A Study on the Form Drag of a Normal Plate Immersed in Turbulent Boundary Layers

In a flow field without pressure gradient， wind tunnel measurements of the pressure distributions on two-dimensional normal plates were carried out by eliminating the blockage effects to correlate with the characteristics of a smooth wall boundary layer in which they were immersed. The drag coefficients are found to be expressed as a logarithmic function of h/δup to h/δ＝1.20，where δ is the thickness of the undisturbed boundary layer at the position where the plate is mounted. Further，a correlation is obtained between the variation of form drag and the plate height h，which is analogous in form to the law of the wall of a boundary layer velocity profile. A method of calculating the pressure distributions on the front surface of The normal plate is proposed to analyse with an aid of a free-streamline theory. The method involves four parameters， however，which must be determined on the basis of experimental informations. The velocity field is integrated to construct the flow pattern for the purpose of comparing with that obtainable by the present analytical method