The Static Hole Error Problem: An Experimental Investigation of Errors for Holes of Varying Diameters and Depths

Experiments have been carried out to determine the magnitude of static hole errors for holes of various diameters and depths. A new approach is tried to the problem of extrapolation to zero hole size for the purpose of obtaining a true value of static pressure. The results obtained are in broad agreement with previous experimental data and confirm the fact that a positive error is obtained for deep static holes, whereas shallow holes with large cavities behind them can involve negative errors. Since the effects of hole size and hole depth are apparently opposite, the use of fairly shallow holes can result in pressure measurements which are very close to the true value, provided that in drilling the holes no distortion of the duct wall is produced and all burrs are carefully removed. This point may be of interest in some engineering applications where the material used in the construction of the duct or model is thin.