Effects of bends in a tubing system for pressure measurement

It is generally understood that distortion occurs in the fluctuating pressure signal in carrying out wind-pressure measurements when the tubing system connects a pressure tap on a model surface with a transducer. When the pressures on both sides of walls or roofs are measured simultaneously, or when the local pressures are measured at a pointed portion or a portion with complicated shape, pipes or tubes connecting the pressure tap and the pressure transducer must be bent at rather acute angles. This paper discusses the applicability of bent pipes based on experimental results on its effects on fluctuating wind pressure signals. The experimental results have clarified that both the position of bend and the number of bend points can nearly be ignored, and that the effects of the sectional area of the bend point can be ignored when a brass bar with the same diameter as the inside diameter of the pipe is inserted into the pipes before they are bent.