Cooled insulation surface temperature control system
An apparatus and method for surface temperature control is provided. Surface temperature control is achieved by flowing coolant in and then out of a low strength porous layer attached to a structural plenum. A semi-permeable layer may be attached to the outer surface of the porous layer to prevent erosion of the porous layer and to facilitate surface film cooling.
1. A method of cooling a surface comprising:
providing a structural plenum bounded by an inner structural member and an outer structural wall;
providing a porous layer attached to said outer structural wall exterior to said plenum;
providing a semi-permeable layer attached to said porous layer;
providing a plurality of openings in said semi-permeable layer;
providing openings in said outer structural wall to place said plenum in fluid communication with said porous layer; and
providing pressurized air within said plenum, wherein a majority of said pressurized air exits said porous layer through the plurality of openings in said semi-permeable layer, and wherein a portion of said pressurized air transpires through said semi-permeable layer in regions between said openings, said pressurized air that exits through said plurality of openings combines with said portion of pressurized air that transpires through said semi-permeable layer to form a cooling film adjacent to said surface being cooled.
2. The method of claim 1 , wherein said pressurized air generally flows through the thickness of said porous layer from said openings in said outer structural wall of said plenum to said semi-permeable layer with some spreading of flow in the plane of said porous layer.
3. A method of cooling a surface, the method comprising:
providing a porous layer beneath said surface;
providing a plenum beneath said porous layer;
providing a plurality of exit holes in said surface;
providing a semi-permeable layer in areas between said exit holes;
flowing coolant from said plenum into said porous layer and through said exit holes; and
transpiring coolant from said plenum into said porous layer and through said semi-permeable layer, wherein a majority of the coolant flows through said exit holes and a minority of coolant transpires through said semi-permeable layer.
4. The method of claim 3 , wherein said plenum is formed between an inner structural member and an outer structural wall.
5. The method of claim 4 , wherein at least one of said inner structural member and said outer structural wall is formed from a metallic material.
6. The method of claim 4 , wherein said porous layer is adhesively bonded to said outer structural wall.
7. The method of claim 6 , wherein coolant flows from said plenum through one or more entrance holes formed in said outer structural wall into said porous layer.
8. The method of claim 3 , wherein coolant spreads in the plane of said porous layer while traveling through the thickness of said porous layer.
9. A method of cooling a surface, the method comprising:
providing a porous layer beneath said surface;
providing a plenum beneath said porous layer;
providing a plurality of exit holes in said surface;
providing a semi-permeable layer in areas between said exit holes;
flowing coolant from said plenum into said porous layer and through said exit holes; and
transpiring coolant from said plenum into said porous layer and through said semi-permeable layer wherein coolant flow exiting through said surface exit holes combines with coolant transpiring through said semi-permeable layer forming a cooling film at said surface.