhance the injection of hot, pressure gas from the engine into the ambient air within the nose cowl to entrain such air and cause the entrained mass to rotate within the nose cowl in swirling rotational motion and thereby cause the temperature of the nose cowl to rise sufficiently to preclude the formation of ice thereon during flight. The improved injection nozzle preferably includes a plurality of serially spaced elliptically shaped jet nozzles arranged longitudinally and tangentially to the center line of the nose cowl to create vorticity in the resultant injected hot gas flow and enhance its mixture with the ambient air within the nose cowl and thereby preclude any tendency for the formation of an area of elevated temperature in the skin of the nose cowl aft of the position of the injection nozzle under certain design criteria.