Accession Number : AD0684891

Title :   INVESTIGATION OF WATER IMPACT OF BLUNT RIGID BODIES-SIZE SCALE EFFECTS.

Descriptive Note : Technical rept.,

Corporate Author : SOUTHWEST RESEARCH INST SAN ANTONIO TEX DEPT OF MECHANICAL SCIENCES

Personal Author(s) : Gerlach,C. Richard

Report Date : 01 NOV 1968

Pagination or Media Count : 41

Abstract : The results of an experimental study of the influence of model size on the blunt body water impact problem are given. It is demonstrated that a size scale effect definitely exists; further, it is demonstrated that the model weight is another important parameter which must be considered. If the weight per unit of model area is held constant, then the peak impact pressure tends to decrease as model size increases for a given drop height (impact velocity). Comparison of the present test data with the theoretical results of Verhagen showed this theory to predict peak impact pressures which are high by a factor of about four. It is concluded that the neglect of water compressibility in the Verhagen model is, at least partly, responsible. Experiments were performed with both two- and three-dimensional air flow conditions; other than reducing the peak pressure values, restricting the air flow seems to have little or no effect on the physical picture of the blunt-body, still-water impact problem. A few tests involving impacts on a disturbed or wavy water surface showed, as was demonstrated in an earlier report, that the peak pressures are greatly reduced (in a random fashion) compared with the still water case. It is concluded that the physical process during impact on a wavy surface is different than with still water. (Author)

Descriptors :   (*IMPACT SHOCK, *HYDRODYNAMICS), (*SHIP MODELS, SCALE), WEIGHT, BLUNT BODIES, MODEL THEORY, WATER WAVES, TWO DIMENSIONAL FLOW, THREE DIMENSIONAL FLOW

Subject Categories : Marine Engineering
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE