Air cooled heat shield
A heat shield is disclosed comprising a formed sheet having a thickness, an exterior shielding surface, and an interior shielded surface, wherein the exterior shielding surface comprises a multiplicity of protruding perforations. The protruding perforations comprise protrusions increasing surface area and generating turbulent flow, and small openings through the shield to allow convection air flow to pass through.
1. An apparatus for reducing the transfer of heat from a heat source to a protected object, the apparatus comprising:
a heat shield having a heat reflective sheet, the sheet having a thickness bounded by a first sheet surface and a second sheet surface, the first sheet surface being configured for exposure to a medium flowing across such surface when the sheet is placed between the heat source and the protected object, the sheeting having a means for providing improved convective heat transfer from the sheet while substantially restricting the passage of the flowing medium and radiant heat through the sheet, the means comprising:
a plurality of turbulence-generating protrusions having a single free edge and extending from the first sheet surface, the protrusions generating turbulent flow within the medium flowing across the first sheet surface; and
a plurality of sheet apertures formed within the sheet, wherein each aperture is positioned substantially adjacent to at least a portion of one of the protrusions, and each aperture is bounded by a sheet edge and the free edge of the one of the protrusions, the free edge being partially maintained within the thickness of the sheet, wherein each of the plurality of sheet apertures has a length and a width, the width being less than the length and measuring between approximately 0.06 and 0.25 millimeters.
2. The apparatus of claim 1 , wherein the protrusion is configured to be biased by an angle towards the heat source, such that the protrusion is configured to substantially shield the aperture from radiant heat.
3. The apparatus of claim 2 , wherein the sheet edge remains substantially undeformed.
4. The apparatus of claim 1 , wherein the medium flowing across the first surface is air.
5. The apparatus of claim 4 , wherein the protrusions are adapted to first engage an air flow via its free edge.
6. The apparatus of claim 1 , wherein the apertures are approximately between 1.5 and 5.0 millimeters long.
7. The apparatus of claim 1 , wherein the aperture is complementary to the protrusion.
8. The apparatus of claim 1 , wherein the free edge comprises a free surface having a thickness substantially equal to the thickness of the sheet extending between the first and second sheet surfaces.
9. An apparatus for reducing the transfer of heat from a heat source to a protected object, the apparatus comprising:
a heat source; and
a heat shield having a heat reflective sheet, the sheet having a thickness bounded by a first sheet surface and a second sheet surface, the first sheet surface being configured for exposure to a medium flowing across such surface when the sheet is placed between the heat source and the protected object, the sheeting having a means for providing improved convective heat transfer from the sheet while substantially restricting the passage of the flowing medium and radiant heat through the sheet, the means comprising:
a plurality of turbulence-generating protrusions having a single free edge and extending from the first sheet surface, the protrusions generating turbulent flow within the medium flowing across the first sheet surface; and
a plurality of sheet apertures formed within the sheet, wherein each aperture is positioned substantially adjacent to at least a portion of one of the protrusions, and each aperture is bounded by a sheet edge and the free edge of the one of the protrusions, the free edge being partially maintained within the thickness of the sheet.
10. The apparatus of claim 9 , wherein each of the plurality of sheet apertures has a length and a width, the width being less than the length and measuring between approximately 0.06 and 0.25 millimeters.
11. The apparatus of claim 10 , wherein each of the plurality of sheet apertures has a length measuring between approximately 1.5 and 5.0 millimeters.
12. The apparatus of claim 11 , wherein the protrusion is configured to be biased by an angle towards the heat source, such that the protrusion is configured to substantially shield the aperture from radiant heat.
13. The apparatus of claim 9 , wherein the protrusion is configured to be biased by an angle towards the heat source, such that the protrusion is configured to substantially shield the aperture from radiant heat.
14. The apparatus of claim 9 , wherein the medium flowing across the first surface is air.
15. The apparatus of claim 14 , wherein each of the plurality of sheet apertures has a length and a width, the width being less than the length and measuring between approximately 0.06 and 0.25 millimeters.
16. The apparatus of claim 9 , wherein each of the plurality of sheet apertures has a length and a width, the width being less than the length and measuring between approximately 0.06 and 0.25 millimeters.
17. The apparatus of claim 16 , wherein each of the plurality of sheet apertures has a length measuring between approximately 1.5 and 5.0 millimeters.
18. The apparatus of claim 17 , wherein the protrusion is configured to be biased by an angle towards the heat source, such that the protrusion is configured to substantially shield the aperture from radiant heat.