Abstract: An auxiliary power unit that can reduce a flow loss of gas includes: a compressor, a combustion chamber, a turbine, a turbine outlet, and a bypass duct, wherein the turbine outlet comprises an exhaust diffuser and a guide portion, wherein the bypass duct connects the compressor with the guide portion, wherein the guide portion is a channel for an air or gas and is extended radially from an outer circumferential surface of the exhaust diffuser and communicates with an inside of the exhaust diffuser via an opening, and wherein the exhaust diffuser has a first portion adjacent to a front end of the opening and a second portion adjacent to a rear end of the opening, and a radius of the second portion is larger than a radius of the first portion so that there is formed a step difference between the first portion and the second portion.

Abstract: Provided are an exhaust duct, an exhaust duct assembly, and an aircraft using the exhaust duct. The exhaust duct has a structure that enables combustion gas to be diverged and discharged from an inlet end to a first outlet end and a second outlet end at respective sides of the exhaust duct. The exhaust duct includes a first housing including a first body forming an outer wall of the inlet end, and further includes second bodies respectively extending on respective sides from the first body and respectively forming the first outlet end and the second outlet end; a second housing spaced apart from the first body, forming an inner wall of the inlet end, and extending curvedly toward the second bodies; and a connection housing connecting the first housing to the second housing and including at least one recess portion recessed toward the inlet end.

Abstract: Provided are a porous structure and a method of fabricating the same. The porous structure may include an aluminum oxide containing at least one of fluorine and phenyl group. For example, the porous structure may be formed from alumina which contains fluorine or phenyl group. The method of fabricating the porous structure may include preparing an aluminum precursor including at least one of fluorine and phenyl group; providing a precursor solution by mixing the precursor with a solvent; and forming the porous structure having 3-dimensional network structure including the aluminum oxide containing the at least one of fluorine and phenyl group from the precursor solution through gelation.

Abstract: Provided are an exhaust duct, an exhaust duct assembly, and an aircraft using the exhaust duct. The exhaust duct has a structure that enables combustion gas to be diverged and discharged from an inlet end to a first outlet end and a second outlet end at respective sides of the exhaust duct. The exhaust duct includes a first housing including a first body forming an outer wall of the inlet end, and further includes second bodies respectively extending on respective sides from the first body and respectively forming the first outlet end and the second outlet end; a second housing spaced apart from the first body, forming an inner wall of the inlet end, and extending curvedly toward the second bodies; and a connection housing connecting the first housing to the second housing and including at least one recess portion recessed toward the inlet end.

Abstract: An auxiliary power unit that can reduce a flow loss of gas includes: a compressor, a combustion chamber, a turbine, a turbine outlet, and a bypass duct, wherein the turbine outlet comprises an exhaust diffuser and a guide portion, wherein the bypass duct connects the compressor with the guide portion, wherein the guide portion is a channel for an air or gas and is extended radially from an outer circumferential surface of the exhaust diffuser and communicates with an inside of the exhaust diffuser via an opening, and wherein the exhaust diffuser has a first portion adjacent to a front end of the opening and a second portion adjacent to a rear end of the opening, and a radius of the second portion is larger than a radius of the first portion so that there is formed a step difference between the first portion and the second portion.

Abstract: Provided are a porous structure and a method of fabricating the same. The porous structure may include an aluminum oxide containing at least one of fluorine and phenyl group. For example, the porous structure may be formed from alumina which contains fluorine or phenyl group. The method of fabricating the porous structure may include preparing an aluminum precursor including at least one of fluorine and phenyl group; providing a precursor solution by mixing the precursor with a solvent; and forming the porous structure having 3-dimensional network structure including the aluminum oxide containing the at least one of fluorine and phenyl group from the precursor solution through gelation.