Swirl anti-ice system

Abstract

A system for circulating heated gases within the circular leading edge of a jet engine housing to prevent ice build-up thereon, or to remove accumulated ice thereform. Hot gases such as air from a hot, high pressure section of the jet-engine are directed through a conduit. The conduit enters the annular leading edge housing, usually from the aft side through a bulkhead, then turns about 90° to a direction tangential to the leading edge annulus. The hot gases exiting the tube entrain the cooler air in the housing, causing a much larger mass of air to swirl circularly around the annular housing. The entering hot gasses heat the mass of air to an intermediate, but still relatively hot, temperature. This large mass of circularly moving hot air is quite efficient in uniformly transferring heat to the skin of the leading edge without leaving any relatively cold areas and preventing the formation of ice thereon.

What is claimed is: 
     
       1. An anti-icing system for .Iadd.a nose cowl for an .Iaddend.annular .Iadd.inlet of an aircraft .Iaddend.jet engine . .housing.!. .Iadd.propulsion system for an aircraft .Iaddend.which comprises: a source of high pressure hot gas;   at least one conduit means to carry hot gases from said source;   a substantially closed annular . .housing.!. .Iadd.single skin nose cowl having an exterior surface and an interior surface and positioned .Iaddend.at the leading edge of .Iadd.an inlet .Iaddend.of a jet engine .Iadd.propulsion system and arranged for grazing flow of ambient air over the outer exterior surface when the aircraft is in flight.Iaddend., the annular . .housing.!. .Iadd.nose cowl .Iaddend.containing a quantity of air;   said at least one conduit means extending into said . .housing.!. .Iadd.nose cowl.Iaddend.;   an outlet on the end of each of said at least one conduit means extending into said . .housing.!. .Iadd.nose cowl.Iaddend., said outlet oriented to eject said hot gases at high velocity substantially tangential to a centerline of said annular . .housing.!. .Iadd.nose cowl.Iaddend.;   the mass flow rate of the gases and air swirling in said annular . .housing.!. .Iadd.nose cowl in a rotational direction around the interior of said annular nose cowl and in direct contact with the interior surface of such nose .Iaddend.being at least about three times the mass flow rate of gases leaving said outlet; and   whereby the high velocity hot gases entrain .Iadd.said quantity of .Iaddend.air within said annular . .housing.!. .Iadd.nose cowl .Iaddend.so that the total volume of air and gases swirling around .Iadd.the interior of .Iaddend.said annular . .housing.!. .Iadd.nose cowl .Iaddend.has a substantially uniform temperature intermediate between that of said air and said hot gases .Iadd.and by direct contact with the interior surface of the nose cowl substantially uniformly heating the nose cowl to a temperature that is sufficiently high to preclude the formation of ice on the exterior surface of the nose cowl by the grazing flow of ambient air when the aircraft is in flight.Iaddend..   
     
     
       2. The system according to claim 1 wherein the aft end of said annular . .housing.!. .Iadd.nose cowl .Iaddend.is closed by a transverse bulkhead having at least one hole to allow air and gases with said . .housing.!. .Iadd.nose cowl .Iaddend.to escape. 
     
     
       3. The system according to claim 2 wherein said conduit means enters through said bulkhead and is bent about 90° to said tangential orientation. 
     
     
       4. The system according to claim 1 wherein said outlet includes a nozzle means to increase the velocity of exiting gases. 
     
     
       5. The system according to claim 1 wherein the source of said hot gases is a hot, high pressure region of said jet engine. 
     
     
       6. The system according to claim 1 wherein said outlet means comprises a converging nozzle extending in the direction of desired gas flow in said . .housing.!. .Iadd.nose cowl .Iaddend.and a converging-diverging sleeve surround and spaced from said nozzle. 
     
     
       7. The system according to claim 1 wherein said outlet means includes a plurality of tubes ending in spaced hot gas outlets extending in the direction of desired gas flow within said . .housing.!. .Iadd.nose cowl.Iaddend.. 
     
     
       8. The system according to claim 1 wherein said outlet means comprises at least one tube extending in the direction of desired gas flow in said annulus and having a converging-diverging nozzle at the tube end. 
     
     
       9. The system according to claim 1 wherein said outlet means comprises at least one piccolo tube extending into said housing substantially transverse to the direction of desired gas flow in said . .housing.!. .Iadd.nose cowl .Iaddend.substantially transverse to the direction of desired gas flow in said . .housing.!. .Iadd.nose cowl.Iaddend., said tube having a plurality of holes along the side thereof in said direction of desired gas flow. 
     
     
       10. An anti-icing system for annular jet engine housings which comprises: a hot, high pressure region of a jet engine;   at least one conduit means adapted to carry hot gases from said region having a temperature of about 100 to 500 degrees F. and a velocity of about 3 to 30 ft./min.;   a substantially annular .Iadd.single skin .Iaddend.housing .Iadd.having an exterior surface and an interior surface and positioned .Iaddend.at the leading edge of said engine,   a bulkhead closing the aft end of said .Iadd.single skin .Iaddend.housing .Iadd.and .Iaddend.having at least one hole to allow air and gases within said housing to escape;   said at least one conduit extending into said housing through said bulkhead;   at least one outlet at the end of each conduit within said housing, said at least one outlet oriented to eject said hot gases at high velocity substantially tangential to a centerline of said annular .Iadd.single skin .Iaddend.housing;   nozzle means connected to said at least one outlet for increasing the velocity of gases exiting therefrom; and   the high velocity hot gases entraining air within said annular .Iadd.single skin .Iaddend.housing so that the total volume of air and gases swirling around .Iadd.the interior of .Iaddend.said annular housing .Iadd.in a rotational direction .Iaddend.has a substantially uniform temperature of from about 35 to 41 degrees F. when the outside air temperature is about -40 degrees F., and the mass flow rate of said gas and air is at least about three times the mass flow rate of the gases leaving said outlet .Iadd.whereby such rotating hot gases and air by direct contact with the interior surface of single skin annular housing raise the temperature of said housing to a substantially uniform temperature that is sufficiently high to preclude the formation of ice on the exterior surface of said housing.Iaddend..