Accession Number : AD0659046

Title :   CHOKING OF STRUT-VENTILATED FOIL CAVITIES.

Descriptive Note : Technical rept.,

Corporate Author : HYDRONAUTICS INC LAUREL MD

Personal Author(s) : Elata,C.

Report Date : MAY 1967

Pagination or Media Count : 55

Abstract : Presented are the results of an investigation of the 'choking' phenomenon in base vented strut cavities. In practice such base vented struts support a ventilated foil and provide the ventilation air for the foil through the strut cavity. An expression for the rate of air entrainment in ventilated cavities is derived. This expression fits previously reported experimental data except at low cavitation numbers, when free surface- solid boundary- and gravitational effects may become important. The shape of the cavity behind a strut, supporting a strut-ventilated foil, is analyzed. It is shown that the shortest section of the strut cavity is at the free surface, and that its length is controlled by the air flow through it. The choking phenomenon is analyzed by relating the air flow through the strut cavity to the air demand of the foil cavity. From this analysis a choking coefficient is defined. A series of experiments is described in which, for three strut-supported foils, the depth at choking was determined as a function of free stream velocity, angle of attack, and air pressure. (Author)

Descriptors :   (*CAVITATION, FLUID DYNAMICS), MASS TRANSFER, DRAG, AIR, HYDROFOILS, PRESSURE, SUPPORTS, HYDRODYNAMIC CONFIGURATIONS

Subject Categories : Marine Engineering
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE