Abstract: A nacelle inlet structure is provided for an aircraft propulsion system. This inlet structure includes an inlet lip, a bulkhead, a nozzle and a plurality of heat transfer augmentation features. The inlet lip includes an inner lip skin and an outer lip skin. The bulkhead is configured with the inlet lip to form a cavity axially between a forward end of the inlet lip and the bulkhead and radially between the inner lip skin and the outer lip skin. The annular cavity extends along a curvilinear centerline within the inlet lip. The nozzle is configured to inject fluid approximately tangentially into the annular cavity. The heat transfer augmentation features are configured with the inner lip skin and operable to interact with the fluid flow within the cavity in order to promote heat transfer between the inner lip skin and the fluid within the cavity.

Abstract: A nacelle inlet structure is provided for an aircraft propulsion system. This inlet structure includes an inlet lip, a bulkhead, a nozzle and a plurality of heat transfer augmentation features. The inlet lip includes an inner lip skin and an outer lip skin. The bulkhead is configured with the inlet lip to form a cavity axially between a forward end of the inlet lip and the bulkhead and radially between the inner lip skin and the outer lip skin. The annular cavity extends along a curvilinear centerline within the inlet lip. The nozzle is configured to inject fluid approximately tangentially into the annular cavity. The heat transfer augmentation features are configured with the inner lip skin and operable to interact with the fluid flow within the cavity in order to promote heat transfer between the inner lip skin and the fluid within the cavity.

Abstract: An improved anti-icing system for a nose cowl of an aircraft jet engine. An improved injection nozzle is provided to passively 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 skin of the nose cowl to rise sufficiently to preclude the formation of ice thereon during flight. A plurality of spaced circumferentially arranged tab members, that are preferably triangularly shaped, are canted inwardly slightly to create large scale longitudinal vortices and transverse stirring during the introduction of hot gas and thereby 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 downstream of the position of the injection nozzle under certain severe design conditions.