Disk fins

Frequently square, rectangular or hexagonal disk fins are attached to tubes, whereby several tubes can also be joined together by the use of sheets of fins through which the tubes pass, Fig. 2.15. In these fins the temperature does not only depend on one coordinate, but two-dimensional temperature fields must be reckoned with. As a first approach, the efficiency r]f of these disk fins can be calculated from (2.81) or (2.82) for an annular fin with the same surface area. Then for a rectangular fin as in Fig. 2.15 we get... 

Fig. 2.15 Disk fins, a rectangular disks on a tube, b tube arrangement with disk fins (rectangular and hexagonal)...

Fuze, PIBD M509A1 or M309. This point-initiating, base-detonating fuze was designed for use in fin-stabilized HEAT projectiles. It contains the electric detonator M48 (qv) and the fuze power source is a polarized ceramic disk with piezoelectric characteristics, which is located in the nose of the pro-... 

Problem A thin annular fin in a vacuum is enclosed in insulation so that there is no heat transfer on one face and around its outside edge. The disk is of thickness b, has an inner radius r , an outer radius r , and a thermal conductivity k. Energy is supplied to the inner edge, say from a solid rod of radius r, that fits the central hole, and this keeps the inner edge at a temperature T . 

Tear off top bypu/fin f fope sharpfy vprrarafs, ignite flare rubbing red disk on fape sharply but firmly across the black blob on the center of the top of flare... 

The disk-like body of the stingray forms an almost perfect rhombus with pointed corners. They have flexible tapering tails that are very often armed with one or more saw-edged, envenomed spines. With only a few exceptions, they don t have dorsal and pelvic fins. Stingrays prefer warmer waters, so when it gets cold, they will seek warmer waters or dive deep er away from cold currents. 

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