Methods of computingthrust deduction usually ignore viscous effects and assume that the flow field of the ship and propeller is irrotational. The present work was undertaken in order to compare the computed values of the thrust deduction with and without the boundary layer and wake. A streamlined body of revolution was selected, and a sink on the axis behind the body was used as a simple mechanisms to simulate the suction at the stern induced by the propeller. A measure of the accuracy of a calculated irrotational-flow pressure distribution for a body in a uniform stream is the nonzero magnitude of its pressure drag. It has been found that, for calculating thrust deduction, the errors of available methods were accpetably large. A procedure for obtaining greatly increased accuracy was developed and applied to calculate the thrust deduction for irrotational thick boundary near the tail of the body is first calculated by a previously developed method, in which the equations of a thick boundary layer and wake are solved numerically by finite differences, and the outer irrotational flow is obtained as the solution of an integral equation. An iteration procedure in which the inner and outerflows are successfully adjusted coverges to the desired solution. (Author)


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    Title :

    Effect of boundary layer on thrust deduction


    Additional title:

    Wirkung der Grenzschicht auf die Schubverminderung


    Contributors:

    Published in:

    Publication date :

    1981


    Size :

    54 Seiten


    Type of media :

    Report


    Type of material :

    Print


    Language :

    English




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