The results of an experimental investigation of the mechanism of reducing surface friction by mounting thin plates — large-eddy break-up devices (LEBUs) — in a turbulent boundary layer parallel to the surface are given. The conditions under which the surface friction reduction is minimal are determined. It is shown that the presence of LEBUs in the turbulent boundary layer leads to a decrease in the frequency of decelerated-fluid ejection from the wall region into the outer region of the boundary layer.
The combined effect of the turbulence intensity ɛ, the turbulence scaleL, and the Reynolds number Re** on the surface friction coefficientc f in a turbulent boundary layer is studied. The dependence of the relative friction increment on the equivalent turbulence level ɛcq, which takes into account the simultaneous variation in ɛ,L and Re**, is determined. The threshold value ɛcq* below which the value ofc f does not depend on ɛcq is found.
We present results from an experimental study into the influence exerted by a countersunk inlet section of a drainage orifice on the error in the measurement of static pressure.
We present the results from an experimental study of the influence exerted by the characteristic dimensions of a drainage orifice on the static-pressure measurement error.
The authors present results of an experimental investigation of the correlations and readings of a Pitot tube in measuring velocity in a turbulent boundary layer. A new calibration relation is proposed for measuring surface friction.
A description is given of the construction and of the results of an investigation of a new miniature friction gauge which is insensitive to the downwash of the oncoming stream.
A method of determining surface friction in a turbulent boundary layer using plane Pitot tubes is described.
A study is made of the applicability of indirect methods for the determination of the local skin friction coefficient in a turbulent boundary layer with a longitudinal pressure gradient.
