Study on Pressure Distribution Along the Tube Wall Downstream to Contraction at Low Reynolds Number.

Abstract

Axial wall pressure distribution caused by the flow through a contraction was investigated by experiment and numerical analysis. By using various contraction with different lengths and diameters, downstream wall pressure were measured at low Reynolds number in the contraction. By the difference of the characteristics of measured pressure distributions, two flow modes, corresponding to laminar and transient flow condition, were distinguished in each contraction condition. In laminar condition, the distribution had well known smooth and unimodal shape. And transient condition, the wall pressure showed large and pseudoperiodic change at the site within a local region. The shape of temporally averaged pressure distribution was unimodal with acute peak. From the numerically calculated pressure distributions, a model expression for determining the location and the value of their peaks, with contraction conditions as parameters, was derived. Moreover a method for giving an approximate pressure distribution was established and verifird by comparing it to the measurement results.