A process for the preparation of a layer of ice controlled elasticity module and a controlled bending strength

摘要

1367230 Testing marine models ARCTEC Inc 27 July 1972 [30 July 1971] 35172/72 Heading B7M [Also in Division F4] A sheet of ice is formed on the surface of a pool of saline water by spraying liquid nitrogen on to the pool, and a scale model of a marine structure is then moved in interaction with the ice sheet for testing purposes. As illustrated, the pool is formed in an open topped container and lies beneath the blackened ceiling 16 of an insulated cold room 10. The liquid nitrogen spraying system illustrated in Fig. 2 is located between the pool and the ceiling and indirectly cools the latter to a temperature of about -320‹ F. Liquid nitrogen is supplied from a tank 31 via a shut-off valve a and a flow rate control valve b to four sets of headers g. Each header bears lower nozzles f for spraying liquid nitrogen and upper nozzles e from which vaporized nitrogen issues. The nozzles are horizontally directed. The required ice growth rate is chosen to give an ice sheet of a salinity which corresponds to the desired properties of the sheet. Using valve b, the temperature of the pool environment is lowered to, and maintained at, a level which will give the required ice growth rate. Valves d are then used to give local control. If the ice sheet properties are to vary along the pool, the pool is temporarily divided by baffles 27 and valves d are used to exercise general control over the separated areas. Probes, Fig. 3 (not shown), monitor the temperature of the environment above the surface of the pool. Further probes beneath the surface of the pool monitor the growth of the ice sheet. When a sheet of sufficient thickness has been formed, fresh air is admitted to the room through a cooling and dehumidifying liquid nitrogen heat exchanger 34 to flush the room and make it habitable for humans. Thereafter, liquid nitrogen is admitted to the headers at a low flow rate to maintain the desired ice conditions while the marine model 14, suspended from a carriage 13, is moved in interaction with the sheet.