回流水槽の定在波と水面勾配に関する研究

抄録

A fluid dynamical grading-up of a circulating water channel is considered by surveying and controlling the steady wave and the free surface inclination. Their fundamental characteristics and effects on model resistance measurments are studied using the new born circulating water channel of the National Research Inst. of Fisheries Engineering. The evidence is shown that the optimum condition exists to eliminate the steady wave by adjusting systematically the flow volume of the channel and setting the angle of the plate of the wave suppressor appropriate. The longitudinal structure of the free surface profile with its inclination is analized and a method to express the free surface inclination is proposed. The best longitudinal setting position of a ship model for resistance tests is found eventually where the model is free from the effects of the free surface inclination. New parameter of so called "effective free surface inclination", similar to effective/nominal wake, -so that different from former "nominal free surface inclination" -is introduced that is obtained more conveniently from resistance tests through traversing ship model fore and aft, and utilized for diminishing the effects of the free surface inclination upon model resistance evaluation. The flow mechanism of circulating water channel is discussed in relation to the blockage effect and the static pressure distribution.